i do not think so. i WISH. so bad

 

seems the Tomei Crane and S3 perform very close. If anyone wants an overlay of any of the cams i can post it.

 

If no graph of the JUN 272s can we get some kind of idea on how they perform?? As in comparable to S2s, S3s, Tomei 280s?? I know they do very well from what I have been told.. and i know my car is VERY strong with them and making great #s even on stock ECU. But a graph would be OH so nice.

 

Yeah! How about the HKS 272, FP4R, and GSC S2.


Now THAT is interesting.


Gary

 

FP4R isnt posted on the first page yet.
but here is S2 vs HKS 272

 

Martin,

When the turbo is happy these tests are showing that choice in cam specs can make an absolutely huge difference, up to 100hp in some cases.

From your experience, will we see the same results when a turbo is pushed to it's absolute limit? For instance, you're running the boost controller wide open and it just won't make any more than XX psi up top. Can changing cams have much of an effect, or will the turbo itself still be the limiting factor?

Thanks for this test!

 

The JUNs have the duration and ramp profile, but are a little down on lift as compared to the GSCs, Tomeis, and Cranes. The JUNs appear to be deliberately designed around the flow limitations of a stock head, and therefore are ideally suited for large turbo/stock head setups, although they would work well in any large turbo situation.

In short, a strong head with a milder cam works well. A large cam with a mild head is where one tends to run into issues.


What the cams are doing is improving the mechanical VE of the engine in the rpm ranges where you are seeing the big improvements. As the boost pressure is increased in those ranges, the power gap will continue to widen until the cams making the most power hit the limits of turbo efficiency.

If the turbo does not have enough reserve efficiency in those ranges to expose the limits of the smaller cams (much less the larger ones), the larger cams will be of limited benefit, especially when the tradeoff in spool characteristics are considered.

What the larger cams do is enable one to make more power, using less boost pressure. This becomes increasingly important as larger turbos with much high rpm reserve efficiency are considered.

 

very useful post.

 

I was having this conversation on sunday with Martin and he was saying the same thing, but I too would like to see how the JUN cams will work with the race head. I do also agree with the rest of your post as I am in a pickle when it comes to cam choice b/c everything changes as soon as I think about just doing a full race head instead of sticking with the stocker.

 

Cool I now know real results on most of the cams out there and my car will have a similar setup. Thanks AMS

 

This is what is supposed to be in Part 3, don't think the mag is on the stands yet:

Gary

 

great INFO

 

FP 4R's are up!

 

Very nice, I can't wait to see the 5R's!

 

AAHHH you skipped the Kelfords... sad face