Cyl Head Comparison For A Stroker
Cyl Head Comparison For A Stroker Out of curiosity, how would a LS3 head compare to something like a TFS235 on a 40xci stroker given the same turbo, cam, intake, c.r., etc.?
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If you're looking for power potential when it comes to boost, the magic is in the amount of boost you run and not particularly in the head flow.
370 with aftermarket heads or 408 with 241 heads? Assuming budget doesn’t allow both.
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243 heads or aftermarket. Contrary to popular belief here, a good set of heads will actually help you more in a boosted application than a NA application. A high velocity large port head will help maximize air potential in the upper rpm range, which is where you want to freight train the non turbo guys. Contact Tony mamo, trickflow, afr, dart or whoever and ask them for yourself. They could also clean up some myths about compression as well.
243 heads or aftermarket. Contrary to popular belief here, a good set of heads will actually help you more in a boosted application than a NA application. A high velocity large port head will help maximize air potential in the upper rpm range, which is where you want to freight train the non turbo guys. Contact Tony mamo, trickflow, afr, dart or whoever and ask them for yourself. They could also clean up some myths about compression as well.
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Anyone who's going to follow up advice with a sales pitch is going to be biased.
On a 4-bolt block, deck thickness is about as important as flow numbers. You can hit basically any power goal with even most of the factory heads. The problem is going to be lifting the heads at some point, which will be your power limit. Thicker deck might extend that out a little further, but we're talking 1300-1500 horsepower territory. Below that, you can basically use what you have and be fine.
Blowers tend to need head flow more than turbochargers because of RPM limitations. Turbos can spin much faster and their RPM isn't a direct function of engine RPM, so a better flowing head will help more with power potential.
All of that said, stock LS3 heads are more than enough for 1000whp. Even the stock LS3 intake has been 1400 whp. Use good studs to keep the heads down
On a 4-bolt block, deck thickness is about as important as flow numbers. You can hit basically any power goal with even most of the factory heads. The problem is going to be lifting the heads at some point, which will be your power limit. Thicker deck might extend that out a little further, but we're talking 1300-1500 horsepower territory. Below that, you can basically use what you have and be fine.
Blowers tend to need head flow more than turbochargers because of RPM limitations. Turbos can spin much faster and their RPM isn't a direct function of engine RPM, so a better flowing head will help more with power potential.
All of that said, stock LS3 heads are more than enough for 1000whp. Even the stock LS3 intake has been 1400 whp. Use good studs to keep the heads down
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Lots of guys faster than I’ll ever be on 241 and 243 heads as well. The question isn’t whether $2500 plus heads are better than untouched 243’s, but rather can you make as much power with 243’s with more boost without spending $2500 on heads.
Up to a point, sure. Look at what Capazzi is running on 243's. Though his are ported, he is making more power than most with aftermarket heads. Last I looked he was on his 90th pass this year...so It's as reliable (if not more so) than most 1400+hp engine's IMO. Been doing full 1/4 and 1/8th passes on it as well. Leading me to believe the ability to keep the heads down is mostly in the tune and less a factor of deck strength and head fasteners. (not that I've had much luck keeping my heads down! )
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Boost is a double edged sword when it comes to head flow.
CFM and PSI have no relation to each other. A cubic foot of air is a cubic foot of air, it has no bearing on the mass of the air. 300 CFM at 2 Bar absolute is twice as much air as 300 CFM at 1 bar absolute.
If your heads flow enough to support 500 horsepower N/A, then they flow enough to support 1000 horsepower at 1 bar of boost, 1500 horsepower at 2 bar of boost, etc.
Cramming tons of extra pressurized air in there doesn't suddenly force the head to be a restriction unless it was a restriction N/A.
The double edge comes from the way CFM is measured on head flow. The flow bench creates a pressure differential to move air from one side of the port to the other.
When you see CFM ratings for flow benches, they usually show you how many inches of vacuum the test was done in. If its done at less vacuum, you'll see less CFM.
Boost increases the pressure differential. If you flow test a head going from ambient pressure to 28" vacuum, you'd get one number. Flow test a head going from 1 atmosphere above ambient down to 28" of vacuum, the numbers will be much higher because the port velocity is increased so much.
