Has anyone conducted flow bench testing on either of the Aussie heads? I have and on the 2v with big valves and major porting etc. the best I can get is 188 cfm at 28 in. On the crossflow under4 similar conditions, the best I have realized is 196 cfm. I am interested in any coments.
Air flow in CFM on the two v and Xflow Aussie head..
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XD and XE heads have more potential than XF heads.
In 1980, the advent of the Alloy Cross flow had flow figures by the Ford Motor Company. There was a Modern Motor magazine with a Silver ESP Falcon which had it in there. I was only 10, and haven't seen the article again but it had flow figures.
From memory, the flow drop was only 25 " H20, and it flowed 145 cfm through what I think was the intake with the stock lift cam.
The Aussie 2V, with a high lift cam of about 0.500 thou, could run 175 cfm at 28" H20. Somewhere here, someone did some figures back in the early days after the forum crash of November 2002.
The Cross flow alloy head, has been reported by Ausse7Mains or MarkZE as being up to 240 cfm at 28"H20 when using cut-down 2V 351C valves and some radical high porting by welding the external face of the long turn radius. Unlike the old iron crossflow, the alloy head has little wall thickness at the top of the port to create an ideal port size. It's hard to go any more than 40 mm unless you weld the top, and then fettle away untill you have a port that gives the right combination of airflow and mixture motion.
The general information from a combination of sources such as D i c k Johnstons Brisbane Engine Centre and Modern motor/Wheels Reporter Michael Stahl (Wheels Feb 1987) was that 196 hp is about as much as you can get with a stock XF head and an ADR 37a compliant cam a modified carb. The intake manifold was reworked, but the porting was stock. 1995 Street Machine Kevin Bartlett felt 185 hp was about all the stock XF EFI could hack without lots of porting.
Dynoed250 has about 290 hp from his 1.96" intake X-flow head with an upside down EB MPI intake.
The stock Cleveland 2V heads with 2.04" intakes can do 205 cfm at 28" with 0.5" lift and virtually no work, I'm told, so it sounds possible to exceed that.
The key is TIG welding to raise the roof, and getting a better port shape. If the base of the intake port can be raised like in the 173 Chevies and some of the old Apple Port Pinto engines, then you should make it over the 200 cfm level. Since XF's have the high swirl ports, it looks like its a good idea to remove the shroading ledges, and create an SVO type quench area in the area opposite the incomming intake.
In 1980, the advent of the Alloy Cross flow had flow figures by the Ford Motor Company. There was a Modern Motor magazine with a Silver ESP Falcon which had it in there. I was only 10, and haven't seen the article again but it had flow figures.
From memory, the flow drop was only 25 " H20, and it flowed 145 cfm through what I think was the intake with the stock lift cam.
The Aussie 2V, with a high lift cam of about 0.500 thou, could run 175 cfm at 28" H20. Somewhere here, someone did some figures back in the early days after the forum crash of November 2002.
The Cross flow alloy head, has been reported by Ausse7Mains or MarkZE as being up to 240 cfm at 28"H20 when using cut-down 2V 351C valves and some radical high porting by welding the external face of the long turn radius. Unlike the old iron crossflow, the alloy head has little wall thickness at the top of the port to create an ideal port size. It's hard to go any more than 40 mm unless you weld the top, and then fettle away untill you have a port that gives the right combination of airflow and mixture motion.
The general information from a combination of sources such as D i c k Johnstons Brisbane Engine Centre and Modern motor/Wheels Reporter Michael Stahl (Wheels Feb 1987) was that 196 hp is about as much as you can get with a stock XF head and an ADR 37a compliant cam a modified carb. The intake manifold was reworked, but the porting was stock. 1995 Street Machine Kevin Bartlett felt 185 hp was about all the stock XF EFI could hack without lots of porting.
Dynoed250 has about 290 hp from his 1.96" intake X-flow head with an upside down EB MPI intake.
The stock Cleveland 2V heads with 2.04" intakes can do 205 cfm at 28" with 0.5" lift and virtually no work, I'm told, so it sounds possible to exceed that.
