383 piston choices- need help

[72chargerguy]

OK, so I finally got my heads for the 383 build. Here is the run down so far-

'69 383 hp block, .030 over
stock crank
Eagle H-beam rods
Edelbrock Victor heads
Edelbrock Victor intake
Lunati valve train
Lunati mechanical roller .600 lift in & ex
Milodon pan and oiling system

So here's the real question- do run the old set of TRW forged 12.5:1 pistons or get a new set of pistons that have way less compression? This is a street-strip motor, but I am really tempted by the 700 hp potential of the 12.5s. I know they are heavy, but what do you guys think? The pistons are used and have some detonation scars. If I drop to 9.5:1, the power will drop to around 630. I am looking for 9s in my '74 scamp, and 700 hp would just about do it. what do you guys think?

 

[moper]

I dont think you'll see anywhere near that figure out of a 383 block with a stock stroke and crank. I do not believe the 2.20 intake valves will clear the bore on a 383. Also, the power band of a small cube engine running those heads will be peaking at 8K rpm or higher and steel rods are not the best idea. Never mind heavy steel rods and a stock factory crank. Have yo researched the issues with building 383s as far as pistons go? 700hp on the battleship TRWs? In a factory block? Not a chance in my opinion.

 

[72chargerguy]

of course these numbers are hypotheticals, but that is what my desktop dyno software is coming up with. 705 hp at 7500. Are you saying the valves won't clear the cylinder bores? I have built two engines that I estimated with the desktop dyno software, and both were within 10 hp on the dyno.

 

[moper]

What were the engines that were that close? What does it predict for torque numbers? I'm going to say I'd bet they were not big HP builds like this one. 1.9hp/inch is not easy to get.
I'm saying I'm pretty sure they will hit, yes. I'm also saying that on the off chance they dont hit, they will be shrouded beyond belief. I'm also sure a N/A 383 at 700hp and a stock block and crank is a time bomb, dyno or no.

 

[72chargerguy]

They were both 400+ engine builds- a Buick 350 and 302. If it blows up, it blows up. I will check everything for clearance, but those heads are supposed to fit the 383. Hot Rod used them with no issues on .060" block. my block is .030"

 

[dusterdon]

I have a similar engine going together now. 383 +.030. I found a new set of the TRW 12.5's for mine. I'm going to use iron heads (uncut) and a steel head gasket. Figures out to 10.7:1 compression. Running a Comp solid Extreme Energy, TTi's, RPM intake . Heads are Muscle Motors stage 1. According to the dyno programs I've played with it whould be in the 520-540 hp ballpark. Coupled with a 150 shot and we should have a decent runner.

 

[Babyblue66]

Call up Ross or JE and have some custom pistons made. The only way to go in my opinion.