Trip to the dyno

Dogeexpress · Jul 31, 2016

We recently had a dyno day in my area so I figured I'd get a baseline on my 2015 8 speed. ( i will note now it was a 3 hour drive to the dyno and I only had at most 20 mins before I was called onto the rollers on a hot day).
306 whp and 313 tq... does this seem a little low to you guys? I figured a 395 crank hp engine would be around the 315 to to 320 whp range?
Does heat soak really affect it THAT much?
Or am I right around where most untuned rams are at? ( only power mods are a vararam, 14" mufflex kit, along with a tb.)

Any input would be great.

Hemi_Express2013 · Jul 31, 2016

You'd be really amazed at how much humidity and heat play a roll on power with your hemi. Hemi 's are not Fond of neither. Throw in the fact that these trucks don't perform well on a dyno's , even with experienced operators. I wouldn't sweat the numbers too much! For a 5600lbs truck they are hard to beat on the sreet.

Kotta390 · Aug 1, 2016

It depends on the dyno type and operator. Such a vast range of each that it's hard to determine what is good and bad. Also did you do a 5th or 6th gear pull?

U&A · Aug 1, 2016

Kotta390 said:
It depends on the dyno type and operator. Such a vast range of each that it's hard to determine what is good and bad. Also did you do a 5th or 6th gear pull?

this is why (IMO) a dyno is a baseline for modifications. get a stock reading and go back to the same dyno run by the same guy and you can see the changes in your performance from modifications. one dyno to another can be very different. + or - 15 hp &torque is normal from one to another. and you will get diff readings on the same dyno on the same day.

someone else with more knowledge about dyno's will help alleviate your concerns.

BigSloth · Aug 1, 2016

HP ratings from the factory are done at SAE specific conditions. Basically it needs to be X temp, X humidity, X pressure, etc and if I recall that temp is near 65*F. So yes, heatsoak has a tremendous effect on HP. Also, depending on whether you are 2wd or 4wd, there can be a 20-25% drive train loss. Transmission gear can also affect it, anything other than 1:1 ratio (6th on the 8spd)and you lose power. I'd say in hot weather with a 3hr drive's worth of heatsoak, you're right on the money.

I have questions. How did you do the pull? In what gear, and we're they able to get a steady pull from it or did you have to get it way up high then stomp it?

Hemi450hp · Aug 1, 2016

That is about right. I have seen stock 8sp dynos that range anywhere from 300-330hp. Even had a 2016 8sp customer a few weeks ago put down 370hp/378tq with just a tune only. Dyno numbers are all over the place on these trucks. Use that number as your baseline, install whichever mods you want to add, and then go back to that same dyno to see how the numbers have changed. That is about all the dyno is good for.

Trip to the dyno

Dogeexpress

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Hemi_Express2013

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Kotta390

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U&A

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BigSloth

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Hemi450hp

Moe's Performance

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