2017 GT on the dyno, questions??

[TOROz06]

So I put the car on a dynojet today my car is a 2017 gt manual, only mod is a magnaflow gt350 cat back, and 275/35r20 tire.
So double checked this morning and looks like people are doing the pull in 5th gear because is closer to 1:1 on 4th they are losing power but when I do my first pull on 5th from 3500Rpm the car topped out at 150mph and wasn’t even close to 7000 rpm 374hp next pull I go down to 4th and it felt better got it all the way up to 7000rpm and made 388Hp. Did I screw something up on the pull? Why is everyone doing 5th pull and I hit 150 mph limiter??

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[ahl395]

You're hitting the speed limiter in 5th because your on the stock tune. You can dyno in 4th but your numbers wont be as high since it's not 1:1.

Once you tune the car it will remove the limiter and you can rev higher in 5th gear, giving you you're higher and more accurate numbers.

 

[Lonmon]

5th gear is the 1 to 1 ratio and the correct gear to dyno in. If you are hitting the speed limiter before making a full pull you will need a tune to remove the limiter. You can dyno in 4th instead but you can't compare the numbers to others results. You can still use the numbers to compare to your own if you like. I would imagine that once you start modding a tune will be done and you can go back to 5th gear pulls. Some dynos will also shut the run down when over 160mph or so. When I had my 15 PP (373 rear gears), I would hit the dyno limiter after about 7600 rpm. My 18 A10 in 7th (1 to 1) hits the dyno limiter after 7300 rpm (315 rear gear).

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