I think i would have to make the comparison when i have the Jeep on the dyno. Doesn't sound possible to me. As i remember the pulls in 3rd were relatively the same in 3rd vs 4th. Certainly nothing that I recall that would make me choose one over the other. I think 3rd may be a better choice to see the dip in power that is in question.
DynoJet with WinPep 7
My boys at Power by the Hour are the best in the country. Check them out. Long time friends. http://www.pbhperformance.com
to talk to this point of 3rd vs. 4th gear, I cannot tell the difference when looking at the charts weather a dyno pull is 3rd gear or 4th gear unless you change the charts parameters to actual speed MPH, and not engine speed RPM.
Otherwise, you could end up laying 3rd gear runs over 4th gear runs and not know that its not apples to apples, in the RPM band, it looks like apple to apples.
Ross - I think you are talking about your 3rd and 4th gear stock dyno runs. I'm talking about Jessee's 3rd and 4th gear turbo dyno runs. The gear made a pretty big difference with the turbo. Want me to post a chart comparing them?
3rd gear definitely showed lower peak number than 4th. This was 100% expected by the shop rolling the dyno and by me. Again - its the idea that a dyno is most accurate where a 1:1 ratio is achieved. I didn't do the math to figure out what gear had my 1:1, I just assumed I should use 4th as was done previously.Originally Posted by UselessPickles
My higher axle gearing would have skewed my numbers down vice the factory 4.10s in a given gear. The higher gearing changes the engine's rate of acceleration as a matter of fact. Faster engine acceleration equals lower bhp. Again - the effect of this is different for every dyno manufacturer and the way it does its math.
I'm feeling another dyno run is in my future.
Ok, here it is. Jessee's torque curve in both 3rd (blue) and 4th (red) gear:
If the pattern continues, I bet a 5th gear pull (which due to 4.88 gears, would be similar to a 4th gear pull on stock gears/tires) would result in an even earlier and higher torque peak that has a shape more like Prodigy's results.
If i can get Prodigy to email me the install manual for the stage 2 upgrade, i can get my dyo passes in.. It was supposed to be today but the shop wouldnt begin without the Manufactures instruction manual. So i had to reschedule for tomorrow, anticipating ill get my hands on the install manual. I have an automatic with 5.13 37" mud grapplers. They will be doing dyno before the install and after the install. Again this is whether or not ill get the install instructions.
I had a conversation with wes today at length. A 5th gear dyno run would bring the truck to like 150 mph. Its out of the question.Ok, here it is. Jessee's torque curve in both 3rd (blue) and 4th (red) gear:
If the pattern continues, I bet a 5th gear pull (which due to 4.88 gears, would be similar to a 4th gear pull on stock gears/tires) would result in an even earlier and higher torque peak that has a shape more like Prodigy's results.
4th gear is the closest to 1 to 1 and the axle gear ratio is a non factor.
Its not going to make 40 more hp if you run it in 5th.
I just sent a message. Trying to nip this missing manual thing.
Not gonna happen!
This will be good info. I"m really looking forward to it.
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