427ls7 vs 440tfs dyno graph
^^^^^What he said.
I believe they used both cams in both motors with negligible differences. I will have to go back and look. If so, it goes to show that the big splits for the LS3 heads may not be as important as though to be. Or it shows that cam timing at a certain point with both heads doesn't really matter because you can only cram so much air into the motor with the above stated restrictions to where the exhaust has enough time to evacuate it at a certain duration and split. Anything above and beyond that doesn't matter. I would have to analyze both cams to see how different their valve events were.
Here is an issue I just saw. They did the test on a 4.030" bore. The 2.165 LS3 intake valve is shrouded on anything less than a 4.060" bore. Not sure how much of a difference that makes. I also noticed both heads flow about the same up to .400 lift. That definitely helped the LS2 head. The CD (Coefficient of Discharge) of the LS3 head is really not all that good till .600 lift or so where it doesn't really matter any more. So the LS2 head is kicking the crap out of it as far as efficiency is concerned.
Edit: Just read both pages of he article and CD is explained in it. My bad.
I believe they used both cams in both motors with negligible differences. I will have to go back and look. If so, it goes to show that the big splits for the LS3 heads may not be as important as though to be. Or it shows that cam timing at a certain point with both heads doesn't really matter because you can only cram so much air into the motor with the above stated restrictions to where the exhaust has enough time to evacuate it at a certain duration and split. Anything above and beyond that doesn't matter. I would have to analyze both cams to see how different their valve events were.
Here is an issue I just saw. They did the test on a 4.030" bore. The 2.165 LS3 intake valve is shrouded on anything less than a 4.060" bore. Not sure how much of a difference that makes. I also noticed both heads flow about the same up to .400 lift. That definitely helped the LS2 head. The CD (Coefficient of Discharge) of the LS3 head is really not all that good till .600 lift or so where it doesn't really matter any more. So the LS2 head is kicking the crap out of it as far as efficiency is concerned.
Edit: Just read both pages of he article and CD is explained in it. My bad.
Last edited by Pray; Aug 31, 2014 at 07:44 AM.
I think they were using a 408. The OP is talking about a 427 and a 440. My comments are based off of a 416 with the larger bore and bigger CID. The OP's 427 LS7 headed car made 520rwhp/472rwtq peak. This can be achieved with just a cam, bolt-ons and no head work these days. Another 20-30 rwhp can be achieved with more overlap before touching the heads and torque curve can be beefed up with proper valve timing. OP's set up was finished in 2008. Cam timing for square port heads have progressed a long way since then. I still like cathedral heads and they have their place. But, I don't believe they are superior to square port heads on a bigger motor.
The intake manifold also plays a part in the torque curve and power band. The LS7 intake has shorter runners compared to cathedral headed intakes which is not conducive to low rpm torque production. However, it does allow for higher rpm peak. GM designed it this way knowing that the engine will see 7,000 rpm in stock form.
Ultimately, it comes down to matching parts properly. Choose the correct heads for the CID and understand the valve timing that works for that head style and intake manifold.
The intake manifold also plays a part in the torque curve and power band. The LS7 intake has shorter runners compared to cathedral headed intakes which is not conducive to low rpm torque production. However, it does allow for higher rpm peak. GM designed it this way knowing that the engine will see 7,000 rpm in stock form.
Ultimately, it comes down to matching parts properly. Choose the correct heads for the CID and understand the valve timing that works for that head style and intake manifold.
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Same scenario when I built my 416 in 06' or 7'. No FAST 102's. No sewer pipe intakes. No 100mm TB's. With cut out's, a 4" intake and ported FAST 102/100 I am sure it would have cracked the 600rw barrier.
Although I think part of your issue is your headers, compression ratio and exhaust duration. Your lobe separation could be hurting some also.
