Questions about Forged 383 build
10-10-2007, 11:17 AM
#1
Questions about Forged 383 build After months of trying to diagnose a top-end misfire and replacing the opti and then switching to a delteq set up I finally decide to rip apart the block only to find shrapnal in the timing cover and to find the crank had definately been walking. I also found that the crank balancer was junk. So now im going with a forged bottom end with AFR 227 76cc Race ready heads and a custom grind cam. I will be shooting for 10-11 CR too. I will also be spraying a 200-300 shot of nitrous through a holley throttle body. Here are the questions I have.
1. Do I have to step up from Pacesetter headers to a 1 7/8 header to accomodate the AFR's?
2. Do I need to use shaft mount rockers on the heads instead of the studs?
3. I want to go big on the cam but how much is too much?
If there is anything else I will need to know about this set up please share your insight.
1. Do I have to step up from Pacesetter headers to a 1 7/8 header to accomodate the AFR's?
2. Do I need to use shaft mount rockers on the heads instead of the studs?
3. I want to go big on the cam but how much is too much?
If there is anything else I will need to know about this set up please share your insight.
10-10-2007, 06:20 PM
#2
To sucessfully run those heads I hope you are going to a LARGE displacement aftermarket block and spinning beyond what the pcm will allow, that compression is way low for a NA/nitrous build too.
You are heading in a VERY bad direction here. You have an extreme case of "bigger is better" mentality and it will result in a slow car for the effort and money poured into it.
If staying 355-383ci and below the 7200rpm pcm hard limit then you will be BETTER off to send your stock heads out to be ported or better yet get the earlier aluminum stock heads and have them ported.
You are heading in a VERY bad direction here. You have an extreme case of "bigger is better" mentality and it will result in a slow car for the effort and money poured into it.
If staying 355-383ci and below the 7200rpm pcm hard limit then you will be BETTER off to send your stock heads out to be ported or better yet get the earlier aluminum stock heads and have them ported.
10-10-2007, 09:31 PM
#3
What is making you think I need to go with a "LARGE displacement aftermarket block" ? Also, how do you figure that 11 CR is too low and why would I have my stock heads ported for $800 plus the cost of new valves when i can buy Fully assembled LT4 AFR 227's that kill stock heads in flow numbers for $1500? Im not stuck in the "bigger is better" mentality but evaluating my long term goals for the car. Why spend $1000+ on stock ported heads when in 2 years im going to want to go bigger?
10-11-2007, 12:05 AM
#4
To sucessfully run those heads I hope you are going to a LARGE displacement aftermarket block and spinning beyond what the pcm will allow, that compression is way low for a NA/nitrous build too.
You are heading in a VERY bad direction here. You have an extreme case of "bigger is better" mentality and it will result in a slow car for the effort and money poured into it.
If staying 355-383ci and below the 7200rpm pcm hard limit then you will be BETTER off to send your stock heads out to be ported or better yet get the earlier aluminum stock heads and have them ported.
You are heading in a VERY bad direction here. You have an extreme case of "bigger is better" mentality and it will result in a slow car for the effort and money poured into it.
If staying 355-383ci and below the 7200rpm pcm hard limit then you will be BETTER off to send your stock heads out to be ported or better yet get the earlier aluminum stock heads and have them ported.
thanks
10-11-2007, 06:04 PM
#5
The early heads are thicker and offer more room for porters to work with.
Well you clearly aren't going to listen to me so maybe you will listen to AFR themselves.
AFR even states the 227cc heads are good for racing engine running 4500rpms and higher.
Even the 210s they seem reluctent to say for highly modified street cars.
The only "LT1" I know of sucesfully using AFR 227s is a Donovan aluminum block converted to everything LT1, waterpump and opti included. 434ci fed 15psi from a blower, one hell of a fast car, it aint something that 99% of us will ever own though. Been invited to the Pump Gas Drags 2 years in a row, not a normal application by any stretch, would call it a somewhat streetable race car, seen it make a Dairy Queen run in 90 someodd degree heat, has run low to mid 9s at 4500lbs and once the custom 13" wide wheels show up he is hoping for 8s.
He is building a milder blower motor for a friend and went with AI ported stockers because for this street/strip application it was a better choice.
Just because something works wonderfully on a race car does not mean it will work on the street.
Well you clearly aren't going to listen to me so maybe you will listen to AFR themselves.
AFR even states the 227cc heads are good for racing engine running 4500rpms and higher.
Even the 210s they seem reluctent to say for highly modified street cars.
The only "LT1" I know of sucesfully using AFR 227s is a Donovan aluminum block converted to everything LT1, waterpump and opti included. 434ci fed 15psi from a blower, one hell of a fast car, it aint something that 99% of us will ever own though. Been invited to the Pump Gas Drags 2 years in a row, not a normal application by any stretch, would call it a somewhat streetable race car, seen it make a Dairy Queen run in 90 someodd degree heat, has run low to mid 9s at 4500lbs and once the custom 13" wide wheels show up he is hoping for 8s.
He is building a milder blower motor for a friend and went with AI ported stockers because for this street/strip application it was a better choice.
Just because something works wonderfully on a race car does not mean it will work on the street.
10-11-2007, 06:20 PM
#6
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Hopefully your not going to spray 300 thru the factory intake. Hopefully your not using the holley nos throttlebody.
When spraying a big shot thru the LT1 intake most of the nitrous ends up in the rear cylinders.
When spraying a big shot thru the LT1 intake most of the nitrous ends up in the rear cylinders.
10-11-2007, 10:04 PM
#7
I have to agree with 96capricemgr - even when on the other board we may disagree 
Your parts list (with a 383 shortblock) is looking full race starting with the heads.
It sounds like you want serious power with adders so probably more than ported stock heads are in order to allow future room to grow..
I'd call AFR - tell them your c.i.d. car weight, rpm limt, rear gears/tires, intended use and quarter mile time - and most of all, budget.
They can best suggest which head/cam/header tube combo will get you there without breaking your motor or wallet.
Good luck.
Your parts list (with a 383 shortblock) is looking full race starting with the heads.
It sounds like you want serious power with adders so probably more than ported stock heads are in order to allow future room to grow..
I'd call AFR - tell them your c.i.d. car weight, rpm limt, rear gears/tires, intended use and quarter mile time - and most of all, budget.
They can best suggest which head/cam/header tube combo will get you there without breaking your motor or wallet.
Good luck.