Ay of you guys hit a dyno with 4.10's and an auto trans?? I got dyno'd the other night and the numbers were WAAAAYYY off. With the mods in my sig I should be somewhere in the 290's at least for HP and 300+ for torque right??

I think my gears threw everything off. It was on a dynojet and my car was the 1st 05-06 gt auto with 4.10's that this guy has done. I was in third gear and he said to bring it up to 60mph and floor it. Well, 60mph in 3rd with my 4.10's is like 4,000+RPM. Needless to say the reading was horrible. 262 hp and 250 torque?? It was 10pm and didn't want to wake up his neighbors so I only got 2 pulls....both were in that range...... I KNOW my car runs better that that. My question is this: With the 4.10's, shouldn't I start at a lower RPM than 4,000?? As soon as i floored it it went straight to the redline like 2 seconds later. I would think my torque would be better measureed at a lower RPM than that. I'm planning on going back again, but wanted some advice because this guy doesn't have the experience with the autos and 4.10's.


I was very reluctant to post this due to my embarassing numbers, but I was hoping someone would have some insight here. By the way, my car only has 1600 miles on it....will my numbers be better once I get some miles on her???

 

I was with Lee for his pulleys installation and dyno run. After we got the pullies on, something seemed very odd about the Dyno Runs with his 4:10 gears in. If anyone of Dyno Expertise or anyone who has dyno'd with 4:10s if you could chime in on this problem, me and lee would love the feedback......

 

Hmmmm. Houston, we have a problem

5R55S is at a 1:1 ratio in 4th gear. Don't worry. Your car's got way more than 250 ft lbs. Trust me. Go back and do the pulls right, and you'll be fine.

Why pull when the engine/tranny ratio is 1:1? Simple. The torque won't be multiplied by the trans, which offers a less biased estimate of your actual engine power. When torque is multiplied, as it will be in every gear below 4th, your car will pull (rev) faster, but at lower volumetric efficiency, which means less power. Pull in 4th, when the torque is not multiplied, and it will take longer for the engine to pull, so the aggregate time between valves opening and closing is longer, allowing more air flow, and making more power. Your guy either didn't want your car to burn up (did he not have any heavy duty cooling fans?), he just got lazy, or he didn't know that 5sp AODE is 1:1 in 4th gear.

 

WHEW! thanks man!

 

I agree on the 3rd gear goof up...

But, don't be surprised it you still fall short of 290/300 with the auto.

 

Your tuner should have a special tune just for the dyno it doesn't change the engine parameters just keeps the trans in 4th for the pull.

 

I also have a vert auto, with C&L CAI and JBA LT Headers, H-Pipe, and tune I ran a 302 rwhp and 318 TQ on a Mustang Dyno, it is my understanding that the mustang dyno reads lower than the Dynojet. I am sure you are higher than 262, probably closer to 280-285.

 

As Don_W said,should be done in 4th on the auto.I know this is after the fact and you've already done it.But you may want to take it to JDM they live and breath S197 auto's.There only maybe 1/2 hr from you.
Just some FYI.
Hope it works out for you either way.
-John

 

i have 3.73 gears and the same mods as you except for the spacer and made 273 hp and259 torque on a 3rd gear pull on a dynojet.mike told me he didnt have the program to lock the trans in 4th gear so my numbers are a little low also so your numbers are probably about right.i was only concerned with the a/f being right and the tune itself being like i wanted it so i didnt worry about the numbers so much.

 

No prob. Be sure to update us once you get new results