Although I think part of your issue is your headers, compression ratio and exhaust duration. Your lobe separation could be hurting some also.
i agree with the exhaust duration comment, but more would make driveability even worse... its already borderline as it is with this cam... any more unmannerly and i'd hate to drive it around town... as for compression i will prob mil the heads to 62cc at some point prob when i need new motor mounts... that should put me at 11.64 compression and 8.4 dcr... i've decided to stay n/a, before was undecided but doing procharger is a pita on my car and i don't like posi blowers for my setup so that's why i had the comp set for 11 was going to lower it to lower it to 10.4 and hit it with 10 psi if i decided to go boost later... only thing i'm worried about with doing 62cc is ptv and also if that cc will work with my 4.08 bore and 2.12 valves 
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That is an awfully weak big cam and header LS7 motor.... most with those modifications will make another 20-40 rwhp than shown. (I made more than that with my LS7 with a much milder cam (Torquer 110) and 100% stock exhaust, unported intake and tb)
Test doesn't seem right. I've discounted it personally just because of how low the LS7 output is as compared to others with similar modifications.
My old motor in the RX-7
427ci (4.125" bore/4" stroke) 11.25:1 compression
LS7 heads with stock size valves (Ti intake, s/s exh), dual springs
WCCH old CnC program from 2008 (exhaust clean up only)
LS7 intake mildly cleaned up, ZR1 injectors, 90mm cable TB
QM600 243/256" .650" lift cam
Straight shot style intake (no major bends)
1 7/8" long tube headers with standard stamped 3" collectors, dual 3" into single 3.5" and Magnaflow muffler
520rwhp/472rwtq peak (e85/91 e30 blend with added timing over 91 tune)
* 91 octane tune was 10rwhp peak less and 2rwtq peak less... but from 5Krpm-7K it carried the power longer before falling off
Test doesn't seem right. I've discounted it personally just because of how low the LS7 output is as compared to others with similar modifications.
My old motor in the RX-7
427ci (4.125" bore/4" stroke) 11.25:1 compression
LS7 heads with stock size valves (Ti intake, s/s exh), dual springs
WCCH old CnC program from 2008 (exhaust clean up only)
LS7 intake mildly cleaned up, ZR1 injectors, 90mm cable TB
QM600 243/256" .650" lift cam
Straight shot style intake (no major bends)
1 7/8" long tube headers with standard stamped 3" collectors, dual 3" into single 3.5" and Magnaflow muffler
520rwhp/472rwtq peak (e85/91 e30 blend with added timing over 91 tune)
* 91 octane tune was 10rwhp peak less and 2rwtq peak less... but from 5Krpm-7K it carried the power longer before falling off
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That is an awfully weak big cam and header LS7 motor.... most with those modifications will make another 20-40 rwhp than shown. (I made more than that with my LS7 with a much milder cam (Torquer 110) and 100% stock exhaust, unported intake and tb)
Test doesn't seem right. I've discounted it personally just because of how low the LS7 output is as compared to others with similar modifications.
Test doesn't seem right. I've discounted it personally just because of how low the LS7 output is as compared to others with similar modifications.
test seems plenty right to me... dynojets can vary up to as much as 40rwhp or more... that's just how dynos are... they are absolutely by no means a way to accurately compare hp to other cars tested on different dynos... dynos are for tunning, that's it... you're dyno was probably really happy
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From: San Francisco, CA
My motor went 111mph in the 1/8 mile and 138mph best in the 1/4.
T56, 2950lbs with driver at the time. e30 fuel mix
http://www.wallaceracing.com/et-hp-mph.php
The final numbers on the dyno don't matter.... its more the difference between the 2 motors as it is the same dyno.
I agree it isn't a great comparison as one is more cubes, has a FAST intake, and smaller port heads. And the QM600 cam is older technology than what is out now.
Does anyone else have a dyno of a 427 with LS7 heads vs. TFS or AFR style heads?
T56, 2950lbs with driver at the time. e30 fuel mix
http://www.wallaceracing.com/et-hp-mph.php
The final numbers on the dyno don't matter.... its more the difference between the 2 motors as it is the same dyno.
I agree it isn't a great comparison as one is more cubes, has a FAST intake, and smaller port heads. And the QM600 cam is older technology than what is out now.
