power difference between different brand cams

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smeg
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Re: power difference between different brand cams

Postby smeg » Wed Sep 13, 2017 3:07 am

HotRodRay wrote:Ive often wondered why "cam twist" never enters unto these conversations.
Theres lots involved in twist.

Now theyre even grinding "4 corner" cams for fuel distribution. Decades ago we had different cylinders ground to different lobes. It worked.

You didn't sell a cam company recently did you?

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Re: power difference between different brand cams

Postby stealth » Wed Sep 13, 2017 6:53 am

So I'll admit... I briefly read these posts but looking for a conclusion...

What makes the "one" company's cam out perform the other "possibly" older design?

Speculation?
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Re: power difference between different brand cams

Postby digger » Wed Sep 13, 2017 6:58 am

I think if you actually plotted out the valve lift curve accounting for lash most questions would be answered. A few numbers on a bit of paper can't full define the system

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Re: power difference between different brand cams

Postby vortecpro » Wed Sep 13, 2017 7:10 am

bigjoe1 wrote:I gave Chet Herbert a very good Isky cam to copy, and his copy was 20 HP LEES than the real thing from Isky- So much for the exact same thing

With these simple BBC flattappet engines I build, it seems the Isky cam likes to rev which is important to me, I also accept the gentle lobes are down on HP, but did the Isky's rev for you?





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Re: power difference between different brand cams

Postby DaveMcLain » Wed Sep 13, 2017 7:46 am

What would be pretty interesting is to see what the differences in some of these cams are after X amount of run time. I'd bet that with some of that Comp Cams XE stuff more than 50% are flat in less than 10,000 street miles.

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Re: power difference between different brand cams

Postby PRH » Wed Sep 13, 2017 10:36 am

I'd be curious to know what the lobe numbers were for the original Comp cam.

25 or so years ago I was using mostly UD cams.
I had several occasions where I pulled something else out, and replaced it with a UD and saw a nice gain in power.
Many times however, the specs also changed a fair amount from cam to cam....... So not really an apples to apples test.

I have plotted out, with a degree wheel and the cam in a motor, a few Herbert rollers...... They were waaaaay off from the specs.
One was off so far that if you didn't have the number stamped on the end of it, you wouldn't have known what it was "supposed" to be.
It ran fine in the motor, but it was quite a different cam than what the specs were.
Somewhat handy with a die grinder.

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Re: power difference between different brand cams

Postby David Vizard » Wed Sep 13, 2017 1:05 pm

Frankshaft wrote:To further elaborate about title, what's the thoughts on similar cams from different manufacturers? I just freshened /fixed an engine for a customer that I originally did from scratch. I think I have cycled out the last set of JUNK comp cams lifters from the engines I have built. Never again comp anything for me. Anyhow, obviously the cam was ruined too. This is a good running 406sbc, Dart block, Rhs heads, that I ported, it makes upper 600's for hp, so its no slouch. On most internet dynos, it would make way over 700, lol. Just a strong, basic bracket race deal. Anyhow, new rings, bearings, fresh hone, gaskets, and new Erson/Morrell super duty lifters, and a Erson cam, to replace the comp grind that was in it. Lucky there was minimal or zero damage from the shrapnelled lifter. Nearly identical specs. 1 less at .050 on intake, same ex duration, same lobe Sep, and same lobe lift on both in/ex as old cam, installed at the same intake centerline. I just had as similar of a cam I could, so no potential changes needed to converter, gear etc was needed. Any guesses ? I know I have heard claims from at least one speedtalker who says comp cams make 20-40 more hp than any other cams that are the same size. This Dyno also repeats 1 year, 3 years, 6 years, etc later like dead on, so, its 100% accurate. This spring I have freshened and redynoed 3 engines, that were originally dynode there, and the sheets and graphs would have overlayed each other to the point they were nearly identical.

Thoughts? Guesses?



Two cams, differing design techniques - both showed excelent dynamics on the spintron - duration at check points +/- about 1.5 degrees - torque & hp within 1.5% as near as could be measured. Next cam tested with not so good dynamics - about 12 hp down.
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Re: power difference between different brand cams

Postby la360 » Tue Sep 19, 2017 10:41 pm

It's a little off topic, but those whom are chasing records etc, what methodology do you use for testing several camshaft profiles?

I work in research in additive manufacturing, the researchers with use various processes to determine a pool of parameters to use for experiments. Just curious if anyone uses a similar way of thinking to selecting lobes.
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Re: power difference between different brand cams

Postby cgarb » Tue Sep 19, 2017 10:55 pm

About the Herbert cams...I've dealt with them some, from what I gather they have a very old set of masters and they are limited in what lobes they have. They will tell you they can grind anything, to some extent I think they mess with the master somehow and fudge lash numbers to get "close" to what you wanted. I haven't had any problems with the rollers I've gotten from them, they ran fine and the ones I have check very close at least on the #1 cylinder. I haven't checked more than that I just get the centerline where it needs to be and adjust to see what it likes. My engine is down on power compared to some modern grind stuff so I would expect to see an improvement going to something better for sure. Old lobes that are easy on springs though...I bought my first couple roller cams from them because it was a big price difference from them to other cam companies. They have raised their prices up now some so they aren't quite the bargain they were before. My next cam will be from a more reputable grinder for sure.


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