Dyno Day Mystery??

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Feb 25, 2004
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O.K.- so about three months ago I dyno'd my 2004 Mach 1 when it was bone stock except for a SLP catback and was pleased to get 283rwhp and 310lb/ft.

Today I had it dyno'd again- this time it has the SLP catback, a Magnaflow off-road Xpipe, a PHP intake spacer and a Diablo Predator Handheld Tune installed...

I was hoping for 295rwhp or so- and was extremely unhappy to get back only 284rwhp and the torque went down to only 300??? WTF??

Does anyone have any idea or advice as to why this could of happened? How could I have only gained 1rwhp and lost 10lb/ft.????

Any and all suggestions/advice is greatly- GREATLY appreciated!!
 
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Did you use the same dyno? Three months ago it was a lot cooler? Did you have those 4.10 installed then? Does the car feel stonger now? Most people look at peak hp which really dont mean squat, look at average horsepower over the entire run? Good luck
 
Weather/climate, engine temp, different dyno, altitude, the person doing the dyno runs, etc. can be major factors. That's why you really can't go by #s alone because they won't be totally accurate.

I think most of us has gone through similar dyno disappointments one time or another. I know I did..

Edit: I see you have 4.10s installed. That alone robs some hp. It actually hid 8-10hp from mine. You still have the hp to the wheels, but it won't show.
 
O.K. some of that makes me feel better- yeah- I didn't have the 4.10's on the last dyno and today's weather was considerably hotter...

The A/F ratio was pretty much the same on both runs- so I know I'm not running lean or rich, so that was good- but it was just incredible that the numbers really didn't change based on the mods made...

I do notice that it runs a helluva lot stronger- so I'll just chuck this one up to a hot day and a bad dyno run??