Camshaft split

[jeff swisher]

I like the magnum and high energy single pattern grinds They make respectable power and excellent mileage.
Daily driver stuff...for the fast stuff i run solid lifter grinds..older crane and crower stuff never ran a comp solid flat tappit.

Ran a couple solid rollers but not street stuff..those were in the 280's duration at .050"..can't complain about any of them.
I did run the 268XE in a numbers matching 327 vette..the plan was not to rev over 6500rpm, good thing because that was the sweet spot on that build..fell off like a rock after that,,,do not know if i like the XE268..mileage was not as good as the 280H nor was the power. But still faster than the owner drives it

[bigjoe1]

The few times I did any back to back dyno testing on street cams, the XE grinds were allways 15 to 20 more peak HP. than the older magnum grinds and in general, they made more HP from 3500 on up to the rev limit. I do remember this, the Isky mega 280 ( 230 at 050 ) was 18 HP BETTER than the Comp 280 magnum ( also 230 at 050 ) I always thought it was the 108 VS the 110 centers



JOE SHERMAN RACING ENGINES

[jeff swisher]

I must agree with you there Joe.
The 108 seems to pull harder in my builds..and now i an hooked on the 106LS if i do not care about mileage. The 110 was a good compromise for mileage and power the 108 was thirstier and the 106ls dont ask, this is not a mileage build

The last one i put together was a single pattern 252@.050 and .536" lift on a 106ls in a 355 solid lifter set up, I figured it would be a little down on power below 3500-4000 man was i wrong..this thing pulls harder from idle to 7500 rpm than any of the magnum grinds i ever played with...revs quick like an old KZ1000..no lack of low end and the 7500rpm was just because i figured that is all the guy neded to rev it... so i chiped it at 7500

Makes me think i need to step up to the 260@ .050" and .555" lift on the next street 350" build

[bigjoe1]

This tighter lobe center thing is why the COmp Cams thumper grinds work so well. They are all cut on 107 centers, and are 5 degrees advanced too when yoy get it.They actually make more power every where ove the XE grinds. Noone at Comp saw that comming


JOE SHERMAN RACING

[novadude]

Makes one wonder why virtually all "shelf" cams for street type applications are on a 110-112 LSA. Probably just to band-aid the "2 steps too large" cams that most street guys pick.

[Dodge Freak]

These traffic lights that stay red for 1 min--or longer might be why some street engines are running a 112. Not everybody wants a very choppy idle, sounds cool but like the 4.56 gears on the freeways gets old quick.

I hate those left turn lights, half the time there is nobody waiting to turn left, yet traffic both ways has to wait another 20 seconds for a short green light.( I'm sure they do help to prevent accidents)

[howey]

As far as where peaks occur, I think heads and manifolds change this way more than camshaft duration or area, I have seen 10-15 degrees of duration difference in camshafts on the same engine not change where the peaks occur.
Chad

That's only the case when the heads or manifold are a restriction.

If you have way too small of a port, or carb, you can add 40 degrees to the cam, and not change peak HP RPM.

When talking about camshaft changes effecting the engine, you have to assume that the engine isn't being restricted by other factors(port, carb, exhaust, etc). Restricted engine applications are a whole other beast.

To me as an interested observer, without much insight to offer, the response from CamKing above is a simple illustration of why you really can't remove the rest of the engine package from a conversation about camshafts. The art, it would seem to me, is understanding enough about the whole package to be able to reasonably predict the effect of every change you make, and optimize the component, in this case the camshaft, for the package you are dealing with.

[jeff swisher]

That is so true..you would not beleive how many people think because so and so is running good with a 292 cam so i will put one in my ride...
I have seen it done.. 292H comp magnum in a bone stock 350 with stock wore out springs aluminum intake and holley and headers,, i guess it aint bone stock...5000 rpm and noses over like it fell off a cliff..A little funny really..He was a manager at oreilly.
He listened to me and his next build he used a 268H, smallest he ever ran, and he stated the quickest accelerating engine he ever built

[andyf]

But I've seen engines peaks not go up by adding duration,

If you've seen that, then something else was restricting the engine.

PS, I'm talking about HP peak. Torque peak is effected a lot more by tuned lengths.

I have an engine on the dyno right now where we dropped cam duration by 10 degrees and the peak power point moved up a small amount. But I changed some other things at the same time so it is really hard to pin point the difference. The original cam was 275/282 duration while the second cam is 266/272. The first cam had .830/.782 lift while the second cam has .727/.681 lift. So we dropped about 10 degrees in duration and reduce lift by 0.100 lift. Power went up from 805 hp to 820 hp and the power peak went up slightly from 6400 rpm to 6700 rpm. But I also changed engine blocks between the tests due to some main web cracks so it is easy to explain away some of the difference there. The second block was thicker so the engine could be making more power just due to ring seal or head gasket seal. The heads, intake, carb, etc. all stayed the same.

I was just a little surprised to see so little power difference with cams that far apart. But as Mike says, the heads or intake might be the real restriction on this engine so any cam in the ballpark might be making the same basic power.

[raynorshine]

But I've seen engines peaks not go up by adding duration,

If you've seen that, then something else was restricting the engine.

PS, I'm talking about HP peak. Torque peak is effected a lot more by tuned lengths.

I have an engine on the dyno right now where we dropped cam duration by 10 degrees and the peak power point moved up a small amount. But I changed some other things at the same time so it is really hard to pin point the difference. The original cam was 275/282 duration while the second cam is 266/272. The first cam had .830/.782 lift while the second cam has .727/.681 lift. So we dropped about 10 degrees in duration and reduce lift by 0.100 lift. Power went up from 805 hp to 820 hp and the power peak went up slightly from 6400 rpm to 6700 rpm. But I also changed engine blocks between the tests due to some main web cracks so it is easy to explain away some of the difference there. The second block was thicker so the engine could be making more power just due to ring seal or head gasket seal. The heads, intake, carb, etc. all stayed the same.

I was just a little surprised to see so little power difference with cams that far apart. But as Mike says, the heads or intake might be the real restriction on this engine so any cam in the ballpark might be making the same basic power.

always interesting when a smaller camshaft makes more power, isn't it? maybe try another 10 degrees less duration..

[CamKing]

The original cam was 275/282 duration while the second cam is 266/272.

That's .050" duration, not seat duration.

[andyf]

Yes, both sets of numbers are 050 duration.