Basically, boost does magical things for head flow. The idea that heads can only support X amount of power when talking about boost is a misunderstanding. Power falling off up top usually has more to do with improper cam/valve events or intake/exhaust restrictions than how much air you're passing through the head.
CFM and PSI have no relation to each other. A cubic foot of air is a cubic foot of air, it has no bearing on the mass of the air. 300 CFM at 2 Bar absolute is twice as much air as 300 CFM at 1 bar absolute.
If your heads flow enough to support 500 horsepower N/A, then they flow enough to support 1000 horsepower at 1 bar of boost, 1500 horsepower at 2 bar of boost, etc.
Cramming tons of extra pressurized air in there doesn't suddenly force the head to be a restriction unless it was a restriction N/A.
The double edge comes from the way CFM is measured on head flow. The flow bench creates a pressure differential to move air from one side of the port to the other.
When you see CFM ratings for flow benches, they usually show you how many inches of vacuum the test was done in. If its done at less vacuum, you'll see less CFM.
Boost increases the pressure differential. If you flow test a head going from ambient pressure to 28" vacuum, you'd get one number. Flow test a head going from 1 atmosphere above ambient down to 28" of vacuum, the numbers will be much higher because the port velocity is increased so much.
Basically, boost does magical things for head flow. The idea that heads can only support X amount of power when talking about boost is a misunderstanding. Power falling off up top usually has more to do with improper cam/valve events or intake/exhaust restrictions than how much air you're passing through the head.
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This is a hard topic just because stock heads will get you there doesn’t mean there the best head for the job a friend of mine has a nitrous powered Camaro on stock ported heads with upgraded valves and valve spring it took around a 450 shot to get it to go 8.50s upgraded to aftermarket heads and port matched the intake first hit went 8.44 on a 300 shot so did the stock ones do the job? Yes but the aftermarket ones do it better and I’m sure will allow the bottom end to live a lot longer as a side effect
How do you figure it will help anything live longer? It takes X amount of power to move Y amount of weight Z distance, period. If that power is made with more nitrous/boost or a better head... it makes no difference. Wear and tear will pretty much be the same assuming the tune is correct.
In the case of a turbo setup... The turbo is already there, why not use it? If you have the a charger large enough to do the job, why not turn the **** up instead of spending more money to reach the same end goal on an aftermarket head and less boost?
In the case of a turbo setup... The turbo is already there, why not use it? If you have the a charger large enough to do the job, why not turn the **** up instead of spending more money to reach the same end goal on an aftermarket head and less boost?
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This is a hard topic just because stock heads will get you there doesn’t mean there the best head for the job a friend of mine has a nitrous powered Camaro on stock ported heads with upgraded valves and valve spring it took around a 450 shot to get it to go 8.50s upgraded to aftermarket heads and port matched the intake first hit went 8.44 on a 300 shot so did the stock ones do the job? Yes but the aftermarket ones do it better and I’m sure will allow the bottom end to live a lot longer as a side effect
N/A, head flow is a MAJOR factor. Aftermarket heads are a must in a lot of situations. Boost is different.
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From: Norn Iron
And if you went for the 408 now...you could upgrade to better heads at a later date.
Although why would the base motor 370 vs 408 really cost any different that you couldnt run the good heads on either ?
The simple answer.....area under the curve. Whichever will give you the most, and as a street car presumably you'd want more torque for daily use etc ?
And if you went for the 408 now...you could upgrade to better heads at a later date.
Although why would the base motor 370 vs 408 really cost any different that you couldnt run the good heads on either ?
And if you went for the 408 now...you could upgrade to better heads at a later date.
Although why would the base motor 370 vs 408 really cost any different that you couldnt run the good heads on either ?
What kind of power are you targeting and at what weight? If you are using an OEM small block, I don’t see why anyone would bore or stroke one with “big power goals”. You are sacrificing a ton of strength for minimal power gains.
If you want power under the curve, use a top end and turbo that is suitable to that goal on a factory bore/stroke. If you want peak numbers for a drag car... do the opposite. If you want it all, buy an aftermarket block or start with a more stout block to begin with. (Big Block)
If you want power under the curve, use a top end and turbo that is suitable to that goal on a factory bore/stroke. If you want peak numbers for a drag car... do the opposite. If you want it all, buy an aftermarket block or start with a more stout block to begin with. (Big Block)