yellowstang
Well-known member
Hey did they ever make oz head for use with a 4bbl carb??
Pete
Pete
is there a 250 4 valve??
- Thread starter yellowstang
- Start date
yellowstang
Well-known member
i am adam, planning a turbo that is.
but iwas talking with the girlfreind and when we figured out how much time i would have in the loghead porting and polishing (my time 40 hrs), 78 later cost, 3 angle, a couple of flow checks, i would only be out another 60 bucks for the oz 250 2v head. so she said that i should go ahead and get it. what can i say she is a keeper. ii think we will get one of the package deals from the az guy. i sent him an email to him last night!!
Hey i found a website for you guys down under last night : board.performanceforum.com they even have a "forced induction and nos" section. i found it truly enlightening. i havent gone thru all the archives yet but needless to say there is a whole lot of info there for the turbo guys. i ran across a great post from our ole freind john mackenzie. i have never met him but man would i like to. he knows alot!!
yeah so i was wondering if i could run that holley 390cfm progressive 4 bbl into a os 250 head?? i bet i will have the flow for it. after reading only a few of the posts from down under i bet i could run at least 15psi boost with the oz head!! man that would be sensational!!!!!!! then get the holley fogger just under the carb!!!!!!! waaaooooowwweeeeeeeee.
then i will need a wing to get some respect! hahahahahaha
i feel that i have been lost to the "dark side" to the side down under
Pete
lost to the oz side
but iwas talking with the girlfreind and when we figured out how much time i would have in the loghead porting and polishing (my time 40 hrs), 78 later cost, 3 angle, a couple of flow checks, i would only be out another 60 bucks for the oz 250 2v head. so she said that i should go ahead and get it. what can i say she is a keeper. ii think we will get one of the package deals from the az guy. i sent him an email to him last night!!
Hey i found a website for you guys down under last night : board.performanceforum.com they even have a "forced induction and nos" section. i found it truly enlightening. i havent gone thru all the archives yet but needless to say there is a whole lot of info there for the turbo guys. i ran across a great post from our ole freind john mackenzie. i have never met him but man would i like to. he knows alot!!
yeah so i was wondering if i could run that holley 390cfm progressive 4 bbl into a os 250 head?? i bet i will have the flow for it. after reading only a few of the posts from down under i bet i could run at least 15psi boost with the oz head!! man that would be sensational!!!!!!! then get the holley fogger just under the carb!!!!!!! waaaooooowwweeeeeeeee.
then i will need a wing to get some respect! hahahahahaha
i feel that i have been lost to the "dark side" to the side down under
Pete
lost to the oz side
It's only the "dark side" during your daytime... Seeing as we're a few hours ahead. 
Jmac lurks on quite a few BBs; he's good at pinpointing issues, and putting theory into the context of a particular "sticky". He lives in Melbourne and works odd hours.
You have two things to consider in your project plans. With an adaptor for a 4-barrel, you will almost certainly need additional clearance on the carb top, and the 200 (if that's your plan) is still in the outer margin for an old-tech six. Expect a couple of cam grinds before zooming in on the best profiles. Roller rockers would be pretty much imperative to keep things optimum.
Your best bet on the turbo sizing is to look for someone with documented ETs on a Holden 202 turbo, and find out their specs. The more info, the better! If you can get flow figures as well, these plus the turbo details should enable you to replicate the engine with Ford specs where they vary.
All BS aside, you can buy a turbo, overhaul it, do the work required to fit, and make it all happen - just that the combination may not be optimised. It'll still run, probably quite well, and should give a lot of enjoyment. It is really when you start chasing more refined characteristics as well as every last neddy, that detail comes to the fore. But with a 200, that's probably something of a concern... Hmm...
Cheers, Adam.
Jmac lurks on quite a few BBs; he's good at pinpointing issues, and putting theory into the context of a particular "sticky". He lives in Melbourne and works odd hours.
You have two things to consider in your project plans. With an adaptor for a 4-barrel, you will almost certainly need additional clearance on the carb top, and the 200 (if that's your plan) is still in the outer margin for an old-tech six. Expect a couple of cam grinds before zooming in on the best profiles. Roller rockers would be pretty much imperative to keep things optimum.
Your best bet on the turbo sizing is to look for someone with documented ETs on a Holden 202 turbo, and find out their specs. The more info, the better! If you can get flow figures as well, these plus the turbo details should enable you to replicate the engine with Ford specs where they vary.
All BS aside, you can buy a turbo, overhaul it, do the work required to fit, and make it all happen - just that the combination may not be optimised. It'll still run, probably quite well, and should give a lot of enjoyment. It is really when you start chasing more refined characteristics as well as every last neddy, that detail comes to the fore. But with a 200, that's probably something of a concern... Hmm...
Cheers, Adam.
1.First of all, yes you can run a 390 cfm four barrel easily on a six. The little Holley works a treat on stock 3.5 liter Buick/Rover V8's, 2 liter Pinto SOHC engines....even Opel and Merceades Benz used similar sized carbs for there 2.8 liter sixes, only the secondaries where MUCH bigger!
2.Oh, and a stock 350 or 500 cfm Holley is just 247 cfm and 354 cfm rated as per the 1.5 inches of Mercury flow drop used to assess air flow on four barrels! That little 390 would be 552 cfm if rated with the 3.0 inches of Mercury flow drop used to assess air flow on two barrel carbs!
3.Thing is though, most of the time it runs through venturis which are around 1.05 inches in diameter, from memory. So that's sort of like running a 180 cfm carb part throttle, and thats what you really need...lean running, hi velocity flow off idle, and 390 cfm on the gas.
4.The old rule is that the 1.5 inch Hg flow rate in cfm can be divided by 1.6 to get the maximum power needed. That's 243 potential net flywheel ponies if you had a perfect intake manifold and a 390. But a log isn't a perfect manifold, and you'd loose 35 % flow on that even if its well ported and de-dagged of casting markes.
5. Excellent intake manifolds loose 15 to 10% flow. The Pinto and Lima 2000/2300 SOHC cam fours with the Holley/Weber carb have one of the most efficent intake manifolds around, and miss out on only 14% of the flow of a bare cylinder head when gas flowed by an expert! That means that even a 2000 cc Pinto with a four barrel 390 could potentially flow 390 cfm minus 14%=342 cfm. Divide that by 1.6, and you get 214 bhp net at the flywheel, in theory. In practice, I've never seen dyno runs exceed 175 hp with a 390 on a 2liter.
