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Originally Posted by Chiketkd
The longer the duration, the higher up in the rpm band that peak power is made (correct me if I'm wrong). What we need to do is to find out on a dyno the rpms at which peak power is reached in our current set-up.
If peak power is being made at 6,100rpms, then we'll have some room to work with. But if peak power is made at a lofty 6,800rpms, then we shouldn't raise it any higher as we may run into issues such as 'valve float' in those higher rev ranges (due to the increase in intake valve lift).
Depending on Harvey's input, maybe the 5/6MT guys can try the same specs (8.0mm lift, 247 degrees of duration) but without retarding the profile by 7 degrees??? I know Harvey came up with those final specs in the way he did, to keep the IRIS system functional.
-Chike
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The set up that Chike used, was to suit the 4.44 auto that he uses to run the quarter, as there was going to be some low rev power loss from the IRIS, it would only be below 3500, on the run up in first gear, and as the power drops after 5700, it was better to move the lobe center higher to fully use the top end, between 5500/6500. With this end of the range pulling harder, there is more power over the rev range that he uses on the strip, 3500 to auto change 6800.
I don't reconmend others use this lobe center setting. If the car has a 3.55 auto, it should use the standard 116*. If it has a 4.11 auto/ 3.9, 4.11 manual, then you could go to 118*. The duration and lift remains the same, you just need to tell Scott what lobe setting you want, when he does them.
Harvey.
