Dyno of STX car at altitude?

[colobrio]

If anyone has a dyno of an STX car or equivalent (header, exhaust, tune) done at altitude, I'd appreciate seeing it. I recently did an EVO school, and after driving my car one of the instructors was convinced it's missing power for some reason. It could just be that he's used to a high HP car at sea level, but he's driven a lot of cars in a lot of places, and was pretty sure something's going on, so it seems worth at least comparing numbers. As a bonus, if he's right, maybe I'm not quite as bad a driver as I think I am! I'm in Denver, so around 5,000 feet, but anything 4-6 should be a useful comparison.

[Breezio]

Post up your dyno at altitude. Might not need to see anyone else's to diagnose yours.
I've got a couple from 2800 ft. Pretty positive the power is down a bit compared to a sea-level car.

[CSG Mike]

Originally Posted by colobrio

If anyone has a dyno of an STX car or equivalent (header, exhaust, tune) done at altitude, I'd appreciate seeing it. I recently did an EVO school, and after driving my car one of the instructors was convinced it's missing power for some reason. It could just be that he's used to a high HP car at sea level, but he's driven a lot of cars in a lot of places, and was pretty sure something's going on, so it seems worth at least comparing numbers. As a bonus, if he's right, maybe I'm not quite as bad a driver as I think I am! I'm in Denver, so around 5,000 feet, but anything 4-6 should be a useful comparison.

Dynos compensate for air density (temperature humidity and..... altitude), just a FYI.

[strat61caster]

https://www.ft86club.com/forums/showthread.php?t=125559

Justin lived in Denver at the time.

[colobrio]

Originally Posted by strat61caster

https://www.ft86club.com/forums/showthread.php?t=125559

Justin lived in Denver at the time.

Thanks Strat61caster, that's exactly what I was looking for. I realize different dynos can read differently, but there's a significant difference. My quick initial attempt to past in the image of my dyno graph failed. I'll sort that this evening, but mine (on a Dynojet) shows max HP at 172 vs Justin's (on a Mustang) at 189. There about the same at 3k rmp, but his goes up more steeply from there, with his peak also coming later. It looks I've got some figuring out to do.

[colobrio]

Originally Posted by Breezio

Post up your dyno at altitude. Might not need to see anyone else's to diagnose yours.
I've got a couple from 2800 ft. Pretty positive the power is down a bit compared to a sea-level car.

My dyno from the spring should be attached. Any thoughts welcome as to whether it shows anything may be amiss, as opposed to maybe just a machine that reads low or whatever.

[alphasaur]

What mods do you have? 172 sounds on the money with elevation.

[cmiovino]

Originally Posted by alphasaur

What mods do you have? 172 sounds on the money with elevation.

Justin's was done with the ACE350 header, which is the best you can basically get. You'll have more top end with EL and given it's "the best", having a few more ponies up top doesn't seem out of the question.

Unless of course you're also running the ACE350. Then you'd have to start seeing if it's "within the noise" of a dyno with humidity, calibration, etc. Usually about 5% each way is accepted.

Then after that, it can be who tuned the car and if it was a more conservative tune vs trying to get everything out of it.

The problems with dynos is you basically need to use the same one for each car and better yet, on the same day. Comparing someone's 170 peak HP to someone else's 180 peak HP on a different dyno, different day, etc is like apples to oranges.

My guess is if someone's commenting you're down in power, it's likely in the mid range, not peak power.

[colobrio]

Originally Posted by alphasaur

What mods do you have? 172 sounds on the money with elevation.

Header - JDL UEL
Exhaust - Perrin, w/ single high-flow cat
ecutek tune.


As long as it seems within the realm people who know more than me would expect to see, I'm not going to worry about it.

[alphasaur]

The dyno above has the revworks uel peaking at 186, which is a touch higher and honestly in line with dynojets I've seen of these cars with bolt ons at sea level. I have a sneaking suspicion the linked dyno was corrected for elevation.

~180ish hp is header and tune on this car on 93, ~200ish is header and tune on e85.

Your torque and hp look smooth, I really wouldn't worry unless something seems off.

edit: in the dyno above the poster says values were corrected for elevation

[Breezio]

Originally Posted by colobrio

My dyno from the spring should be attached. Any thoughts welcome as to whether it shows anything may be amiss, as opposed to maybe just a machine that reads low or whatever.

Well, yours looks better than mine.

UEL catless header, cat-back, OpenFlash OTS tune, 91 octane, 2900 ft above sea level.

[colobrio]

Thanks for the feedback, all. It sounds like it was most likely a false alarm. Back to trying to figure out how to improve the driver.

[colobrio]

So, closing the loop on this -it's been a learning experience. Y'all were right the peak power on the tune was about right, but the tune was still a problem. Below are dyno runs by another shop. Blue is the original tune by Moto East, which I finally was able to restore, thanks to my seller getting his hands on the almost 10 year old tuning kit and getting it to me (thanks, @tigermack). Green is the tune supposedly "improved for altitude" by the local shop. That's a lot of mid-range torque I didn't have this year.

[Pat]

You can also look for the dyno sheets submitted by NASA TT drivers on the NASA national site. They should have their mods listed. Most are done at Dyno Pro, so they are pretty consistent.