Is there a limit to head flow
Posted: Fri Jan 18, 2008 2:25 pm
Let me first thank BigJoe, for the help he gave me on the phone a while back, but the more I thought about what he said, the more questions came up, so I thought I would just post a few of them. I am a long time watcher, bought the pipe max program which caused more questions.
Let me set it up you can see my car in this months March HotRod page 50 SB/NA Drag Week Winner
Motor is: a 427 sbc 4.0 by 4.125 flat top 11.3 to 1, 6 inch rod comp stars, callies crank, world block, wet sump, 1050 Pro Systems dom 95 jets.
Heads are done by Curtis at RFD they are 18x's because of the 68 cc chambers to get comp down they have the push rod pinch fixed and flow 360 at .700 and up to .800 on RFD's flow bench.
Comp cam : Part # 12-000-14 SN# K 9849-07
CS 47s special roller
Grind # CS47 4418s/ 4055s R 114 4/7 .900
Gross Valve lift 704 Intake 672 Exhaust
Duration at Tappet @ 020 307 Intake 332 EXhaust
Valve timing open @050 24 BTDC 80 ABDC
close 73 BBDC 31 ATDC
Measured at Installed 114 Intake center line
I E
Duration @50 277 291
Lobe Lift 414 420
114 lobe sep.
Rockers are Crane shaft 1.7 Intake 1.6 Exhaust
It's installed at 110* intake centerline 4/7 swap
38* timing
Car is a 1980 Malibu stock susp, 4.30, gear turbo 400, 5,200 A-1 conv., msd 7 digital, 3050 with driver, Trans brake.2 inch to 2 1/8 into 4 inch collectors 4 inch all the way out. I race open headers.
Has Drag Radials 28 inches tall, would like to stay around 7000 to 7200 Peak HP rpm its has to be on pump gas and drive down the highway 1500 miles in one week , I won this year with a 9.95 @ 134 I just feel its more of a N2O cam with the exhaust lobe and duration
Is there a limit to the head flow you need in a 11.3 to 1 motor (pump gas 210 psi cranking) I limit myself to .700 lift I could run more if it will live. I dont care how it idles, just so it runs at the track.
I am looking for a different cam. I would like to lower my RPM some down to a peak TQ at 5,000 its now at 5800 395 flat to 6400 on a Mustang chassis dyno and peak HP is 7500 462 but is flat to there from 6100. I now launch at 5000 off the brake and shift at 7800 2nd, 7600 third cross at 7500. I know there is more power to be had I think the cam is the problem. I also have some of Curtis's 12-13 degree heads that flow over 420 at .700
so am I better to fit them to what I am doing keeping in mind the comp ratio or what I have, if I need a cam, I need to know which flowing head is better for the 5000 to 7000 RPM I would like to run. I think those are to much head for this motor.
I have bought several (4 - $400.00) "Vodoo cams" this one above being the last of the just trust me, I wont let you know what it is till I get paid ones.
I wont be buying another one of those, Ed Wilson, Curtis and maybe BigJoe will vouch for me not being the nut this post makes me seem, just getting frustrated with this motor and cam stuff. Any question I will be happy to respond to if I can answer, dont have my other flow # from Curtis yet on the 18X's
Let me set it up you can see my car in this months March HotRod page 50 SB/NA Drag Week Winner
Motor is: a 427 sbc 4.0 by 4.125 flat top 11.3 to 1, 6 inch rod comp stars, callies crank, world block, wet sump, 1050 Pro Systems dom 95 jets.
Heads are done by Curtis at RFD they are 18x's because of the 68 cc chambers to get comp down they have the push rod pinch fixed and flow 360 at .700 and up to .800 on RFD's flow bench.
Comp cam : Part # 12-000-14 SN# K 9849-07
CS 47s special roller
Grind # CS47 4418s/ 4055s R 114 4/7 .900
Gross Valve lift 704 Intake 672 Exhaust
Duration at Tappet @ 020 307 Intake 332 EXhaust
Valve timing open @050 24 BTDC 80 ABDC
close 73 BBDC 31 ATDC
Measured at Installed 114 Intake center line
I E
Duration @50 277 291
Lobe Lift 414 420
114 lobe sep.
Rockers are Crane shaft 1.7 Intake 1.6 Exhaust
It's installed at 110* intake centerline 4/7 swap
38* timing
Car is a 1980 Malibu stock susp, 4.30, gear turbo 400, 5,200 A-1 conv., msd 7 digital, 3050 with driver, Trans brake.2 inch to 2 1/8 into 4 inch collectors 4 inch all the way out. I race open headers.
Has Drag Radials 28 inches tall, would like to stay around 7000 to 7200 Peak HP rpm its has to be on pump gas and drive down the highway 1500 miles in one week , I won this year with a 9.95 @ 134 I just feel its more of a N2O cam with the exhaust lobe and duration
Is there a limit to the head flow you need in a 11.3 to 1 motor (pump gas 210 psi cranking) I limit myself to .700 lift I could run more if it will live. I dont care how it idles, just so it runs at the track.
I am looking for a different cam. I would like to lower my RPM some down to a peak TQ at 5,000 its now at 5800 395 flat to 6400 on a Mustang chassis dyno and peak HP is 7500 462 but is flat to there from 6100. I now launch at 5000 off the brake and shift at 7800 2nd, 7600 third cross at 7500. I know there is more power to be had I think the cam is the problem. I also have some of Curtis's 12-13 degree heads that flow over 420 at .700
so am I better to fit them to what I am doing keeping in mind the comp ratio or what I have, if I need a cam, I need to know which flowing head is better for the 5000 to 7000 RPM I would like to run. I think those are to much head for this motor.
I have bought several (4 - $400.00) "Vodoo cams" this one above being the last of the just trust me, I wont let you know what it is till I get paid ones.
I wont be buying another one of those, Ed Wilson, Curtis and maybe BigJoe will vouch for me not being the nut this post makes me seem, just getting frustrated with this motor and cam stuff. Any question I will be happy to respond to if I can answer, dont have my other flow # from Curtis yet on the 18X's