Gents,

I bought an LY6 last year that turned out to be rusty enough inside that I want to bore it, and want to go 4.03 with it.

I would like to purchase forged pistons because this is a boosted motor (10-12lbs, pulley limited), but I want to keep the stock rods because this is a 600whp build, and the stock stuff is supposedly good to 1000 +/- a few based on tune.

Does Wiseco (or anyone else) make a forged 4.03 piston for the stock rod?

Anyone has a set they want to sell?

 

I'm not sure I have seen any for stock rods with that bore. Then again I have never looked.

You would want a compression height of about 1.33 for a stock rod with the block being decked to approx 9.239 or less depending on compression goals.

 

Stock comp on an LY6 is ~9.67 make it 9.5 for easy math. Would like to stay there. I have found hypereutectic pistons in 4.03 (its really only .03 over current bore), but I would like to pick a forged slug.

Thank you for the info on the comp height. 10.0 would be ok because of the lower boost number, but I would like to avoid having to buy an entire rotating assembly and push rods. If I can get by with pistons, I'd be happy.

 

These are a handful of options:

https://www.summitracing.com/search/...rder=Ascending

 

Probably my best option:
https://www.summitracing.com/parts/w...make/chevrolet

Puts me 10.5-11.0 as for as comp goes, depending on head and block cutting

 

DSS makes a forged piston in a -5 variety that nets 10ish

https://www.summitracing.com/parts/d...make/chevrolet

Never heard of them, but they seem to have good reviews.

 

I have never heard of them either.

 

I might give them a shot. Ford guys seem to like them, and I read more good about them on the web than bad. Since I have limited myself to stock rod length, I have limited piston options: and those have been limited to A) probably too high comp for 91 and B) uncommon brand with an alloy not advertised.

Either way, still better than a eutectic piston, I hope

 

Because of the desire to boost this motor, the wrist pin being .945-.947 (depends on your source, I mic'd mine out at .9463) and the availability of pistons that have a .947 wrist pin, 4.03 dia AND LS3 valve reliefs: I have concluded I need a rod/piston package or a rotating assembly and a 408.

So back to the drawing board

 

Unless, you bought these Carrillo rods I have! You can run any stoker piston with them, and still use the factory 3.622 stroke crank.. Basically have a long rod 370