Stock bore aftermarket pistons

[EggplantS14]

Is anyone using aftermarket pistons with stock bore? Usually Ive always gone .20 over to clean up it up a bit and ive heard stories of the pistons not fitting right once they have been through the heat cycle and either have been to loose or to tight after. I have a chance to pick up some stock bore Wiseco pistons for a killer price brand new. Ive also emailed them directly to see what their thoughts are but I thought I would come on here

Thanks

[Dakota_gsx]

Is anyone using aftermarket pistons with stock bore? Usually Ive always gone .20 over to clean up it up a bit and ive heard stories of the pistons not fitting right once they have been through the heat cycle and either have been to loose or to tight after. I have a chance to pick up some stock bore Wiseco pistons for a killer price brand new. Ive also emailed them directly to see what their thoughts are but I thought I would come on here

Thanks

I would definitely go over bore. that way you know you wont have clearance issues. Dont take a short cut just cause you have a deal through somewhere. I also have a set of weisco pistons if you are interested. not saying all this just to get you to buy them, but it seriously is a good idea to bore out when building an engine. stock is 86mm and i have 5 86.5mm bore weisco pistons with upgraded pins. i would give you the 5 for 250 bucks plus shipping. you would just need to buy a new one from weisco. they were in the car for 2000kms. floated a valve in cylinder 6, had to bore out again. if you are interested.

But seriously, dont stay with stock size. the pistons are the last thing you want to have troubles with with a rebuild. becuase you have to rip everything apart again.

[gezed]

I had this talk with a pretty knowledgeable machinst, he said engines such as ours with such high mileage, age and such abuse its not uncommon for the cylinder walls to eventually go out of round, at that point the only thing you can really do is overbore cause you will be losing compression at stock bore even if you rehoned the walls, wear on ringland would be unevenly loaded as well which potentially reduces lifespan of the engine

[rolyaT]

^ I am a machinist and I approve this
message hehe

[cschepp]

I am going to run my engine till she pops. But when all said is done how much do you think it would be to do all the machine work? I know it will differ I just want to have an idea for when I build a motor.

[Dakota_gsx]

For just bottom end work, cleaning the block, balancing and polishing the crank, and reassembly, I believe I was around 1500-2000 dollars range.

[Dakota_gsx]

For labour***

[EggplantS14]

Yeah Ive heard the same thing about all high mileage engines not just the rb series. I might run the stock block for the season and pick up a spare block to build slowly. I only plan on making 450hp and keeping the revs down. Im pretty sure with the proper engine helpers and a good tune this wont be a problem to hold me out till mid summer where I hope to have the other engine built and ready to go.

[Billy_Jack]

I am going to run my engine till she pops. But when all said is done how much do you think it would be to do all the machine work? I know it will differ I just want to have an idea for when I build a motor.

.5 over on mine was $40 per cylinder, just for the bore, theres a start

[NismoS-tune]

Just buy some stock sized Cosworth pistons. Save all the cylinder thickness for maximum reliability. You're not gonna see much gainst from .5 overbore.

[gezed]

I actually had it all done at a local shop and heres the breakdown of the costs:

bore+hone $190
micropolish+crank collar fitting $180
resurface head + block $150
hot tank block $45

if you assemble the short block yourself you save yourself quite a lot of money, as long as you check the bearing clearances with pastigauges and have a good torque wrench should be no problem

oh and about the crank balancing, the shop said it wasn't necessary unless the crank has been damaged or if the new piston/rod's weight is significantly different from stock

[GTRADDICT]

I actually had it all done at a local shop and heres the breakdown of the costs:

bore+hone $190
micropolish+crank collar fitting $180
resurface head + block $150
hot tank block $45

if you assemble the short block yourself you save yourself quite a lot of money, as long as you check the bearing clearances with pastigauges and have a good torque wrench should be no problem

oh and about the crank balancing, the shop said it wasn't necessary unless the crank has been damaged or if the new piston/rod's weight is significantly different from stock

I beleive a stock RB26 crankshaft will start to vibrate at 7200 RPM. I would have it done if everything is opened up already...