272/272 cam timing test and tune
Wow...the Comps must spool the turbo significantly faster than the HKSs. Sounds like a better street set up or someone without cam gears.
I just read this entire post and it is still not clear on the setting of -4/-1.5 cam gear settings being the best for idle and drag racing with the HKS 272's. Also like posted before, were any changes made in the map for this adjustment?
"Best" is too definitive of a term to use here, but definitely better than the regular straight-up settings where a broad peak power curve is desired.
Some cam timing changes necessitate retuning (usually the ignition map) for best results, although it isn't mandatory to observe the difference.
Some cam timing changes necessitate retuning (usually the ignition map) for best results, although it isn't mandatory to observe the difference.
"Best" is too definitive of a term to use here, but definitely better than the regular straight-up settings where a broad peak power curve is desired.
Some cam timing changes necessitate retuning (usually the ignition map) for best results, although it isn't mandatory to observe the difference.
Some cam timing changes necessitate retuning (usually the ignition map) for best results, although it isn't mandatory to observe the difference.
I got my AEM and 50 Trim tuned on the +2,0 setting, so what your saying here is that I can go to the -3, -1 setting and still see a power difference w/o any negative effects to my engine? but if the timing maps were altered a bit, it would be even better...
right?
You'll see the difference in the curve if you map one over the other, and if the degree of change is sufficient, you'll feel it in the seat.
Yes, because of the difference in effective cylinder pressure at different engine speeds, the detonation threshold will change, which means in some places the motor will take more advance, and less in others.
Yes, because of the difference in effective cylinder pressure at different engine speeds, the detonation threshold will change, which means in some places the motor will take more advance, and less in others.
You'll see the difference in the curve if you map one over the other, and if the degree of change is sufficient, you'll feel it in the seat.
Yes, because of the difference in effective cylinder pressure at different engine speeds, the detonation threshold will change, which means in some places the motor will take more advance, and less in others.
Yes, because of the difference in effective cylinder pressure at different engine speeds, the detonation threshold will change, which means in some places the motor will take more advance, and less in others.
will my low end-midrange suffer much?
Ok in that case when I go for a retune these are the 3 settings I will test:
1) -3, -1 camgear settings, 29-31 PSI boost
2) 0,0 camgear settings, same as above boost
3) +2,0 camgear settings, same as above boost
I'll run the setting that gives me the best midrange and topend gain that gets me down the track fastest.... for street driving I guess I can tolerate a little bit of lag in the low-end since I'm not planning to race people from red light to red light....
will report back when the results are in....
1) -3, -1 camgear settings, 29-31 PSI boost
2) 0,0 camgear settings, same as above boost
3) +2,0 camgear settings, same as above boost
I'll run the setting that gives me the best midrange and topend gain that gets me down the track fastest.... for street driving I guess I can tolerate a little bit of lag in the low-end since I'm not planning to race people from red light to red light....
will report back when the results are in....
One thing I know for sure from my past readings is that 0,0 works well for a good overall power band.
+2,0 works best on a stock style turbo, to give the best low-midrange gain w/o sacrificing too much top end......
with -3,-1 I dont know how it'll feel on the 50 trim and like 29-30 PSI, but I'm hoping it'll help me with more mid-range and top end.....and I'm willing to sacrifice a bit of low end for that....
+2,0 works best on a stock style turbo, to give the best low-midrange gain w/o sacrificing too much top end......
with -3,-1 I dont know how it'll feel on the 50 trim and like 29-30 PSI, but I'm hoping it'll help me with more mid-range and top end.....and I'm willing to sacrifice a bit of low end for that....
Yes, +2/0 is great for around town and the twisties but, I wouldn´t think it´s advisable for drag racing, or other high revving endeavors. Aside from the loss in topend power, the other big drawback with it on straight 91 octane pump gas is that it is prone to preignition, not letting you run much spark advance down low.
Last edited by sparky; Jul 6, 2007 at 10:21 AM.
You'll see the difference in the curve if you map one over the other, and if the degree of change is sufficient, you'll feel it in the seat.
Yes, because of the difference in effective cylinder pressure at different engine speeds, the detonation threshold will change, which means in some places the motor will take more advance, and less in others.
Yes, because of the difference in effective cylinder pressure at different engine speeds, the detonation threshold will change, which means in some places the motor will take more advance, and less in others.
A dial indicator is typically used when one is trying to determine cam timing, or, trying to determine if the cam is true to specs.
You should not need a dial indicator to set the cam gears.
You should not need a dial indicator to set the cam gears.