The key is TIG welding to raise the roof, and getting a better port shape. If the base of the intake port can be raised like in the 173 Chevies and some of the old Apple Port Pinto engines, then you should make it over the 200 cfm level. Since XF's have the high swirl ports, it looks like its a good idea to remove the shroading ledges, and create an SVO type quench area in the area opposite the incomming intake.
hey
well i know of one bloke who has 320cfm at 28 water presure
Heres what the receipt says
* Portwork and Flow Test
* Polish Chambers
* Stainless Steel Ferrea Valves
* Cut down valves to suit
* K Line Guides
* Throat out 12 ports
* Cut seats
* Valve grind & Back cut Inlets
It flows 320cfm. Inlet Valves 1.800" and Exhaust Valves 1.570"
so the flow is there this is on a leaded head (no number on the side)
but the best flowing stock head is an e2 from the little info i have managed to get and from personal ecperience
mark
well i know of one bloke who has 320cfm at 28 water presure
Heres what the receipt says
* Portwork and Flow Test
* Polish Chambers
* Stainless Steel Ferrea Valves
* Cut down valves to suit
* K Line Guides
* Throat out 12 ports
* Cut seats
* Valve grind & Back cut Inlets
It flows 320cfm. Inlet Valves 1.800" and Exhaust Valves 1.570"
so the flow is there this is on a leaded head (no number on the side)
but the best flowing stock head is an e2 from the little info i have managed to get and from personal ecperience
mark
That early data on the 2v head at 175cfm @ 25inches water is from a test i did many years ago at luigi's head shop in perth.
If someone is telling you they have 320@ 25 then Id be EXTREMLY suspicous as that is far higher than a good cleveland could get.
Without redesigning the entire port and valve arrangement you wont get within a bulls roar of 320.
A7M
If someone is telling you they have 320@ 25 then Id be EXTREMLY suspicous as that is far higher than a good cleveland could get.
Without redesigning the entire port and valve arrangement you wont get within a bulls roar of 320.
A7M
Addo, Xtaxi I am shooting for 270+ hp and torque on a 200 cid with a 2v head and 375 to 400 on a US 250 with an aluminum xflow head. Both engines are naturally aspirated. The 200 has one engine dyno session with a best of 240 hp adjusted @6500and 225 lb ft torque @4000. The reason for the querey on airflow is I use 1.7 hp for cfm to approximate maximum theoritical hp and torque. At 188 cfm on the 2v head, in theory it is capable of 320 hp. Using a 7% cntingency factor,300hp will be very difficult to achieve.I read on the Southern Cross web site that the Argentine Turismo Careterra is fielding 200 cid engines in the 340 hp range. They must be flowing more air than I am. I'm still experimenying with port configuration on the 2v. I am up to 192, but that is a long way from the 220 I need. The xflow is driving me nuts. Just looking at it, I thoubht 220-230 cfm would be a walk in the park.I am struggling to break 200 cfm. I am taking xflow taxi's advice and will tig weld and raise the back roof of the port. Fortunately, I have a spare aluminum head. I'll keep you posted on results. Anyone that is getting better numbers than I am, please clue me in. I am about to try some radical grinding and welding to pull more power from these heads. Let me know what works.
No worries ET alloy, Fingers.
I tried loading Desktop Dyno an age ago, but my beloved wife wiped out a file ( after I told her it was okay...). A 33 mm alloy head port isn't a world beater, but its darn good for a stocker.
If your looking at the Aussie 250 2v, then the ports are huge. The old iron headed 1976 to 1980 X-flow has poorer, non uniform port shape, but is bigger than any X-flow alloy head by 3 to 8 mm in port diameter, depending on year.
I've not used the critical air speed or intake runner volume or port size to determine ideal CFM for a given application, but there is a critical flow formula, and it is suggested that if its over 265 feet per second at maximum revs, then the port is too small for performance. Others get past this by engineering cunning which I've foot noted.
What I use is the completed flywheel net figure with headers and exhast optimised.
I use a composite Aspiration ratio, load up 11 variables, and work out how critical each facet is. I've docummented this in some of my earlier posts.
The issue isn't that a 200 cfm port can't get 320 hp. It can, you just make it :
1)do more time on duty by cycling the engine more,
2)and raise the roof on the rev limit,
3)increase the vaccum reading under full power,
4) use scatter cams and rocker ratios (varying LCA's, running longer rocker ratios on outer cylinders to improve the poorly fed cylinders, some exhast valves may use smaller rocker ratios to reduce scavanging on certian cylinders).
The people from Argentina a some of the smartest around. They use a mixture of American parts with Latin passion, yet do it on a shoe string budget which would have us 'Rich Westies" starving. When I see one big 48 mm Weber 5 iches off the 2-bbl inttake, and a 183 cid engine with Chev pistons, special rods, special 2.76" cranks, and 1 port heads, I see the Lamborghini's Dallara, Ferraris Lamperdi/Columbo philopsophy of short stoke and huge bores. These engines don't hand granade blocks or cranks becasue they are under very little side loads.
