So it seems safe to conclude that this engine likes a bit more plenum volume, and/or the transition to the plenum was better w/ the tapered spacer. You guys ever used shear plates?
I'm a little confused...so the torque peaked at 3700 w/ all intakes, but w/ the carb spacer on the M1 peaked at 4900? Or was this just a blip on the curve and it's otherwise flat, maybe carrying it out a bit farther in the last test? Seeing if any conclusions can be made about in runner length and peak torque....
Do you have the runner min CSA available and where in the runner it occurs?
Ya know, I don't see it mentioned, what are you using for exhaust?
This is great info...thanks.
Back to back runs M1, M1 w/spacer torque only, I'm tired.
RPM..............M1..............M1 + Spacer
3000...........424..................428
3100...........423..................439
3200...........427..................457
3300...........452..................467
3400...........477..................478
3500...........480..................488
3600...........479..................492
3700...........487..................502
3800...........487..................492
3900...........485..................490
4000...........479..................485
4100...........477..................487
4200...........480..................489
4300...........488..................494
4400...........498..................507
4500...........503..................514
4600...........497..................507
4700...........490..................509
4800...........493..................512
4900...........504..................512
5000...........499..................512
5100...........493..................502
5200...........495..................504
5300...........499..................510
5400...........493..................505
5500...........482..................495
5600...........469..................480
5700...........465..................473
I haven't measured the min CSA.
Our dyno headers are short tube step 1-3/4, 1-7/8, 2" to a 3" collector.
Impressive numbers there!
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A few questions on the XE285HL cam you are using. Do you think that cam would perform better than the old 509 cam in a 451 with 915 heads? 13 to 1 C/R. Also, would the stock stamped steel rocker arms work OK at that lift of .545"? And does that cam with the hyd lifters lose the ability to follow the cam profile at higher RPMs (above 5500)? Due to a lifter problem? Ok thanks.
I wouldn't run the stock rockers on the XE285HL. The reason being, as you suggested, valve train instability. Yep we lost control at about 5,300 rpm and that was with very little preload, maybe 1/16 turn. The cam should be run at zero preload as far as I'm concerned. I've backed the preload off, not to the point of lifter rattle but very close. It will now wind to 5,700 before it will stumble. I've not tried higher rpm's yet. I'm just going to put solid lifters on it now. The springs they recommend (924-16) have too much lift before coil bind. They dance around and chew up the spring shims. I've shortened the installed height from 1.900 to 1.850 (110# to 140#, no it didn't effect the valve train stability) and the shim wear is much better now.
I don't know which would be the better of the two cams. they are in kinda what I would call a transitional lift range and the cylinder head lift flows would determine which cam to use. (cylinder heads, cylinder heads, cylinder heads!) I chose the Comp Cam because I needed more lift to test some of our theories.
