Quote:
Originally Posted by Colt4g63
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??
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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.
Quote:
Originally Posted by EVOlutionary
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?
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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.