Improved Power AND Fuel Economy
Originally Posted by trinydex
hey have you tried uhm... silversurfer's -4/-1 setup... he also claimed more low end and stock idle, better than stock in fact plus a lotta other lalalala ... i can't remember everything he said but i'm very interested in cam timing...
i know that the seperation keeps idle liveable... as long as you keep the overlap apart by 2-3 degrees.... but silver surfer has his numbers flipped from yours... are you guys sayin' the same thing? which is exhaust and which is intake? (this was directed at superhatch)
and then silversurfer said that you should never go to the positve end... but obviously ted has gone to the positive... i'm not sayin' silver surfer is all knowing or anything... i actually advocate against the single spring mod in the greddy type-s but he did make some interesting reading with the cam timing before this post here...
more info please!
https://www.evolutionm.net/forums/sh...timing+testing
here is that thread btw.
i know that the seperation keeps idle liveable... as long as you keep the overlap apart by 2-3 degrees.... but silver surfer has his numbers flipped from yours... are you guys sayin' the same thing? which is exhaust and which is intake? (this was directed at superhatch)
and then silversurfer said that you should never go to the positve end... but obviously ted has gone to the positive... i'm not sayin' silver surfer is all knowing or anything... i actually advocate against the single spring mod in the greddy type-s but he did make some interesting reading with the cam timing before this post here...
more info please!
https://www.evolutionm.net/forums/sh...timing+testing
here is that thread btw.
https://www.evolutionm.net/forums/sh...d.php?t=100413
And then this:
https://www.evolutionm.net/forums/sh...d.php?t=131534
And you'll have your answers on what Ted thinks of -4/-1 (he actually tested -4/-1.5, but it's close enough). Also, my 0/-2 is 0 degrees intake, -2 degrees exhaust, and I did that to decrease the LSA to increase low end punch. However, I didn't go to the extreme that Ted did (+2/0) b/c I wanted to see if I could shift the low end punch to a slightly higher RPM, which I think I did. Ted links a webpage that explains cam timing quite well in the second thread I linked. What we've done with our cams settings might make more sense then.
- Steve
Generally speaking, what Silver Surfer said about not going tighter on the LSA is good advice for a turbo car with cams that give a 110deg LSA. However, there are other factors that play into this, which are seemingly poorly resolved in this particular application, and hence my desire to experiment a bit.
Widening the LSA while delaying the intake cam at the same time, such as in going to -4/-1 gives a smoother idle and good top end efficiency, but at the expense of slower spool.
I selected a relatively unorthodox cam timing scheme because I wanted to maximize the potential of the TME turbo and get as much midrange torque as possible. I've definitely done that. I reasoned that the HKS 280 cams had enough duration not to compromise top end power too much, and that also seems to have worked well. There is little doubt that I could gain another 10-15whp at the peak by adjusting the cam timing...but I'd probably give up at least that in torque.
Widening the LSA while delaying the intake cam at the same time, such as in going to -4/-1 gives a smoother idle and good top end efficiency, but at the expense of slower spool.
I selected a relatively unorthodox cam timing scheme because I wanted to maximize the potential of the TME turbo and get as much midrange torque as possible. I've definitely done that. I reasoned that the HKS 280 cams had enough duration not to compromise top end power too much, and that also seems to have worked well. There is little doubt that I could gain another 10-15whp at the peak by adjusting the cam timing...but I'd probably give up at least that in torque.
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Oct 23, 2012 03:49 PM
