I finally got my h22a1(obd1) rebuilt and now i have to figure which pistons to run. I now which model, MAHLE Gold Series, but which piston. I know the inverted dome is better for boost, but how inverted should i go? I plan on boosting around 15lbs after the initial break in.

Also, whats the max boost can a closed deck a1 handle without sleeving the block and run comfortable?

 

I believe Mahle only makes one off the shelf piston for turbo, which is 9:1 iirc. It's either that, stock compression, or 11.5:1 if memory serves me.

 

ok. so basically, the 9:1 is the -7cc invert right?

how much boost can a stock a1 block hold though? that will determine which set i get. really appreciate it.

 

15lbs on what turbo? The differences between a TD05 and say a GT4094R are a bit different. There's no limit set in stone, but I'd question reliability above 300-350whp

 

What do you think would break first? Do you think you'd end up cracking a sleeve?
I've seen some nasty block damage on B/D builds with forged pistons in stock sleeves.
I lose interest fast when people talk about PSI like its Torque instead of referring to things like CFM.

 

Garrett GT3076R is the turbo that i am going to be using.

i have also seen some damaged block due forged pistons on a stock block. im a victim with my d.So basically you are saying that I have no knowledge of CFM, LFM, Velocity Units, Volume Airflow Units or whatever you call it..quick question: (no googling) how many cubic ft are in a lb? thats was a smarta** move right?

j/k...seriously, i have never dealt with the FRM lining and since MAHLE makes a forged piston for boost, why not push it? I was just seeing if anyone has used them and what was the highest they got and still have decent reliability. Thats all.

P.S. no way shape or form is PSI like TORQUE...two different animals!

 

what the smart *** is saying is that you should be more concerned about is cfm not psi. because the cfm is going to be different for different sized turbos. properly sizing the turbo with the set up and goals is very important. psi doesnt mean much.

 

I think you read too far into it. Nothing can really be judged by PSI, and it appears you know that.
FT/LB I can't say I know, not a turbo guy........just sick of the PSI-ness craze!

I'll take the SMART *** as a compliment.....Would rather be a smart *** than a dumb ***.

 

did you even read my post? not bashing, really appreciate everyone's help.

 

I understand that you know all that stuff. I was trying to dumb down what asshat said earlier more for my sake.

as for power. there was someone on here making 500+ on a stock bottom end h22. ran for 8months and then dropped a valve. no doubt the sleeves will hold. I don't think that anyone has really pushed the mahle pistons. It would be interesting to see how they do.

 

well ill keep posting. im puttuing in the cables now. ive heard that ppl ran them, but never heard the outcome. im looking for mid 4's on the stock block and fully built head, so dropping valves wont be an issue..hopefully! but yeah, i will post the dyno sheets up when i take it in.

cause i know ive seen a f20 s2k running close to 600 on the frm lining, so i figure why not try it.

 

they are rated about 125 hp per piston according to someone i spoke with from Mahle. so that would be about 500whp,right? I would not try to push more than that on stock sleeves.