9.5:1 Pistons In Rb25det Neo

[aaron1259]

My parts provider has been trying to sort me out with some forged pistons for my build, however he said the best he could do was a set of forged pistons matched with a 1.8mm MLS head gasket, he said I would be getting around 9.5:1, is this too high? Will I be increasing the risk of det by much compared to something lower? I will only be running 98 pump.

[gtr jet]

If you don't intend to run that much boost then it would be fine but I don't see that happening if you're building the engine.

Maybe you need to talk to another parts provider.

[KiwiRS4T]

With the right turbo, exhaust and tune you should be fine so long as it is 9.5 and they are not 9.5 pistons for an R33 in which case it would be getting a bit high in a Neo,

[aaron1259]

Turbo will be a GTX3076R, max 24psi, 3.5" turbo back. I have a feeling they are for a r33, that's why he's putting the thicker head gasket to bump it down, he said it won't be over 9.5

[GTSBoy]

You won't likely get it down below 9.5 using a headgasket if the pistons are really for an R33. The Neo chamber is ~10cc smaller than the 33. That's a LOT of headgasket.

[aaron1259]

Picked up the pistons, can anyone tell me any information about them?

[GTSBoy]

I don't think JE understand that there is a difference between the old 25 and the Neo. They list that piston as suiting both. It can't. They have a 14cc dome on them.

If you go to JE's site and separately search for pistons for a 33 and for a 34 (on two different tabs) you can flick back and forth and see the exact same list. It can't be right. Have a search around on SAU for threads discussing the CR difference you get with a NEO head on 33 pistons. I can't remember the exact numbers, but they're not good (for boost). Might be good for E85, so long as there aren't valve-piston clearance issues.

Edited October 7, 2015 by GTSBoy

[Kinkstaah]

I specifically got JE/Nitto to make pistons for my Neo. They were custom made to fit.

You have R33 pistons in your hand, dude.

[aaron1259]

Just an update, yeah the pistons still had a high compression even with the 1.8 MLS gasket, so he decked the pistons he worked the comp to be 9.2:1

Is this still quite high, I have decided to use e85. Turbo is a Garrett gtx3076r, what would be the highest, safest boost I can run, I have all supporting mods.

[Ben C34]

Till it bangs minus 2 psi

[Ke55pig]

How well it tunes will show how much boost it will take and how well it was built . Theres no reason it wont beable to take 25 if built right and doesnt start detonating earlier

[KiwiRS4T]

9.2:1 should be fine. Use 3 bar. Or whatever the tuner can get to work.

[XGTRX]

3 bar? You sure?

[gtr jet]

She'll be right

[sneakey pete]

108 octane race ethanol and see how she goes. just turn the timing back, who cares if its making any power. 3 bar!