Strapped my M3 to a Mustang Dyno Today.

[Scharbag]

Here is my dyno.

Stage II, Dinan throttle bodies (not convinced that they matter), under drive pulley, Challenge X-Pipe (with cats), 91 Octane, Dinan cans and Dinan intake.

Shop is about 10m above sea level. Weather was cool (January in Victoria).

Cheers,

[SYT_Shadow]

Originally Posted by Scharbag

Dinan throttle bodies

Apparently they do matter but require a specific tune as it alters the filling parameters. So when your tune doesn't compensate for that your car is like WTF and becomes unhappy

[Scharbag]

Originally Posted by SYT_Shadow

Apparently they do matter but require a specific tune as it alters the filling parameters. So when your tune doesn't compensate for that your car is like WTF and becomes unhappy

Good times...

[Sgbimmer8888]

Originally Posted by pbonsalb

I think the graphs do not cross at 5252 because the torque and hp scales are not the same.

I agree 323 lbs rwtq is not possible. Could be a wheelspin spike or maybe there is some other explanation.

383 rwhp is also unlikely from a tune, cat back and intake.

But you can compare to other mustang dynos that were set up exactly like the one you ran on. If you can find any.

The main success is your before and after runs. Regardless of the dyno, you gained power.

Hmm I am confused. From my graph, I thought 383 is my crank hp, while 288 is my rwhp? Hence I felt that my rwhp is very Low compared to others.

Yes I agree the delta is important, but I was just concerned that my absolute rwhp was still very Low.

Could it be the correction factor that the operator used on the mustang dyno?

I am confident mine was a cf of 1.0.

[Redd]

Originally Posted by Sgbimmer8888

Hmm I am confused. From my graph, I thought 383 is my crank hp, while 288 is my rwhp? Hence I felt that my rwhp is very Low compared to others.

Yes I agree the delta is important, but I was just concerned that my absolute rwhp was still very Low.

Could it be the correction factor that the operator used on the mustang dyno?

I am confident mine was a cf of 1.0.

Unless they took the engine out of the car, all dynos measure power/torque at the wheels, and then calculate crank numbers. Which means you can pretty much ignore the crank numbers since they are just estimates.

Your numbers don't look far off if they are in kW/Nm. In fact, they seem high. 288kW = 390rwHP and that's very high assuming the Mustang is a heartbreaker dyno.

But I would be most concerned about the smoothness of the curves. The S65 is known to have an absolutely flat torque curve between 3k - 7.5k. Yours spikes and dips in a manner that is not normal. Same goes for the power curve, you have a flat spot at 5.8k that's not normal.

Not sure who this tuner is but I would highly recommend you get a tune from a more reputable source.

[Sgbimmer8888]

Originally Posted by Redd

Unless they took the engine out of the car, all dynos measure power/torque at the wheels, and then calculate crank numbers. Which means you can pretty much ignore the crank numbers since they are just estimates.

Your numbers don't look far off if they are in kW/Nm. In fact, they seem high. 288kW = 390rwHP and that's very high assuming the Mustang is a heartbreaker dyno.

But I would be most concerned about the smoothness of the curves. The S65 is known to have an absolutely flat torque curve between 3k - 7.5k. Yours spikes and dips in a manner that is not normal. Same goes for the power curve, you have a flat spot at 5.8k that's not normal.

Not sure who this tuner is but I would highly recommend you get a tune from a more reputable source.

The numbers are in rwhp..hence my rwhp of 288 is much lower than what I see on the s65 dyno database.

Could it be that the mustang dyno database numbers are based off a correction factor of 1.15-1.2? Hence explaining the higher rwhp numbers?

[M43S7RO]

Maybe the labels are incorrect? 323 hp and 288 tq would prob be more likely, although still low numbers for the given mods.

[Sgbimmer8888]

Originally Posted by M43S7RO

Maybe the labels are incorrect? 323 hp and 288 tq would prob be more likely, although still low numbers for the given mods.

good thought..but quite unlikely given the curves..

[Redd]

Originally Posted by Sgbimmer8888

The numbers are in rwhp..hence my rwhp of 288 is much lower than what I see on the s65 dyno database.

Could it be that the mustang dyno database numbers are based off a correction factor of 1.15-1.2? Hence explaining the higher rwhp numbers?