6. The big problems with four barrel carbs are not the risk of over carburation, as the 390/430 carbs are small in the primary area. No, its the persistant prblem with huge intake runner volume that afflicts most aftermarket 4-bbl intakes. They are great for a high reving N20 pumped drag race engine with 4.56's but a dead loss out of the wide open throttle envirnoment. Some 1970 Valiant Pacers in Australia ran Carter AFB- style 4-bbls on there 245 Hemi sixes, and they were not as good as the punny 2-bbl versions in a race conditions, even though they were down in the low 16's at the drags. The volume under the carb and in the intake runner was too big to flow at a high enough velocity.
7. Some Offenhuaser manifolds for Buick 215/Rover 3.5 liter and Pinto 2000/Lima 2300 SOHC were split port and these are the only items I'd consider to have dealt with the low flow situation. They had the primaries flowing through the bottom port, and the secondary flowing through the top, with a horizontal cast insitu 1/4 inch aluminum plate splitting things from the carb to the intake ports. Amazingly simple idea! I'm fairly sure that they were the best street manifolds you could get, even if they did sacrifice some top end flow.
8. I remember in the early 1970's AMC Jeep did some pyrometer work on the flow distribution of 4-bbl aftermarket mainfolds verses the 1 and 2 barrel items on there 258 I6, and the four barrel was VERY bad.
9. Kevin Bartlett, a Chevy lover who piloted small block V8 F5000 racers in the seventies, did an article on Falcon sixes, Windsor and Cleveland V8's in an Australian Street Machine in the mid 1990's, and he said he'd use a 600 cfm 4-bbl on a 250 six, but he was worried about the poor mixture distribution.
10. If a four barrel is a must for an Argentine or Aussie 2V head, I'd consider doing someting just fitting a 1/4 inch tooling plate aluminum four barrel adpator plate to the 2-barrel intake manifold, and centre the secondaries and primaries midway. Then look at taking a bare minimum off the flow area below the throttles. You can then TIG weld the plate to the intake if you really must. My next door neighbour did this with his E49 Valiant Charger 265 Hemi. It had 327 Chev pistons, 277 cubes, and ran a 650 Holley Spreadbore. It was brilliant! He found much better tractability than when he ran an ex FE V8 390 Autolite or the 500 cfm Holley 2-barrels he used earlier. Again, the cast iron intake manifold runner volume was for the stock 2-barrel carb Australian Chrysler Valiants ran, which was much smaller than the aftermarket or Pacer 4-bbl.
11.There are some lovely four barrel 2V 250 intakes around, but you have to consider if a 390 cfm carb is better on these or the original 2V manifold that came with the head! My belief is that a 2V intake would liberate 210 real hoses on a 200, if the cam and head were optimised.
12. As for non turbo potential with a 200 cube engine, look at what the Aussies do! Triple carbed GM XU1 Holden Toranas which ran three Zenith Stromberg carbs could hit 216 net flywheel hoses with a 300 degree cam and 202 cubic inches, 1.65 inch intake valves and cast iron twin exhast port headers. I've seen 236 hp form a Triple SU Holden 202 with the stock twin exhast headers. And 201 flywheel horses from a 500 cfm 2-barrel Holley 202 Holden, a mild cam, and tube headers. Even worked HQ 202 Holden racers with 260 degree cams could hit 170 net flywheel horses...with a nasty little 1V Bendix Stromberg carby a lot like your Carter. Enough for a 115 mph top speed in a 3000 pound four door, and sub 16 second quarters!
13. Right, I've thrashed that horse! Adam picked up on doing a turbo installation. How does 535hp from the flywheel and 403 horses from the rear wheels with just port injection, 202 cubes, alloy head and a Garret T04B turbo. And just cast ACL pistons and it still revs to 7500 rpm!. Its in a GM Holden Torana (a narrower Maverick 2-door size) and runs flat 9.92 quarters at 135 mph! Gears are 3.7:1, it runs a Powerglide, and copes 30 sq in of boost! Pinch yourself..its real!
This is what Aussies do to there GM sixes in there spare time, what you gonna do to your Finer Ford In-liner?
2.Oh, and a stock 350 or 500 cfm Holley is just 247 cfm and 354 cfm rated as per the 1.5 inches of Mercury flow drop used to assess air flow on four barrels! That little 390 would be 552 cfm if rated with the 3.0 inches of Mercury flow drop used to assess air flow on two barrel carbs!
3.Thing is though, most of the time it runs through venturis which are around 1.05 inches in diameter, from memory. So that's sort of like running a 180 cfm carb part throttle, and thats what you really need...lean running, hi velocity flow off idle, and 390 cfm on the gas.
4.The old rule is that the 1.5 inch Hg flow rate in cfm can be divided by 1.6 to get the maximum power needed. That's 243 potential net flywheel ponies if you had a perfect intake manifold and a 390. But a log isn't a perfect manifold, and you'd loose 35 % flow on that even if its well ported and de-dagged of casting markes.
5. Excellent intake manifolds loose 15 to 10% flow. The Pinto and Lima 2000/2300 SOHC cam fours with the Holley/Weber carb have one of the most efficent intake manifolds around, and miss out on only 14% of the flow of a bare cylinder head when gas flowed by an expert! That means that even a 2000 cc Pinto with a four barrel 390 could potentially flow 390 cfm minus 14%=342 cfm. Divide that by 1.6, and you get 214 bhp net at the flywheel, in theory. In practice, I've never seen dyno runs exceed 175 hp with a 390 on a 2liter.
6. The big problems with four barrel carbs are not the risk of over carburation, as the 390/430 carbs are small in the primary area. No, its the persistant prblem with huge intake runner volume that afflicts most aftermarket 4-bbl intakes. They are great for a high reving N20 pumped drag race engine with 4.56's but a dead loss out of the wide open throttle envirnoment. Some 1970 Valiant Pacers in Australia ran Carter AFB- style 4-bbls on there 245 Hemi sixes, and they were not as good as the punny 2-bbl versions in a race conditions, even though they were down in the low 16's at the drags. The volume under the carb and in the intake runner was too big to flow at a high enough velocity.
