383 pistons
Thread Starter
Racer
Joined: Oct 2002
Posts: 416
Likes: 2
From: Westfield MA
383 pistons
I need some advice on what pistons to use in the 383 I am putting together. It will be a "mild" daily driver retaining the stock TPI and 58cc stock alum. heads. I noticed most of the 383 kits have pistons that are rated at 10 to 1 or higher when using 58cc heads. My GM service manual lists the ratio at 9.0 to 1 for my '87 coupe. I don't want to have problems with detonation. The only pistons I have found that are close to 9.0 to 1 are K.B. 28cc dished. Any opinions? Thanks
Burning Brakes
Joined: Apr 2000
Posts: 1,145
Likes: 1
Re: 383 pistons (SS409 425HP)
Most people here are going to tell you that 10:1 and even higher is not a problem with an aluminum head. I am shooting for 10.5:1 on my 383 and am using a KB hyperuetectic pop-up that was machined to give me the correct compression with a 74 CC head. It is now almost a flat top, but not quite.
Chris
Chris
Instructor
Joined: Mar 2002
Posts: 181
Likes: 0
From: Allen TX
Re: 383 pistons (SS409 425HP)
You may want to read this thread as well...
http://forums.corvetteforum.com/zerothread?id=491862
Your camshaft choice also plays a role in the amount of "compression" that your engine can tolerate.
This URL : http://www.flatlanderracing.com/ has a large selection of pistons SRP/KB/etc. with a listing of static compressions vs combustion chamber size. You should be able to build a 383 with "off the shelf" pistons with a static compression anywhere between 9.0 and 12.0.
See ya,
John
http://forums.corvetteforum.com/zerothread?id=491862
Your camshaft choice also plays a role in the amount of "compression" that your engine can tolerate.
This URL : http://www.flatlanderracing.com/ has a large selection of pistons SRP/KB/etc. with a listing of static compressions vs combustion chamber size. You should be able to build a 383 with "off the shelf" pistons with a static compression anywhere between 9.0 and 12.0.
See ya,
John
Safety Car
Joined: Aug 2000
Posts: 3,909
Likes: 26
From: Clymer PA
Re: 383 pistons (SS409 425HP)
Around 10.5 to with cast iron heads works fine (that's what I'm running), even in the hottest heat I have never experienced detonation. Everyone will tell you that it's too much compression for a street car but mine runs fine with 93 octane. With aluminum heads you can run around 11:1 and not have detonation simply because the aluminum heads dissipate more heat.
