...with a technical rep at Techtonics Tuning (Audi/VW tuning parts). They do not recommend forged pistons in engines unless that engine will see substantial 7500+ RPM usage. The reason they say this is that forged pistons expand more than cast pistons when they are hot. Since they expand so much, they need looser cylinder wall clearances (which is obviously not good for boost as you'll lose compression past the rings in some instances). Looser clearances are seriously bad on engine life (piston rings, increased oil comsumption, etc...)

****...now I have to seriously rethink my 2003 GLE-T engine design, which sucks b/c I already bought the damn parts AND got the Swain Tech coated...

And I know there's no way in hell I'm going to build my engine to run 7500+ RPM...



Edit-- I originally found out about this info from Eurotuner Magazine in one of TT's part ads, then called them to confirm. Thier number is (503) 843-2700 if anyone cares...

 

Hm...they're Audis....screw them! Ha...there was a SC GTI VR6 at my work today...bad as hell!! Thats really interesting though.

GLE-T just sounds mean!

 

Quick google search looks like they are correct. Also, sounds like "hyper-eutectic" cast pistons are the best of both.

You wanted them for their lower compression, so you can run 15+psi on pump gas and they'll tolerate detonation better then cast.

I say keep them, just make sure your machine shope hones the bore to the piston manufacturers specs EXACTLY plus use the correct rings. Lots of **** I don't care to think about.

 

Hmmm do they still have high and low silicone content forged pistons? One was better at controlling explansion and one was not so good for turbo applications.

 

Yeah, but I can't believe I've never heard this before yesterday. I've never had any problems with past vehicles and forged pistons (with turbos). Oh well, I already spent the money. Now I have to find an exceptional machine shop...

 

Regarding Icy's post. The machine shop could do excellent work. But if they have to account for pistons that expand xx amount, they will have to account for that. So bascily, you will have some larger piston/bore clearances when the car is cold. Nothing that people haven't been doing for years though. I would think it would only significantly affect engine life if you ran the engine hard before it was properly warmed up. Now you will just have to be that much more aware about bringing it up to operating temps.

 

Thanks for letting me vent/talk fellas. That just put my mind at ease. For a little bit, I thought I had just wasted some serious cash...

 

But don't trust just us. Talk to everyone you can so you can make sure you are doing the right thing.

 

Hah, that should be in the Motor Bilble...

 

the det pistons are "hyper-eutectic"

 

Hmmmnnnnn....

We need to find a JDM source for just the pistons or get Courtesy to stock them like the MEVI kit they now sell.

 

what are the compression of those again? 8.5

im wondering if these would be a good candidate for the hybrid project this summer

 

I believe that's right...SR20DEs are 9.5:1 IIRC, so that makes sense.

 

Do you got anything informative to add besides random comments?

 

no, he doesnt.

bijan--are you even boosted yet?

 

Boosted? Smoky is still trying to get a 4th gen.

 

Dijan is hyper-idiotic

 

All stock VQ30DE pistons are hyper-poopoo, or pressure cast. Forged is stronger, will take the beating. Are you really expacting to get 100k out of a hardcore race motor? I'm not!

FWIW, I just called Kyle at SGP, they CP pistons are low silicone and are resistant to high heat expansion. Several sets have been installed and no piston slap has been reported.

Rest well!