Has anyone made a 1920 a blow through yet? I feel it would still be possible to make good hp numbers with one. I read a thread on here from 2008 about using one. I think it'd be the best route and most cost-friendly one at that.

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1965 Plymouth Belvedere II Turbo Project - SOLD
2002 Subaru OBS
1995 Lexus LS400 Race Car

it depends on what kind of boost you are planning on running from what ive read. if you only plan on 5 psi or so you could be fine. anything more than that your gonna lean out pretty quick. thats just from what ive read.

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1966 Plymouth Valiant, 225, 3 on the tree, 8 1/4 3.21 sure grip, hyperpac, holley 650dp, holset h1c

Thanks Junior, I'm going to experiment with it and see. It'd deffinetly be nice if I can have it at 10 p.s.i.. Imagine the mileage and how easy it would be to tune!

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1965 Plymouth Belvedere II Turbo Project - SOLD
2002 Subaru OBS
1995 Lexus LS400 Race Car

that sounds like wishful thinking. make sure you get a wideband setup in there so you dont blow your motor from the start. good luck with it. make sure you post some video when you get that thing sliding around.

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1966 Plymouth Valiant, 225, 3 on the tree, 8 1/4 3.21 sure grip, hyperpac, holley 650dp, holset h1c

I don't think you'll get enough fuel through the power valve circuit to keep the mixture safely rich. The inlet needle and seat are also a restriction. This assumes that you'll be getting decent mass flow rather than just "10 p.s.i." and to get decent mass flow (to make good torque/horsepower) you need to do more to improve breathing than just turbocharging a stock engine. Read Forced Induction Performance Tuning by A. Graham Bell and then plan your engine build.

http://www.amazon.com/Induction-Perform ... 1859606911

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Joshua

What about if I put the biggest possible jet on? and I'm not set on 10 p.s.i., its just a number thrown out there. The motor will have a ported/polished head with enginebuilder valves and a comp cams 264s cam with lifters and valves. I will have a afr gauge, and in tuning I will figure out how much boost I can actually run. I think this would be a good experiment for the community because it will cut the cost of a lot of the turbo builds.

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1965 Plymouth Belvedere II Turbo Project - SOLD
2002 Subaru OBS
1995 Lexus LS400 Race Car

And also, I dont know alot about carbs, but could I put a bigger needle in the carb or no?

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1965 Plymouth Belvedere II Turbo Project - SOLD
2002 Subaru OBS
1995 Lexus LS400 Race Car

Using too large a main jet will make the off-boost performance lazy, ruin fuel consumption, wear out the rings and cylinders, make your eyes water from the fumes and still may not provide enough fuel under boost. Either you can afford to build a high performance turbo engine with all the necessary supporting equipment or you can't. Using a 235 CFM carburetor with fuel circuits designed to feed less than 200hp worth of fuel on a boosted engine is false economy. Go read theturboforums.com for 8 hours or so to begin to get an idea of what's required to make a blow-through carb work. I don't mean to sound harsh, but getting to where you appear to want to go is going to require a lot more planning and knowledge.

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Joshua

I think you misunderstand what my plan is... I am not sticking to this. I am seeing what the potential of the one barrel is. I am aiming for a two barrel setup. But I am just curious as to what can come from a blow through 1 barrel. I know you aren't trying to be harsh, thank you. When the setup is done with the one barrel I will post the results on here.

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1965 Plymouth Belvedere II Turbo Project - SOLD
2002 Subaru OBS
1995 Lexus LS400 Race Car

Experimenting is all fine and good, but be careful. You can burn a piston or blow the head gasket running lean. Fuel delivery is of prime importance and the Holley 1920 won't pass much fuel. The internal passages become restrictions and the jets no longer control the flow.

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Joshua

Ok, thank you Josh. I will make sure I have a boost and afr gauge during the first startup/tuning. I'll start off with super low boost and work my way up. As well as jet size. Do you have any suggestions as to what would be the biggest jetting size I could use?

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1965 Plymouth Belvedere II Turbo Project - SOLD
2002 Subaru OBS
1995 Lexus LS400 Race Car

Anyone else's opinion on this?

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1965 Plymouth Belvedere II Turbo Project - SOLD
2002 Subaru OBS
1995 Lexus LS400 Race Car

Well, you asked for an opinion, so here's mine.

It looks like from the previous posts, a 1920 carb is not a very good choice for this project. Turbocharging a slant six is hard enough when you have all the right parts; believe me, I have learned the hard way.

TUNING is the important thing in this endeavor, and I am talking about A/F ratios. It is a jungle... And, critical to a lot of things, not the least of which is engine longivity!
MY opinion would be to acquire a 350cfm Holley 2-bbl carb and put it on a Super Six intake manifold. That would give you access to a large variety of tuning information and parts. For the most part, Holley 4bbl stuff works on this carb.

Also, if you are only going after 5 pounds of boost, I think you'd be better off just adding a cam, a set of headers and milling the head .100" rather than going to all the trouble to turbocharge this engine, with all the many problems that turbocharging can lay at your doorstep.

Ten pounds is a totally different story; you'd have to do a lot more to gain the kind of performance on a N/A engine, that ten pounds of boost will give you.

But, a one-barrel "experiment" and 5 pounds of boost; you're not doing yourself any favors when all is said and done. Minimal performace gain for a lot of trouble...


The ten pound thing is definitely worth doing! But, not with a 1920.

My opinion, only.... Good luck in whatever you decide!

Bill in Conway, Arkansas

I know you are all probably going to question this, but I have decided to try it. Heres the plan:

Fresh Rebuilt 225
1920 Blowthrough
Ported/Polished Head With Enginebuilder Valves
Comp Cams 264s Cam Kit with Lifters
Modified Exhaust Manifold with TD04 Turbo

I'm not planning on sticking with this. Just seeing what the capabilities are.
I have a super six and 350cfm holley sitting around for afterwards. I will post the afr, max psi I ran on dyno, when boost kicks in, what jetting size I used, and 1/4 mile time. This will be in front of a rebuilt 904 with quick shift kit, and 2.76 gears (welded diff).

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1965 Plymouth Belvedere II Turbo Project - SOLD
2002 Subaru OBS
1995 Lexus LS400 Race Car

You are going to find that the welded diff won't last long if grunted on...Back when I did demo derby I welded up an 8 1/4" 2.76 and the 318-2v grenaded it on hard cornering (and that was on a mud/dirt track- the car was a 1973 Dodge Charger that had seen lots of better days). The 8 3/4" would be better (they lasted longer when welded-but never on pavement), but you might look at getting a spool for it.

-D.Idiot