Turbos and Carbs

[patkeefe]

Anyone running a turbocharger with carbs out there? I'm just curious about the details.

Pat

[air-cool-me]

you got my view

[350HP930]

Its a pretty bad combination.

[Superman]

I've never heard of such a thing.

[patkeefe]

Before there was really expensive and sometimes unreliable fuel injection, there were carbs. Back in the stone age! We had turbochargers back then.

[silverc4s]

Corvair Monza Turbo, Olds F-85 turbo, Maserati BiTurbo, a few British POS's as well.
You have two choices when you combine carbs and a turbo:
1. Pressurized carburetor containment chamber
2. Compressing air/fuel mixture
Both have been done, neither one works very well for a number of reasons...

[patkeefe]

I've actually had draw throughs work fairly well. I'm contemplating upgrading to a low boost turbo for the SC, so my options are carbs or CIS. Other options discounted because I'm cheap.
Pat

[david.avery]

Blow through's and draw through's are quite popular with VW type I and type IV... they stick one SU or IDA carb at right off the manifold for draw through, or use duals with a pressurized air cooler housing. 300hp for under 5K is not uncommon.

http://www.cbperformance.com/catalog.asp?ProductID=285

http://www.et-studios.com/motorsports/motorspy/predelivery.html

[silverc4s]

Well all 911 turbos prior to the 964 were CIS injected, that ought to tell you something...;-)

[silverc4s]

Originally posted by david.avery
Blow through's and draw through's are quite popular with VW type I and type IV... they stick one SU or IDA carb at right off the manifold for draw through, or use duals with a pressurized air cooler housing. 300hp for under 5K is not uncommon.

http://www.cbperformance.com/catalog.asp?ProductID=285

http://www.et-studios.com/motorsports/motorspy/predelivery.html

David:
What you say may be correct, but both of your references are to fuel injected VW engines - looks like some carb bodies converted to butterflies, with injectors below...

[350HP930]

With cost effective EFI solutions out there fabbing up a turbo system with anything less makes no sense.

[asphaltgambler]

Turbos and carbs go together like tequila and pepto

[patkeefe]

OK. I'm throwing in the carburetor towel. I have seen the error of my stone age ways.

Pat

[silverc4s]

I believe there is somone on this board who restored an older aftermarket turbo system for the CIS engine, and has it running on his car.. maybe someone recalls who that was.

BTW Pat, don't go by my views on this subject - I am not a big fan of turbos on street gasoline engines period! But that's another subject.

[trader220]

Yea that Maserati biturbo with the carbs was a real treat. maybe 11 days a year it ran correctly.

[350HP930]

Well, if someone wants to take the factory CIS route I still have some of my old 930 CIS stuff for sale.

[sammyg2]

I have sucessfully built a tuirbocharged porsche with a carb, but it was a 914 with a 4 cylinder. if I had to do it over again i would install CIS on it. Does that tell you anything?
MAJOR PITA dialing in a carb with a turbocharger. CIS does it for you, up to a point.

[patkeefe]

Yeah, I'm thinking that the CIS route will likely be the way to go. I don't have to reinvent the wheel that way

[david.avery]

Originally posted by silverc4s
David:
What you say may be correct, but both of your references are to fuel injected VW engines - looks like some carb bodies converted to butterflies, with injectors below...

Heh sloppy of me

Here ya go:

http://www.shoptalkforums.com/viewtopic.php?t=85128

http://www.pbase.com/550joe/jason

[patkeefe]

Those look like blow throughs to IDF Webers, pretty common on the type I engines. Some you see are draw throughs with DCOE Webers. It's the extra two cylinders that present a plumbing problem. Those Webers are pretty tolerant to turbos on mid to high boost once they're jetted correctly.