Originally Posted by THE FAT CONTROLLER
Hi guys i have a 79 corvette l82 that has a steel crank and pink rods in it . I want to liven it up but first want to know should i stick with the crank and rods .
I'm doing a 30+ bore so i need a good set of pistons
edelbrock rpm heads
edelbrock performer intake and will be running a street avenger 670
i currently have a comp cams magnum 270 cam
wanna wake it up but not go made, gas in the uk is *** ripping
may be to 350 hp
open to idea's thank martin
The L82 came stuffed with the factory hot rod foundation of a rock solid, usually 010 block casting, forged crank and pink rods. Then they gelded the top end with large chamber heads, a mild cam that looks like a decent duration till you measure it only to discover that much of those duration numbers are opening and closing ramps, an ok for the job 750 CFM Q-Jet on a crappy iron manifold.
You have licked the top end limitations. The crank and rods are way overbuilt for the original engine’s installed power, so what you need is a decent set of pistons. For this you want some good flat tops or D dish types if you need to lower the compression in line with what the octane of the fuel is that you wish to use. For a performance street engine hyper-eutectic castings are fine. But in keeping with the theme of this engine before it was choked up with SMOG reduction changes; a forged piston would be appropriate. For the street, I prefer alloy 4032 which is closer to the silicon contend of hyper eutectic pistons. This makes the forging more temperature stable so it can be run with tighter side clearances that are more like current production engines. This keeps the pistons quiet, reduces the chance of busting the skirt, and minimizes blow-by by keeping the ring package square to the cylinder wall which increases fuel efficiency and power while reducing emissions. The 2618 alloy will take more abuse as it absorbs some punishment but it expands and contracts a lot with temperature and that demands loose clearances which rattle the piston till it gets warmed up. I would make an eductated guess that with your part choices, on an engine dyno this would show about 420 hp around 6000 RPM, while a sturdy output is by no means a race engine so I'd go with the 4032 alloy piston as they're plenty strong enough and won’t bring cold running problems of noise, fragging the skirts, and high blow by.