Alright guys, my Magnaflow exhaust will be here thurs or friday and i have dyno dyno scheduled for wed and its no prob to get it on the dyno again the next tues.
Would anyone be interested in seeing the changes before and after? Or is it even worth it?

 

You should dyno the same day to get good comparison results. Don't wait even one day. A catback is easy to install on the 8. See if the dyno shop will help you swap them out while your there.

 

thats cool, i can probably do that. i guess the car will be warm both times so it shouldnt make a difference, should it?

 

Not really, but if you can take the above advice as no matter what, you will always want a baseline dyno.

 

well, i just got off the phone with the dyno shop, he said we can do it same day but he also said the dyno they just got corrects for all variables concerning when you dyno, he said its accurate to one percent even if i dyno weeks apart. Is this possible?
Its a new Dyno Dynamics dyno

 

The correct formula is highly flawed. Its gotten to the point where you can't even compare one car to another anymore.

Here's some articles on how rediculous dyno variance has become.

First off is an article comparing a 4 wheel dyno to a 2 wheel dyno.
http://www.sportcompactcarweb.com/ed...ble/index.html

Second is an article taking a 350Z (same car) to 7 different dynos.
http://www.turbomagazine.com/tech/03...ash/index.html

This article is especially eye opening, as there is a 228.9 whp to 265.7 whp variance...on the exact same vehicle.

Here's some old articles on dyno cheating. (How manufacturers show gains)
http://www.sportcompactcarweb.com/ed..._technobabble/

http://www.turbomagazine.com/tech/04...yno/index.html

 

crossbow is like a walking encyclopedia :D

 

So basically, even using the same dyno on 2 different days and using the correction formula, we cannot get close numbers. Am i reading all that right? good find btw.

Its just a time crunch getting the exhaust on and the dyno done 2x in one day. Im installing the exhaust for free and would have to drive to the dyno, run it, then have the exhaust installed and run it back. Just kinda a headache.
But, if i have it installed at the dyno shop, it would be interesting to get results with factory exhaust, w/o factory exhaust, and with the magnaflow exhaust just to have 3 different charts.

 

You'll get differences...but you can't sit there and say...

"This is 100% accurate because of the formula"

Its more like 75% accurate. As long as you understand that, and don't take the data as absolutes, you'll be fine.

The problem stems from when people see one car dyno like 180 whp, and then they dyno 165 whp, and start wondering whats wrong. So they try different mods, to catch up, based on other dynos. They end up hitting like 175 whp on another dyno, while the original 180 whp guy does the same mods, and hits 170 whp on another dyno.

Always use the same dyno for everything if your trying to do comparisons.

 

Thanks, this will be the only dyno my car will ever see. Because of my being friends with the owner and the fact that he advertises on one of my websites, he gives me a great deal, so i would really like to dyno before and after every mod i do, just to see the differences and post the results each time