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Wed Oct 22, 2008 8:01 am

I'm rebuilding my 2007 and want to increse the displacment. My question is how much will a AS41 case hold 2165 2276 or bigger. I will be running 7.8 comp approx and 30+ lbs of boost form a T66 hybrid. I'm running this setup now with my 2007 I just dont know how big I can go befor I start pulling studs.

Wed Oct 22, 2008 8:16 am

2110 would be optimal.

Wed Oct 22, 2008 5:15 pm

as big as you can go

Wed Oct 22, 2008 5:17 pm

The Noof wrote: 2110 would be optimal.

Why? :?:

Wed Oct 22, 2008 5:37 pm

90.5mm P/C vs 94mm P/C with 30+ PSI boost......think about it.

Wed Oct 22, 2008 6:42 pm

DarthWeber wrote: 90.5mm P/C vs 94mm P/C with 30+ PSI boost......think about it.

Been there, done that. 1915 is what I decided upon. The same rules that apply to N/A engines also apply to turbos- larger bores make room for larger valves (somewhat nullified by forced induction aspect), oversquare engines are RPM friendly, there's no replacement for displacement, ect.

There's nothing wrong with 94 bore, it's been proven time and again. I'll be running 18 lbs through the 1915 as soon as I get the water-to-air intercooler installed; won't be any problems.

Wed Oct 22, 2008 6:44 pm

Yeah but 30+ psi?? I would think you'd want the extra wall thickness as a safety factor, no?

Wed Oct 22, 2008 6:55 pm

DarthWeber wrote: Yeah but 30+ psi?? I would think you'd want the extra wall thickness as a safety factor, no?

They'll hold. If integrity is a concern, Jaycee makes special jugs without fins- obviously not an option on a street ride. There's a plethora of folks beating the snot out of 94's- guys on lots of laughing gas, massive boost, and both. 8)

Wed Oct 22, 2008 7:05 pm

DarthWeber wrote: 90.5mm P/C vs 94mm P/C with 30+ PSI boost......think about it.

Got it. When he wrote 2110 I was thinking 82x90.5 combo. A 76x94 would produce more power for a turbo.

Wed Oct 22, 2008 8:01 pm

Oh come on, you know you want 82 x 94! :twisted:

Based on miniman's response, that removes all doubt for me about using 94s.

Wed Oct 22, 2008 8:28 pm

DarthWeber wrote: Based on miniman's response, that removes all doubt for me about using 94s.

Just to be clear, I should qualify what I said: nothing's bulletproof and everyone knows that. People who build these engines know what the parts can take, people that don't automatically assume that because the bore got bigger reliability went down. I've said it before, I'll say it again- Mahle P+C's can take a lot more abuse than people give them credit for. Generally with engines, people make the assumption that they'll have to replace the factory stuff in the quest for more power. While well intentioned, in this case it's an unfounded fear. Mahle makes a good piston, it's what I have at 10 PSI, and I'll still have them in the engine when I crank it up to 18.
To me, the whole forged vs cast debate is dead and gone. The real question is: will it take the abuse? With Mahle, the answer is YES. We've seen problems with AA 94's in race engines, but for a street engine they're probably OK. Weisco, JE, Arias, and CP are all very reputable companies, and I'd have no reservations using any of their pistons in an all out build.

For the purposes of this discussion, I'm not sure a Mahle would last. 30 PSI is a lot (I'm assuming a race engine here), so the common sense thing would be to source a stronger part from one of the vendors I mentioned above. Jaycee jugs would probably be a good idea if driving on the street isn't gonna be done. Whatever you choose to do, take pics and post them, for God's sake!!! :twisted:

Wed Oct 22, 2008 8:30 pm

This sounds like a race car, so cram in the biggest pistons and crank you can fit.

Thu Oct 23, 2008 8:33 am

The Noof wrote: 2110 would be optimal.

I would also like to know why you think this is the best size. I use it for street/ strip.

Thu Oct 23, 2008 8:58 am

90.5mm combo has proven it's reliabilty.smaller diameter block register leaves maximum material near the case savers.90.5mm cylinders are nice and thick for high boost applications.82mm stroke doesn;t require too much clearincing of case or cam, optimizing strength.

Thu Oct 23, 2008 11:45 am

The Noof wrote: 90.5mm combo has proven it's reliabilty.smaller diameter block register leaves maximum material near the case savers.90.5mm cylinders are nice and thick for high boost applications.82mm stroke doesn;t require too much clearincing of case or cam, optimizing strength.

Strongly disagree. I have seen no evidence of a lack of reliability with 94s.

My daily driver is 88x94 turbo. So i guess i don't see the problem.

Thu Oct 23, 2008 11:53 am

2stroke wrote: The Noof wrote: 90.5mm combo has proven it's reliabilty.smaller diameter block register leaves maximum material near the case savers.90.5mm cylinders are nice and thick for high boost applications.82mm stroke doesn;t require too much clearincing of case or cam, optimizing strength.

Strongly disagree. I have seen no evidence of a lack of reliability with 94s.

My daily driver is 88x94 turbo. So i guess i don't see the problem.

Where did i say that 94's are unreliable?

Thu Oct 23, 2008 2:35 pm

The only arguement I see here is reliability under very high boost pressure. smithers original post said he would be running 30+ lbs. of boost. :shock:

Thu Oct 23, 2008 2:40 pm

I'm thinking 2165 (78x94) with Wiseco's should be cool.

Thu Oct 23, 2008 3:05 pm

So smithers, is this a race only, street/race or street motor? What kind of cam are you going to run? And heads? Draw thru, blow thru, efi? Inquiring minds want to know.

Thu Oct 23, 2008 3:29 pm

Street/ strip motor
GB 310 cam
CB FI BIG Injectors
Ultra Wedge Ports (LS1)
GB 1.4 forgred rockers
Blow thru Turbonetics T66

I know someone will ask
Snow Performance progressive meth kit
and I run VP MS109 full time

This is my current setup (except for the new heads). I'm rebuilding for next season.