7. Some Offenhuaser manifolds for Buick 215/Rover 3.5 liter and Pinto 2000/Lima 2300 SOHC were split port and these are the only items I'd consider to have dealt with the low flow situation. They had the primaries flowing through the bottom port, and the secondary flowing through the top, with a horizontal cast insitu 1/4 inch aluminum plate splitting things from the carb to the intake ports. Amazingly simple idea! I'm fairly sure that they were the best street manifolds you could get, even if they did sacrifice some top end flow.
8. I remember in the early 1970's AMC Jeep did some pyrometer work on the flow distribution of 4-bbl aftermarket mainfolds verses the 1 and 2 barrel items on there 258 I6, and the four barrel was VERY bad.
9. Kevin Bartlett, a Chevy lover who piloted small block V8 F5000 racers in the seventies, did an article on Falcon sixes, Windsor and Cleveland V8's in an Australian Street Machine in the mid 1990's, and he said he'd use a 600 cfm 4-bbl on a 250 six, but he was worried about the poor mixture distribution.
10. If a four barrel is a must for an Argentine or Aussie 2V head, I'd consider doing someting just fitting a 1/4 inch tooling plate aluminum four barrel adpator plate to the 2-barrel intake manifold, and centre the secondaries and primaries midway. Then look at taking a bare minimum off the flow area below the throttles. You can then TIG weld the plate to the intake if you really must. My next door neighbour did this with his E49 Valiant Charger 265 Hemi. It had 327 Chev pistons, 277 cubes, and ran a 650 Holley Spreadbore. It was brilliant! He found much better tractability than when he ran an ex FE V8 390 Autolite or the 500 cfm Holley 2-barrels he used earlier. Again, the cast iron intake manifold runner volume was for the stock 2-barrel carb Australian Chrysler Valiants ran, which was much smaller than the aftermarket or Pacer 4-bbl.
11.There are some lovely four barrel 2V 250 intakes around, but you have to consider if a 390 cfm carb is better on these or the original 2V manifold that came with the head! My belief is that a 2V intake would liberate 210 real hoses on a 200, if the cam and head were optimised.
12. As for non turbo potential with a 200 cube engine, look at what the Aussies do! Triple carbed GM XU1 Holden Toranas which ran three Zenith Stromberg carbs could hit 216 net flywheel hoses with a 300 degree cam and 202 cubic inches, 1.65 inch intake valves and cast iron twin exhast port headers. I've seen 236 hp form a Triple SU Holden 202 with the stock twin exhast headers. And 201 flywheel horses from a 500 cfm 2-barrel Holley 202 Holden, a mild cam, and tube headers. Even worked HQ 202 Holden racers with 260 degree cams could hit 170 net flywheel horses...with a nasty little 1V Bendix Stromberg carby a lot like your Carter. Enough for a 115 mph top speed in a 3000 pound four door, and sub 16 second quarters!
13. Right, I've thrashed that horse! Adam picked up on doing a turbo installation. How does 535hp from the flywheel and 403 horses from the rear wheels with just port injection, 202 cubes, alloy head and a Garret T04B turbo. And just cast ACL pistons and it still revs to 7500 rpm!. Its in a GM Holden Torana (a narrower Maverick 2-door size) and runs flat 9.92 quarters at 135 mph! Gears are 3.7:1, it runs a Powerglide, and copes 30 sq in of boost! Pinch yourself..its real!
This is what Aussies do to there GM sixes in there spare time, what you gonna do to your Finer Ford In-liner?
yellowstang
Well-known member
i like the idea of the 390 which for my case would flow that 552 cfm.(thanks for that info) i like it because its progressive and i can run the secondaries real rich at hi flow situations. thats the only reason i am not leaning toward the holley 2bbl 500. both barrels open at the same time. i would think it would be harder to tune the holley 500 for the wot and the lean condition that happens with a turbo. the 5200 is the same as the weber 32/36 progressive. but it flows around 320 cfm. i think it might be a little small. >>>>isnt it funny when we go to a buffet we always stack the plate extra high??
i found the performance.board forum for you aussie guys and there is alot of info for doing exactly what i am doing. i am still doing reseacrh. i didnt go to bed till 1:44am last night
i am going to run that T3/T4 hybrid turbo with an intercooler. i have seen the use of a mazda rx-7 s5 turbo. it has oil passages and is even plumbed for water cooling. cooler air charge means more ponies!!
get the 8:1 forged pistions. they have a ridge around the perimeter of the piston. machine it off for lower compression. i will port and polish the head (oz head) unshroud where i can. cc the chambers, i would like to get the comression below 8:1 maybe even 7.5:1.
what are the largest valves i can go on the oz head?? will i have to do much porting and polishing at all???
i want to the stock cast exhaust manifold and not the headers. will they bolt up?? reason is i dont think i have much room. bolt a j tube or a plate and mount the turbo.
i have the isky cam (256) which doesn't have too much overlap but lift is about .450. and 112 degree lobe seperation. some say that too much overlap on a boosted engine just shoves fuel and air out the exaust which results in lost gains. get the 1.6 roller rockers and let the flow happen. that would give .480 of lift. did i do that right?
run synthetic oil, oil cooler up front, and a larger fl1 oil filter.
all this in a 68 stang convertible.
i like the idea you had of putting in a port divider into the intake and splitting the circuits if you will. one primary and one sedondary to the front 3 cylinders and 1 set to the rear. i think that would help speed the flow in a high volume situation. and use the 2v head not the 4 valve head( as you suggest).
so what your saying is that if i use the 390cfm divide by 1.6 to get 243 hp then subtract 15% for the oz head would put me at 207 hp? that would be great. is that naturally aspirated or turbo'd?? i would love 200+ hp.
throw in T5, 3.5 posi rear end, 16" wheels, lowered 1", high back buckets, paint job and i am for the next rocky mountain mustang show!!!!! everybody swaps the 6 for the 8. last year over 400 cars only 2 sixes. wait till they open my hood!!!
hey adam, what are the more refined charcteristics that i should i be chasing? to optimize?? and why is that a "concern"? have i overlooked something? please explain??
so what do you think is it a good plan so far??
it seems that my plan stays the same but some of the components change.
