Well I'm not sure yet, but I think my motor may have finally had it and siezed. So with your help, it's time to start figuring out how I'm going to build my 383. I've got some questions.

I want to do an all forged, Turbocharged, 383 Stroker. I'll be running no more than 15psi boost on pump gas (Daily Driver!)

Here's what I'm thinking:

4043 eagle forged stroker crank
forged connecting rods ----------- not sure what kind
forged 2618 pistons -------------- not sure...
rings ---------------------------- not sure...
splayed center caps
stock ported heads
stiffer valve springs
ARP rod/head/main bolts or studs

I'm not sure as to what pistons or rods to use.
As I understand, you can use either 5.7" or 6" rods depending on the compression distance of the pistons being used?
I want a compression ratio of 9.0:1 to 9.5:1 so I'm thinking a 5.7" rod with a taller piston that has a taller ring land would be best, but I'm not sure.

Also what cc dish would give 9 to 9.5 compession with stock 54cc heads? 26cc dish?

I want to get some opinions, especially of the guys who have built (turbo) 383's.

 

Use good heads and lower the boost number. If a 383 is done well 15psi will be a HUGE amount of power. Boost is a measure of what is NOT getting into the engine, use good heads and power will come up while boost goes down.

Use a different crank Eagle is not that good.

www.advancedinduction.com is the best choice for ported stock heads and they offer Compstar rotating assemblies. I would suggest you get ahold of them for the heads, valvetrain and bottomend. Get as much as possible from one place and you have the best chance of it coming together as you want it too.

The Compstar stuff is far better quality than Eagle and the price difference is peanuts. If you are not familiar Compstar is Callies "budget" brand, machined here in the US(forged overseas), For $1800 you can buy forged Eagle rotating assembly that needs to be rebalanced at a cost of at least $150, for $2100 you can get the Compstar speedpack with Mahle pistons(better than what Eagle uses) balanced by Callies.

The forged Eagle stuff does not seem to actually break and in loose clearance race motors seems to last OK but there are dimensional issues that seem to cause problems on the street. It is just cheap chinese stuff, sure it often can work, but sometimes fails spectacularly and in this case the cost to go to MUCH better stuff is very little.

One of AI's customers put down a little over 1000rwhp with their 200cc heads on an admittedly Eagle 355 is a turbo car, no idea what the boost was but the cam is smaller than what most of us use in a stock shortblock heads/cam motor. Look on their results page.

 

Yeah, I understand what you mean, and I agree with you. Horsepower has nothing to do with how much "boost" you run. It has to do with the ammount of airflow through the engine. Using better flowing heads will increase the volumetric efficiency, therefore increase the amount of pressure that makes it into the cylinders, therefore increase the ammount of airflow. This will require less boost to make the same HP (airflow rate), as increasing boost pressure just increases flow.

It's definitely the way to go, but aftermarket heads are just so damn expensive.
It's easy enough to change later, so for now, I'm just going to port out my stock heads/intake and maybe use a stronger valve spring to help cope with the boost. I may look into a turbo-friendly camshaft, or I might just use the stock one, I'm still undecided. Any input? keep in mind this car must be completely streetable as it ismy daily driver.

Thanks for the tip on the crankshaft, I'm going to look into that for sure.


Does anybody have any input on rod/piston combinations?

 

I think stock heads are a great choice for most applications. They are dismissed WAY too quickly.
The over 1000rwhp example I gave was with ported stock heads.

The heads package I am suggesting comes with a cam.

The Compstar rods and cranks are available with pistons, believe Mahle is the first choice but there are others.

 

My goal is somewhere around 700 engine hp.

The main thing that worries me is getting a piston with a thick enough top ring land.

 

All blower designated pistons have that feature.

I know the results some have had with stock heads but what the stock heads don't have in this application is an appropriate sized combustion chamber. You have to make concessions eleswhere to achieve your CR.

 

Does anyone know what CR a -26cc dish piston will give in a 383 with the stock 54ish cc heads?

 

With a .010 deck, .027x4.040 Cometic gasket it is 9.9.

I bet if the chambers are ported but the head NOT milled beyond a cleanup though you could get 56 or so, bring it down to 9.7.

I knwo that still sounds high but consider 10.4:1 stock on 91 octane with terrible quench and I think this could work with the good quech I choose and good tuning and fuel. There are a lot of 12:1 NA LT1s out there wso this is low compression.

 

Aren't the guys running the -31cc dish pistons down at like 8.8:1? or are they also running larger heads?

 

https://www.camaroz28.com/misc/

There is a compression ratio calculator for download there.