Draw through setup

[cook11]

I have seen in a few books and also on the internet a few Ford inline sixes running draw through turbo setups. Is there anyone on this forum with experience running this setup? Is it worth looking into if someone is looking at a budget turbo setup? How much power can you potentially get with a draw through compared to a blow through setup when using the same turbo size? Is it comparable? It seems the majority of setups I've seen are using the early Turbo Buick setups or AK Miller. The draw through setups have been really popular with the aircooled VW crowd for many years now. They seem to get a lot of power using these setups.....so perhaps its not such a bad setup after all.

Thanks!

 

[powerband]

... you mention the (carb'd) "early Turbo Buick setups", I'm working on adapting the early Buick setup rather than build a system integrating unknown components. The draw-thru setup first of all requires a specialized turbo built for fuel-thru and the Carburetor operates non-linearly unlike a blow-thru carb needing it specialized for draw-thru turbo use. You may hear there are no good draw-thru carb'd turbo setups and only fuel injection will make it actually workable. Secondly - Ignition timing vs boost is a considerable concern which now can be made workable with MSD type boost-referenced black boxes or more home brewed solutions.

... here's a page from MaCinnes' book , although dated it describes a Ford 250 draw thru setup using a Rajay turbo and Weber DCOE45 setup, if you can believe the dyno figures it claims to improve the 4000 RPM RWHP figure from the stock 88HP to 191HP...




> my current project D7DE 250 cid mostly stock with 1980's Buick V6 TBO3 turbo, very specifically built Quadrajet and head re-worked but OEM 62cc chambers retained for running SCR @ 7.83:1 . Runs good static on test stand and currently working on ignition timing/boost controls (home brewed) before road tests.

. . .

Blow-thru vs Draw thru each has distinct challenges but if you are ambitious enough to attempt to build a turbo setup, members can help with the specifics... There are a few blow-thru setups among the members and experienced and road tested info is available. With the advice from members and what I've learned, I'm also working on an alternate blow-through setup and building a blow-thru capable Holley 2300 2Bbl to use.

have fun 8) .

 

[cook11]

I am interested to know how power you can get with a custom draw through setup similar to what the VW Bug guys are using. They seem to be using much larger turbos and large 4bbl carbs than the Buick system. They have been running these setups for years now and are getting a lot of horsepower using this setup. Do you know how much boost the Regal draw through setups can produce? It appears that the blow through stock Ford I6 setups are managing about 20psi so I am assuming the draw through can do the same safely. Are you planning on running a water injection system? Very cool build.....

 

[pmuller9]

I am interested to know how power you can get with a custom draw through setup similar to what the VW Bug guys are using. They seem to be using much larger turbos and large 4bbl carbs than the Buick system. They have been running these setups for years now and are getting a lot of horsepower using this setup. Do you know how much boost the Regal draw through setups can produce? It appears that the blow through stock Ford I6 setups are managing about 20psi so I am assuming the draw through can do the same safely. Are you planning on running a water injection system? Very cool build.....

On a blow through setup the carb size is determined by the engine cfm requirement, proportional to engine size, VE, max rpm and does not depend on boost.
The carb for a blow through can actually be smaller than the same engine operating N/A.

On a draw through setup the carb size is determined by the turbocharger compressor inlet flow and increases with boost.
So a carb for a 20lb boosted engine is very large compared to a 6 lb boosted engine.
The larger carb will not have the low end response as the smaller carb.

It is also not recommended to run an intercooler with a draw through as it will add a large volume of gasoline/air mixture that can be ignited.

 

[First Fox]

I am interested to know how power you can get with a custom draw through setup... It appears that the blow through stock Ford I6 setups are managing about 20psi so I am assuming the draw through can do the same safely......

My bet is that you will make more power ultimately with a blow through setup mainly because it allows for higher boost levels due to the option of intercooling. I don't believe that 20 psi could be done safely with a draw through due to intake temps being so high. After a hard pass at even 12 psi on my blow through 200, the intercooler inlet was too hot to touch but the outlet was barely warm. That hot of air, uncooled through a draw through will be much more likely to detonate. Detonation at 20 psi breaks things. Don't ask me how I know. 8)

Also, the power valve circuit on a one or two barrel carb is really the only way to add fuel under boost. On a draw through setup, the power valve will not function under boost as the carb is under vaccum and will thus not activate the power valve at all. Something like a Weber 2 barrel with a separate secondary system would work on an application though as it is mechanical and would add the necessary fuel as long as throttle were opened enough to activate the secondary system.

 

[drag-200stang]

Draw-thru made sense 40, 50 years ago,I did it 41 years ago,but today it will cost more. It has more lag,poor off boost drive-ability, not as good fuel economy ,hard cold starting, more detonation prone .....Just do it like Cobra six or Does 10s early build or if is in the budget Will's last build.

 

[xctasy]

... you mention the (carb'd) "early Turbo Buick setups", I'm working on adapting the early Buick setup rather than build a system integrating unknown components. The draw-thru setup first of all requires a specialized turbo built for fuel-thru and the Carburetor operates non-linearly unlike a blow-thru carb needing it specialized for draw-thru turbo use. You may hear there are no good draw-thru carb'd turbo setups and only fuel injection will make it actually workable. Secondly - Ignition timing vs boost is a considerable concern which now can be made workable with MSD type boost-referenced black boxes or more home brewed solutions.

... here's a page from MaCinnes' book , although dated it describes a Ford 250 draw thru setup using a Rajay turbo and Weber DCOE45 setup, if you can believe the dyno figures it claims to improve the 4000 RPM RWHP figure from the stock 88HP to 191HP...




> my current project D7DE 250 cid mostly stock with 1980's Buick V6 TBO3 turbo, very specifically built Quadrajet and head re-worked but OEM 62cc chambers retained for running SCR @ 7.83:1 . Runs good static on test stand and currently working on ignition timing/boost controls (home brewed) before road tests.

. . .

Blow-thru vs Draw thru each has distinct challenges but if you are ambitious enough to attempt to build a turbo setup, members can help with the specifics... There are a few blow-thru setups among the members and experienced and road tested info is available. With the advice from members and what I've learned, I'm also working on an alternate blow-through setup and building a blow-thru capable Holley 2300 2Bbl to use.

have fun 8) .

The turbo Celica in question.

http://www.toymods.org.au/~rod/Celicas/ ... _Turbo.pdf

Without intercooler, and a DCOE 40 or 45, 2.1 times the stock power is possible. 1600 2T Hemi, or 250 L code in line log head six.


David Inall basically created the draw through Falcon six Turbo. Mike Vine (MVT) , Ray Hall, and Bensons turbo center, NormalAir Garret Australia, and AIT used his systems. AIT was his company from 1982 to 1988, when it folded.


The draw thru system is here in 31 frames

http://www.mikevineturbochargers.com.au ... llery.html

https://www.shannons.com.au/auctions/20 ... LEVJ47C9T/

 

[powerband]

I finally put some wheels under the BOP based draw-thru turbo 250 . Using a Maverick as a donor, I swapped the setup off the 'built' engine onto the stock 250 to finish fitting and accessories. the Maverick 250 only has DS-II/HEI upgrade and otherwise is all OEM 74 250 . Started right up with oil press at turbo, , idled and ran ran surprisingly well static while I chased down leaky coolant and oil line gremlins before attempting drive. Driving performance is similar to unboosted 250 with adequate low end torque but as boost builds at mid throttle there is an additional powerband never available NA. I have not modified the distrib. yet other than severely retard static timing so limited my boost driving to data and performance but still managed to blow the OEM muffler apart after some more testing...


have fun

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. .

 

[1964f100240]

i like that you going to need a tall hood scoop looks cool

 

[turbo2256b]

dRAW THROUGH SYSTEMS PULL FUELL INTO THE OIL AND OIL INTO THE FUEL depending on pressure differentials between turbine and compressor ends. One must use turbos with seals unlike a blow through system. Have to change oil often with a draw through and replace the compressor seals often or the enge will get burned up do to the fuel in the oil.

 

[RustyRedTurbo]

Hi All,

I am new here so I figured I would introduce myself. Name is Aaron and I am running a t3 draw through turbo on my old 68 f100 and I need some help with stronger piston options I have killed two motors already (both my own fault) . It seems these 300 stock pistons don't really like more than about twelve pounds both cases of blown motors are cracked pistons . Thanks for any input.

 

[pmuller9]

Hi All,

I am new here so I figured I would introduce myself. Name is Aaron and I am running a t3 draw through turbo on my old 68 f100 and I need some help with stronger piston options I have killed two motors already (both my own fault) . It seems these 300 stock pistons don't really like more than about twelve pounds both cases of blown motors are cracked pistons . Thanks for any input.

Racetec is one of the least expensive forged piston suppliers.
They will make you a set of forged 2618 alloy pistons.

What year engine are you using?
What are you using for ignition timing control with boost retard?
Stock camshaft?

 

[RustyRedTurbo]

Hi Pmuller9,

The block is a 1980 the head is 1968 I did some mild port work chevy springs custom titanium retainers stock cam with 250 chevy rockers. The truck pulls like heck but I keep lifting ring lands so far I have been lucky that I have not sent the insidy parts to the outside The pistons break between the first and second ring lands I get crazy blow by it runs I five I limp it home. I should add this was a rebuilt bottom end that used speed pro pistons H519P40 so +.04. AFR is 12.0 to 12.3 plugs look good I cut them apart nice fuel ring at wide open throttle no detonation signs. I would like to see 16 pounds on pump gas with my water meth but 14 seems to be the point of no return. What am I doing wrong?

 

[RustyRedTurbo]

ohh one last thing ignition is edis 6 with mega jolt controller ten by ten ignition mapping with load based ignition retard -1 degree of timing with every pound of boost is what I am running currently.

 

[pmuller9]

IMO It looks like you have all bases covered except for the piston material.
Hypereutectic pistons are brittle. The Speed Pro Hypers have a 16% silicon content. You get glassware for pistons.

The 2618 alloy pistons have very low silicon content (0.25% max) and are very malleable.
We have bent rods and wrist pins, hit valves, melted piston domes slightly and damaged ring lands but the pistons always stay in one piece. (Blown Alky)

If you are looking to make more Horsepower with the same amount of boost, consider going to a longer duration camshaft.
Is this a low rpm workhorse truck, a highway hauler or a mixture of both?

What are you using for an exhaust manifold?

 

[RustyRedTurbo]

It's a Rusty Red Toy it doesn't do to much hauling just lots of hot rodding When it's running I don't spin it past 4500. The exhaust manifold is my own creation it started life as a pair of split headers that merge into one and feed the turbo charger. It's different that's for sure?

The 2618 alloy for pistons I read that they will put up with a lot but because they are of a softer material if they touch the cylinder walls they are pretty much guaranteed to gal or get the black death skirt scuffing. Don't misunderstand me I realize any piston that touches the cylinder wall will experience problems but 2618 is not very forgiving in this area.

The piece of the puzzle that I don't understand is how guys are getting away with running high boost on stock motors with cast pistons? Is the cast a little better at taking the abuse than a hyper or is it that there tuning techniques are better? I just had a thought the turbo set up that I am using is off a buick GN but I did not have the Rochester carb that came with it so I used the 500 cfm edel I had. When I shift I get a brief lean spot that goes away when the secondary's open do you think that this could be a contributor to broken pistons besides the pieces of 4 inch fine china I have for pistons?

So what are you running on blown alch? I bet that thing goes!

 

[pmuller9]

I like your exhaust system. Much more efficient than the log style!
Can you post a photo?

I'm assuming you are still using a power valve in the carb.
Unless you have made modifications, When you back off the throttle to shift, the vacuum goes very high under the carb since the turbo is still sucking which shuts off the power valve and will stay off until the secondaries open and drops the vacuum below the PV rating.
You can plug the PV chamber passage that goes to the base plate and drill a passage to the outside of the carb with a nipple so a line can be run to the intake manifold for the correct vacuum reference.

I also suspect the carb should be larger if you want to run more boost.

Second possibility is the top piston rings need extra end gap when used under boosted conditions.

2618 alloy pistons simply need extra piston to wall clearance because they grow more with heat. The clearance will be specified by the piston supplier.
If installed properly they do not have any more of a problem with cylinder wall galling than any other material piston.

Just a quick response so the thread does not get side tracked.
I don't own but presently work with:
http://missmerionbluegrass.com/

A few years ago: 49 Ford twin 88mm turbo 430 cid SBF, methanol, 2400 hp.
https://dl.dropboxusercontent.com/u/393 ... ngine2.JPG
https://www.youtube.com/watch?v=cGX-3u_huvc

 

[deere114]

One thing that sticks out to me is you say your 12.0-12.3 afr @15 psi. That's good for making power, but I think jetting it richer will help keeps things cool and stay together. I believe somewhere I read sick6 is somewhere around 11.0 but don't quote me on that. I also agree with pmuller in that you should look into a larger cam in search of more power at this point as apposed to adding more boost. Also what he said about the power valve is very relevant and sick6 posted the solution to that. He calls it "the cure" and there's a there's a thread explaining it here. Pictures more info and videos are always good by the way!

 

[RustyRedTurbo]

Ok I got a lot of photos for you guys to see my late nights of mad science. http://s328.photobucket.com/user/agmachinist/slideshow/

 

[RustyRedTurbo]

Pmuller9, deere114

I checked out your videos and pics that's a sweet car you wrenched together. 2400 pony's out of 430 cubes is pretty darn impressive.
The hydro planes look like a lot of fun my brother in law works for mercury he is currently putting together a 80s racing boat for fun I don't know a ton about it but he is hoping for about 80 mph on the water with 200 hp merc.

I am going to have to find that post about power valve modification it sounds like this is something I over looked and could be a contributor to my problems.
What would you suggest as a good cam? I had a carb guy tell me ditch the edel for a holley 600 cfm double pumper I would have better luck with tuning it.

I think if I haven't hurt this motor too bad this time I am going to throw some new slugs and rings in the holes get it back running and go mild with the boost Summer is coming and I would like to drive it around. Looking forward I am going to search for a donor block to build that I can put some good parts in to get into the some what wild area. I am open to build ideas with the turbo charging?