If i havent said it enough, THANKS for all the help
Pete
i found the performance.board forum for you aussie guys and there is alot of info for doing exactly what i am doing. i am still doing reseacrh. i didnt go to bed till 1:44am last night
i am going to run that T3/T4 hybrid turbo with an intercooler. i have seen the use of a mazda rx-7 s5 turbo. it has oil passages and is even plumbed for water cooling. cooler air charge means more ponies!!
get the 8:1 forged pistions. they have a ridge around the perimeter of the piston. machine it off for lower compression. i will port and polish the head (oz head) unshroud where i can. cc the chambers, i would like to get the comression below 8:1 maybe even 7.5:1.
what are the largest valves i can go on the oz head?? will i have to do much porting and polishing at all???
i want to the stock cast exhaust manifold and not the headers. will they bolt up?? reason is i dont think i have much room. bolt a j tube or a plate and mount the turbo.
i have the isky cam (256) which doesn't have too much overlap but lift is about .450. and 112 degree lobe seperation. some say that too much overlap on a boosted engine just shoves fuel and air out the exaust which results in lost gains. get the 1.6 roller rockers and let the flow happen. that would give .480 of lift. did i do that right?
run synthetic oil, oil cooler up front, and a larger fl1 oil filter.
all this in a 68 stang convertible.
i like the idea you had of putting in a port divider into the intake and splitting the circuits if you will. one primary and one sedondary to the front 3 cylinders and 1 set to the rear. i think that would help speed the flow in a high volume situation. and use the 2v head not the 4 valve head( as you suggest).
so what your saying is that if i use the 390cfm divide by 1.6 to get 243 hp then subtract 15% for the oz head would put me at 207 hp? that would be great. is that naturally aspirated or turbo'd?? i would love 200+ hp.
throw in T5, 3.5 posi rear end, 16" wheels, lowered 1", high back buckets, paint job and i am for the next rocky mountain mustang show!!!!! everybody swaps the 6 for the 8. last year over 400 cars only 2 sixes. wait till they open my hood!!!
hey adam, what are the more refined charcteristics that i should i be chasing? to optimize?? and why is that a "concern"? have i overlooked something? please explain??
so what do you think is it a good plan so far??
it seems that my plan stays the same but some of the components change.
If i havent said it enough, THANKS for all the help
Pete
aussie7mains
Famous Member
There was only three manifolds available to suit 250-2v heads.
Stocker, for two barrel stromie carb
Lynx for triple webber
lynx for triple SU
All rare nowdays.
If you want to turbo, then use the stock 250-2v head and intake blow into that.
OR, junk the whole thing and get a 200 or 250 alloy crossflow engine.
You could possibly pick up a turbo setup used.Theres a guy down here in Perth who runs a 190ci crossflow with turbo and methanol which makes around 850bhp (racer).
A7M
Stocker, for two barrel stromie carb
Lynx for triple webber
lynx for triple SU
All rare nowdays.
If you want to turbo, then use the stock 250-2v head and intake blow into that.
OR, junk the whole thing and get a 200 or 250 alloy crossflow engine.
You could possibly pick up a turbo setup used.Theres a guy down here in Perth who runs a 190ci crossflow with turbo and methanol which makes around 850bhp (racer).
A7M
I hope Adam comes in quick from painting his engine bays because I'm kinda scared I'm gonna baffle you all with BS!
If you hate imperial, don't read this, brothers!
As for you Yellow Stang, you'll want to copy this lot and check it out with a turbo expert and get proper quotes. And as ever, someone else shold comment on this before I lead you astray!
1. To answer your question, yes, the figures I gave were were for non-turbo sixes which had poor head flow. They are only GM Holden, after all!
2. Everyone needs to know that Holley, Carter, Edlebrock, Rochester, Autolite, Motorcaft, Impco, OHG, or whatever use ratings at 1.5 (20 inches of water), 2.0 (28 inches of water), or 3.0 inches of mercury (which is a little over 40 inhes of water) because they are trying to replicate the flow condition of the engine the carb is likely to end up on. Since a carb, head or manifold is just a pipe with a venturi in it, you can increase the cfm flowed, by just bumping up the flow drop or pressure.
Example A:-One head machiners may claim their cylinder head port flows say, 300 cfm at 500 thou lift, but if that was at 28 inches of water( 2.0 inches of mercury, or Hg ) then the one that flows 290 cfm at 500 thou lift and at 20 inches of water (1.5 inches of Hg), would clean up the 300 cfm one for maximum power. Its just like a hose. Up the pressure, up the flow.
Example B:- if you use the common carby formuae of
(rpm*cubes) all divided by 3456,
then a 400 Ford reving to 4000 rpm is likey to be flowing more than 462 cfm if it has 100% volumetric efficency! In practice, they had a VE of more like 75% at 4000 rpm, so the stock 2 barrel they used would have needed to flow 347 cfm just to yeild maximum power. Thats 217 hp net, tops
Note that VOLUMETRIC EFFICIENCY IS REALTED TO CARB, CAM, HEAD,COMPRESSION. You either apply the intake loss and forget about the VE, or estimate the VE and forget the intake flow loss... do not add both!
If you wrongly applied both, you'd get a conservative 25% flow loss on that awfull 2V intake they ran, then the peak cfm is now down to a lowly 278, then its likely the peak net flywheel hp would have been 278 divided by 1.6, or 174 ponies.
In practice, VE is the governor, and it takes a bit of work to figure it out! If the 2-barrel carb they ran was rated at, say, 450 cfm at 3.0 inches of mercury, then the actual pressure drop at the carb can be calculated. That calculated cfm by the formuae at the top is critical. If the carb does 450 cfm at 3.0 inches Hg , then at the calculated 347 cfm the pressure drop is likely to be 450/347 cfm, which is (1.29683 squared) less than the 3.0 inch figure. The 1.29683 must be multiplied by itself, and then the result is divided from the number 3.0. That is, the actual pressure drop on the 400 engine was 3.0 divided by ( 1.29683*1.29683), which is 1.78 inches of mercury. This was no where near the rated CFM at 3.0 inches.
Example C: A 650 cfm Holley carbed NASCAR used in the Winston Cup back in the early 1990's could churn out 650 horsepower at the flywheel at 7500 rpm. The 357 Windsor/Cleveland SVO block had alloy heads, the best Jack Roush intake manifold, and a volumetric efficiency of over 100 % because of the mild tunnel ram of those single plane style intakes. Doing the sums again,
(357*8000)divided by 3456 = 826 cfm needed. That only gives 516 horses calculating by dividing the cfm by 1.6. But they only had a 650 carb. Thats only 406 hp! Something screwy? Nope. They actually ran a pressure drop of over 2.56 inches of mercury, enough to flow 1040m through that little 650 cfm carb! The intake flow was less than 10%, and it was cancelled out by the mild supercharge from the almost vertical intake runners! So the 650 hp was still cfm divided by 1.6, but there was so much suction that it was 1040 cfm. Take actual rated carby cfm at 1.5 inches, divde by formulae cfm (826 cfm)... this gives us 0.7869 to square. Now divide he 1.5 rating standard by 0.7869*0.7869...its 1.906 inches of Hg. Dividethat by 1.6, and we only get 516 hp. Clearly, only the VE or the revs can change in the formula, so those NASCAR engines would have had to run theoretical volumetric efficiencies of over 125, and that 1.6 CFM to HP value derived from a engineer siting at a dyno cell was pessimistic for these special Holley carbs. At 200 mph, the air pressure at the carby would be more than atmospheric, and even the collector pipe exhast would have had a scavange effect placed on it from the moving air.
2. Turbo power calculations:-these are sorta different when you do net flywheel figures from the rated cfm at 1.5 inches of mercury (gage pressure drop from inlet of carb to the downstream flow) readings.
Two reasons. In an old fashioned draw through with a 600 cfmVac Sec Holley carb, a turbo pumping in 15 pounds per square inch of pressure is raising the flow rate at the carb from its normal level. It's no longer 1.5 inches of mercury pressure, but something different!
Example A: Unturboed. On A 200 cube six, a non turbo 2V engine with good forged rods, bolts, and a 256 cam wouldn't get within a bulls roar of 200 hp. I'd say a 390 cfm carb would be only a small oversupply on a 200 cube six, and I think that you'd only get 173 to 180 hp with it only using 277 cfm of its peak flow at 1.5 inches Hg. It's likely peak pressure drop would be 390cfm rated divided by 277cfm as calculated below, gives a flow drop of only 1.408*1.408 from 1.5 inches of Hg, which is 1.5 divided by 1.982, and therefore only 0.757 inches of flow drop at wide open throttle. But don't worry. Most engines can handle being 40% over carbed. 351 Cleveland V8's only need 550 cfm to get 340 hp, but the always like a 780 cfm #3310 much more!
The actual amount of Hp would be rev dependant. A 256 with a nice 1.75 inch intake and 1.44 inch exhast may hit the 175 cfm at 480 thou lift mark at 28 inches of water(2.0 in Hg). Chevy OffRoad and Marine Engineering in Aussie say that with a hydraulic cam, a little V8 265 SB Chev with 175 cfm of intake flow can hit a maximum power of 175*2*0.80 equals 280 hp net. Since a 200 is 3/4 of a V8, 210 is all that is likely unless you raise the cam lift and take a loss in drive-ablity. Often you get less. All those Aussie sixes ran hotter than 256 duration cams. A turbo or Nitrous is needed for streetablity. My calcs say, unturbo'd, with a 256 cam, and 175 cfm at 28 inches H20 head, you'd get need a cam that would rev to 6000 rpm, with power at 5500 rpm. Then you'd maybe hit 180 horses. There would be plenty below 3000 rpm in the torque department, maximum torque at 4000 rpm. But even single barrel 202 racing HQ Holdens have 260 duration and 170 Hp. Your loosing power for a mimimal drivablity improvement. To get 210 Hp, you'd need a 272-292 degree cam with around 500 thou lift. Go for more lift, you get more cfm flow, more power. At 5500 rpm, with 200 cubes, divide by 3456, multiply by 0.87 for your VE, you'd need 277 cfm at 1.5 inches of Hg, and could hit 173 hp. To raise VE, go for a 272 to 292 cam, and loose torque and races from the lights!
Example B: Using a turbo, you could go for a draw through or blow through installation. Draw throughs are not the idea for a streeter as the carb never seams to atomise the fuel air mix enough before it hits the turbo. You'd need a bigger than 390 cfm carb if you were running more than 9 pounds per sq inch boost. ( I'd prefer a 600 cfm Vac Sec) At 9 pounds, the peak flow drop on a draw through as described above in Example 2A, can be calculated. Its boost in pounds plus 14.7 all dived by 14.7 pounds (the air pressure at sea level). The boost ratio is 1.62. That means, as long as little heating occurs, you have a theroretical cfm increase from 277cfm to 449 cfm. The good thing is, your 256 cam would love this.Now, your 390cfm might just love that too, but your engine is now behaving like a 327 cube Chevy, and could use the extra carburation of a carb rated 449 cfm at 1.5 inches Hg, or larger. Definately no smaller. The worst thing you can do to a turbo is run it out of fuel. In practice, the heat added into the engine reduces the intake flow, and thus the peak hp, required from the carb. The potential rise from 180 hp to 290 hp (1.62 times) wouldn't occur ..it'd be more like 260 horses. This is why people use an "intercooler" on blow through turbos. I've also heard them called aftercoolers...depends which culture you hang out with, I guess.
Example C: Using the 390 carb mounted on the intake, not ahead of the turbo, we can pressurise it to 9 pounds. Various things need to be done to the carb...throttle spindles need presurised air to the shaft by drilling holes into the cast alloy adaptor under the carb to stop the turbo pressure coming out (boost referencing, its called), the fule pump needs to either raise its pressure to 9 pounds or face prblems, the float needs to be heavy duty brass or nitrophol, the operation of the carbs secondary circuit needs to be changed. In reputable Australian magazines, there are often photos of turbo V8's with aluminum or stainless steel sealed boxes around the carb. Lots of work here. But the results are worth it!
Example D: Use the Aussie 4.1 Cross-Flow EFI system, spend US $1000 on doing the extra inch or so of cast iron welding around the lifter gallery on your 200 I6, and fit the Oz cross flow. The AIT/Mike Vine/HKS/NormalAir Garret turbo system was develpoed in the 1980's for this engine, and it doubled the power of a stock carb six.
Example E: This is my pick. Grab just the Aussie cross-flow alloy head EFI intake manifold and injectors and thorttle body, and drill the 2V ports for the Aussie fuel rail. Then turn the EFI manifold around 180 degrees and make a tubing intake header from 1.5 internal diameter steel thbe bends. Then ask Jack about the Simple Fuel Injection system he uses on his Aussie EFI 250 1966 Stang. Then use a Garret T04B turbo to blow through to a in front of radiator Mitsubishi Evolution 5 intercooler, then back to the injection throttle body.
