You need to dyno it always in 5th gear! That is your 1:1 gear ratio. This will yield the most accurate numbers.

Now once you put about 100-200 miles on the car you will notice the ECU has adapted. The throttle response and pull throughout the entire RPM range will feel like a completely different animal.

You should never get a CEL. The only way you would is if you had an exhaust leak coming from where the header meets the engine, or a fouled out O2 sensor!

Enjoy it all and do not hesitate to call me directly with any questions that you may have. Again, thank you for your business, it is greatly appreicated...

Tony

Yeah for my 7AT, my baseline dyno was done in 3rd gear (dunno why) but it only gave me 248whp/210tq... Then after getting the headers/cbe I had another dyno, this time they did it in 4th and I got 283whp/230tq... I wanted them to do a dyno in 5th gear like what's been recommended, but when he did the dyno (you can check my vid's) he took it to 6500rpm (140mph) then stopped because he said he didn't wanna run the dyno that high... :wtf: So I don't really know exactly where I stand, I think I need to take it to another dyno... It just sucks because I can't get an accurate estimation of how much power I've gained due to inconsistent dyno's... :mad:

You can only dyno in up to 4th on the 7AT with a stock ECU and rear end. In 5th it hits the stock speed limiter before it hits the redline.

I didn't realize that. I have always done 3rd or 4th. I'm not sure how comfortable my dyno guy will be with 5th gear. But I will ask him when I got back for a tune.

Yep, 5th gear is 1:1 for both manual and auto trannies.
http://i.imgur.com/xGrET.png

Comfortable or not, it is the only right way to do it! That chart above is very useful. I need to save that to my computer!

Tony

Very useful, thank you!

Tony

10 months and 14k-ish miles and no CEL.

Here's the video... you'll see that I still had 1k rpm left to go before redline, and it topped out at 140, so he still could probably make it to redline before 155...

And thanks for that image, Saved as well! :tup:

Here is the video of the dyno run.

If it's a 7AT with the stock rear end and stock ECU (well, and stock tire diameter), it cannot make the redline in 5th gear, it's just a mathematical fact of the gearing + speed limiter. Check your setup using the numbers from the service manual here if you've changed the rear end ratio or the tire size: http://www.f-body.org/gears/. I've tried it myself on the dyno and hit the limit.

Then how are other people managing to do their dyno's in the correct gear and still hitting redline? No tunes...??

:ugh2:

The 6MT guys have no problem doing a dyno in 5th, and that's the right gear for them. The limitations I'm talking about are with the 7AT. 7AT has a rear diff ratio of 3.357:1 whereas the 6MT has 3.692:1, which is why they have different speed ranges in 5th even though 5th is "1.0" on both transmissions.

You can remove the speed limiter with UpRev, etc to get around it, or just dyno in 4th. FWIW, on Dyno Dynamics we pulled in 3/4/5 on my 7AT in the past and didn't see any significant difference (up to the limit in 5 anyways). Some dynos are more susceptible to gearing difference than others, depends on the measuring methodology I think.

Interesting input.

You can dyno the automatic in a gear that is lower than 5th or not a 1:1 ratio. However your peak numbers will be lower. Now if you were just looking for comparison numbers, you could do the baseline in 4th and just do the later dyno is the same gear.

Tony

I want a rear diff swap then! :mad: :rofl2: