in what gear do you dyno your car?

[themadhatter]

also, does swapping out the diff (eliminating a 1:1 final drive) alter your final results?

-Ron

[SilverStreak]

I think you always dyno it in the gear where the tranny ratio is 1:1 (5th in your case, right?) regardless of the diff ratio...

[ZeroG]

also, does swapping out the diff (eliminating a 1:1 final drive) alter your final results?

-Ron

Every car is different. Based on your rear end and Tranny. If it is a Manual they cars are usually dynoed in third or forth gear. Sometimes 4th. takes to long so you would dyno in third and you'll get a little better results.

-Chad

[Dinan330ic]

4th

3.15 m3 diff

[nickdrivesm3]

Ive heard of most places doing it in 3rd, however DINAN does all their dynoing in 5th (Direct Drive). I think thats thw best way to get real results because the engine and tranny are at the same speed.

[95RogueM3]

Most places dont want to run their dynos up that high in order to run a car in 5th gear. (where m3s are 1:1)

Most will do 4th gear and get good results.

-Richard

[jimmyz2]

Ive heard of most places doing it in 3rd, however DINAN does all their dynoing in 5th (Direct Drive). I think thats thw best way to get real results because the engine and tranny are at the same speed.
Interesting info.I got better results in 4th instead of 3rd.Have not tried 5th(yet)

[Armo95]

The general rule of thumb for most places is that they won't take it above 120mph ...

So whatever gear that may be in the car is where they'll let off(in this particular case, 4th gear, 3.15 ratio).

Also, at least for the several E36 M3 cars that I've witnessed, the difference between 3rd and 4th gear dynos were within 5rwhp, so it's not that big of a deal.

I have NEVER seen a 5th gear dyno for an E36 M3.

[highboostingm3]

The general rule of thumb for most places is that they won't take it above 120mph ...

So whatever gear that may be in the car is where they'll let off(in this particular case, 4th gear, 3.15 ratio).

Also, at least for the several E36 M3 cars that I've witnessed, the difference between 3rd and 4th gear dynos were within 5rwhp, so it's not that big of a deal.

I have NEVER seen a 5th gear dyno for an E36 M3.
Mine was done in 5th on the Dynapack since 5th is thought to be 1:1. I have a 3.46 LSD.

[Armo95]

Mine was done in 5th on the Dynapack since 5th is thought to be 1:1. I have a 3.46 LSD.

What mph did they reach?

[buldogge]

Mine have all been done in 5th (1:1) as well (first 3.73 and now 3.46 diff)...also on a Dynapack.

Frankly, I can't remember the "speed", and the dyno operators weren't concerned in the least bit!

Of course, Dynapack is direct drive. Perhaps the Dynojet guys are concerned with slipping on the rollers/tie-downs/etc.???

[///3oris]

4th.

[Armo95]

That could be it.

I personally have never dyno'd or been to Dynapack before.

[RogRacer]

5th gear at 7000 rpm with a stock diff is something like 155+ mph....most dynojet operators become very very nervous near a tire spinning that fast... :eek: ...hence most people dyno in 4th.

BTW...the lower the gear you test in, the more drivetrain inertial effects come into play on a dynojet and contaminate the measurement, hence it's best to test in as high a gear as possible.

[highboostingm3]

5th gear at 7000 rpm with a stock diff is something like 155+ mph....most dynojet operators become very very nervous near a tire spinning that fast... :eek: ...hence most people dyno in 4th.

BTW...the lower the gear you test in, the more drivetrain inertial effects come into play on a dynojet and contaminate the measurement, hence it's best to test in as high a gear as possible.

They were told to let off at 6500 with mine which is probably only 135mph. I know I know...I need a 2.93 badly.