If you hate imperial, don't read this, brothers!
As for you Yellow Stang, you'll want to copy this lot and check it out with a turbo expert and get proper quotes. And as ever, someone else shold comment on this before I lead you astray!
1. To answer your question, yes, the figures I gave were were for non-turbo sixes which had poor head flow. They are only GM Holden, after all!
2. Everyone needs to know that Holley, Carter, Edlebrock, Rochester, Autolite, Motorcaft, Impco, OHG, or whatever use ratings at 1.5 (20 inches of water), 2.0 (28 inches of water), or 3.0 inches of mercury (which is a little over 40 inhes of water) because they are trying to replicate the flow condition of the engine the carb is likely to end up on. Since a carb, head or manifold is just a pipe with a venturi in it, you can increase the cfm flowed, by just bumping up the flow drop or pressure.
Example A:-One head machiners may claim their cylinder head port flows say, 300 cfm at 500 thou lift, but if that was at 28 inches of water( 2.0 inches of mercury, or Hg ) then the one that flows 290 cfm at 500 thou lift and at 20 inches of water (1.5 inches of Hg), would clean up the 300 cfm one for maximum power. Its just like a hose. Up the pressure, up the flow.
Example B:- if you use the common carby formuae of
(rpm*cubes) all divided by 3456,
then a 400 Ford reving to 4000 rpm is likey to be flowing more than 462 cfm if it has 100% volumetric efficency! In practice, they had a VE of more like 75% at 4000 rpm, so the stock 2 barrel they used would have needed to flow 347 cfm just to yeild maximum power. Thats 217 hp net, tops
Note that VOLUMETRIC EFFICIENCY IS REALTED TO CARB, CAM, HEAD,COMPRESSION. You either apply the intake loss and forget about the VE, or estimate the VE and forget the intake flow loss... do not add both!
If you wrongly applied both, you'd get a conservative 25% flow loss on that awfull 2V intake they ran, then the peak cfm is now down to a lowly 278, then its likely the peak net flywheel hp would have been 278 divided by 1.6, or 174 ponies.
In practice, VE is the governor, and it takes a bit of work to figure it out! If the 2-barrel carb they ran was rated at, say, 450 cfm at 3.0 inches of mercury, then the actual pressure drop at the carb can be calculated. That calculated cfm by the formuae at the top is critical. If the carb does 450 cfm at 3.0 inches Hg , then at the calculated 347 cfm the pressure drop is likely to be 450/347 cfm, which is (1.29683 squared) less than the 3.0 inch figure. The 1.29683 must be multiplied by itself, and then the result is divided from the number 3.0. That is, the actual pressure drop on the 400 engine was 3.0 divided by ( 1.29683*1.29683), which is 1.78 inches of mercury. This was no where near the rated CFM at 3.0 inches.
Example C: A 650 cfm Holley carbed NASCAR used in the Winston Cup back in the early 1990's could churn out 650 horsepower at the flywheel at 7500 rpm. The 357 Windsor/Cleveland SVO block had alloy heads, the best Jack Roush intake manifold, and a volumetric efficiency of over 100 % because of the mild tunnel ram of those single plane style intakes. Doing the sums again,
(357*8000)divided by 3456 = 826 cfm needed. That only gives 516 horses calculating by dividing the cfm by 1.6. But they only had a 650 carb. Thats only 406 hp! Something screwy? Nope. They actually ran a pressure drop of over 2.56 inches of mercury, enough to flow 1040m through that little 650 cfm carb! The intake flow was less than 10%, and it was cancelled out by the mild supercharge from the almost vertical intake runners! So the 650 hp was still cfm divided by 1.6, but there was so much suction that it was 1040 cfm. Take actual rated carby cfm at 1.5 inches, divde by formulae cfm (826 cfm)... this gives us 0.7869 to square. Now divide he 1.5 rating standard by 0.7869*0.7869...its 1.906 inches of Hg. Dividethat by 1.6, and we only get 516 hp. Clearly, only the VE or the revs can change in the formula, so those NASCAR engines would have had to run theoretical volumetric efficiencies of over 125, and that 1.6 CFM to HP value derived from a engineer siting at a dyno cell was pessimistic for these special Holley carbs. At 200 mph, the air pressure at the carby would be more than atmospheric, and even the collector pipe exhast would have had a scavange effect placed on it from the moving air.
2. Turbo power calculations:-these are sorta different when you do net flywheel figures from the rated cfm at 1.5 inches of mercury (gage pressure drop from inlet of carb to the downstream flow) readings.
Two reasons. In an old fashioned draw through with a 600 cfmVac Sec Holley carb, a turbo pumping in 15 pounds per square inch of pressure is raising the flow rate at the carb from its normal level. It's no longer 1.5 inches of mercury pressure, but something different!
Example A: Unturboed. On A 200 cube six, a non turbo 2V engine with good forged rods, bolts, and a 256 cam wouldn't get within a bulls roar of 200 hp. I'd say a 390 cfm carb would be only a small oversupply on a 200 cube six, and I think that you'd only get 173 to 180 hp with it only using 277 cfm of its peak flow at 1.5 inches Hg. It's likely peak pressure drop would be 390cfm rated divided by 277cfm as calculated below, gives a flow drop of only 1.408*1.408 from 1.5 inches of Hg, which is 1.5 divided by 1.982, and therefore only 0.757 inches of flow drop at wide open throttle. But don't worry. Most engines can handle being 40% over carbed. 351 Cleveland V8's only need 550 cfm to get 340 hp, but the always like a 780 cfm #3310 much more!
The actual amount of Hp would be rev dependant. A 256 with a nice 1.75 inch intake and 1.44 inch exhast may hit the 175 cfm at 480 thou lift mark at 28 inches of water(2.0 in Hg). Chevy OffRoad and Marine Engineering in Aussie say that with a hydraulic cam, a little V8 265 SB Chev with 175 cfm of intake flow can hit a maximum power of 175*2*0.80 equals 280 hp net. Since a 200 is 3/4 of a V8, 210 is all that is likely unless you raise the cam lift and take a loss in drive-ablity. Often you get less. All those Aussie sixes ran hotter than 256 duration cams. A turbo or Nitrous is needed for streetablity. My calcs say, unturbo'd, with a 256 cam, and 175 cfm at 28 inches H20 head, you'd get need a cam that would rev to 6000 rpm, with power at 5500 rpm. Then you'd maybe hit 180 horses. There would be plenty below 3000 rpm in the torque department, maximum torque at 4000 rpm. But even single barrel 202 racing HQ Holdens have 260 duration and 170 Hp. Your loosing power for a mimimal drivablity improvement. To get 210 Hp, you'd need a 272-292 degree cam with around 500 thou lift. Go for more lift, you get more cfm flow, more power. At 5500 rpm, with 200 cubes, divide by 3456, multiply by 0.87 for your VE, you'd need 277 cfm at 1.5 inches of Hg, and could hit 173 hp. To raise VE, go for a 272 to 292 cam, and loose torque and races from the lights!
