boost psi vs head flow for 427
boost psi vs head flow for 427 Ok not sure how to word this
On a 427 engine in the perfect world how much would the heads need to flow so at 6k rpms and 7 rpms to fill the cylinders 100 percent?
SO X (maybe 350) cfm of head flow fills the cylinders 100% now put 15 psi of boost on that in perfect world would fill it to 200 %
Now a engine should make more power at a higher boost pressure cause the starting point of the cylinder pressure will be higher at what point is added head flow not worth its and just adding more psi benfits the hp goals more?
I keep hearing how boost means nothing its just a restriction which i agree to a point. But wouldnt a 427 with 350 cfm head at 30 psi make alot more power then a 427 with 700cfm heads at 15 psi?
Sorry about how badly worded this is. ill edit it if i can figure out how to ask the question more clearly.
On a 427 engine in the perfect world how much would the heads need to flow so at 6k rpms and 7 rpms to fill the cylinders 100 percent?
SO X (maybe 350) cfm of head flow fills the cylinders 100% now put 15 psi of boost on that in perfect world would fill it to 200 %
Now a engine should make more power at a higher boost pressure cause the starting point of the cylinder pressure will be higher at what point is added head flow not worth its and just adding more psi benfits the hp goals more?
I keep hearing how boost means nothing its just a restriction which i agree to a point. But wouldnt a 427 with 350 cfm head at 30 psi make alot more power then a 427 with 700cfm heads at 15 psi?
Sorry about how badly worded this is. ill edit it if i can figure out how to ask the question more clearly.
8 sec potential, 12 sec slip
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Basically, all that matters is cfm. Boost is a measurement of how much restriction the heads are. Regardless if its 20psi, or 10psi of boost, if your blower is outputting 1500cfm, your engine has no choice but to consume all that 1500cfm of air thats being forced into it. The boost is just a measure of head flow efficiency so thats why people say not to worry about it so much.
ummmm no.
ummmm no.
**From page 57 of the April 09 GMHTP**
According to the findings of Jason Haines from Lingenfelter Performance Engineering: "Cylinder head flow is not as critical on turbo applications as Jason has found that LS1, C5R, and LS7 heads make nearly the same power".... Thats pretty interesting stuff in itself...
According to the findings of Jason Haines from Lingenfelter Performance Engineering: "Cylinder head flow is not as critical on turbo applications as Jason has found that LS1, C5R, and LS7 heads make nearly the same power".... Thats pretty interesting stuff in itself...
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**From page 57 of the April 09 GMHTP**
According to the findings of Jason Haines from Lingenfelter Performance Engineering: "Cylinder head flow is not as critical on turbo applications as Jason has found that LS1, C5R, and LS7 heads make nearly the same power".... Thats pretty interesting stuff in itself...
According to the findings of Jason Haines from Lingenfelter Performance Engineering: "Cylinder head flow is not as critical on turbo applications as Jason has found that LS1, C5R, and LS7 heads make nearly the same power".... Thats pretty interesting stuff in itself...
can you send me that artical?
please
Head flow is head flow. The more you can use the more power you will make. Take heead y that flows 270cfm and put it on an engine. You may make 500 hp at 7lbs of boost. Take head x that flows 340cfm and put it on the same engine. It may still make 500hp, but at 4psi. This argument has been covered a lot on here if you search for any of the ls6, vic jr, fast, ls2 intake manifold comparisons.
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If a engine is at 100 percent VE with a 350 cfm head and make 500hp. Then 700hp at 7 psi
It should make more power at 15psi with a 350cfm head then a 700 cfm head at 7 psi
Cause you have a more dense mixture of a/f at 15 psi in the cylinder.
Cfm flow is only good to a point then the compressed amount should come in to play
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But there has to be a point where head flow doesn't matter as much as the boost psi.
If a engine is at 100 percent VE with a 350 cfm head and make 500hp. Then 700hp at 7 psi
It should make more power at 15psi with a 350cfm head then a 700 cfm head at 7 psi
Cause you have a more dense mixture of a/f at 15 psi in the cylinder.
Cfm flow is only good to a point then the compressed amount should come in to play
If a engine is at 100 percent VE with a 350 cfm head and make 500hp. Then 700hp at 7 psi
It should make more power at 15psi with a 350cfm head then a 700 cfm head at 7 psi
Cause you have a more dense mixture of a/f at 15 psi in the cylinder.
Cfm flow is only good to a point then the compressed amount should come in to play
If cylinder holds 1 cbf of air then it means nothing if the head flows 300 cfm at 7 psi. Cause engine will still make a lot more power with a head that flows 100 cfm at 15 psi cause the cylinder will have twice the amount of a/f. Which is a much denser mix.
FYI.........just because you can throw more boost at an engine....or the turbo can make more boost, does not mean your heads/motor can flow it, or make any more power with it. Regardless of the size turbo you have on it.
Why though this is kinda on the lines of what im asking. This is what i here but i cant understand it. IF IAT temps stay the same or close to the same adding PSI should make power and flow shouldnt matter cause cfm though ports will stay same but just a much denser mix flowing though
.
Why though this is kinda on the lines of what im asking. This is what i here but i cant understand it. IF IAT temps stay the same or close to the same adding PSI should make power and flow shouldnt matter cause cfm though ports will stay same but just a much denser mix flowing though
.
.
If this was not the case, I would be able to max out my turbo on the lt1 that I had.....but I can't. Nor can others with simmular set-ups......the just turn up the boost theory only goes so far....then your done. There is nothing to argue..you cant just keep turning it up to get more power...at some point...with out other mods, your done.
Last edited by otherwhitemeat; Mar 9, 2009 at 11:34 PM.