I don't think you understand the terminology. 'rwhp' means 'rear wheel hp', and is a measurement of power at the rear wheels.

Power has the following units - kilowatt (KW), PS or HP. This is switchable within the dyno machine, depending on preference/location. 288HP at the wheels for S65 is very low. Stock cars dyno at around 320-330HP (Dynojet). 288kW (approx. 390HP) is high but not unheard of for tuned S65 (again on Dynojet).

The 'correction factor' you mention is a curve smoothing correction and not a multiplier. The raw dyno data points without correction applied would look like the teeth of a saw, very jagged. Dyno operators apply a correction factor (SAE Smoothing 1, etc) to smooth out the curve to make it easier to read. Sometimes correction factors can slightly bump up - or bump down - numbers by 1-3hp, but never by a huge amount.

Hope this helps you understand the charts more.

[Sgbimmer8888]

Originally Posted by Redd

I don't think you understand the terminology. 'rwhp' means 'rear wheel hp', and is a measurement of power at the rear wheels.

Power has the following units - kilowatt (KW), PS or HP. This is switchable within the dyno machine, depending on preference/location. 288HP at the wheels for S65 is very low. Stock cars dyno at around 320-330HP (Dynojet). 288kW (approx. 390HP) is high but not unheard of for tuned S65 (again on Dynojet).

The 'correction factor' you mention is a curve smoothing correction and not a multiplier. The raw dyno data points without correction applied would look like the teeth of a saw, very jagged. Dyno operators apply a correction factor (SAE Smoothing 1, etc) to smooth out the curve to make it easier to read. Sometimes correction factors can slightly bump up - or bump down - numbers by 1-3hp, but never by a huge amount.

Hope this helps you understand the charts more.

Yea that really helps. Thanks a lot!

You are right - 288hp at the wheels is really very Low. Even though mustang dynos typically read lower, this is still Lower compared to the typical mustang dyno results.

Thanks for the explanation on the correction factor.

So what could explain the extremely Low rwhp on my mustang dyno?

Likely an issue with the car? Or the operator itself?

[Redd]

Well it's hard to say. In my personal opinion I would not trust just any tuner with our cars. I'm Msian, and as far as I know there are no reputable tuners for the S65 in our part of the world. Just cos someone can install a JB4/BM3 or a Racechip doesn't make them a 'tuner'. So I would start there.

There's also tons more S65 data on Dynojet so maybe try a different dyno shop. You might also want to confirm the units for HP and torque used by the Mustang dyno.

Of course there is always the possibility of car issues. Bad plugs, coils, O2 sensors and intake/exhaust leaks can impact power. If your tuner is familiar with S65 they would know that the numbers are off.

[Sgbimmer8888]

Originally Posted by Redd

Well it's hard to say. In my personal opinion I would not trust just any tuner with our cars. I'm Msian, and as far as I know there are no reputable tuners for the S65 in our part of the world. Just cos someone can install a JB4/BM3 or a Racechip doesn't make them a 'tuner'. So I would start there.

There's also tons more S65 data on Dynojet so maybe try a different dyno shop. You might also want to confirm the units for HP and torque used by the Mustang dyno.

Of course there is always the possibility of car issues. Bad plugs, coils, O2 sensors and intake/exhaust leaks can impact power. If your tuner is familiar with S65 they would know that the numbers are off.

i confirmed with my tuner that the units were hp not KW on the mustang dyno. So 288wrhp is indeed extremely off.

Another workshop told me that it could be related to the TCF, and that if a tuner uses a TCF of 1.2/1.3 instead of 1.0, the numbers you get will be falsely elevated.

He suspects that my tuner used a TCF of 1.0, and hence my rwhp results are significantly lower than many others.

[Redd]

Originally Posted by Sgbimmer8888

i confirmed with my tuner that the units were hp not KW on the mustang dyno. So 288wrhp is indeed extremely off.

Another workshop told me that it could be related to the TCF, and that if a tuner uses a TCF of 1.2/1.3 instead of 1.0, the numbers you get will be falsely elevated.

He suspects that my tuner used a TCF of 1.0, and hence my rwhp results are significantly lower than many others.

The dyno TCF (Transmission Correction Factor) will impact the calculation/estimation of engine/crank HP. It does not impact wheel HP which is actually measured by the dyno. If 288hp is your crank number and not wheel number, then you have even bigger problems. Secondly, TCF=1.0 implies that there are zero drivetrain losses. I would be wary of using any dyno where the operator doesn't understand what a TCF is and how it's used.

