[Drsagacity]

When tuning the car does anyone really use the HP and TQ measurements? Anyone know how accurate they are? Compared on a dyno?

For the record, I suspect the numbers are going to be different based on mods and likely not accurate...however, just like the dyno, the Hp Torque ratings from HO Tuners probably does provide a good sense of that the car is doing and improvements from change to change.

[Camaros & Coffee Norcal]

Originally Posted by Drsagacity

When tuning the car does anyone really use the HP and TQ measurements? Anyone know how accurate they are? Compared on a dyno?

For the record, I suspect the numbers are going to be different based on mods and likely not accurate...however, just like the dyno, the Hp Torque ratings from HO Tuners probably does provide a good sense of that the car is doing and improvements from change to change.

Yes, torque is used to find the MBT. Horsepower is an equation of engine torque over time or engine torque x rpm / 5252, so technically it's being used all the time.

[Gunkk]

Well anything the car measures at the flywheel would be the equivalent of an engine dyno.

Which of course gets me thinking... if HP Tuners can see the flywheel torque signal, then maybe just maybe HP tuners can be made to see that sensor's calibration tables... ... and once that's possible, a good honest tweaking just might allow the M6 guys-n-gals to blow a kiss goodbye to the TM bog

[ZNix]

Originally Posted by Gunkk

Well anything the car measures at the flywheel would be the equivalent of an engine dyno.

Which of course gets me thinking... if HP Tuners can see the flywheel torque signal, then maybe just maybe HP tuners can be made to see that sensor's calibration tables... ... and once that's possible, a good honest tweaking just might allow the M6 guys-n-gals to blow a kiss goodbye to the TM bog

Its all math from my understanding. There isn't a load sensor. If we knew where the 'constant' was, maybe that could be changed.

[Drsagacity]

Once we are done with the tune, I will be sure to log and compare Hp tuner to the dyno and I will share the results.

[Drsagacity]

Ok. I got to the dyno to log some runs and the HP tuner HP and Torque calculations are reasonably close.

The torque number with HP tuners only shows 640tq, I actually had 695. The HP showed 726 when the dyno showed 705.

Bottom line is, the numbers are reasonably close and could be used as a tool. Most important thing is HP tuner is NOT showing HP/Torque from the engine, it is definitely closer to the wheel HP.

[DarkFangz1100]

The formula I used is

((Torque*RPM)/5252)*.80

[Drsagacity]

Originally Posted by DarkFangz1100

The formula I used is

((Torque*RPM)/5252)*.80

Why would you think there is a 20% loss? That math doesn't hold true for my car comparing the HP tuner calculations and comparing to my dyno results. I would see the modifier as closer to .965 (not .80).

As an example, when I logged the run with HP tuners, it calculated my HP as follows:
run 1: 700hp @6331 vs actual real wheel HP 675
run 2: 729hp @6394 vs actual real wheel HP 705

In other words, the HP tuner appears to be calculating WHP, not FWHP. After multiple logged runs, I would say HP tuner is within 96-97% accurate on my application.

That might be based on all of the MAP settings and everything else. So that if it is seeing the correct data the calculations are accurate. This is important because if accurate, then I can run on the street and get some numbers and feel reasonably accurate that we are dealing with the right numbers (multiply results from HP tuner by .965 and it should be very close).

I will run another test his coming week. I am going to have the pulley overnighted so that I can up the boost. Then I am going to get a run in 4th on the street and compare it to the dyno. In fact, I may try to get one 4th gear run on the dyno just to erase a variable then I will also run in 5th to make sure I have apples to apples with my last dyno run.

[KingLT1]

My HPtuner log shows 563ft lbs @ 4800rpm and 472ft lbs @ 6400 rpm in 85 degree weather. I don't think I am making that to the wheels. At 15% drive train loss that would be 491whp 479wtq, using 20% loss would be 462whp 451wtq.

[Drsagacity]

Originally Posted by KingLT1

My HPtuner log shows 563ft lbs @ 4800rpm and 472ft lbs @ 6400 rpm in 85 degree weather. I don't think I am making that to the wheels. At 15% drive train loss that would be 491whp 479wtq, using 20% loss would be 462whp 451wtq.

Do you have an actual dyno and did you add the HP channel?

On mine, Hp tuner reflects a lower torque number than what I have to the rear wheels. However, the calculated Hp is right on with my actual wheel HP. For me it’s beautiful because I am ordering three different pulleys and I will be able to have a real good feel for my power level before I go back to the dyno (because I don’t plan on taking the car to the dyno with each pulley).

I will take it for my final street tune and for my final track tune.

[steelheadrob]

I was comparing my dyno to a recent track day. Here is what I am seeing.

Dyno 5,250 rpm crossing point 605 HP&TQ vs 636 HP&TQ on the HP Tuners on the track, not noticing much difference on which gear it is in for the the HP Tuners numbers. Max HP on the dyno 657, max on HP tuners on the track was 716HP. TQ dyno 650 vs TQ track on HP Tuners 652.

[DarkFangz1100]

Originally Posted by Drsagacity

Why would you think there is a 20% loss? That math doesn't hold true for my car comparing the HP tuner calculations and comparing to my dyno results. I would see the modifier as closer to .965 (not .80).

Reason why I did .80 because I couldn't find ANY information in regards to the lose of power on an I4.

[Drsagacity]

Originally Posted by DarkFangz1100

Reason why I did .80 because I couldn't find ANY information in regards to the lose of power on an I4.

It appears that everyone has a different outcome. I assume it's based on the way the tunes are configured. I guess the best thing is to run the dyno and compare and then you have a ballpark number and compared to the dyno and your tune, you find the number that works.

My HP tuner is off by about 3.5% compared to actual rwhp.

I wasnt really looking st torque, but HP tuner caps mine at 640...even though I am running 50wtq more.

[KingLT1]

Originally Posted by Drsagacity

Do you have an actual dyno and did you add the HP channel?

On mine, Hp tuner reflects a lower torque number than what I have to the rear wheels. However, the calculated Hp is right on with my actual wheel HP. For me it’s beautiful because I am ordering three different pulleys and I will be able to have a real good feel for my power level before I go back to the dyno (because I don’t plan on taking the car to the dyno with each pulley).

I will take it for my final street tune and for my final track tune.

No... I just figured it using a calculator with the same formula that you program the channel to use. I found peak tq and hp from a wot log and plugged the delivered engine torque value in the formula.