NA Pistons in a Turbo

[Justin]

How many people have done this?

Turbo: 8.4
N/A : 9.2


I have NA pistons that only have 10K miles on 'em so I would imagine they're in good shape (stock NA)

I'm rebuilding a JDM GTE with a MHG and ARPs

The benifits that I've heard is a faster spool and more power... what are the downfalls to doing this?

 

[rakkasan]

what are the downfalls to doing this?

Detonation at higher boost levels

 

[Supra Blues]

Yeah, you'd have to be careful with that setup. I don't think you'd be able to boost as much with NA pistons vs T pistons.

 

[Justin]

Yeah, you'd have to be careful with that setup. I don't think you'd be able to boost as much with NA pistons vs T pistons.

Definatly would have to be carefull, but would the added compression compensate for the lack of boost?

 

[Supra Blues]

Dunno, you'd have to ask one of the N/A-T guys around here.

I've been told its really only safe to run about 3-5 psi of boost on the na pistons.

 

[Justin]

I've been told its really only safe to run about 3-5 psi of boost on the na pistons.

Oh geez, that's really low

 

[boost PSSH boost]

A local guy was running 11psi on his 1/2 NA-T...only problems he had were the stock HG and his clutch that coudn't handle the torque.

His car could pull mine on the highway, and I had a bigger turbo, upgraded fuel+ lexus afm...full 3" exhaust, intake...he had safc, intake, upper hardpipe, and 2.5" exhaust at the time, only running 9 psi...compression makes a big difference.

 

[Justin]

A local guy was running 11psi on his 1/2 NA-T...only problems he had were the stock HG and his clutch that coudn't handle the torque.

His car could pull mine on the highway, and I had a bigger turbo, upgraded fuel+ lexus afm...full 3" exhaust, intake...he had safc, intake, upper hardpipe, and 2.5" exhaust at the time, only running 9 psi...compression makes a big difference.

its stories like this that make me want to go that route

I'm going with full 3" all the way back, and eventually a FFI with all the nessesary fuel mods.

 

[Darkcyde]

A friend of mine is running 12psi on his NA-T for 6 mo. without problems so far.

He just ran a 13.117 with turbo-back custom exhaust, lex afm, hardpipes, K&N, and G-Force drag radials.

 

[SupraMario]

well 8-9psi safely, NA pistons are bigger, so i dont know how ur going to get them into the turbo motor, i would be very afraid of detination if you go over 10psi. and they say the 8-9psi on an NA is like boosting 13-14psi on a turbo motor.

 

[7MGTEJoe]

well 8-9psi safely, NA pistons are bigger, so i dont know how ur going to get them into the turbo motor

WTF? The NA and turbo engine have identical bores.

I believe John Lunsford is running 9:1 JE pistons. You really should talk with him about how that works in a 7M.

In general, increasing compression is exchanging potential mid range and peak power for more torque off boost and some improvement in spool up.

 

[GrimJack]

I agree with Joe.

You gain low end torque, and spool is faster.

You lose potential top end... so you're never going to build a 900rwhp monster with NA pistons unless you mount a head spacer to drop your compression again.

John Lunsford is absolutely running high compression pistons, see if you can get some info from him - or from his 7M Power page.

 

[SupraMario]

WTF? The NA and turbo engine have identical bores.[\QUOTE]

hey dont get so pissed i was just stating what i knew.

 

[Supra Blues]

Okay, I guess you can run more the 3-5 psi.

Take a look at what other mods those guys have that are running in the 8-15 psi range though.

I could just be :blah: :blah: though.

Good luck man.

 

[figgie]

umm i know of people running 10:1 comp ratio and had no detonation problem. Of course they had a standalone to control the ignition curve though.

 

[Justin]

A friend of mine is running 12psi on his NA-T for 6 mo. without problems so far.

He just ran a 13.117 with turbo-back custom exhaust, lex afm, hardpipes, K&N, and G-Force drag radials.

No 550's, just a lex? Are those the only relivent mods?

I believe John Lunsford is running 9:1 JE pistons. You really should talk with him about how that works in a 7M.

Thanks, I'll see if I can get ahold of him

You gain low end torque, and spool is faster.

You lose potential top end... so you're never going to build a 900rwhp monster

hehe, you could have just stated I was never going to build 900rwhp and put a period after it. I doubt i'll ever get over 400 if that... unless I get a job where I can afford that much power


Thanks for all the help guys, this is exactly what I was looking for.

My plans are just to build the eingine using all ARP hardware, a MHG, possiably a BIC DDP, definatly a full 3" downpipe, and an apexi power intake for now.

after I build my savings account back up I was going to do emanage/550's/some type of air flow mod


What would I use to make sure that all was running well if I were to go this route? I'm definatly getting a wideband but I was hopnig on putting that off till i started adding more mods.

Would there be anything else I needed to do or just put in the pistons, run the stock boost of ~8-9 PSI with intake/exhaust

 

[NATAN666]

if i were to run NA pistons in my turbo motor, would i need na rods too? im new to engine building so im not entirely positive on the basics. na pistons in a turbo motor wouldnt affect stroke or displacement correct? just compression?

 

[IJ.]

Same rods Natan.

 

[Darkcyde]

No 550's, just a lex? Are those the only relivent mods?

Yes.

 

[TONY!]

I have discussed raising my compression with a bunch of members at one time in the chat room (GrimJack, Suprra_Girl, drjonez, sponsored1, projectsupra) since many months ago. Suprra_Girl has high compression pistons in her 7M-GTE.

Sammydafish is the one that got me thinking about raising compression in the first place. He once told me that just by doing that you can get a very noticable increase in power (it was a reply to a PM of mine that I sent him to say, "hi you must be not too far from me" kind of thing since we are both in Upstate NY). And I have been thinking of what he has said since.

I imagine you would have slighly better gas mileage (a feature of high compression motors).
You would also get more power ("free") since that is also a feature of high compression motors (unless you are sacrificing boost).

I have also been thinking of using N/A pistons because if the N/As can be turbocharged with their pistons (assuming they use their original pistons), why can't I.

I don't plan on going hi psi (figured like 10psi max), and I also don't plan on making a race machine, I just figured more power and slightly better gas mileage--how can you beat that?

My intended set-up may be different than yours though, Justin. I am only building very close to stock (my need for speed only gets quenched on 2 wheels).

Paging Suprra_Girl to this thread. hehe