drbobvs

I posted this on another forum too.

Went to the Mustang Dyno again since I had my JDM and VMP tunes "updated". Justin from VMP added 2% more fuel this time and the JDM hesitation issue has been fixed.

The weather was about 15 degrees warmer this time and the oil temp was 190 degrees at startup. I had just gotten back from giving someone a "demo ride" too, so the car was driven hard before the run.

Since my last run I added BBK shortys and a new tensioner. Here's the sheet from 4/24 and the 2 sheets from yesterday RPM vs MPH.






Now I know heat can deplete power but at some points I'm down nearly 40 Ft-lbs!! The boost is down about .4 psi, perhaps from the heat too but maybe partially due to the headers also. I've emailed JDM to get the AFR into place, so hopefully they can do that this week.

Does heat really make that much of a difference day to day?? The car sure feels strong but I just can't believe the sheets. What do you guys think?[/align]

mustard05

how much did you make all together, i lost my glasses and really cant read the numbers to good, but from what im thinking that im seeing, with the 10psi pully, it doesnt look right

mustard05

is this the only dyno youve ever been on, ive heard diff opinions on mustang dyno's

sevenleaf

I don't mean to scare you but when I lost 50 horsepower in dyno's (3 different dyno's) a month later my input shaft snapped. We couldn't figure out what was going on for atleast 2 months. On the road the car was AWESOME but the dyno's showed a different story. Good luck keep us updated.

Z06 Killer

Heat makes a HUGE diffence in force induction. If you can cool it back down you will see the power come back

Derf00

+1 temperature is the biggest enemy with FI. I bet if you had a baseline timing chart (cooler temps) and compared it to where it was at on your last run you'll find your timing has been way retarded to keep you from detonating. Detonating in an FI application = boom!! It also equates to lower power.

You can't do a real comparison until the conditions are similar (Ambient temperature and pre dyno conditions of your car)

forensicsteve

Agreed and not only heat. High humidity means thatair is beingsaturated with water molecules. Last time car ran it was 92 temp with 90% humidity...everybody we spoke to with FI was off as much as 0.6 of a second from expected times, including us.

sactown

heat could is probably the biggest issue, but how does you A/F look during the entire run? Maybe its just me, but could it be a little off, mine is in the 11's during my dyno pulls. I am no expert but it would not hurt to check.

GT Bob

The boost is down because of the addition of the shorties. Better flowing exhaust will always cost you a littler bit of boost, but should not hurt your production of power in the least.

As for the power... I am guessing your an auto because of the 3.73 gears... Three things I am seeing.. One, that spike in the VMP tune is likely something funky going on with the locking or unlocking of your torque converter and chances are it's effecting ther whole run, just not showing anywhere but there. Second is that the AFR's are very different and thats having an effect on power... and the third is all that heat you built up giving the demo run is killing you, combined with the fact that you dynoed once in April and once in June. Despite there only being a 15 degree difference in temp, you also hafta look at humidty.

drbobvs

Yes that spike in the curve is the TC locking. The A/F is about the same april-June in the JDM tune, but the VMP tune went from 12 - 11.4 in the VMP tune after Justinadded 2% fuel, and also due to the warmer temps.

(Dyno graphss, as well as sig pic, currently down due to a problem with Photobucket's website)