HOT ROD head comparison (cathedrial vs square)
10-20-2010, 08:47 PM
#23
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They said they were going to do a follow up test with the LS3 / LS7 heads which would be real interesting. I always thought L92 heads needed a different cam so I was surprised to see them do so well.
10-20-2010, 08:50 PM
#24
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Glad to see some numbers showing that the square port making power unlike a lot of people on her like to say
I think if this test was done on a larger bore you would really see the square port really start to shine.
I think if this test was done on a larger bore you would really see the square port really start to shine.
10-20-2010, 09:44 PM
#25
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Yes sir I have been saying it all along.....marketing has brain washed the masses....
Its ok to drink the kool-aid as long as Jim Jones didn't make it......
10-21-2010, 07:02 AM
#26
Nice to see a direct comparison but kind of unfair to run 30 degrees of timing on ever head. Not all the combustion chambers use the same design and will make peak torque / hp at different levels of timing. 243 style heads normally make peak torque / hp around 23-25 degrees of timing, the TEA's could have made even more power. Than again every head could have made more power. Either way it goes to show a certain amount of airflow will support X amount of C.I. at a given rpm to make similar HP (within 10). Basically a 40x CI engine's airflow requirements are easily supported at 6500 rpm by most of these heads.
10-21-2010, 07:20 AM
#27
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Nice to see a direct comparison but kind of unfair to run 30 degrees of timing on ever head. Not all the combustion chambers use the same design and will make peak torque / hp at different levels of timing. 243 style heads normally make peak torque / hp around 23-25 degrees of timing, the TEA's could have made even more power. Than again every head could have made more power. Either way it goes to show a certain amount of airflow will support X amount of C.I. at a given rpm to make similar HP (within 10). Basically a 40x CI engine's airflow requirements are easily supported at 6500 rpm by most of these heads.
Could the weaker bottom end drops around 3000-3400rpm be contributed to no time consuming tuning?
10-21-2010, 07:28 AM
#28
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Over the stock 241 heads, that is a difference of 52-79 hp which is although a big difference. If not counting the World Products 255 heads, the difference is only 63-79hp over the 241's for the other 9 heads tested.
Last edited by camz28arro; 10-21-2010 at 07:33 AM.
10-21-2010, 11:25 AM
#29
This shows what a lot of us already knew...good heads are all very close in power production...this includes the square port heads. This is also why very few head swaps are just that; when someone is trumpeting their brand of heads. What I mean is the head swap always involves thinner gaskets, higher compression, port matched intakes, larger intakes, larger throttle bodies, better intake tracts-filters, steeper intake valve seat angle, better exhaust, different camshaft, bore matched chambers, lighter thinner headed valves, better valvesprings, pushrods, rocker arms, etc. The reason this arguement is so good is that everyone is mostly right. So get the most bang for your buck on heads suitable for your application and optimize everything else...cause "everything else" will get you a lot more hp than the heads themselves.
10-21-2010, 02:50 PM
#30
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If you get to see the whole article, look at Average and Average horsepower figures. They are much closer together than the max hp and torque numbers. Shoot, some are so close they are within the testing accuracy of the dyno facility.
Now look at the measured flows (by the testers, not the suppliers) of the heads. Using .600 or .650 lift would be a fair way to compare max flow with lift in the .640 range on the test engine. Flow numbers varied a ton from one head to another, but output did not. To me that was the most interesting part of the test.
I kinda wish they had run a stock LS6 head with the same 64 cc chamber size as all the rest. I was also surprised how well the stock LS1 head did on a 408.
As far as I can tell, this was a fairly run test.
Jon
Now look at the measured flows (by the testers, not the suppliers) of the heads. Using .600 or .650 lift would be a fair way to compare max flow with lift in the .640 range on the test engine. Flow numbers varied a ton from one head to another, but output did not. To me that was the most interesting part of the test.
I kinda wish they had run a stock LS6 head with the same 64 cc chamber size as all the rest. I was also surprised how well the stock LS1 head did on a 408.
As far as I can tell, this was a fairly run test.