A 250 2v would not like 7500 rpm for a standard 300 hour Ford durability test, even with a 320 degree cam and three 48 IDA's , but the engines the single duce 188/221's the Argentine guys run are very special, with little rotating mass, and some amazing work done with the six swinging legs on the crank.
For the 200, I'd be running the Iapel pistons and Brazilian 2300 Lima 5.2" 4" style rods which you get from SVO. That should allow 7500 rpm. The cam then gets custom made to add power after the CFM flat lines.
APT do this service for a cost if you can supply details. They are used to doing it for A-series engines and other formula races where the intake or heads have to be stock to compete. David Vizard sometimes uses scramble cams using Cranes services. This is high end stuff, about 0.001% of engine rebuilders would never get into it. Other companies (FSPP, Clay Smith, Crow Cams in Australia and others run standard grinds based on years of experience from customers who come to them again for repeat business. These guys can a picklist suitable choices for each cylinder, or APT could devise there own. The lift rates and master cams are already in existance.
6banger noted that engines that have heads that flat line before well before the peak rpm tend to hit a wall. The camshaft robs lower end characteristics, and then tries to build a purely top end engine. The head could loose maybee 35% flow on an aftermarket head, but a custom cam will regain the amount of hp lost by pushing the air flow speed to a super sonic levelb y making the car rev and suck more air through the carb.
The tradeoff is huge cam grind expense, and low speed power drop off.
I tried loading Desktop Dyno an age ago, but my beloved wife wiped out a file ( after I told her it was okay...). A 33 mm alloy head port isn't a world beater, but its darn good for a stocker.
If your looking at the Aussie 250 2v, then the ports are huge. The old iron headed 1976 to 1980 X-flow has poorer, non uniform port shape, but is bigger than any X-flow alloy head by 3 to 8 mm in port diameter, depending on year.
I've not used the critical air speed or intake runner volume or port size to determine ideal CFM for a given application, but there is a critical flow formula, and it is suggested that if its over 265 feet per second at maximum revs, then the port is too small for performance. Others get past this by engineering cunning which I've foot noted.
What I use is the completed flywheel net figure with headers and exhast optimised.
I use a composite Aspiration ratio, load up 11 variables, and work out how critical each facet is. I've docummented this in some of my earlier posts.
The issue isn't that a 200 cfm port can't get 320 hp. It can, you just make it :
1)do more time on duty by cycling the engine more,
2)and raise the roof on the rev limit,
3)increase the vaccum reading under full power,
4) use scatter cams and rocker ratios (varying LCA's, running longer rocker ratios on outer cylinders to improve the poorly fed cylinders, some exhast valves may use smaller rocker ratios to reduce scavanging on certian cylinders).
The people from Argentina a some of the smartest around. They use a mixture of American parts with Latin passion, yet do it on a shoe string budget which would have us 'Rich Westies" starving. When I see one big 48 mm Weber 5 iches off the 2-bbl inttake, and a 183 cid engine with Chev pistons, special rods, special 2.76" cranks, and 1 port heads, I see the Lamborghini's Dallara, Ferraris Lamperdi/Columbo philopsophy of short stoke and huge bores. These engines don't hand granade blocks or cranks becasue they are under very little side loads.
A 250 2v would not like 7500 rpm for a standard 300 hour Ford durability test, even with a 320 degree cam and three 48 IDA's , but the engines the single duce 188/221's the Argentine guys run are very special, with little rotating mass, and some amazing work done with the six swinging legs on the crank.
For the 200, I'd be running the Iapel pistons and Brazilian 2300 Lima 5.2" 4" style rods which you get from SVO. That should allow 7500 rpm. The cam then gets custom made to add power after the CFM flat lines.
APT do this service for a cost if you can supply details. They are used to doing it for A-series engines and other formula races where the intake or heads have to be stock to compete. David Vizard sometimes uses scramble cams using Cranes services. This is high end stuff, about 0.001% of engine rebuilders would never get into it. Other companies (FSPP, Clay Smith, Crow Cams in Australia and others run standard grinds based on years of experience from customers who come to them again for repeat business. These guys can a picklist suitable choices for each cylinder, or APT could devise there own. The lift rates and master cams are already in existance.
6banger noted that engines that have heads that flat line before well before the peak rpm tend to hit a wall. The camshaft robs lower end characteristics, and then tries to build a purely top end engine. The head could loose maybee 35% flow on an aftermarket head, but a custom cam will regain the amount of hp lost by pushing the air flow speed to a super sonic levelb y making the car rev and suck more air through the carb.
The tradeoff is huge cam grind expense, and low speed power drop off.
