I'm ordering a cmotorsports cam kit within the next couple days and I need to know which is better. I want to go with the higher lift version of the 224/236 and Sam at CM suggested I go with the 227/239 saying that more duration substitutes for higher lift.

What do you guys say?

I think that is a good plan for me. Also, should I ask for it to be ground on a 115 or 116 lsa or stick with 114? What about intake centerline??? Specs please.

 

Yes, in terms of peak power, slightly more duration will make up for slightly less lift. But, you also give up low end and idle quality with more duration and less lift.

The trend over the years has been towards less duration and more lift because you can make the power of a larger cam without the poor gas mileage, rough idle, and poor low-end.

A friend of mine had a SOLID lift flat tappet cam that was 318/329 advertised duration with .480"/.480" lift. The car only ran low 13's at 105. I spec'd out a Comp Extreme HYDRAULIC cam that was 284/290 advertised with .540"/.550" lift and the car now runs low 12's at 113 mph. The shorter duration netted him enough low-end to drop a full second, and the increased area under the lift curve picked him up 8 mph.

I, for one, am sold on Extreme cams, but it is important that you have enough valve spring pressure to control the valve train with the aggresive Extreme ramps.

Another good example of the importance of short duration, high lift, aggresive ramp rates, and high area under the lift curve, is SAR2K's car. That car dyno'd 450 rwhp with a stock compression, stock displacement, ported head LT1 (around 250 cfm), with an Extreme hydraulic cam. It made more power than the stock heads/cam even at <3000 rpm.

I'm actually dissappointed in Cmotorsports for making such a statement.

Mike

 

You don't list all the specs for the two cams, so it's hard to say. The duration sure is close though. I am using the high lift 224/236 XE HR lobes on a 116LSA and am very pleased, FWIW.

Rich Krause

 

So based on your info if Im comprehending this right is that for a blower application on stock heads,stock displacement. A 227/239 would be a overall better cam then say the 224/236 low lift version. Only reason im asking is b/c im in the process of rebuilding a spare forged piston motor and thought about going slightly up in cam profile. I was looking at this cam at cmotorsports and it looked like a good cam choice. My question is under ordinary conditions, wouldnt I see more overall power with the 227/239 over the 224/236 low lift version?.

 

That what I was thinking... the 227/239 is only adding 3* duration on both sides. The lift is .560/.577 which in my opinion is quite enough for my setup. I think I'm just going to end up going with that cam and see how it works out. Anybody else have opinions???

 

Duration and lift don't tell the whole story either. The Extreme lobes maximize area under the curve for any give lift and duration. So, "no", the 227/239 won't necessarily make more overall power than the 224/236 Extreme.

There is much, much more to a cam profile than lift and duration. A drag race specific profile may have 300 degrees advertised duration, 260 degrees at .050", 180 degrees at .200", and .500" lift in a lift-restricted class. A street solid roller may have the same 300 degrees advertised, 240 degrees at .050", and 150 degrees at .200", with the same .500" lift. So, the advertised duration and lift are the same, but the area under the curve is far greater on the drag race cam.

One way to compare them is duration at .200" lift. The Extreme hydraulic roller lobes have a very long duration at .200" compared to other cams of the same advertised and @.050" durations. I'd be willing to bet that the Extreme 224 lobe has around 5 degrees more duration at .200" than the 227 Cmotorsports lobe.

I find myself wondering, if you had decided on a cam already, why did you ask for input?

Mike

 

Well I hadn't really decided, I narrowed it down to the two. I never mentioned the word extreme... I mean what if the 227/239 was extreme as well?? Would it then make more power. I understand how area under the curve is most important. I will check the specs throughout the lift range. Thanks.

 

Yes, it is true, that the Cmotorsports cam may have aggresive ramp rates also.

If the Cmotorsports cam has ramps as aggresive as the Extreme lobes, then with slightly more duration, it will make more power.

I urge you to check the duration at .200" before buying a new cam.

Both Crane and Comp publish their duration at .200" on the Internet, and the Extreme Comp hydraulic roller lobes are the most aggresive, but the Cmotorsports lobes may be good also.

Mike

 

Thanks for all that info Mike! I am going to look into it before I purchase.

 

All CMotorsports cams are Comp cams aren't they?

 

Yea they are I am pretty sure.