Additional M vs. K cam testing

[isaac]

Because Michael suggested it, I went ahead and did 2 more tests to show off 3rd gear performance (as opposed to 4th gear in 2 of the last 3 tests) for the M and K cams. I was gonna do the B cam too, but only had enough time yesterday to test the M, swap it out, and put in the K and test it. Drilling out the broken pin in that cam has turned out to be a real bit breaker btw. I should put two notches in the end of the cam to signify this.

Anyway, about the new tests: A 30-50mph 3rd gear acceleration test (full throttle like all the others), and a 50-70mph 3rd gear acceleration test. All test conditions were the same, except it was a little cooler outside. K cam is 6 degrees advanced, M straight up.

The 30-50mph test started at 1,950rpm and pulled to 3,050rpm. Though this is just another torque test, it starts at a less 'unfeasible' rpm.

The 50-70mph test started at 3,050rpm and pulled to 4,350rpm. This test should help to better isolate the powerband between 3,000 and 4,500 compared to the previous tests I posted.

Results:

30-50mph 3rd gear acceleration-

M cam - 7.41 seconds
K cam - 7.726 seconds

50-70mph 3rd gear acceleration

M cam - 8.53 seconds
K cam - 8.243 seconds

You can see by this that the M is still the low end torque champ. However, side by side, starting in 3rd gear at 30mph and continuing to 70mph, the K, which was .31 seconds behind the M by 50mph, is hauling it in between 50 and 70mph. This means that somewhere between 3,000 and 4,350rpm, the K starts making more torque than the M. Anyone who's driven a K cammed car can tell you this, but there are the stats. Keep in mind that the K was running 6 degrees advanced. I didn't bother running it straight up, because like I've said before, it still pulls great to 6,000rpm and I've got a hard limiter at that point.

I started a new thread for this because I wanted everybody to see the results and figured maybe a few too many people got burned out about the verbal melee that the 'M cam vs. B cam vs. K cam' thread turned into.

 

[245gti]

Thanks for those results Isaac. Changing cams isn't the most fun thing to do although not terribly difficult. Kudos to you for taking the time...

Wonder how the "T" would've done in those tests? Is slightly more agressive than the "M" if I'm not mistaken. This is without comparing stats, just from memory.

[quote:b8e784f102]Drilling out the broken pin in that cam has turned out to be a real bit breaker btw. I should put two notches in the end of the cam to signify this.
[/quote:b8e784f102]

With the proliferation of "B" cams out there, wouldn't it have been easier to get another?

 

[Guest]

Thanks for the additional info. I wish someone had some dyno plots of various cams in the NA motors, but I guess it just isn't out there. If I ever get a chance to do one, I'll post it.

Issac - did you notice any falloff in high-end power by advancing the K?

 

[Anonymous]

I will hopefully have a dyno chart for my motor in a few weeks. I'll post it when its available....

 

[towerymt]

I wish someone had some dyno plots of various cams in the NA motors, but I guess it just isn't out there.

I'm putting my B230F/M47/VX3 on the dyno soon. Hopefully we'll have a few dyno sheets to show for the day.

 

[isaac]

No there wasn't any power falloff at all nearing the hard limiter. I actually feel it pulling a little harder as it passes 5,000rpm. 6 degrees advancement in a car with a hard limiter creates a much more useful powerband overall. You've got it stretched nearly 1,000rpm further south in the revband, and lose nothing at the top.

 

[245gti]

[quote:a1497c354a]6 degrees advancement in a car with a hard limiter creates a much more useful powerband overall. [/quote:a1497c354a]

Hmmm...sounds like a bit of a plug for that adjustable timing gear...

 

[Anonymous]

i've run all the cams except the H and B in my b21ft, but with no turbo, it failed a long time ago. the t sucked, monster low end torque, but driveablity was severely limited due to it running out of steam around 4250 rpm, it was timed straight up. the next cam was the A. i really liked this cam, it actually reved up, and there was still low end torque to it. the A hit the end of it's powerband @ ~ 5500 in my car and it was timed straight up. then i had to switch to the M for inspection, this cam sucked big time. although it reved better than the T, overall it was just bland. nothing really stood out about it at all. the top end didn't totally suck (died out around 5000rpm) but it wasn't great either. the low end felt the same way to me, and the cam was timed straight up. now i'm running the K cam with 6 degrees of advance drilled into my cam sprocket, but the belt is stretched out (with 10,000 miles on it) so it came out to about 4 degrees advance. this cam is pretty dead below 2000rpm, but i'm usually not down there anyway, besides first gear is pretty short. this cam really shines above the 2000 rpm mark, it starts coming alive, and pulls the engine strong all the way to 6000 rpm. excellent power band compared to the M cam, but then again probably almost anything would be.

so overall, i guess i'd say my favorite is either the K or A, i'm not totally sure yet, i guess it depends on my driving situation, but if you're unwilling to compromise, i'd say the K. of course, i'm sure i'd like both cams even more if i had some decent compression.

harley