Dyno and Timed Run App Perfexpert Tested

[Aevus]

Just started to play with this Perfexpert smartphone app and it looks very promising. Will sure be very useful to test the upcoming modifications on my gen 3.

I like the fact that almost every thinkable variables are in that app, including weather instantly downloaded for each Dyno or Timed run, weight for passenger(s) and cargo, final gear ratio, level of gas, and even pitch angle per G (suspension stiffness).

Everything to make a simple phone app as precise as possible. They advertise 0.5% to 2% precision compared to a real Dyno or Timed run, which is very good. Dozen bucks well spent!



Here is my first Dyno run:


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Stock gen 3 engine but bolt-ons: K&N + BBK TB + Headers + Hi-flow cats + 93oct generic tune + UD pulley


I think it makes sense but I sure will run few other tests....

[Aevus]

Note: it's not connected to the car, it's standalone, so it cannot accurately know about actual RPM (my rev limiter is 6,250 rpm) so the 6,593 at maximum speed is obviously not accurate, the car was simply accelerating a little after the engine cutoff...


Here are few other screenshots:


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[Aevus]

Now, I'm not sure about the curb weight of my car, there is few mods that changed the weight for sure... BUT one cool feature on the app is you can edit POST-TEST many things, including passengers, cargo, curb weight, final gear ratio, etc... so you can correct if needed and also see what kind of impact each variable can have on the results.

Now, I'm not sure the crank v.s. wheel horsepower is accurate. That app can only know about wheel horsepower (if you have perfect traction) so I assume the +/- 15% deducted from engine power (bhp) is generic and not precisely for the gen 3 Viper. I assume with poly engine/trans mounts and my Wavetrac diff I'm about 12% loss, but it's very difficult to know for sure so I would say that only wheel HP is reliable on that app.

[Aevus]

IMG-8533.jpg

Also you can use different weather corrections, explained here:

https://www.perfexpert-app.com/faq

Does PerfExpert manage the influence of atmospheric condition on engine performance?

Yes, PerfExpert applies a correction ratio to power, based on the weather conditions at the time of measurement, in order to to bring back the power of your engine to the power it would produce in normalized atmospheric conditions. You can use one of five international standards currently in use by car manufacturers : DIN 70020, SAE J1349, CEE/E, JIS D 1001, and ISO 1585.

I have no idea which one is the best so I used the default DIN 70020.

[Aevus]

Did few more runs and it's pretty consistent regarding horsepower: 488whp average @ 6,050rpm

Correction feature (passengers, gas level, cargo, weather, etc..) seems to work very well also.

On the other hand, torque numbers: from 449 to 492 are not very consistent and I'm not sure why but I suspect my phone holder not being tight enough on the dashboard.

[Old School]

Now, I'm not sure about the curb weight of my car,

I weighed my 2003, without me in it, half tank of fuel, was 3340.

[Aevus]

I weighed my 2003, without me in it, half tank of fuel, was 3340.

ok thanks, so 57 lbs extra for the fuel = 3397 lbs total with full tank which is pretty close to the 3373lbs I am using now, taken from Wikipedia:

https://en.wikipedia.org/wiki/Dodge_Viper_(ZB_I)


They say 3450 lbs here:
https://www.ultimatespecs.com/car-sp...-Roadster.html

and... it says 3309 lbs on my (Canadian) registrations