Re: Head Flow vs HP
[Re: JACK1440]
#2189534
11/04/16 04:49 PM
11/04/16 04:49 PM
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Joined: Aug 2003
Posts: 43,718 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,718
Bend,OR USA
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If you use that formula with your size motors C.I. then it gets harder to make 2.0 HP per C.I. My pump gas 518 C,I. street stroker motor made a best of 775 HP with a set of CNC ported 440-1 heads that flowed 370 CFM, my 526 C.I. race gas bracket motor with the same heads and carb. made 845 HP missing due to the header flanges being to small for those heads It might have made another 5 to 20 HP , not near enough to get 2.0 HP per C.I. I've built and dyno tested several roots blown 426 Street Hemi type motors that both made over 2.0 HP per C.I. at or above 10 lbs. of boost
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Head Flow vs HP
[Re: Cab_Burge]
#2189636
11/04/16 08:44 PM
11/04/16 08:44 PM
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Joined: Oct 2011
Posts: 3,036 bean town ....Ca
WHITEDART
master
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master
Joined: Oct 2011
Posts: 3,036
bean town ....Ca
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If you use that formula with your size motors C.I. then it gets harder to make 2.0 HP per C.I. My pump gas 518 C,I. street stroker motor made a best of 775 HP with a set of CNC ported 440-1 heads that flowed 370 CFM, my 526 C.I. race gas bracket motor with the same heads and carb. made 845 HP missing due to the header flanges being to small for those heads It might have made another 5 to 20 HP , not near enough to get 2.0 HP per C.I. I've built and dyno tested several roots blown 426 Street Hemi type motors that both made over 2.0 HP per C.I. at or above 10 lbs. of boost I have 8 Second Time Slips at 3100 lb..in 4600ft air....I bet math is pretty close
In the 8s N/A.with Brett miller W8's 5.07 at 133 at 2700lb
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Re: Head Flow vs HP
[Re: 451Mopar]
#2189876
11/05/16 04:51 AM
11/05/16 04:51 AM
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Joined: Aug 2003
Posts: 43,718 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,718
Bend,OR USA
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Last edited by Cab_Burge; 11/05/16 03:11 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Head Flow vs HP
[Re: AndyF]
#2190211
11/05/16 07:12 PM
11/05/16 07:12 PM
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Joined: Oct 2011
Posts: 3,036 bean town ....Ca
WHITEDART
master
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master
Joined: Oct 2011
Posts: 3,036
bean town ....Ca
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Big engine with small heads causes a different problem so the 2 hp/cfm rule might not apply. There is also a velocity rule that has to be obeyed. If the velocity gets too high or is too low then the engine won't make 2 hp/cfm. Big engine with small heads has high velocity while a small engine with big heads has slow velocity. Either too fast or too slow will kill off the performance. there is no issue at all with having big heads on a small motor... as a matter fact you can't get a big enough.. Bob books small block mopar Motors at 400 cubic inch... have heads flowing close to 500 CFM....it is all about rpm ...and at 3hp per cubic inch.. I would say very impressive
In the 8s N/A.with Brett miller W8's 5.07 at 133 at 2700lb
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Re: Head Flow vs HP
[Re: JACK1440]
#2190656
11/06/16 01:13 PM
11/06/16 01:13 PM
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Joined: Oct 2007
Posts: 4,219 New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,219
New York
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WRT "there is no issue at all with having big heads on a small motor"
Ford made that mistake with the Boss 302, which won't pull the skin off a chocolate pudding. The cure: 351" by stroke increase. Harley-Davidson did the same thing with the K model in 1952: a 750cc twin with 1.56" intake ports, 50% larger than needed. The cure: 900cc by stroke increase.
Missing from the "cfm" rule: "as long as the minimum air speed in the required RPM range is about 200 f/s". Adjust the minimum depending on the application (LSR can be slower than oval). A 3" sewer pipe flows a lot of cfm, but useless on any automotive engine.
Boffin Emeritus
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Re: Head Flow vs HP
[Re: polyspheric]
#2190740
11/06/16 03:06 PM
11/06/16 03:06 PM
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Joined: Apr 2005
Posts: 2,128 Salt Lake City
camastomcat
top fuel
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top fuel
Joined: Apr 2005
Posts: 2,128
Salt Lake City
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WRT "there is no issue at all with having big heads on a small motor"
Ford made that mistake with the Boss 302, which won't pull the skin off a chocolate pudding. The cure: 351" by stroke increase. Harley-Davidson did the same thing with the K model in 1952: a 750cc twin with 1.56" intake ports, 50% larger than needed. The cure: 900cc by stroke increase.
Missing from the "cfm" rule: "as long as the minimum air speed in the required RPM range is about 200 f/s". Adjust the minimum depending on the application (LSR can be slower than oval). A 3" sewer pipe flows a lot of cfm, but useless on any automotive engine. I love your calculated responses Polysheric. You don't get enough credit here. Would love to talk with you about my stuff some time.
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Re: Head Flow vs HP
[Re: camastomcat]
#2190754
11/06/16 03:34 PM
11/06/16 03:34 PM
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Joined: Oct 2011
Posts: 3,036 bean town ....Ca
WHITEDART
master
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master
Joined: Oct 2011
Posts: 3,036
bean town ....Ca
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WRT "there is no issue at all with having big heads on a small motor"
Ford made that mistake with the Boss 302, which won't pull the skin off a chocolate pudding. The cure: 351" by stroke increase. Harley-Davidson did the same thing with the K model in 1952: a 750cc twin with 1.56" intake ports, 50% larger than needed. The cure: 900cc by stroke increase.
Missing from the "cfm" rule: "as long as the minimum air speed in the required RPM range is about 200 f/s". Adjust the minimum depending on the application (LSR can be slower than oval). A 3" sewer pipe flows a lot of cfm, but useless on any automotive engine. I love your calculated responses Polysheric. You don't get enough credit here. Would love to talk with you about my stuff some time. what did you gap your points at on your two examples.haha.. I don't think they had ignition valve spring or cam technology to take advantage of the heads
Last edited by WHITEDART; 11/06/16 06:12 PM.
In the 8s N/A.with Brett miller W8's 5.07 at 133 at 2700lb
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