Cathedral vs Ls3 test
10-24-2018, 05:59 PM
#41
TECH Senior Member
10-24-2018, 06:05 PM
#42
heres The thing. We all know the two heads need different cams, intakes etc etc....to perform optimal. But what I think would be more interesting is just see what the simple differences between just the heads only would be. Then if you really want to be particular, take the same shortblock. Not two similar ones. And then get the best heads you can for ls3 and cathedral and then get similarly species cams but tailored to the heads and then the best intake and headers and then go at it.
10-24-2018, 06:17 PM
#44
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Thread Starter
10-24-2018, 06:18 PM
#45
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Thread Starter
10-24-2018, 06:19 PM
#46
TECH Senior Member
I just saw the article. Just below the 5000 mark, it DOES appear to trade places with the cathedrals pulling stronger from there down, but since we can't see that part of the curve we can only assume that to be evident. That would follow common reasoning about cathedrals though. They are a better low-end power head.
10-24-2018, 07:29 PM
#51
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10-24-2018, 07:40 PM
#53
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my point is whether you have 350 or 400 ft\lbs of tq at 3000 rpm you aren’t even close to using it just driving around. Likely only using 150-200
10-24-2018, 08:59 PM
#54
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iTrader: (8)
Tq @ 6500 ftw
It don't take much to move a car so wot tq at 3k rpm really don't matter much.
10-25-2018, 06:56 AM
#55
Yeah if you want to be cool guy that shows off doing burnouts on the street, than the cathedral's few more ft lbs at 3000rpm maybe better. But if you want better chances at winning a street race, the torque at 6500rpm the Ls3 heads bring is likely the better choice. I'd rather win races than do donuts.
For me, it would make no difference having 350 ft lbs vs 400 ft lbs at 3500rpm on the street. I don't know about everyone else, but I've never started a street race at 3500 rpm. Why would anyone do that who knows better? Not sure why that extra 50 ft lbs at 3000rpm is so important to pass granny on the highway....? lol
For me, it would make no difference having 350 ft lbs vs 400 ft lbs at 3500rpm on the street. I don't know about everyone else, but I've never started a street race at 3500 rpm. Why would anyone do that who knows better? Not sure why that extra 50 ft lbs at 3000rpm is so important to pass granny on the highway....? lol
10-25-2018, 09:34 AM
#56
Most people favor more available torque at lower RPM for a streetcar since that is where it spends most of its time. That’s because when there is more torque at WOT, it takes less throttle opening and less RPM to get the same 150-200ft-lbs when you’re just driving around.
10-25-2018, 09:35 AM
#57
Yeah if you want to be cool guy that shows off doing burnouts on the street, than the cathedral's few more ft lbs at 3000rpm maybe better. But if you want better chances at winning a street race, the torque at 6500rpm the Ls3 heads bring is likely the better choice. I'd rather win races than do donuts.
For me, it would make no difference having 350 ft lbs vs 400 ft lbs at 3500rpm on the street. I don't know about everyone else, but I've never started a street race at 3500 rpm. Why would anyone do that who knows better? Not sure why that extra 50 ft lbs at 3000rpm is so important to pass granny on the highway....? lol
For me, it would make no difference having 350 ft lbs vs 400 ft lbs at 3500rpm on the street. I don't know about everyone else, but I've never started a street race at 3500 rpm. Why would anyone do that who knows better? Not sure why that extra 50 ft lbs at 3000rpm is so important to pass granny on the highway....? lol
10-25-2018, 10:33 AM
#59
The fairest evaluation of cathedral vs rectangular woild be full dyno graph from 2,500 to 7,500 with both heads having the same type of free flowing intake manifold that levels the manifold playing field so the heads are really what's evaluated.
Individual Throttle Body intake manifold.
Optimized cams for the heads & intake, same compression ratio say 11.5 to 1 or 12 to 1 (definitely not 87 octane friendly 9.8) and equivalent rocker arm ratios. In other words 1.8's on cathedral intake port. Ideally, several cams should be tested like optimized for drag race, road race, street - strip etc. List brake fuel consumption and vacuum at idle.
Show all the details and the whole power band of both set ups so folks can make a well informed decision.
Individual Throttle Body intake manifold.
Optimized cams for the heads & intake, same compression ratio say 11.5 to 1 or 12 to 1 (definitely not 87 octane friendly 9.8) and equivalent rocker arm ratios. In other words 1.8's on cathedral intake port. Ideally, several cams should be tested like optimized for drag race, road race, street - strip etc. List brake fuel consumption and vacuum at idle.
Show all the details and the whole power band of both set ups so folks can make a well informed decision.
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