Example B: Using a turbo, you could go for a draw through or blow through installation. Draw throughs are not the idea for a streeter as the carb never seams to atomise the fuel air mix enough before it hits the turbo. You'd need a bigger than 390 cfm carb if you were running more than 9 pounds per sq inch boost. ( I'd prefer a 600 cfm Vac Sec) At 9 pounds, the peak flow drop on a draw through as described above in Example 2A, can be calculated. Its boost in pounds plus 14.7 all dived by 14.7 pounds (the air pressure at sea level). The boost ratio is 1.62. That means, as long as little heating occurs, you have a theroretical cfm increase from 277cfm to 449 cfm. The good thing is, your 256 cam would love this.Now, your 390cfm might just love that too, but your engine is now behaving like a 327 cube Chevy, and could use the extra carburation of a carb rated 449 cfm at 1.5 inches Hg, or larger. Definately no smaller. The worst thing you can do to a turbo is run it out of fuel. In practice, the heat added into the engine reduces the intake flow, and thus the peak hp, required from the carb. The potential rise from 180 hp to 290 hp (1.62 times) wouldn't occur ..it'd be more like 260 horses. This is why people use an "intercooler" on blow through turbos. I've also heard them called aftercoolers...depends which culture you hang out with, I guess.
Example C: Using the 390 carb mounted on the intake, not ahead of the turbo, we can pressurise it to 9 pounds. Various things need to be done to the carb...throttle spindles need presurised air to the shaft by drilling holes into the cast alloy adaptor under the carb to stop the turbo pressure coming out (boost referencing, its called), the fule pump needs to either raise its pressure to 9 pounds or face prblems, the float needs to be heavy duty brass or nitrophol, the operation of the carbs secondary circuit needs to be changed. In reputable Australian magazines, there are often photos of turbo V8's with aluminum or stainless steel sealed boxes around the carb. Lots of work here. But the results are worth it!
Example D: Use the Aussie 4.1 Cross-Flow EFI system, spend US $1000 on doing the extra inch or so of cast iron welding around the lifter gallery on your 200 I6, and fit the Oz cross flow. The AIT/Mike Vine/HKS/NormalAir Garret turbo system was develpoed in the 1980's for this engine, and it doubled the power of a stock carb six.
Example E: This is my pick. Grab just the Aussie cross-flow alloy head EFI intake manifold and injectors and thorttle body, and drill the 2V ports for the Aussie fuel rail. Then turn the EFI manifold around 180 degrees and make a tubing intake header from 1.5 internal diameter steel thbe bends. Then ask Jack about the Simple Fuel Injection system he uses on his Aussie EFI 250 1966 Stang. Then use a Garret T04B turbo to blow through to a in front of radiator Mitsubishi Evolution 5 intercooler, then back to the injection throttle body.
When I referred to optimums and "concern", I was alluding to the fact that a 200 is quite highly stressed to pop out a lot of HP.
This is why things like the 221 are popular in Australia - if you go to the Schjeldahls' compression calculator and change the stroke to 3.46, look what happens to your theoretical HP for the same other specs. These engines weigh only a few pounds more (literally) than a 200.
So, getting back to my earlier remarks, you are looking at minimum friction (roller rockers), valvetrain reliability (geardrive), and knowing some of your head specs, flow-wise. As for valves, it looks like even on the 2V, the exhaust is the limiting factor. A set of 1.785/1.595 back-cut valves on moderately worked ports is about the limit. Hypereutectic pistons will not take as much to warm up as forgies, and will do almost any application. Check with FTF if you're not sure.
Again, for optimisation, a custom fabbed header/manifold (coated, of course) would be best, but maybe the 250 cast one will suffice.
XECUTE has some tech figures and ideas I'm not going to dispute, as my own turbo ideas are very much on the far shelf right now. The GM sixes people blow here are taken to the max so hard that bore flex becomes a real concern. But the performances can be stunning.
A7M has a point about crossflows and the like. It seems they are pretty cheap and available in the US, now. They are smaller than the US 250 by a little, and depending on how much investment you've already in your 200, may be worth swapping to.
Last year, when I did some calcs for an inquiry, I figured USD$4700 would see a serious N/A crossflow built, shipped and installed (100% ready to drive). This was calc'd off very conservative margins, too - quite possibly a grand could be shaved off.
The real problem with building a turbo, is that until you put the blower on, it's a dog of a motor. Makes it hard to progressively build.
What have I left off this time?
Regards, Adam.
This is why things like the 221 are popular in Australia - if you go to the Schjeldahls' compression calculator and change the stroke to 3.46, look what happens to your theoretical HP for the same other specs. These engines weigh only a few pounds more (literally) than a 200.
So, getting back to my earlier remarks, you are looking at minimum friction (roller rockers), valvetrain reliability (geardrive), and knowing some of your head specs, flow-wise. As for valves, it looks like even on the 2V, the exhaust is the limiting factor. A set of 1.785/1.595 back-cut valves on moderately worked ports is about the limit. Hypereutectic pistons will not take as much to warm up as forgies, and will do almost any application. Check with FTF if you're not sure.
Again, for optimisation, a custom fabbed header/manifold (coated, of course) would be best, but maybe the 250 cast one will suffice.
XECUTE has some tech figures and ideas I'm not going to dispute, as my own turbo ideas are very much on the far shelf right now. The GM sixes people blow here are taken to the max so hard that bore flex becomes a real concern. But the performances can be stunning.
A7M has a point about crossflows and the like. It seems they are pretty cheap and available in the US, now. They are smaller than the US 250 by a little, and depending on how much investment you've already in your 200, may be worth swapping to.
