Dynamometer Results & Comparisons - This is why you cant trust the butt dyno

I went from a cam only set up that made good under the curve power to heads and a TRex. I switched set ups to see if I would like a big cam if set up properly. So I went with the Trex. After getting the car tuned it felt great! Pulled like crazy up top. One problem though......it felt as if I lost all my power under 4k. I blamed the cam right away. I was wrong, my ass lied to me!:eek2:

I compared my old cam only set up to the current set up and my current set up makes more torque! I decided to compare my dyno graphs and the TRex with heads out performs the cam only 236/232 110-1 everywhere.

Here the list of differences

Here the set up
Dyno jet
236 110-1 torque cam
slp smooth bellow
ls6 intake
10 bolt 4.10s 16 inch wheels
light spec clutch
Mac mid length headers
cut out


Mustang Dyno
Trex 59cc ported 5.3s/ ls6 valves
ls1 intake
9 inch/4.30s 17 inch zr1s
heavy ls7 clutch
hooker long tubes
cut out
Stock bellow
As you can see, the trex combo has A LOT going against it in the case of putting up numbers. Ls1 intake, Mustang dyno, heavier drivetrain.

Heres the results
236 vs Trex
Torque
@3k
300/330
@4k
370/370
@5k
370/380
@6k
320/330
@6.5k
270/350
@6.8k
250/310

Horsepower

@3k
170/200
@4k
270/280
@5k
350/360
@6k
380/400
@6.5k
380/416
@6.8k
360/412
This is not a cam vs cam, this is just to prove studderin's point of big cams can feel like they have no power down low because they pull so hard up top. Even though my torque cam felt faster below, it clearly wasnt. The trex set up would have looked even better vs the torque cam if it was on a dyno jet. If it was on a dyno jet it would have been around 430-440 horse and around 400 lbs if not more.

And yes I realize they were not dynoed on the same day or even on the same dyno ior even the same year. I feel like the Trex had the cards stacked against it in terms of putting out numbers down low. Even though it did, it still matched and beat the smaller cam. Yes I know there are smaller cams that would kill this set up don low. Dont care. I made this thread to show people not to always trust how the car feels.

So lesson learned, DONT TRUST YOUR BUTT:chug:

Oh, and the ls1 intake sucks balls. I will get a new intake once I buy a few more things for the car

LOL, I was just reading your thread oin how you hated the trex. Glad it worked out for you!

Nice numbers. I've heard the same about the infamous butt dyno.

LOL, I was just reading your thread oin how you hated the trex. Glad it worked out for you!

Me too. I thought I lost a lot down low, I was wrong. Just wanted to point this out to help people

sometimes the horsepower/torque output and the ass dyno don't match because often the ass dyno relies on things like throttle response, which a dyno doesn't. A smaller cam may feel faster because it reacts faster and results in quicker, crisper throttle response, as well as part-throttle behavior characteristics. None of this shows up on a dyno. All of that is why I like TPI so much, even though it doesn't dyno worth a damn.

Interesting. It would be cool to have track times to see if the added hp and torque = a faster car.

yes a bigger cam will not suffer down low if the compression if bumped enough.
nice job! :cheers:

:angel:

This isn't true for every setup. So there not both even a dynojet?

I just saw guys like you that have/had a bigger cam I've had in my car and did back to back dyno to something else. And saw comments about how it feels like all top end power, and not alot under 4K ect. Were taking WOT numbers here, part throttle is different. But think going to something else (most of the time a smaller custom spec) for more mid range, and the phrase more "area under the curve" used hear alot. People use with no dyno or track numbers, Just off the butt dyno how it fells like it picked up. That most of the time misleads others into switching to something that makes less hp AND tq at EVERY rpm. That can be a truth on the dyno, but is not for part throttle power or driveability, or not having supporting mods.

I wrote some other stuff but it starts getting way off topic on this.:eyes: But check out the thread I made about what cam only setups (346 LS1) broke 400whp. Guess what there no tq cams in there.

the dyno HP is tq x rpm, Big power is going to have big torque :D
http://en.wikipedia.org/wiki/Dynamometer