A sanity check you can do is to take the manufacturer claimed engine hp, minus drivetrain losses, and that shd give you your wheel hp. I typically use 12-15% losses for FWD, 20% for RWD and 22-25% for AWD. Add another 3-5% for automatic transmission (DCT is considered manual). Of course many will come and say its not as simple as that, and drivetrain losses are not always a fixed percentage, but as a general rule of thumb its good enough. So BMW claimed 414hp minus 20% drivetrain losses is 330hp. I've owned enough cars and done enough dynos that I know these percentages are close enough for me.

[Sgbimmer8888]

Originally Posted by Redd

The dyno TCF (Transmission Correction Factor) will impact the calculation/estimation of engine/crank HP. It does not impact wheel HP which is actually measured by the dyno. If 288hp is your crank number and not wheel number, then you have even bigger problems. Secondly, TCF=1.0 implies that there are zero drivetrain losses. I would be wary of using any dyno where the operator doesn't understand what a TCF is and how it's used.

A sanity check you can do is to take the manufacturer claimed engine hp, minus drivetrain losses, and that shd give you your wheel hp. I typically use 12-15% losses for FWD, 20% for RWD and 22-25% for AWD. Add another 3-5% for automatic transmission (DCT is considered manual). Of course many will come and say its not as simple as that, and drivetrain losses are not always a fixed percentage, but as a general rule of thumb its good enough. So BMW claimed 414hp minus 20% drivetrain losses is 330hp. I've owned enough cars and done enough dynos that I know these percentages are close enough for me.

If you look at my mustang dyno table, my tuner generated a third row labelled as "crank pwr (Hp)", which i never see in other mustang dyno tables (usually just Eng torque T WC and Eng power T WC".

And the crank Pwr listed there was 383Hp after these bolts on and custom ECU tuning, which is even lower than the listed stock HP of 414hp by BMW..

Or is it more accurate to calculate my crank hp by dividing:
414hp (stock crank hp)/267rwhp (baseline rwhp on dyno) = 1.55,
then multiply 1.55 x 288 (tuned rwhp on dyno) = 446hp at the crank.

[Redd]

I usually dyno on Dynojet but I will take a stab at this. I think one thing to always remember is that the dyno measures power and torque at the wheels. Everything else is derived from that measurements. According to this video, there is high potential for error/manipulation based on Mustang dynos:

Hilarious video!

For all intents and purposes of this discussion, let's assume that those measurements are correct. So you have a measured baseline of 267 HP at the rear wheels. This alone is very far off from the 330-320 rwhp most stock S65s get.

TCF only comes into play when estimating crank/engine HP from wheel HP. I don't know the exact formulas that Mustang use to estimate engine/crank HP, but assuming front-engine, rwd losses are approx. 20%, 267hp divided by (1-0.2) = 334hp stock. That's way off.

Thing is, drive train losses should be same across the same type of car. Your E9x M3 should not have drastically different drivetrain losses from another E9x M3. Using the same calculation for a 320 rwhp car with 20% drivetrain losses, we get 400hp at the engine/crank (which is well within the manufacturer's claim ballpark). If we assume TCF to be 1.55 then all the other M3s will also be reading much higher power than your car.

Summary:
1. TCF should not impact rear wheel HP which is measured.
2. If the rwhp measurement is wrong, then everything else is wrong
3. According to the video, there is high potential for error/manipulation on Mustand dynos

I'd get your car on a Dynojet for a second opinion before you crack your brain any further on this problem. It may just be dyno operator error and your car could actually be making much more HP that shown on the Mustang dyno.

[pbonsalb]

There is too much odd stuff with that dyno graph. Correcting from 288 rwhp to 383 crank hp is odd. Having more rear wheel torque than hp on a 4.0L V8 that revs to 8400 rpm is odd.

[Sgbimmer8888]

Originally Posted by pbonsalb

There is too much odd stuff with that dyno graph. Correcting from 288 rwhp to 383 crank hp is odd. Having more rear wheel torque than hp on a 4.0L V8 that revs to 8400 rpm is odd.

yeap. the operator employed a 1.33 conversion from rwhp to crank...

and yes to the higher rear wheel torque...really odd.