I got a free dyno run a couple months ago. A local speed shop was giving one free dyno run per car at there grand opening. The Dyno was a Mustang Dyno and it worked off of speed instead of rpm's so I got cut a little short. I didn't know where 4th gear topped out so I had to guess. I guessed a little short and only got to make a run to 5250 rpm's.

I am curious, what gear should I make a dyno pull in if I go backand pay for one. They were trying to get me to do it in 3rd. I don't think that is right. 4th is one to one I believe.


What gear

 

4th is what I have always dynod mine in.

 

As stated above you want to dyno your car in 4th gear (1:1 ratio).

 

It should be in 1:1, not only for accuracy, but for higher #'s as well.

But if your car goes thru the traps in 3rd(for a manual), then you should see what power your developing in 3rd.

 

IMO, get dynoed on an inertia dyno. You SHOULD dyno in 4th, as it is 1:1, and is technically the most "efficient" gear. My car club has a good connection w/ out local dyno guy (has a mobile Dynojet). Inertia dynos spin a drum, and calculate HP based off of RPM and how fast the car speeds up the spinning of the drum (the acceleration of the drum). Doesn't matter what speed it spins, it's how it accelerates based on RPM (that's how it doesn't matter what gear it is in to at least get a reading).

 

Here's my stupid question, how do you keep it in fourth on the dyno? I know past a certain mph it will stay in fourth, but that would cheat you out of lower rpm dyno. Plus, I have custom programming in my truck and it seems no matter what speed I am at, it always down shifts. I haven't gotten into the higher mph just yet, still trying to get all the bugs out before i kill myself.

plus, chevy high performance mag just did a article on the different types of dynos and their pros and cons, good read.

 

6-speed = manual transmission.

For a 4L60E, it's 1:1 gear is 3rd. To get it to not downshift, you have to just reprogram the PCM for the shift points you would want on the dyno. Basically, have it shift like normal until 3rd, then change the setting to where it can't downshift back into second to a MPH that the car would be above. Basically, you have a shift program setup for the dyno. I have a few 4L60E friends that do this, and it works perfectly.

 

lol, sweet, thanks for the info, was thinking something like that but didn't know if anyone tinkered like the way I do.

let me get this running right, and i'll let you all know.

 

I'd say do it in fourth. 1:1 gear. BTW 4th should end about 115 or so mph....

 

Thanks guys.

I really thought I should do it in 4th but I wasn't sure. Now I know.

Time to go get some better numbers.

 

I don't know but 1:1 seems logical. Wouldn't the term "overdrive" mean less than a 1:1 ratio?

Jeff D

 

You do not need to reprogram an automatic to dyno it. If you want to dyno from a low rpm, you will have better luck if you have changed those settings.