turbo: blow thru vs. draw thru

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This is the main book you'll want to get and is a must have for an old school draw thru turbo set up. 1971 edition wrote by Huge MacInnes. That guy was the MASTER turbo guy of his day, and in fact turbos today are using HIS designs. Rajay turbos are almost indestructible and that's why the FAA certified them as the ONLY turbo for aircraft up till the 1980's. A single 40 year old Rajay with FAA certs still sells for $2000 used.
That's a 1970 Olds Cutlass 350 with a factory twin turbo from Oldsmobile using a 600 CFM Holley.
 

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Rolls Royce Merlin Supercharger and carb from late 1940's
9" inducer, vain plate is upside down to show vains, 50 psi on a 1700 cid engine turning 3000 rpm at the engine and 3500 horsepower.
 

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EFI for the win . Draw through is not even on the table , that scenario is ridiculous and foolish in this day and age. Blow through is usually relegated to people that are afraid of EFI and are trying to cheap out and clutch to their familiar dated carburetor. .....................IMO :)

:wack: Its your way or the highyway huh..thats the way a teen or bone headed 20 something thinks...Nobody knows crap but you...Bravo:finga:
 
"Ridiculous and foolish"..And playing with 45 year old carbed motors is not? Haa haa! :)
 
Resurrecting this thread as I'd like to see any progress on the projects that have been discussed.

Also I wonder if anybody has an "inside view" of gale's manifold?

I've thought of trying to fab a similar setup and wondered if a butterfly, boost referenced with a vacuum pod, could be used to divert the intake charge between pressure and vacuum during throttle transitions. I'm just not sure how easy it would be to set up or acquire reed valves. I appreciate opinions either way.
 
Why not just mount carb to inlet and blow into manifold off "wall"? The reed valves are available, there is a guy who built one here , painted the entire thing red, remember?
 
Here is a draw thru that works. no turbo lag. no cooler. on a cool day I have to open a water valve to warm up the manifold to keep it from icing up. it does not load up. I run 11 psi of boost on the street. It has a new up to date TO4 Garrett carbon sealed turbo. it requires a big hole in the hood. they have been known as bolt on and go but if a builder hangs around and tune's on it they have lot of potential. yet, due to a step up in a class I'm in the process of building a blow thru turbo big block in which I dread. I'm not ready with the hassle the the blow thru is going to create but I need a 1000 hp which the small block cannot bring. I'm just bringing back the topic of this system that are of today rare- Old school. this car has been a blast with this system.
 

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can you get the Carbon seals for any turbo like a KKK, SW or Garrett? are these needed for a draw through?
 
I'm not sure on other brand's. I think you can on Garrett's. The carbon seal's as I was told by expert's of the day are what they recommend to use on these draw thru's
 
Thats a pretty a pretty cool set up Jimmyrigged , I love seeing cars like this . ( I still think you guys are crazy. LOL )
 
Here is a draw thru that works. no turbo lag. no cooler. on a cool day I have to open a water valve to warm up the manifold to keep it from icing up. it does not load up. I run 11 psi of boost on the street. It has a new up to date TO4 Garrett carbon sealed turbo. it requires a big hole in the hood. they have been known as bolt on and go but if a builder hangs around and tune's on it they have lot of potential. yet, due to a step up in a class I'm in the process of building a blow thru turbo big block in which I dread. I'm not ready with the hassle the the blow thru is going to create but I need a 1000 hp which the small block cannot bring. I'm just bringing back the topic of this system that are of today rare- Old school. this car has been a blast with this system.

Very cool, any close up pics of the manifold under the carb? how much power is the small block making?
 
Jimmy your compressor is way to small to get more power out of it. Of course if you upgrade the turbo you could make more power in theory. That is if the exhaust manifold is up to the task to flow that extra air through it. No reason you cant get 1000hp from a small block turbo car at all. **** im going for 1500+rwhp from my small block hemi and turbo. Just not a draw threw or carb.

Blow threws are no where near as bad as being said. The reason they didnt work back in the days was because there was new carb on the market every week and nobody knew **** about them. The ones that did didnt talk much about it. Now there are people that can build you one for your ride and be ready for battle and cruising right out of the box. No muss no fuss. Ive seen several with my own eyes work perfect no jet changes out the box. One of those made 2000+hp and won dragweek a few years ago. Do not fear the bt setup. Way easier than a draw threw of old. Draw threw is pretty cool relic for damn sure. Tuned a few in my younger years.
 
Here is my blow through set up its not a turbo but still the same concept.It did take a bit of tuning to get the system to work but that is part of doing forced induction. I agree that hot rodding,muscle cars are all about building,challenges and fun.I think whatever system you build as long your doing the build you want to do ,spending what you can afford and the results are where you want them to be then the difference is in what your wanting to do. I am not trying to speak out of place but it doesn't matter what type of system you build they all require tuning. Some just less than others.
I went with blow through do to cost I wanted EFI but for me it was not worth an additional $5000.00 dollars for almost no horsepower gain. Carburetors make awesome power and are a little harder to tune if your not use to it but when you get them dialed in blow through or draw through they work great and do not require much additional tuning.
EFI with forced induction requires just as much tuning its just done on a laptop but still requires tuning.With my blow through system I made 840 hp and 839 torque with 15 pounds of boost.

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turbofreek that's cool about making that much HP out of a small block. I have changed my direction. I would rather build a twin blow threw 408 then a big block whenever I get to run outlaw 10.5. No doubt blow's are far-far superior then the old draw threw's but what fun it is to put some one on the trailer with this 340ci and a Hillbilly supercharger and still drive it to the track and home again. I will look you up for some advise when I go to blow threw.
 
What are the pluses and minuses of each system?
My brother put a pair of 280ZX turbos on a 340 in his Scamp. It was a draw-thru with a Holley 600 sitting on a sheet metal box and the turbos drawing thru a pair of long tubes with the turbos sitting ahead of the motor and the box sitting on the intake. It didn't look like it should work very well, but it did. It's all that's left since he wrapped it around a tree. Ran pretty good, but needed better gas. Should have gone with a bigger carb I think. You can see that the downpipes run out thru the top of the fenderwells. Stock exhaust manifolds were used. The stock wastegate system was used and stayed at 7PSI.Here's a very bad photo of it.
 

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Draw through.
 

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Really like your setup baker, and have seen your build thread. Did you have to have someone machine your reed valve plate? Fear of that is what had me considering my kooky vac-op butterfly idea. I have a lot of stuff/tools in my garage, but don't know if I can handle that.
 
Made the valve plate with a drill press and a router with a wood tip in it. Just have to be careful .
 
Wow wish u woulda found this site before I gave up on my draw thru system. We ran an old accel kit on a 408 in our pulling tractor but just couldn't t manage fuel effectively even with a 1150 dominator and meth inj we just kept melting Pistons with 12 lbs of boost
 

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Wow wish u woulda found this site before I gave up on my draw thru system. We ran an old accel kit on a 408 in our pulling tractor but just couldn't t manage fuel effectively even with a 1150 dominator and meth inj we just kept melting Pistons with 12 lbs of boost

If you're burning Pistons with a 1050 carb, your intake or turbo to intake piping was bad and caused centrifugal force to sling out the fuel before it made it to the cylinder. That's all explained in the 1971 book as to the do's and do not's of the intake system from the pressure side of the turbo, to the cylinder.
 
Trike is still a work in progress. Hope to fire it up in the next month.
 

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