Hamilton Cams
ignorant
- Joined
- Jun 28, 2007
- Messages
- 2,639
I have had every Tom, Dick and Harry in the last few months, call and tell me that their head outflows our casting.
In any case I thought it was timt to do a little splainin on the heads. Flow bench numbers are like Dynos, they mean absolutely nothing unless they are calibrated to each other, and even then there is room for discrepancy. Let's face it, these are tough times. In tough times, people will say what they need to get by. If my head flows 228 CFM out of the Box, their stock ported head will flow 250+. A few things to note on this scenario. 1. people lie. Don't believe everything you hear and half of what you see. 2. Flow benches are all over the place, flow numbers usually only are meaningfull when they are a comparison of two heads on the same bench with the same operator.
3. Just because a head flows 300cfm at .700" lift doesn't mean you will see any gain out of it. A head that flows well at high lift like that is probably a pretty fat port. Fat ports are lazy at lower lifts. With all of that port volume, the air velocity takes a second to respond. Add low compresion and it will be even lazier. What, you only have a cam that produces .400" lift at the valve? You are wasting your time worring what is happening at .800".
4. If you do have a legitimate head that flows big at .800", and you don't care that it is lazy under 3,000RPM and is a pig on the street, it is a nickels worth of material from being a boat anchor because of the thin port walls. Spent 3-5k on it and at any moment it could be worth zilch, zero, nada, a big goose egg.
Long story short, a flow number on one of our heads will never compete against a fluffed flow number from a porting guy down the road. We put a lot or time and work into the head we sell. You will see a higher velocity in our head than a given head that has been ported. That will mean better flow and a wider power range. If you do decide to take it to the limit, you will not have to worry about port wall thickness as much as with a stocker.
Desired rpm range dictates duration, duration dictates maximum lift possible, maximum lift and rpm range together dictate a lot about the port and valve angle. Keep this in mind when building an engine. You are not racing flow benches, you are racing trucks. And keep in mind it takes a given CFM through the engine to make a given power. If you have a Hx35 and you think because you have our head you will have 1,000 Hp, you will be sorely dissapointed. Our head is not perfect for every application under the sun, but in most instances and with the correct combination of parts, it will have a definite advantage over most combinations with OE heads.
Use your head not your wallet.
Zach
In any case I thought it was timt to do a little splainin on the heads. Flow bench numbers are like Dynos, they mean absolutely nothing unless they are calibrated to each other, and even then there is room for discrepancy. Let's face it, these are tough times. In tough times, people will say what they need to get by. If my head flows 228 CFM out of the Box, their stock ported head will flow 250+. A few things to note on this scenario. 1. people lie. Don't believe everything you hear and half of what you see. 2. Flow benches are all over the place, flow numbers usually only are meaningfull when they are a comparison of two heads on the same bench with the same operator.
3. Just because a head flows 300cfm at .700" lift doesn't mean you will see any gain out of it. A head that flows well at high lift like that is probably a pretty fat port. Fat ports are lazy at lower lifts. With all of that port volume, the air velocity takes a second to respond. Add low compresion and it will be even lazier. What, you only have a cam that produces .400" lift at the valve? You are wasting your time worring what is happening at .800".
4. If you do have a legitimate head that flows big at .800", and you don't care that it is lazy under 3,000RPM and is a pig on the street, it is a nickels worth of material from being a boat anchor because of the thin port walls. Spent 3-5k on it and at any moment it could be worth zilch, zero, nada, a big goose egg.
Long story short, a flow number on one of our heads will never compete against a fluffed flow number from a porting guy down the road. We put a lot or time and work into the head we sell. You will see a higher velocity in our head than a given head that has been ported. That will mean better flow and a wider power range. If you do decide to take it to the limit, you will not have to worry about port wall thickness as much as with a stocker.
Desired rpm range dictates duration, duration dictates maximum lift possible, maximum lift and rpm range together dictate a lot about the port and valve angle. Keep this in mind when building an engine. You are not racing flow benches, you are racing trucks. And keep in mind it takes a given CFM through the engine to make a given power. If you have a Hx35 and you think because you have our head you will have 1,000 Hp, you will be sorely dissapointed. Our head is not perfect for every application under the sun, but in most instances and with the correct combination of parts, it will have a definite advantage over most combinations with OE heads.
Use your head not your wallet.
Zach
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