I've never used nitrous, but I understand from reading stuff here that with even slight miss-tuning nitrous can kill the stock aluminum/steel insert pistons (225) rather quickly.

That said, how well will the stock pistons (in a good condition stock engine) hold up to a turbo producing... say 8-10lbs. of boost?
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Vaporizer Wholesale

Actually our stock pistons are quite strong. Detonation from any cause kills parts and higher horsepower (greater pressure) kills them quicker. Charlie S and other have run nitrous on stock pistons, many people have run boost levels you're contemplating. If you're careful with the fuel and timing the pistons should be fine. There have been reports of some aftermarket pistons that were not as good as the older pistons and OE pistons. Do you know the origin of your pistons?

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Joshua

They are aluminum with the steel expansion inserts inside, and have the Mopar logo inside as well (the Pentagram). I have no reason to believe they are not the original pistons from the factory (and the bore is standard size). They are in good shape.
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FREE STARBUCKS GIFT CARD

Run them I had 10 -12 pounds of boost and still pulled a trailer, then handled 22 psi for a year before the bottom end gave

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Nick
86 d150 turbo /6.
64 valiant 4 door

No matter what piston you put in it, if the tune-up is wrong, they will die.

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Official Cookie and Mater Tormentor.

Zillas right, I remember my first turbo project ..........too much timing no intercoooler......I kept a head gasket and extra pistons around got so good at it I could change a piston in 2 hours then after the intercooler and fuel injection was added never changed another

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Nick
86 d150 turbo /6.
64 valiant 4 door

Education is expensive.

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Official Cookie and Mater Tormentor.

Well, my original intention with this slant was to do a standard type build ( compression, cam, four bbl manifold, headers...etc.) but after reading some posts and particularly Wayne's article at the bottom of the Articles section, turboing seems a better way to go. From reading the article, I assume Wayne's engine was stock (stock compression. stock pistons, etc) and held up well.

There wasn't too much detail about what carb he used and how he tuned it(jetting and such), or mention of how the (assumed) stock pistons held up, which being aluminum, concerned me. I certainly understand that proper tuning of such an engine is primary to it's survival, but perhaps I need to find out more about specifically how he tuned it. Any suggestions on how to approach this?
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Weed

Frankly speaking, Wayne's setup was primitive and had a number of flaws. The turbo was too small which increases back pressure and thermal loads in the engine. The back pressure also leads to higher boost numbers because the exhaust can't get out of the way of the incoming air/fuel charge. Higher pressure from the turbo compressor means more heat in the incoming charge which hurts detonation resistance.

Wayne eventually switched to a Holley 600 and wired the secondaries closed. Easier than this would be to use a Holley 2300 series 2bbl. It's well known what a Holley needs to operate under boost. See this site: http://www.turbomustangs.com/

Wayne contacted me years and years ago about a higher volume fuel pump. Boost referencing the stock pump evidently will only work at lower power levels. I believe everyone currently running a blow-through turbo is using an electric pump.

So here's what you need and why:

1. The right size turbo. Already covered what happens with too small a turbo. Too large and you don't get boost until high RPM and the car is not very fun to drive at low speeds.

2. A tunable carburetor. The trouble in trying to work with a carb which has small internal passages is that no matter how big a main jet you use it won't flow enough fuel.

2b. Fuel injection is very nice and isn't that much more money when compared to some of the blow-through carbs from the big shops.

3. Adequate fuel supply. With a carb you have to supply 5 psi more fuel pressure than the boost pressure. Ignore this and it won't run under boost or if it's marginal you have a melt down.

4. Timing control. If you retard the timing the fuel economy goes down the toilet and the throttle response before the boost hits will stink. A street car needs a good timing curve and an electronic control to reduce the spark advance as the manifold pressure increases.

5. A good exhaust system. Restrictive exhaust raises the turbine inlet pressure and heat in the engine. Very much like too small a turbo as described above.

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Joshua

Here yee Here yee my turbo experience is still in it's infant stages considering my turbo motor has been only up and running for less than a month but I can second the elec fuel pump/ boost sensitive regulator thats what i got and seemed like the best way to go. I'm running a barry grant bloowthrough demon 650cfm the carb is on the big side so i've had to jet up to compensate but I seem to be working all the bugs out slowly but surely just gotta get a new trans under the duster since that went kaboom a couple days ago. My exhaust system consists of almost a completely straight pipe with a high flow muffler bolted at the end that i will pop off during track time or heavy testing sessions. Msd dig 6 box with the retard switch that i haven't messed with yet i may tinker with that or just weld my dist slots to 20deg total.

Kev

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Okay! Good info. Considering the responses, and what I am planning, what advantages or disadvantages (other then extra plumbing) might there be to a draw-through system?

I understand that fuel pressure and carb choice are less difficult in a draw through system. How and why? What turbo would have given Wayne a better system...and why? Thanks!

Draw-through requires a dynamic seal on the turbo compressor. Most turbos do not have a dynamic seal, but T3s used Chrysler Turbo I cars were this way as the throttle was before the turbo. Draw-through also requires moving the power valve sensing to after the turbo. Draw through was abandoned mostly because it makes intercooling impractical. It also makes for worse throttle response off-boost. Because a draw-through carburetor only sees more flow and not more pressure it's easier to tune. But having the turbo after the carb means more fuel puddling and cold driveability problems. Because the carb isn't pressurized the fuel system only has to supply normal fuel pressure. Blow-through pressurizes the carb and tries to keep the fuel from flowing into the carb so fuel pressure has to rise with boost.

Wayne's turbo was too small. The exhaust back pressure made for high boost numbers, but also low mass-flow through the engine and therefore relatively low horsepower. What was needed was a higher capacity turbine for less exhaust restriction and a larger compressor to handle the increase in mass flow.

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Joshua

More good info. Okay, Wayne's turbo was too small, but what sould he have used? I keep hearing that the turbo's off of Buick GN 3.8 V-6's are a very good match. Agree or not?

A grand National Buick turbocharger would have been a good choice. The Buick V6 is within 1/10th of a liter in displacement and is also a 2-valve per cylinder engine so the breathing capacity is very close to that of a 225ci slant six. A turbo for a 2-valve 2.5 liter 4 cylinder which Wayne used, and which, by the way, was too small for the engine it came from, is only about 2/3rds the capacity needed.

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Joshua

Much better choice.

I bought Wayne's turbo setup, and currently none of the parts from it remain on my car. The manifold eventually cracked where the turbo was welded to the flange, and the turbo was so small I could get 10 PSI at 1500 RPM, but the engine didn't like revving over 3000. It was like having a diesel, and not in a good way.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair