hi all:
what's the correct ratio if I want to dyno a S on a dynapack, 5th gear, and how much the difference there is between 4.6 and 5.5 ( I am talking about the ratio parameter you enter to the computer for teh dyno) thanks.

 

You need to multiply the gear ratio by (4.10*1.16). For 4th gear I believe the ratio is 1.16 (I have it on my Dynapack, don't need to remember any more).

If the load time is kept the same for each gear, the difference should be about 1%.

UL

 

^
say, assuming the load time is not consistant, how much of difference there might be, 30%?
thanks

 

Nah, not that much. Usually if we go from a ramp rate of 500 rpm/sec to, say, 1000 rpm/sec (half the load time) we'll see a drop of 10-12% (on average - it depends upon flywheel weight, etc.).

UL

 

ummm, ok, here is the situation,
my dyno number is once again low, 180s on dynopack, that's with toda racing header and cams. Yes, I have an ARC intake but it's not the reason, I swapped back to stock airbox and the dyno # is 2 hp lower. the head has been inspected during camshaft installation, nothing wrong. compression # comes OK, all 4 cylinder in the 200s, no leak down on every cylinder. The only thing weird I see is the ratio on dynapack is 4.6 as opposed to 5.5... trying to figure out why.