Author Topic: Piston and rods for turbo 2.5 build ? ?  (Read 1012 times)

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GPSAR TJ

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Piston and rods for turbo 2.5 build ? ?
« on: November 14, 2010, 04:19:27 PM »
 Just pulled the motor and was gonna swap in another 2.5 as a temp fix till my original motor is fully built...well I dont feel like doin this twice so Im just gonna rebuild the original. have most of what I need in terms of turbo stuff so thats good but would like some advice on the actual motor build. can I get forged pistons and rods for this motor without being outragously expensive (goin for reliability so Im thinking 5-7 psi boost?) do i even need forged stuff? what brand bearings, pushrods, ect.ect. ? should I be looking for a certain type of head gasket? Since its getting rebuilt anyway I may as well put in the best stuff I can afford (within reason) to give me a little peace of mind.  also please let me know what parts/brands to avoid. Thanks alot , Jason

Offline sharpxmen

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Re: Piston and rods for turbo 2.5 build ? ?
« Reply #1 on: November 14, 2010, 04:53:34 PM »
Just pulled the motor and was gonna swap in another 2.5 as a temp fix till my original motor is fully built...well I dont feel like doin this twice so Im just gonna rebuild the original. have most of what I need in terms of turbo stuff so thats good but would like some advice on the actual motor build. can I get forged pistons and rods for this motor without being outragously expensive (goin for reliability so Im thinking 5-7 psi boost?) do i even need forged stuff? what brand bearings, pushrods, ect.ect. ? should I be looking for a certain type of head gasket? Since its getting rebuilt anyway I may as well put in the best stuff I can afford (within reason) to give me a little peace of mind.  also please let me know what parts/brands to avoid. Thanks alot , Jason

a set of custom forged pistons would run you about $500.

for 6 psi of boost you'll be fine without forged pistons

Mopar performance multilayered steel (which was made by Victor Reinz) is the best head gasket but would increase your CR and i don't think you can get them anymore, i got a VR upper set and the headgasket is just a regular one.

Clevite is good for bearings
pushrods you can use regular ones unless you go with high perf valve springs in which case you need an upgrade (i can tell you for sure that the stock ones will slightly deflect if you use them with strong valve springs as i measured the valve travel with stock springs and 120# installed pressure springs and there's about 0.010 difference between them)

buy new lifters and at least replace the stamped rockers with new ones if not going to roller rockers.

'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
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GPSAR TJ

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Re: Piston and rods for turbo 2.5 build ? ?
« Reply #2 on: November 15, 2010, 04:55:48 PM »
Cheif squirell blower ! thats fuuunny !   thank you very much for the advice and the quick response. hyper utes it is. I used to use the mopar gaskets on my 2.2 turbos. should I do the rollers ? what about stock rods, are they decent ?thanks again, Jason.
« Last Edit: November 15, 2010, 04:57:26 PM by GPSAR TJ »

Offline sharpxmen

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Re: Piston and rods for turbo 2.5 build ? ?
« Reply #3 on: November 15, 2010, 05:58:46 PM »
Cheif squirell blower ! thats fuuunny !   thank you very much for the advice and the quick response. hyper utes it is. I used to use the mopar gaskets on my 2.2 turbos. should I do the rollers ? what about stock rods, are they decent ?thanks again, Jason.

if you mean the connecting rods i think they are ok, since your goal is to keep the redline where it currently is i would say they're safe. Rather look in balancing the crank and pistons/rods assembled - i'd think the money would be better spent that way. the rollers will give you some extra lift as the stock rockers flex a bit (they are advertised at 1.6 but effectively you get 1.5, the rollers will give you the advertised ratio) - check my roller rockers thread in the member's projects section for details on that.

if you want to dish the pistons i think the hypereutectic have a thinner piston top but i can't confirm, the stock pistons and like (regular cast) are safe to dish to about 8.6 CR from what i read here and there (6 cyl stroker builds cover that).
'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
Latest: Corbeau BajaRS heated seats :dance: keeping warm the rear end

GPSAR TJ

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Re: Piston and rods for turbo 2.5 build ? ?
« Reply #4 on: November 15, 2010, 08:06:13 PM »
rollers sound like a good idea, will check out your threads. was searching the web for rebuild kits, seems like theres no shortage of complete kits, mines a 98 and most seem to spec. hyperutectics for that app. any advice on complete kits? looks like I can upgrade to rollers, mix and match bearing manufact. and other parts with some companies, ..partial to anyone who sells this stuff. thanks for all your help.

GPSAR TJ

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Re: Piston and rods for turbo 2.5 build ? ?
« Reply #5 on: November 15, 2010, 08:24:42 PM »
 read the thread, rollers no longer sound like a good idea..ha! wow, what will the chineese copy next. thats alot of work and some damn good r + d ,but its the little things that add up to overall performance right. Im not sure Im ready to go that far though (budget wise) may stick with the new stock rockers and look into a cam , will a higher duration cam kill those stamped rockers? I dont wanna wear you out asking alot of crazy questions and I do appreciate your advice sharp.

Offline sharpxmen

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Re: Piston and rods for turbo 2.5 build ? ?
« Reply #6 on: November 15, 2010, 09:23:12 PM »
read the thread, rollers no longer sound like a good idea..ha! wow, what will the chineese copy next. thats alot of work and some damn good r + d ,but its the little things that add up to overall performance right. Im not sure Im ready to go that far though (budget wise) may stick with the new stock rockers and look into a cam , will a higher duration cam kill those stamped rockers? I dont wanna wear you out asking alot of crazy questions and I do appreciate your advice sharp.

a cam would work but depending how aggressive it is you might need valve springs also. You can get bolt on rockers, what i am doing with the 1.7 is def not walk in the park but the extra lift is worth it (in my case at least) - you can get a reground cam for about $100 with probably same results as the rockers if not better both would probably be the best combo. If you get a cam and since you plan for a turbo look for one with less overlap (the stock is 47 deg if i recall correctly, mopar mild perf cam was something like 38 or 36 or so which should work better in your case).
'95 YJ, NSG370 6spd / Hurst shifter, Dana 300 + 4:1 Doubler / tri-stick, Custom skid, Super D35 / Auburn LSD / 4.88, 35x12.5x15 BFG KM2, 64mm t/b, 1.7 RollerRockers, MkVIII e-fan, Dual Diaph Booster
Latest: Corbeau BajaRS heated seats :dance: keeping warm the rear end