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Im thinking about getting my 2017 GSF Dynoed (stock) for a BAseline... Just had a few questions?
1) Do all 3 pulls need to be done in a certain gear/setting?
2) I read somewhere that Pulls should be done in 5th gear?
3) Is there a difference between calculation/method between Dynos? (Dynojet, DynaPack etc)
Just want to make sure i get everything done correctly!
2. Regarding the gear, should be done in 6th gear actually because 6th gear in the GSF is 1:1. Most dyno operators would advise to use the gearing that's closest to 1:1 for a dyno. Theoretically, gearing doesn't really matter but I believe this is solely because of the dynos calculation.
3. Dynojet calculates HP based on the rotation and acceleration of the rolling thingy (Whatever you call it). Not too familiar with other dynos though other than the mustang dyno which I think is based on load.
So I had my 1st dyno day with my friend ('15 Challenger SRT8 supercharged by Hennessey). The Mopar was tuned to make 600 bhp, on the pad it made 580-ish bhp with the hood closed, so the owner was statisfied. It's just a proof, that the dyno pad was correctly functioning and measuring real numbers.
Althrough my '18 GSF (K&N filter, GTHaus headerback exhaust, everything else is stock) produced only 396 bhp and ~310 lb-ft (almost -80 hp less than stock numbers), see the dyno sheet below. Note that this pad calculates bhp, NOT whp. We pulled in 5th gear, Sport S+, in expert mode (PCS, TRC and the other safety system were turned off). After the dyno we checked the ECU via Techstream with my Lexus dealer, no error codes or faults. So now I am worried what could have caused this performance loss. My butt dyno doesn't feel an almost 100 hp loss, my 1/4 mile time is between 12.90-13.10 (we raced above 90°F), which not great, not terrible.
The guys at GTHaus are claiming +36 whp gain on the RCF vs stock numbers with the same exhaust as mine, althtrough they might have tuned it's ECU. Now I have - 80 bhp (or - ~65 whp) loss vs stock numbers Did we messed up the pull? What do you guys think?
How does it measure BHP? Does it estimate driveline loss?
The best way to measure real horsepower/kW/PS is look at your trap speed on a timed run from a standing start. Trap speed is everything. ET doesn't really matter for calculating HP.
2. Regarding the gear, should be done in 6th gear actually because 6th gear in the GSF is 1:1. Most dyno operators would advise to use the gearing that's closest to 1:1 for a dyno. Theoretically, gearing doesn't really matter but I believe this is solely because of the dynos calculation.
3. Dynojet calculates HP based on the rotation and acceleration of the rolling thingy (Whatever you call it). Not too familiar with other dynos though other than the mustang dyno which I think is based on load.
Great feed back .. on our gsf , the closest 1:1 gear ration is in 6th gear . But for some reason some
dynos don’t do it .
How does it measure BHP? Does it estimate driveline loss?
The best way to measure real horsepower/kW/PS is look at your trap speed on a timed run from a standing start. Trap speed is everything. ET doesn't really matter for calculating HP.
So here is my trap speed measured at the drag strip. I run only 109.1 mph from a standing start, so I think I definitely lost some power.. (my data is in the right column).
What was the density altitude when you raced? Your trap speed should be ~181 km/hr, not the 175,61 if your track's altitude is anywhere close to sea level.
I was racing 510 ft above sea level, air temp was around 90 F and there was a slight upwind..
I did something sort of dumb when I first took the GSF to the track. I had my GSF for two weeks and took it to the track and consistently did 108-109 mph and I thought my car was down on power.
Eventually, I learned that if I stepped on the pedal harder there was an inch of button feel when you fully press on the pedal. It didn’t seem to make the car feel faster but when I took it to the track again I did two runs for comparison. One where I didn’t fully depress the pedal and one where I pressed on the pedal fully to include that final inch of button feel. The difference in MPH was significant as the first run I did 109 mph and 2nd I did 112 mph.
Thank you Trevor, I will try it next time. That trap speed was with stock car or was it modded performance wise?
Car is 100% stock. The pedal thing was new to me, I’ve never owned a car with a pedal button before so it could be that you weren’t fully depressing the pedal as hard as you could.
or you could be having other issues, just trying to throw ideas your way.
04-26-18, 09:13 AM
GSF Dyno Questions
Did we messed up the pull? What do you guys think?
