3.4tdc forged pistons for boost?and anyone used a GT32 turbo

[sabotage]

I m looking to build a 3.4 dohc engine with chevy 5.7" rods and forged low compression pistons anyone know where I can find these pistons? and has anyone used a GT32 turbo for boost? what are your thoughts of the size of this turbo for this engine?

[Guest]

RE: 3.4tdc forged pistons for boost?and anyone used a GT32 t

hve to go custom pistons or you can use Hyper pistons for a 3.4 pushrod motor. They will yeild about a 8.7:1 compression ratio or so. Stronger then cast as well but not as strong as forged but will save you a bundle of money. then haev the pistons coated which willhelp them last longer too.

The GT32 is a sweet turbo. Would be good for a dohc. it all depends on your power goals however.

I personally think a GT35 is better suited but thast just me.

like I said it depends on your power goals.

[imported_germ]

GT35R would be my personal choice for a turbo and the DOHC or 3400

the GT32 is just a TAD bit undersized

[sabotage]

my Hp goals are from 390 and when turned up around 420 I know the GT32 supports 420hp and the GT35 supports up to 500 which is too much... and would the hyper pistons from the 3.4 pushrod motor take this abuse?(420hp)

[Kohburn]

as long as you don't get any detonation

Chris West was runngin 12psi on stock dohc pistons for several years - he just o-ringed the heads and block and ported the combustion chamber to lower compression. a thicker copper headgasket should do the trick though.

I plan on running 8-12 on my build next year with a high-low switch on the interior

[Guest]

Chris west does not run 12 psi.

Well I should say never has but I can pretty much see it not being daily. He doesnt' have the proper tuning, IMO, to be able to run that safely. Esp non intercooled and with a Shitty ass GN turbo.

I could be wrong

So let me get this straight. You want 390 and then 420 with it turned up? Turned up to what? Thats like a 2 psi increase. You only want 30 more hp on high boost? SO you want like 10 psi for low or something like that and then 12 for hi? Thats not much of a change.

A GT35R is good. Go with that.

[imported_germ]

just because the turbo specs state that the turbo can support up to 500 hp, that doesnt mean that its to much or to big, it just means you have more available power at your disposal if you want it.

you NEVER want to run a turbo at its max power, you allways want to oversize just a tad because you never want to run over the efficiancy range of the turbo.

the GT32R is good for a 2.8 or 3.1
the GT35 is good for the 3100
GT35R is good for the 3400 and 3.4 DOHC all the way up to the 3800's.

by the way, if you want a GT35R or any GT series turbo, plan on spending $1000-$3500 on just the turbo. (dont fall for the $799 deals on ebay, they are not real GT series turbo's most of the time)

[nocutt]

Chris west does not run 12 psi.

Well I should say never has but I can pretty much see it not being daily. He doesnt' have the proper tuning, IMO, to be able to run that safely. Esp non intercooled and with a Shitty ass GN turbo.

I could be wrong

You are not only wrong you are absolutely WRONG
Chris West ran as much as 12psi+ on an absolutely stock engine...yes the engine was not properly tuned as in 'NOT dyno'd'. However with more racing experience and 'real world data', I can guarantee that engine engine COULD have seen more...
and there is nothing wrong with a "shitty ass GN turbo"...it produced more useable power within the range used on the street and for road racing...that is user & creature comfort!?!?
I digress...

[timg]

GT35R is the way to go. I'll probably run either a GT35R or GT40R in the future.

I've never heard anything about the pushrod pistons before, but they sound interesting. Is there a cheap forged version available? How does it affect quench area?

Tim

[Guest]

cheap and forged do not go togethor.

the pushrod pistons have a dish about 12 cc or so. THe dohc pistons have valve reliefs. Quench won't be affected that much if at all. You still have a good compression height with those pistons but the dish helps to lower the compression

If you want a cheap forged, then get hypers, and then coat the tops. This will help keep the pistons cooler which will allow you to run more boost and it also helps to fend of detonation.

Or go with custom forged. but forged and cheap don't belong in the same sentence. So either don't try and be a cheap ass and just get cast pistons or go with a set of forged and shell out the bucks. Building a turbo motor isnt' cheap

You are going to run a turbo and then skimp out on one of the most importaant parts of the motor to save a few dollars? What if it blows? Then it will cost even more. Do it right the first time.

You have to pay to play.

[timg]

cheap and forged do not go togethor.

the pushrod pistons have a dish about 12 cc or so. THe dohc pistons have valve reliefs. Quench won't be affected that much if at all. You still have a good compression height with those pistons but the dish helps to lower the compression

If you want a cheap forged, then get hypers, and then coat the tops. This will help keep the pistons cooler which will allow you to run more boost and it also helps to fend of detonation.

Or go with custom forged. but forged and cheap don't belong in the same sentence. So either don't try and be a cheap ass and just get cast pistons or go with a set of forged and shell out the bucks. Building a turbo motor isnt' cheap

You are going to run a turbo and then skimp out on one of the most importaant parts of the motor to save a few dollars? What if it blows? Then it will cost even more. Do it right the first time.

You have to pay to play.

I probably should have rephrased some of my posts. I know cheap and forged don't go together. I also know that custom and cheap don't go together.

From what I have seen, I can expect to spend $500 on rods and another $500-750 on custom forged pistons. That isn't a big deal. I would guess that the rebuild will be $2500-3000 total (It had better be, I can sleeve my S2000 block and add all new forged pistons and rods for that much!). I was hoping any premade (non-custom) forged pistons could save me a few hundred dollars. I have considered hypereutectic pistons with Swain Tech coated tops and skirts (I have seen pistons coated by Swain Tech survive quite a bit); however, coating hypereutectic pistons will probably cost just as much as forged pistons would have in the first place.

Pushrod pistons definitely sound promising. What compression ratio would they yield?

I'm much more worried about doing it right the first time and building a motor that lasts than I am about saving a few $$- I always have been. My stock motor has 145k+ and has over 20k boosted. Currently, it's at 10 psi. I have over $5k invested in engine management, turbo parts, and supporting mods (fuel pump, exhaust, etc).

The only way I think I would consider cheaping out is buying a new crate motor and adding a low compression custom MLS gasket from Cometic.

tim

[timg]

I've done more searching. Forged Aluminum rods for a 3.4 pushrod engine are $564-618 from www.ftpp.net They also sell forged Ross Racing pistons for the 3.4 pushrod engine for $480-540. Not a big fan of the rods (aluminum), but the pistons may work perfectly.

Ross can also do custom pistons for a 3.4 DOHC for $480-600. CP, Arias, JE, and Wiseco will also do custom pistons, but I don't know how much they would cost. It seems that all forged pistons, forged rods, new pins, new rings, and new rod bolts would cost $1250-1500.

Forged SBC rods range from $429-579 (Eagle H beam vs Manley H beam) for a set of 8.

For a cheaper alternative, Speed Pro has a set of 3.4 DOHC pistons that are Hypereutectic with coated skirts for around $215. These are probably the way to go for 95% of the DOHC engine rebuilds.

Tim

[dk05]

For a cheaper alternative, Speed Pro has a set of 3.4 DOHC pistons that are Hypereutectic with coated skirts for around $215. These are probably the way to go for 95% of the DOHC engine rebuilds.

You wouldn't happen to know the part #'s for these pistons by any chance, would you? Thanks

[timg]

H684CP (96-97) and H813CP (91-95)

Tim

[timg]

27.39 each, less than $165 total!

http://store.summitracing.com/default.asp?target=partdetail.asp&part=STL-H813CP

http://store.summitracing.com/default.asp?target=partdetail.asp&part=STL-H684CP

Tim