Piston selection

[69340]

I pulled out the motor last weekend she was using a lot of oil . After some measuring i found i will have to bore the 340 to .040. What pistons and rings do FABO members recommend for a good stout street /strip motor. Any input would be awesome.

 

[lead69]

If your not using nitrous I think these would be good.http://store.summitracing.com/partdetail.asp?part=UEM-KB243040-8&autoview=sku I also use the speed pro moly rings that sumnmit sells,I think they are around $70.00.

 

[69340]

Thanks for the input Lead69 I was looking at the kb pistons as well . Anybody else have any input.

 

[rumblefish360]

I'd rather the KB-107's for a bit less compresion for a street engine. They'll come up to a zero deck height while giving up a ratio of 9.8-1 with an open chambered head and .039 thick gasket.

Some machining may be required due to varying deck heights from the factory. I myself didn't need to deck the engine block.

 

[3404spdvaliant]

KB243 hyper for 340 10.5 factory replacements that are WAY LIGHTER than the original factory ones @ around 575 grams compared to 740+grams.

I run them in my .030 340 with pump gas no problems.

Use nitrous all you want within the guide lines of their recommendation for ring gap and HP limits.

 

[moper]

the KBs a rea good way to go for a mixed duty build. But, pay attention to details if you want to run a closed chamber head. When they are in at zero deck, they will protrude .018" out of the block due to the design. (Identical to the older TRW/Speed Pro designs) So you want to make sure you either leave the deck tall, or mill the piston down to get a true zero deck and set your quench with a closed chamber head. If you run iron, don't sweat it. For a step up, I'd run Diamonds, but because you need .040 over, the usual Diamonds/Ross will be a special order and a bit more cash. Anything over .030 over in the higher end pistons ends up being a custom piston with the associated charges.

 

[69340]

Thats great input guys . I am running X- heads i CCd one head today and got a reading of 72 cc after doing the math looks like the compression would be around 9.8:1 using kb243 pistons. That was using a .038 gasket.
thanks for all the reply's keep them coming it's good to see what others are doing