"Big Cylinder Head Test Changes My Thinking On Low Rpm Torque"
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I watched that yesterday.
This is why you have to test.
What he just found out some of us knew 40 years ago.
A good big port beats a good small port every time.
A bad port is a bad port no matter what.
And, I’ll say it again. When using OE architecture area is KING. You can’t get enough of it.
Darin Morgan has said that several times across several formats.
Edit: I say this all the time. The perfect example of screwing up a build is using 240 TF heads on an engine over 400 inches. They are too small.
The TF 270 should be the starting head for any 400 plus CID big block Chrysler, yet TF sells the crap out of them.
For the small block a W2 head is the MINIMUM for 340 inches. MINIMUM. They take very little work for that displacement.
For the 4 inch stroke crowd a fully ported W2 is the MINIMUM if you want to make power. A well ported W5 is a better start.
The best option is the W7 head for the 4 inch stuff.
This is why you have to test.
What he just found out some of us knew 40 years ago.
A good big port beats a good small port every time.
A bad port is a bad port no matter what.
And, I’ll say it again. When using OE architecture area is KING. You can’t get enough of it.
Darin Morgan has said that several times across several formats.
Edit: I say this all the time. The perfect example of screwing up a build is using 240 TF heads on an engine over 400 inches. They are too small.
The TF 270 should be the starting head for any 400 plus CID big block Chrysler, yet TF sells the crap out of them.
For the small block a W2 head is the MINIMUM for 340 inches. MINIMUM. They take very little work for that displacement.
For the 4 inch stroke crowd a fully ported W2 is the MINIMUM if you want to make power. A well ported W5 is a better start.
The best option is the W7 head for the 4 inch stuff.
Yea I was wondering what his thought process was (and where did it come from) that this test disproved? Nothing here really shocked me either, making power anywhere is all about how much charge you can get into the cylinder. I would have liked to see the TrickFlow with the exact same cam with more like a 110/112 LCA as well as it flows so much better to prove/disprove that theory (my money is it would prove it). Engine Masters had a 440 that they did some mild porting on stock heads and it brought the torque curve up dramatically at low RPM.
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PRH
Well-Known Member
The thing with that scenario is, properly bowl porting factory 440 Mopar heads can show fairly substantial flow improvements with a minimal increase in runner volume.
So, they’re better, but hardly any “bigger”.
I've been noticing this for a while, everyone is always going about killing 318 bottom end and how you got to treat it with kid gloves or it will vanish, Which every dyno/build I've seen don't show that to be true with those and the results from other engines.
It's hard to gain a large amount low speed torque (idle-3000 rpm) for a given displacement besides a basic hop up over a low performance 2bbl engine. You would need like a 413 cross ram type setup which very impractical. But seem a little harder than a lot think it is to kill bottom end torque.
I really question how important is torque at those rpms, even with factory gears and stall how long do you spend under 3000 rpm's on a full throttle run, plus hp isn't very sensitive to torque changes at those rpm's, hp is 25% of torque at 1313 rpm and 50% of torque at 2626 rpm.
Richard did a similar test on 3 different engines. I agree with Richard final statement bigger heads allow smaller cams to make similar power as the other way around, so even if you lose some throttle response still more streetable than a big cam with a weak head.
It's hard to gain a large amount low speed torque (idle-3000 rpm) for a given displacement besides a basic hop up over a low performance 2bbl engine. You would need like a 413 cross ram type setup which very impractical. But seem a little harder than a lot think it is to kill bottom end torque.
I really question how important is torque at those rpms, even with factory gears and stall how long do you spend under 3000 rpm's on a full throttle run, plus hp isn't very sensitive to torque changes at those rpm's, hp is 25% of torque at 1313 rpm and 50% of torque at 2626 rpm.
Richard did a similar test on 3 different engines. I agree with Richard final statement bigger heads allow smaller cams to make similar power as the other way around, so even if you lose some throttle response still more streetable than a big cam with a weak head.
Plus I've been thinking that for a while about the exhaust port, if you look at 4.8l/5.3l LS heads the intake ports don't flow crazy numbers for the hp they can get from fairly small cams but the exhaust side flows very well, same our magnum heads.
I've noticed that with a lot of these porters to make factory type heads to work they'll generally sacrifice other aspects for volume.
It was interesting to learn from Darin, I think for Hemi super stock the crazy amounts of time and money spent to find more volume not for more peak hp but to get enough rpm over peak just for better shift points.
But this is where this test might poke a holes in conventual wisdom that smaller always fills better at lower rpm. I think it's not that hard to fill at lower speeds so it probably somewhat hard to F up.
Plus you look when adding a basic mild cam headers and 4 bbl to a low performance 2bbl engine they generally gain even down low showing they can use more airflow even down low.
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