Al,

I have an 03, stock turbo, stock cams, TBE and custom tune by you that I am autocrossing in Street Prepared (different class than Daddio, more restrictive). I am planning to go to the 2005 10.5T turbo (only class legal option).

Real question is, can Adj Cam Gears be used to shift the power band lower so that spool up starts sooner? If so how much, 100 rpm, 500 rpm? Will it totally destroy the top end?

Autox is all about having a high average speed which equals a low elapsed time, if I can get better spool at the cost of some top end I'll take it.

 

OPINION: If you like low speed autocross then keep the 9.8 hotside.

Cam gears can lower the rpm the peak torque hits at but on stock cams I wouldn't even dick with them.




When I switched to the 10.5 hotside I hit peak torque at 3750. After cams and cam gears I saw peak torque at 4000 but I added more peak torque. I actually had more torque at 3750 than I did without cams but it took 250 rpm to add the additional 27wtq I picked up with cams. The difference between cams at 0/0 and cams at -2/-2 was about -200 rpm sooner peak torque and a bit more torque in the mid range with about 15 less up top.

 

Adjusting the cam gears can be used to make significant TQ gains - my suggestion is rent a dyno and move the gears till you find the max tq gains

 

Well I simply cannot argue with ^

But I'm just not sold on cam gears at all.... especially on stock cams.

 

I thought about this a little more and decided that the risk vs reward isn't there. How much power/shifting will actually occur vs time and $$ spent. The other factor is adding another possible failure point. I like to keep the car as close to stock as possible to maximize reliability, broken cars don't win events.

I may try the 05 turbo though since they aren't too pricey. Al, would this require a retune? Only change is going from 2003 9.8 turbo to 2005 10.5 turbo.

BTW, your tune has been great so far, I just wish the 03's had the same "kick" as the 06's, those 9's really rock.