Turbocharging 40 years ago

[squirrel]

Point distributor...stock Quadrajet....what fun!

[JOES66FURY]

too coo!

[TheSilverBuick]

Draw through! Too bad I dislike plumbing so much =P

I wonder if with today's head gaskets if the o-rings in the heads would even be necessary. He's running 7 to 12 psi of boost.

I like the theme, making sure it's muffled to the point it sounds just like a stock smogger engine. That is sleeper material right there, and that's what I like!

[silver_bullet]

I probably still have that issue...Damn I feel old now...

[squirrel]

me too...it's one I bought when I was 13.

[Barry Donovan]

Draw through! Too bad I dislike plumbing so much =P

I wonder if with today's head gaskets if the o-rings in the heads would even be necessary. He's running 7 to 12 psi of boost.

I like the theme, making sure it's muffled to the point it sounds just like a stock smogger engine. That is sleeper material right there, and that's what I like!

That is a great plan for the 80s subarus.
the wasp and pause sound is simply a msd6530 away from perfection...

[Scott Liggett]

I always wondered why draw throughs are used today. Wouldn't itsolve a lot of carb and boost issues?

[squirrel]

I think part of it has to do with not being able to use an intercooler on a draw thru system? for a larger engine, with limited boost, it should work ok.

[TheSilverBuick]

I think part of it has to do with not being able to use an intercooler on a draw thru system? for a larger engine, with limited boost, it should work ok.

Agreed, no good way to use an intercooler. Not that in this day and age a small water heat exchanger like used on the superchargers might work decently, but hard to say. Plus, there is certainly a cooling effect of the intake charge with a pressurized carb.

I briefly contemplated trying a draw through on the OHC engine. Then I jumped in the deep end with the EFI.

[RockJustRock]

Of course the main problem with draw through is boost control. Any kind of wastegate would be an invitation for chaos. Boost management and that "split second" of NOTHING made them pretty useless for most racing applications. The primordial boost stuff is interesting. In one recipe for disaster I think it was Yenko that put out a turbo Vega four. Then there was Mr. Norm's Paxton blown Demons. Then Ex-Funny Car driver Gary Dyer said "screw the vision problems" and fired up his Bridgeport cranking out 6-71 kits for anything causing turbos to be forgotten for hot rods for a while.

[dieselgeek]

Of course the main problem with draw through is boost control. Any kind of wastegate would be an invitation for chaos. Boost management and that "split second" of NOTHING made them pretty useless for most racing applications. The primordial boost stuff is interesting. In one recipe for disaster I think it was Yenko that put out a turbo Vega four. Then there was Mr. Norm's Paxton blown Demons. Then Ex-Funny Car driver Gary Dyer said "screw the vision problems" and fired up his Bridgeport cranking out 6-71 kits for anything causing turbos to be forgotten for hot rods for a while.

I think he means "any kind of blowoff valve" - a wastegate would be OK in a draw thru system. The other problem with draw thru is fuel separation from the charge as it gets slung around inside the compressor.

[RockJustRock]

Sowwy..

[STINEY]

Fuel separation was my impression too.

That and a blow-thru carb can be tricked into automatically enriching the air-fuel mix with little known items known as modulator rings - they create a pressure differential which makes the carb "see" the need for more fuel. That and boost referencing the mechanical fuel pump is all that is really needed up to about 10-12 psi.

A draw-thru has to be jetted super rich for the fuel needs at WOT on boost. Anything less will burn the pistons up at WOT. The fuel-air will be super rich and run crappy at less than WOT with this setup.

[dieselgeek]

I'd actually like to try this, or an MFI system with turbocharging, some time. I talked with Gene Adams about the Hilborn turbo digger from way back in the 60s, and he says that the only real problem was the unavailablity of wide or narrow band oxygen sensors. If you think about how hard it is to tune without one (I've tuned turbo engines IN A PINCH without O2 sensors and this is not for the faint of heart or shallow pocketbooks), it make sense. In reality a good MFI system, and I'm betting a properly setup carb, would work fine if you just had the tools to know where to point things.

[BigAL]

Draw- thru systems aren't that good, the fuel will separate from the air in the turbo and cause puddling, the turbo become less efficient do to it having to move a heavier air/fuel mixture, then you have the carb creating a pressure drop and then the turbo trying to increase pressure, which all adds up to an increase in intake temps. And by all means don't run an intercooler, the fuel will collect in the intercooler and essentially make it a bomb if you ever have a backfire.