The only time excessive overlap is good is in a high revving motor, and last time i checked, we had a 7g redline...So propeller head is right about needing the upgraded springs and retainers to make the 280's beneficial, but how many evo owners do that?

 

Could be too ..

I've the other side tho .. which is strange .. and this is conflicting results too ..
2 evos with 3037 and 272 vs 2 evos 3037 with tomei 270s .. everything suggest that tomei will win hands down .. and it wasn't the case .. the result was similar to what GT40 found out .. past 6000 the HKS just walked away from the tomeis ..

I do not know the specs of the newer 280 cams .. but the 272 has barely any overlap (if none at all) .. these cams are so new .. those poor spools could just be bad tuning

 

Anyone have the link to Buschurs #s with 280s?

 

That's what I was wondring as well? Did Dave ever post his dyno graphs with the 280s?

 

I'll admit, I'm bench racing. I'll keep an open mind. I'm interested to see what the results are once the graphs have been sorted out.

 

Good info... to bad I dont have this data for 264/272's I wounder how they are different then the 264/264's


Good job guys!

 

Sorry guys it was late last night and I typed the wrong run per cams. I had them switched, but I fixed it allready. Yes the 280's spooled slower and actually made less power than the 264's on pump gas. As for the idle, I was able to tune it out almost smooth but I really couldn't imagine running these without full standalone.

 

Regardless of spool the 280's should make more power than the 272's. So there COULD be comething wrong with the tune because the 280 peak hp were the same as the 264's which it shouldnt. We all know 280's make more hp thatn 272's but its somehow the same as the 264's. I am so lost. LOL

 

My guess is the increased overlap is allowing the intake charge to blow right through the cylinder and out through the exhaust valves. A larger turbo or one that has been optimized might be able to overcome this. Dunno.

 

How do we all know they make more power on stock turbo.... have you seen any graphs posted other than mine?

Its not the tune, its the fact that with the 280s the stock turbo had a hard time holding the boost on topend. For example with the 264's would hold 2 lbs more boost on topend than the 280's. The 280's are just to large and flow more air than the stock turbo can push. To compare apples to apples you would need a larger turbo that could hold the same boost consant to redline. It is then you would see a larger gain from the 280's.

 

Well, you know your stuff so I wont even go and argue with you because I was just guessing. I need to know how David got so much power with the 280's, unless I misread his thread.

 

Ported exhaust housing, turbo, and 10.5. If I remember right.

 

What were the cam timing settings you used?

 

Cams were set at zero zero

 

That probably isn't the best setting for those cams.

I suggest widening the angle of separation and delaying the intake cam. Try the -4 int / -1 exh setting and that should clean things up a bit.