Jon
10-21-2010, 04:14 PM
#31
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Glad you guys liked the story. I did, too, and Richard Holdener killed himself doing it. And I have part 2 on my desktop as I type this...it's the test of all the rec-port heads. The first test was all cathedral-ports except the Mast units. I was stunned how the power output changed almost not at all regardless of port cross section, cc, or flow.
BTW, timing sweeps were executed on each head, and they all seemed to want 30.
The next story on the rec ports is with a 468ci motor.
BTW, timing sweeps were executed on each head, and they all seemed to want 30.
The next story on the rec ports is with a 468ci motor.
10-21-2010, 06:26 PM
#34
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This shows what a lot of us already knew...good heads are all very close in power production...this includes the square port heads. This is also why very few head swaps are just that; when someone is trumpeting their brand of heads. What I mean is the head swap always involves thinner gaskets, higher compression, port matched intakes, larger intakes, larger throttle bodies, better intake tracts-filters, steeper intake valve seat angle, better exhaust, different camshaft, bore matched chambers, lighter thinner headed valves, better valvesprings, pushrods, rocker arms, etc. The reason this arguement is so good is that everyone is mostly right. So get the most bang for your buck on heads suitable for your application and optimize everything else...cause "everything else" will get you a lot more hp than the heads themselves.
10-21-2010, 07:10 PM
#35
This was well done, if I would have wanted anything different it would have been to try two different cams with all these heads. The cam used has a pretty decent split, I would like to see how the power would have been with a cam in the same size category but with a 3 or 4 degree split.
Probably just me..
Probably just me..
10-21-2010, 08:02 PM
#36
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If you get to see the whole article, look at Average and Average horsepower figures. They are much closer together than the max hp and torque numbers. Shoot, some are so close they are within the testing accuracy of the dyno facility.
Now look at the measured flows (by the testers, not the suppliers) of the heads. Using .600 or .650 lift would be a fair way to compare max flow with lift in the .640 range on the test engine. Flow numbers varied a ton from one head to another, but output did not. To me that was the most interesting part of the test.
I kinda wish they had run a stock LS6 head with the same 64 cc chamber size as all the rest. I was also surprised how well the stock LS1 head did on a 408.
As far as I can tell, this was a fairly run test.
Jon
Now look at the measured flows (by the testers, not the suppliers) of the heads. Using .600 or .650 lift would be a fair way to compare max flow with lift in the .640 range on the test engine. Flow numbers varied a ton from one head to another, but output did not. To me that was the most interesting part of the test.
I kinda wish they had run a stock LS6 head with the same 64 cc chamber size as all the rest. I was also surprised how well the stock LS1 head did on a 408.
As far as I can tell, this was a fairly run test.
Jon
10-21-2010, 09:32 PM
#37
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Cam, intake and exhaust do not sell heads. Flow numbers sell heads to many (most?) people. Double Ds hanging around the navel are big numbers and appeal to many, but a nice B may be a better performer, if ya' get my drift.
I don't think there was much holding the power back for what the mule engine was. 185 psi BMEP at power peak rpm isn't bad for a non-optimised combination. With everything optimised, but using the same intake, you might see 195-200 psi BMEP at power peak rpm (~6500). That would be 650-670 peak hp. To get substantially more hp you need rpm and a shorter runner (e.g. single plane) manifold.
A plug to HRM: With three years of mags for less than the cost of a mediocre bottle of bourbon and with articles like this one and their Bonneville coverage, they are the best of their genre, IMO.
I lked the cover blurb: "STUNNING RESULTS! 11 NEW LS HEADS TESTED". The "stunning" part was the virtually equal performance of 10 of them. The 11th (stock LS1) was fairly surprising in it's own way.
Jon
10-21-2010, 09:48 PM
#38
Moral of this story could be to spend your money on cubes and cams since they seem to be what really controls how much power you make.
Granted, the torque cruves all sounded pretty different, and I'd prefer the heads that make the same power up top, but also give great low to mid range power, which is the MAST heads. They made the highest torque at 3000rpm and also kept up at peak torque/peak horsepower.
Granted, the torque cruves all sounded pretty different, and I'd prefer the heads that make the same power up top, but also give great low to mid range power, which is the MAST heads. They made the highest torque at 3000rpm and also kept up at peak torque/peak horsepower.
