Do you really need forged pistons?

[kwhauck]

i blew the #6 piston at 13-15psi.......

[rickykline]

if hes running a tgp chip im guessing hes still obd1.....

[blackbombshell95]

u still obd 2?

[MidnightriderZ24]

not too much http://www.v6z24.com/registry/midnightriderz24/4

[fivepointhustla]

yeah midnight what the hell are you runnin. Those some awesome #s for 9psi

[AaronGTR]

Not entirely true. The largest factor is going to be fuel ratio and timing while under boost. Thats will be the difference between a failure and a reliable motor. Sure metal flaws might be a factor. But it is not the most important one. Also depending on the temperature of the boosted air you might not have any problems at 15 PSI on one setup but might be overwhelmed at 9PSI on another setup

Every piston and bearing surface is imediatly suspetable to failure under detonation. Every piston top is going to run excessivly hot under a lean condition even if there is no detonation.

Heat makes power. But too much melts stuff

Good points, but also just reinforces what I said. Remember that A/F ratio and timing and air density (temp) are just factors that affect cylinder pressure. Peak cylinder pressures and max HP are reached with optimum A/F ratio and timing. If your other factors aren't right though and you run too hot or too close to detonation then obviously you have to dial back timing and/or add fuel and/or try to cool the air charge and engine down in other ways. I kinda figured that was a given and we didn't need to go into that.

[rickykline]

358 on 9psi.... DAMN... what bolt ons.... i want specifics..lol

[boostedrs]

totally agree here. im running 12 now, dyno'd 358whp with 9 psi. i am intercooled and have a way better tune than kenton (89jy). i think i could easily run 15 psi but im not going to, traction is limited at 6 psi, try 12 psi!! a limited slip should fix that soon.

358@9#'s???? it took me 18 psi to hit 412.what size turbo u running?

edit nm i just noticed its a 3400 motor,mine was done on a iron headed 3.1,though im in the middle of a 3xxx swap now and switching to twin turbos

[MidnightriderZ24]

Not entirely true. The largest factor is going to be fuel ratio and timing while under boost. Thats will be the difference between a failure and a reliable motor. Sure metal flaws might be a factor. But it is not the most important one. Also depending on the temperature of the boosted air you might not have any problems at 15 PSI on one setup but might be overwhelmed at 9PSI on another setup

Every piston and bearing surface is imediatly suspetable to failure under detonation. Every piston top is going to run excessivly hot under a lean condition even if there is no detonation.

Heat makes power. But too much melts stuff

totally agree here. im running 12 now, dyno'd 358whp with 9 psi. i am intercooled and have a way better tune than kenton (89jy). i think i could easily run 15 psi but im not going to, traction is limited at 6 psi, try 12 psi!! a limited slip should fix that soon.

[boostedrs]

ive gone 18 psi + 35 shot of nitrous on my engine once,and ive continously run 18 psi on the motor without the nitrous,and its held together,on stock pistions.the main weak point is the top ringland,open up the ring gap a bit and u should be fine ,as long as ur tune is good .
i have had only one pistion falure between 3 diff motors,and it was due to going dead lean @ 20+ psi and detonating to hell (wastegate came unhooked).

[geoffinbc]

I think there definitely is a HP limit to what the pistons will take, even without detonation. You have to remember that HP is the result of increased cylinder pressure pushing down on the piston and eventually it will reach it's limit. That said, I also don't think there is a definitive HP number that can be used. Given the low tolerances and variences in metal quality and grain of stock pistons, the limit could be different for every engine. This is evident when some people run 12psi with no problems and other break a piston at 10psi. Obviously the one that broke at a lower level had some flaw from the factory.

I would say just for peace of mind and to lower the risk of damaging the rest of your engine with a blown piston, you should probably consider forged pistons for anything over 10psi or approaching 300whp.

Not entirely true. The largest factor is going to be fuel ratio and timing while under boost. Thats will be the difference between a failure and a reliable motor. Sure metal flaws might be a factor. But it is not the most important one. Also depending on the temperature of the boosted air you might not have any problems at 15 PSI on one setup but might be overwhelmed at 9PSI on another setup

Every piston and bearing surface is imediatly suspetable to failure under detonation. Every piston top is going to run excessivly hot under a lean condition even if there is no detonation.

Heat makes power. But too much melts stuff

[rickykline]

there have been several break 350whp with stock pistons.. i plan to upgrade to forged soon just so i can push the envelope

[AaronGTR]

I think there definitely is a HP limit to what the pistons will take, even without detonation. You have to remember that HP is the result of increased cylinder pressure pushing down on the piston and eventually it will reach it's limit. That said, I also don't think there is a definitive HP number that can be used. Given the low tolerances and variences in metal quality and grain of stock pistons, the limit could be different for every engine. This is evident when some people run 12psi with no problems and other break a piston at 10psi. Obviously the one that broke at a lower level had some flaw from the factory.

I would say just for peace of mind and to lower the risk of damaging the rest of your engine with a blown piston, you should probably consider forged pistons for anything over 10psi or approaching 300whp.

[farmerz24]

yes i was running 10 psi for not a long time but did you see my piston cracked and the only thing holding it together was the cylinder wall? if i had kept goin it would have ended up like 89jyturbos and shattered.

forged are a must, especially if you want to be reliable.

[MidnightriderZ24]

ive been running 12 psi on stock 3400 pistons for awhile and no sign of slap or any piston noise. really the only noise is the timing chain is a little loose. with my built 3500 i plan on runnin 20+ psi