Ever since the first mod we have put on these cars, there has always been a question of "Why are my dyno numbers so low?" I think I have found the answer. Below is a graph of 6 different dyno runs all done in 3rd gear. The parameter you are looking at is called gear ratio and it is a measurement that helps identify converter slip in addition to many other possibilities. What I have noticed is that the more power you make, the more the converter slips to the point of hurting dyno numbers. I first noticed then when the exact same car on 2 different days dynoed 30hp less than the original dyno from the previous day. We let the car cool down and all the power came back. The only difference was with this gear ratio, the lower run was significantly higher than the higher dyno number. Since I know it isnt tire spin (another problem seen by logging gear ratio), the only other possibility is over-powering the converter in the car to the point that the numbers are significantly lower than actual results. I will outline peak tq numbers for each of the colored lines below to show that as you increase in power, you are also increasing the amount of slipping in the converter and therefor not seeing the actual gain from said product. Green and Dark Blue are right on top of each other, but there is minimal differences in tq between them Light Blue: 349rwtq Green: 379rwtq Dark Blue: 383rwtq Red: 401rwtq Maroon: 426rwtq Pink: 474rwtq So as you can see, I think allot of peoples inaccurate dyno numbers (especially heavily modded) are due to an increase in converter slip. I am told that the Mopar TCM aids in converter lockup, so we ordered 2 of the Mopar TCM's and we will be testing them in numerous vehicles to see if it does indeed aid in converter lockup and increase the hp/tq numbers. Stay Tuned.
Andy just a heads up make sure to do the TCM Calibration steps or you will get some rather odd behaviour on the cars. Should prove to be intresting. -R
Yes, I kick the tire and if my foot bounces back, the tires are good to go. lol. No I do not, but that wouldnt explain letting a car cool down and running it again and getting a higher number. 30rwhp isnt from the engine cooling down, but the tranny fluid is cooling down allowing for a better engagement of the converter.
I understand that. We've documented at least 9 hp difference depending on tire inflation alone. It's just another variable I'm pointing out that many people completely miss. I fyou start dynoing all of your builds with 42 psi in the tires, you will magically invent 7-10 more HP on every build.
Im not what that info will do for you. We are not looking at hp numbers. These are 5 different cars, Im not sure which cai they all had. Of course, less loss in the sidewall flex with a tighter tire.
Here's a question...does the aftermarket stalls do a better job of converter lock-up compared to the stock ones or is this loss apparent with both once the horsepower really goes up?
Will the Mopar TCM make any difference on an SRT? I believe the SRT TCMs are programmed the same as the Mopar TCM, which is why they don't make a Mopar TCM for the SRT models...
Aftermarket converters are better, but not by much. Completely different tcm's. Verified by a person capable of reading what is in the tcm.
Well I'm glad I got one of your "new" converters headed my way!!!! I'm gettin that beotch on as soon as it comes in!!!!!! REALLY ANXIOUS to see what my sled does then mofo!!!!! :rockon: Chase
Wow! That is alot just for tire pressure, I never realized that.....very interesting information to know. I guess as they say the dyno should be a tuning device and the track is the measuring device.
