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Acceleration
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Discussion Starter · #1 ·
Ok well we've had a bit of a discussion in the 1jz section about retarding the exhaust cam 2.5 degrees, some saying that the 2jz stock twin record guys run -4/+1 (should only be done with high octane) and how a 2.5 degree retard on the exhaust cam gear will also show positive performance results. Is this true? Can anyone explain how retarding the exhaust cam gear 2.5 degrees will benefit performance? How will it change the hp/tq curves?
 

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Changing the cam gear timing has effects on the engine that result in tradeoffs between low and high rpm performance. Cam gears allow you to shift the torque range up or down. When retarded on the exhaust side, the peak torque will move up. In my experience -3e/+1i is the best compromise for the street in adding some mid/high end while maintaining low end. -3.5e,-4e, and -4.5e settings gave me greater top end but at the expense of low end. These results may not be the same for you, as they vary slightly from car to car, but I suspect are similar for most.
 

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Acceleration
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Discussion Starter · #3 ·
Thanks for the quick help, so do you think that just -3e would give a good increase in peak torque without sacrificing anything other than low end? I don't care about low rpms, the only time acceleration matters to me is higher RPMs, cuz otherwise I just downshift to go faster. I go through the gears quick (4.30 lsd, 16" rims :)) and I'm just looking to be faster, I don't want to sacrifice actual speed just to get higher peak numbers. I guess what I'm trying to say is I'd rather have 330 rwtq for 3000 rpms than 320 rwtq for 2500 rpm and 335 rwtq for 500 more rpm.. if that makes sense. I'm not about numbers, just the fastest acceleration :bigthumb:
 

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Real Girl Thread FTW!
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Best way to determine if you gain or loose from it, is to dyno the car with different settings, you also have to take in consideration temperature changes, atmosphere and humidity....
Good luck on your task!
 
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