Some interesting high lift, short duration grinds here.

http://www.hughesengines.com/Index/prod ... 0xOTg3KQ==

Thanks for posting. The lobes look interesting, although none of them are at all wild for a 225. As usual, no one at that cam company has a clue about the particulars of Slant 6 engines. At least the centerlines are advanced some. I might rework a couple of those (use their lobes) and try something. Reed cams used to make lobes similar to those.

Lou

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Home of Slant6-powered fun machines since 1988

I like the high lift short duration lobes. One of those grinds ground in RDP mode might make a nice cam for a driver.

Too bad they got the intake and exhaust lobes swapped.

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Joshua

Yup.

You'll have to be careful as the slant does have a certain "ratio" when looking at duration vs. lift.... unless you are using a boosted engine where you want to open things up and slap it shut quick with minimal overlap without the headache of going to a roller cam....

220+ @.050 is pretty mild at at the .470-.51 lift ranges, but the shorter cam in the 210-212 range does get finicky over lifts of about .44-.45....

I know because the hyperpak manifold had great torque characteristics in all rpm bands with the comp 252....but I had figured out through a fair amount of messing around that there was still more breathing room in there if the lift was closer to .440-.445, but no one at the time made a lobe like that, and the comp 264 had the lift but the added duration did nothing for low end torque for daily driving... Eventually Comp had a new line of lobes and I figured that the short overlap event an duration in the 25x range and the higher lift was the key...so I popped for a Comp Xtreme 256/256 110 LSA, degreed it in 4 advanced like my previous 252, but lift on this lobe was .466....

Compared to the existing cams at the time:

On the low end at normal street rpm low end torque suffered compared to the Comp 252, but was better than the stock 1972+ mech cam...
After 2000 rpm the power band started and things were moderately better
(better power from 2000-5000 than the 252, low vacuum readfing at idle, but got better and peaked at 2000-2800 rpm...but not as good 'overall' as the Erson 270 or 280 cams)....

I eventually sold it since it was a disappointment, I went to the Erson cam which overall did not disappoint... My theory was that too much lift at the short duration, or the lobe ramp and lifter acceleration, killed the port velocity compared to the lift of the valve through the event (too much lift too soon compared to piston position and resulting vacuum---some support to this was vacuum readings at idle and while driving compared to previous engine iteration...the higher lift was 2-4" lower than the 252 and stock cams...)...

I can also say that the reverse is also true, I had OCG grind a cam to be similar to one of McNichol's cams in his race car (he used a slant cam ground to Chrysler 300 specs at the time)...which for those years was about a 284/284/106 with a .43+/- lift...... same thing there (and same block and set up as the Xtreme comp... so apples to apples)... the cam has low vacuum (installed the cam at 8 adv...) at idle through about 2500 rpm (11-13" average...cam is lumpy)....torque curve is high so it's fairly gutless compared to the stock cam up to about 3000 rpm....then things pick up...but still not as good as the Erson in the same rpm ranges with the .47 lift...(figure that even though the duration would allow a longer open event to draw a similar volume vs. short duration/high lift cams, that it's not using the full potential of free port area with the valve opened less for a longer time)...



So like we always say, make sure that your components play well together, and sometimes "more" is not always better.... (although I wondered if one of comps high lift zero lash solid race cams would
have been OK for a boosted application 27X adv. duration and a .6x lift....)

Probably if I won the lottery I'd just have a private engine dyno facility just to see where the "sweet spot" for various cam combinations was (and luckily we only have a limited set of intake manifolds and exhausts o choose from too...LOL...

I agree,

I was frustrated by both the comp 252 and 264 .....the tendency to ping went up with the 252 with little power to show for it.

If you have increased compression the Erson cams RDP grinds really wake things up.

Buying a cam should be the last step in a math intensive exercise. The math should only start after the valve work is done.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

If it hasn't got at least .550" lift, it belongs in a lawnmower.

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Official Cookie and Mater Tormentor.

According to Mr. Tilley, the fast rate cams did not work well on his NA motors. Higher lift also did not help, above about 0.550". However, there is still so little data for these engines it is hard to predict much. I would reserve the fast rate cams for a boosted motor.

Lou

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Home of Slant6-powered fun machines since 1988

Yeah, Mike found about the same thing, but because the heads just run out of wind. I have a couple of Mike's experimental cams that he never used. Both are around .625 ish on lift. I have enough parts laying around to build a motor for the Daytona to try one.

It's only money.

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Official Cookie and Mater Tormentor.

Can someone shed some more light on this for my pea brain. I would think with a N/A engine you would be looking for as fast of opening ramp as possible? I am assuming that is what you mean by fast rate? And the last I spoke to Mike that is what he told me I should want, if memory serves me correctly.

Rick

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

I do not understand this (fast ramp not as good), but I can imagine that a smoother transition to high flow into or out of a port might have an advantage in some situations. All I can say is what I heard. I can tell you that people make lots of power with slower rate lower lift cams, so it may be that the cam should not be where you want to MAX things out. A slower rate, lower lift cam will be easier on parts, especially at higher RPM. If there is no clear gain with a fast ramp or high lift cam, I'll take the long wearing one myself.

Lou

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Home of Slant6-powered fun machines since 1988

This turned out to be a very interesting thread. Thanks for all the great input guys

Rick, aren't you running a howards cam that is relatively high lift short duration design?

This is only a guess, but I would bet it has a lot to do with the poor flow characteristics of the Slant head.

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Official Cookie and Mater Tormentor.