Last year, when I did some calcs for an inquiry, I figured USD$4700 would see a serious N/A crossflow built, shipped and installed (100% ready to drive). This was calc'd off very conservative margins, too - quite possibly a grand could be shaved off.
The real problem with building a turbo, is that until you put the blower on, it's a dog of a motor. Makes it hard to progressively build.
What have I left off this time?
Regards, Adam.
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Anonymous
Guest
XECUTE said:
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Anonymous
Guest
If your thinking of turbo, Check out Ford Australias new Twin cammer turbo six than.I am thinking of converting one into my 65 falcon. 240 kw standard in a car that doesn't weigh much(About 1300 kg)approx.Would push the old girl into 13 second 1/4 mile times.All so the engine runs 6psi of boost and drops to 0 psi at 4500 rpm.Think of the possiblities.Any how just have a look at it. youll find them in australias XR6 turbo Falcon. I figuire that an engine and computer should be around $10000 Australian. Then i will fit up my own box.A lot less stuffing around in my books and could work out about the same as building a 250 turbo from scratch. Anyhow ithought of doing the same thing as well knowing the xflow does have alot of potental. Talk later Darren
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Anonymous
Guest
I cant wait until someone begins selling aftermarket computers for the Barra240. As it stands now, with the EEC-VI computer, you'll need lots of things from a BA to make it work. Too bad there aren't any computers out there right now that will make the drive by wire throttle work, with the dual VCT banks, and the distributorless ignition. I think its the DBW and dual VCT thats holding things back. Word on the street is that Wolf is currently working on a solution...
14PSI 320kW... Now wheres that drool smilie?
14PSI 320kW... Now wheres that drool smilie?
I'm mega worried about what will happen when some clever dude Does The Right Thing And Ups The Boost in a 4V XR6 Turbo 4.0. At six pounds and 322 hp (oooops...240 killer Watts ) the T5 tranny won't say Dingo and have a lunch break. At 9 or 14 pounds, 400+ raging ponies will hurt the gearbox. A BTR should hack it, but aftermarket lock-up converters are still a little thin on ground if you want to build some boost on take-off
T56 and Tremecs are gonna be hot property soon....why didn't Ford just start off with some reserve strength...penny pinching at $A500 million? Nasty!
Hope the block bores out 48 thou to 250 cubes without crapping itself. A 300KW Twin Cam Turbo six in an early Falcon would be quite a weapon. Now lets hope CRS's Rod Hadfield does a new alloy sump that fits 1960 to 1997 Falcons.
T56 and Tremecs are gonna be hot property soon....why didn't Ford just start off with some reserve strength...penny pinching at $A500 million? Nasty!
Hope the block bores out 48 thou to 250 cubes without crapping itself. A 300KW Twin Cam Turbo six in an early Falcon would be quite a weapon. Now lets hope CRS's Rod Hadfield does a new alloy sump that fits 1960 to 1997 Falcons.
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Anonymous
Guest
Just a word on compression ratios. I noticed Yellowstang you mentioned removing the rim around the edge of the dish psiton to lower your compression down.
I would suggest you are better off leaving the compression high and leaving this band in place.
I went to a lot of trouble to get the compression down to 7.8:1 in my allow head crossflow turbo engine and have since found out that it was not needed. I am now screwing 20 psi into my engine with 20° total timing in it. I will be looking at more timing when I get the engine on a dyno.
One of the quickest 250 sixes I know runs 28 psi boost on 8.5:1 compression using 100 octane avgas fuel. If you can get 98 octane like we have here in aus you will comfortabley run 20 psi boost with 8.5:1.
The secret to this is having good control over mixtures and ignition timing. My engine and the one I mentioned run programmable aftermarket injection.
Removing the band around the piston will reduce you squish band and actually promote pinging in the engine. The squish band is important as it squishes the fuel to the centre of the chamber where the spark plug can effectively ignite the fuel in one central area.
Without an effective squish band the chamber can ignite from more than one point causing the collision of two flame fronts which leads to pinging.
Just my opinion on turboing a falcon engine. I know first hand the amount of heat that the manifold and turbo pump out. My turbo glows red after I have been out for a trash at night!
I would hate to have that amount of heat sitting right beside my inlet manifold as would be the case with a 2V non crossflow head. I can't hold my hand on any part of my engine bay on the exhaust side on the car. A lot of my 2 pac paint has blistered oon the inner guards and firewall near the manifold and turbo.
If you are going to the trouble of custom making a whole bunch of manifolds etc, do yourself a favour and start out using an allow crossflow head!
Also on the topic of the Drive by wire throttle on the new Falcon twin cam turbo. I know that Motec have already got the wiring diagrams from Ford and have developed software to run their systems on the turbo engine. I don't know if it is ready yet but it won't be far away.
I would suggest you are better off leaving the compression high and leaving this band in place.
I went to a lot of trouble to get the compression down to 7.8:1 in my allow head crossflow turbo engine and have since found out that it was not needed. I am now screwing 20 psi into my engine with 20° total timing in it. I will be looking at more timing when I get the engine on a dyno.
One of the quickest 250 sixes I know runs 28 psi boost on 8.5:1 compression using 100 octane avgas fuel. If you can get 98 octane like we have here in aus you will comfortabley run 20 psi boost with 8.5:1.
The secret to this is having good control over mixtures and ignition timing. My engine and the one I mentioned run programmable aftermarket injection.
Removing the band around the piston will reduce you squish band and actually promote pinging in the engine. The squish band is important as it squishes the fuel to the centre of the chamber where the spark plug can effectively ignite the fuel in one central area.
Without an effective squish band the chamber can ignite from more than one point causing the collision of two flame fronts which leads to pinging.
Just my opinion on turboing a falcon engine. I know first hand the amount of heat that the manifold and turbo pump out. My turbo glows red after I have been out for a trash at night!
I would hate to have that amount of heat sitting right beside my inlet manifold as would be the case with a 2V non crossflow head. I can't hold my hand on any part of my engine bay on the exhaust side on the car. A lot of my 2 pac paint has blistered oon the inner guards and firewall near the manifold and turbo.
If you are going to the trouble of custom making a whole bunch of manifolds etc, do yourself a favour and start out using an allow crossflow head!
Also on the topic of the Drive by wire throttle on the new Falcon twin cam turbo. I know that Motec have already got the wiring diagrams from Ford and have developed software to run their systems on the turbo engine. I don't know if it is ready yet but it won't be far away.
