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| Carb to Turbo Arrangement. https://slantsix.org/forum/viewtopic.php?t=24028 |
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| Author: | Greg Ondayko [ Thu Jul 12, 2007 7:01 pm ] |
| Post subject: | Carb to Turbo Arrangement. |
I picked up an issue of hotrod for august 2007 and there is a vw Bug with a 750 CFM Holley 4 BBl on it and a turbo on it too. The carb was plumbed to the turbo's intake, so it was not a blow-thru setup. I guess you could say it was setup like the old street superchargers. A GMC 6-71 Blower with the carbs on top. Would this arrangement work well? on a Slant? I would seem a whole lot easier in trems of plumbing etc to Have the turbo suck the air out of the carb instead blow thru it, But I have only seen blow thru applications where a turbo is used, until now.. Thoughts? Greg |
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| Author: | Charrlie_S [ Thu Jul 12, 2007 7:22 pm ] |
| Post subject: | |
Take a look here. Old pics of my turbo slant. http://www.1962to1965mopar.ornocar.com/schmid.html |
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| Author: | Joshie225 [ Thu Jul 12, 2007 8:22 pm ] |
| Post subject: | |
Yes, draw through turbo systems work. The problem is you don't want to try a conventional intercooler because it makes for a large reservoir of highly combustible mixture. Then there is puddling, bad fuel distribution, etc. So you essentially can't intercool a draw through turbo system. |
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| Author: | LUCKY13 [ Thu Jul 12, 2007 9:36 pm ] |
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It has been proven that draw-thru does not perform as good as Blo-Thru. It also takes special seals in the turbo (expencive) on a Draw-Thru setup. With all the fuel distribution problems the /6 has, I cant see anything but a EFI setup working right on a /6 (or maybe a perpose built intake/carb setup). If your just wanting a few pounds of boost and a little extra perfomance that might be a bit of a diff story. But dont expect to be able to push it much. With that said, there has been good performing draw-thru setups, but it wasnt just a turbo tacked on before a Manny & carb. They where built with a lot of thought & effort. I think one think that helps the Blo-Thru setup so much is that you are only heating up the air & not the fuel. Plus the fuel on a blow-thru helps cool the air on a carb setup (also EFI but not as much). Either way the fuel is not heated like a Draw-Thru setup does. Plus the fuel takes up space in the turbo that could be all air in a Draw-Thru. In a nut shell, the Blow-Thru setup is much more effiecant, with less problems and danger. Jess |
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| Author: | Doctor Dodge [ Thu Jul 12, 2007 9:43 pm ] |
| Post subject: | |
Here is a photo of the draw thru set-up a tried last year.  1986 Buick 3.8 set-up, made a stock 170 run mid 14s.... until it blows-up. Blew-up 2 engines in a 3 week period, (it will generate 12 lbs of boost) I swapped back to my HyperPak set-up because my wallet was getting "thin" and my back was hurting. Turbos work best with EFI. DD |
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| Author: | Joshie225 [ Thu Jul 12, 2007 11:06 pm ] |
| Post subject: | |
So, Doug, what gave out under 12 psi? |
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| Author: | Doctor Dodge [ Thu Jul 12, 2007 11:52 pm ] |
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Burned a hole in #6 piston, two different times. I did some minor manifold baffeling between the 1st and 2nd test, obviously,... not enough. To solve this problem, I will have to get more serious about testing the way the A/F mixture is swerling out of the Turbo and into the intake manifold. DD |
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| Author: | Shaker223 [ Fri Jul 13, 2007 5:13 am ] |
| Post subject: | |
So far it is early but I have 17 psi in a blow thru set up on a stock 225. my A/F is still rich at 10.5 but want to work it to 11.5. I'd rather be way rich than lean! |
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| Author: | Joshie225 [ Fri Jul 13, 2007 9:07 am ] |
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Quote: Burned a hole in #6 piston, two different times.
Ahh, holed pistons don't work so well. In the old Hugh MacInnes book Turbochargers I saw instances of people using a perforated plate where the pressurized mixture enters the intake manifold to homogenize the mixture. I wonder if I cone shaped screen at the turbo outlet or manifold inlet would do the job? It worked for economy according to this post... http://slantsix.org/forum/viewtopic.php ... arb#112376I did some minor manifold baffeling between the 1st and 2nd test, obviously,... not enough. To solve this problem, I will have to get more serious about testing the way the A/F mixture is swirling out of the Turbo and into the intake manifold. DD Also, what's up with the fuel solenoid on the regulator? |
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| Author: | Doc [ Fri Jul 13, 2007 9:38 am ] |
| Post subject: | |
I also have NOS plumbed into this system. I never had a chance to use and sort-out the NOS part of the system design. The thought here is that a shot of NOS can be used to quickly spool the turbo. There are additional tapped nozzles ports at different locations along the fuel path, my thinking is to use the NOS system to help enrich and/or cool the mixture as needed. As for all the distribution issue, I bet this problem can be worked-out. Truth is that I put this system together with a "junk" 170 just to see what the issues/problems would be. After a week of testing, that engine "melted". I installed a second but better 170, did some more intake manifold adjusting and the system was working better but not good enough. Engine #2 burned the same piston after 2 weeks. I get the feeling that the A/F mixture enters the manifold in a high velocity swirl and I need some better baffles to break the swirl up. DD |
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