Does anyone else have a dyno of a 427 with LS7 heads vs. TFS or AFR style heads?
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test seems plenty right to me... dynojets can vary up to as much as 40rwhp or more... that's just how dynos are... they are absolutely by no means a way to accurately compare hp to other cars tested on different dynos... dynos are for tunning, that's it... you're dyno was probably really happy
But, I do agree with you about dynos, they are simply tuning tools....
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Then everybody's dyno is happy, because you won't find a Z06 with Headers and a .650 lift - 24x/25x cam making just 520 rwhp......do some searching and you'll find that is well below the average for that combination.
But, I do agree with you about dynos, they are simply tuning tools....
But, I do agree with you about dynos, they are simply tuning tools....
vengeance's is the happiest by far at 32rwhp higher than the lowest one... that's a pretty big split and there is an even happier dyno in town where i'd make 550 lol... if i cared that much about numbers... maybe op's dyno was stingy?, but i still think that's about right for the ls7 heads and his mods, that ls7 prob make 550+ on vengeance's dyno if numbers are important?... i've run plenty of people that claim xxxhp more and show me a dyno sheet and then lost... numbers are just numbers, and everyone's dyno can be fiddled around with to some extent as well
For a comparison. My best MPH's with my 416 that made 573/530rw on what I would call a "stingy" dyno ran 107 1/8th and 138 1/4 at a little over 3,400lbs. But the car was really not set for drag racing. Stock gears, heavy beefed up trans, stock suspension, and a Tex Twin. The Tex twin was not known for it's slipping ability. IIRC my best 60ft was only a 1.52 or 1.55.
As long as you did the test on the same dyno that has been maintained then to me that is what really matters.
As long as you did the test on the same dyno that has been maintained then to me that is what really matters.
this is 3 different dynojets in my town... mods on my car are the same... just different dynos...
vengeance's is the happiest by far at 32rwhp higher than the lowest one... that's a pretty big split and there is an even happier dyno in town where i'd make 550 lol... if i cared that much about numbers... maybe op's dyno was stingy?, but i still think that's about right for the ls7 heads and his mods, that ls7 prob make 550+ on vengeance's dyno if numbers are important?... i've run plenty of people that claim xxxhp more and show me a dyno sheet and then lost... numbers are just numbers, and everyone's dyno can be fiddled around with to some extent as well
vengeance's is the happiest by far at 32rwhp higher than the lowest one... that's a pretty big split and there is an even happier dyno in town where i'd make 550 lol... if i cared that much about numbers... maybe op's dyno was stingy?, but i still think that's about right for the ls7 heads and his mods, that ls7 prob make 550+ on vengeance's dyno if numbers are important?... i've run plenty of people that claim xxxhp more and show me a dyno sheet and then lost... numbers are just numbers, and everyone's dyno can be fiddled around with to some extent as well
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vengeance didn't tune it, just brought it to their dyno day... my tuner is really conservative... he left it at 12 since it will lean out a bit on the street(12.3 or so) and also because of today's inconsistent fuel... no reason to lean it out for 5hp or so
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Go dig up the dyno graphs for the 454 that Brian Tooley built that had a TFS 245/ Fast 102 top end.... google search Thump on pump...
Then go dig up the info on that 472 inch motor that Nelson built that had Mast 305's on it...
Tooleys 454 outpowered the bigger motor everywhere except for peak horsepower... the 472 made just 7 ( yea just seven) more horsepower...
the 472 was down 25 lb feet of torque... and had a much more peaky curve... Tooleys 454 was above 600 for over 1800 rpm iirc.... the 472 was only above 600 for 500 rpm...
Then go dig up the info on that 472 inch motor that Nelson built that had Mast 305's on it...
Tooleys 454 outpowered the bigger motor everywhere except for peak horsepower... the 472 made just 7 ( yea just seven) more horsepower...
the 472 was down 25 lb feet of torque... and had a much more peaky curve... Tooleys 454 was above 600 for over 1800 rpm iirc.... the 472 was only above 600 for 500 rpm...
