[omniphil]

I know this isn't an exact thing, but in the past AWD cars I always assumed had pretty good drive train losses. 15 to 20%. As cars get newer and drivetrain component get heavier, wheels/tires get heavier I'd expect that to rise?

I've seen some wheel horsepower numbers for a stock X3M at around 460whp.
Adding 15% to that seems like an unrealistic number so maybe the efficiency of modern cars actually makes it lower?

For the dyno folks out there that can calculate drivetrain loss to some extend what is a good rough percentage of loss?

[Potatohead-M2]

I would guess in the 15-18% range for this vehicle.

BMW always underrates their power ratings it seems recently. Although these are rated at 503 it seems likely they are more in the mid 500 range.

[omniphil]

So with the Bootmod3 stage 1 93 tune you are looking at 550 at the wheels.
Adding back in 15% you are looking at 630 or so at the crank. That seems a little on the high side?

[Kevin_The_Clean1]

BMW is very conservative when it comes to their numbers. That 0-60 MPH they claim is measure with 4 medium sized passengers & a full or half tank of gas believe. That's why people often achieve better acceleration numbers.

And the same goes for their quoted power numbers too. That 503 HP for the Comp model is really how many ponies are transferred to the ground to all 4 wheels on 93 octane. So this means the S58 makes about 560 HP at the flywheel.

If you don't believe me, go ahead & spend hours looking this stuff up. BMW uses a very VERY efficient ZF 8-speed & many strong relatively lightweight parts. So in today's world we often see about a 12% drivetrain loss. I've had 4 different flavors of F97's in less that 4 years. So I tend to know my stuff a touch better then the average Joe might.

[Oldgixxer]

FWIW,my stock LCI X3MC put down 506awhp at EuroMpire on their DJ w a tank of 93. There's pics/vids if you feel like searching

[TacosRule!]

Originally Posted by Oldgixxer

FWIW,my stock LCI X3MC put down 506awhp at EuroMpire on their DJ w a tank of 93. There's pics/vids if you feel like searching

what was the correction factor? Ambient temperature? Humidity? Thats pretty good. Need to dyno mine non comp

[Oldgixxer]

Originally Posted by TacosRule!

what was the correction factor? Ambient temperature? Humidity? Thats pretty good. Need to dyno mine non comp

This is what it made on this particular dyno,on that day etc. As I'm sure you know all dynos read different and and will produce different results yadda yadda yadda...but,I was really only interested in the back to back runs and the gains I got from the RC.
Just puttin that out there for anyone reading this for the 1st time;your particular results may vary up/down

https://x3.xbimmers.com/forums/showthread.php?t=1944152

[omniphil]

Originally Posted by Kevin_The_Clean1

BMW is very conservative when it comes to their numbers. That 0-60 MPH they claim is measure with 4 medium sized passengers & a full or half tank of gas believe. That's why people often achieve better acceleration numbers.

And the same goes for their quoted power numbers too. That 503 HP for the Comp model is really how many ponies are transferred to the ground to all 4 wheels on 93 octane. So this means the S58 makes about 560 HP at the flywheel.

If you don't believe me, go ahead & spend hours looking this stuff up. BMW uses a very VERY efficient ZF 8-speed & many strong relatively lightweight parts. So in today's world we often see about a 12% drivetrain loss. I've had 4 different flavors of F97's in less that 4 years. So I tend to know my stuff a touch better then the average Joe might.

12% certainly seems like a good number. Certainly these X3M's as well as some other BMW's usually put out whp numbers that are what they are advertising as crank numbers.

460whp and 490whp are typical dyno numbers for a Non comp vs Comp. Which can certainly be skewed up if the dyno brand changes or the correction factor is altered.

[Kevin_The_Clean1]

Originally Posted by omniphil

12% certainly seems like a good number. Certainly these X3M's as well as some other BMW's usually put out whp numbers that are what they are advertising as crank numbers.

Exactly. This is the main point I was trying to convey to others. This is also why BMW's are often quicker than cars that claim to have more HP. BMW is a clever company that doesn't just build great cars, they also build marvelous motors / engines too!

[FastRedPonyCar]

I've seen a couple YT videos of guys in the UK tuning M3 and m-sports with Xdrive and they all are estimating 20~22% drivetrain loss.

[TacosRule!]

Originally Posted by FastRedPonyCar

I've seen a couple YT videos of guys in the UK tuning M3 and m-sports with Xdrive and they all are estimating 20~22% drivetrain loss.

ugh that sucks if true.

[Kevin_The_Clean1]

Originally Posted by FastRedPonyCar

I've seen a couple YT videos of guys in the UK tuning M3 and m-sports with Xdrive and they all are estimating 20~22% drivetrain loss.

Don't believe everything you see or hear on You-Tube. That's for sure...

[FastRedPonyCar]

Originally Posted by Kevin_The_Clean1

Don't believe everything you see or hear on You-Tube. That's for sure...

There are smart people on youtube but I'm also friends with a couple guys at APR (big in the porsche, Audi, VW scene) and they say that the quattro AWD system in the VW/Audi's suck right at 20~21% and they had first hand experience with engine dyno numbers vs the numbers of the engines in the cars to back it up.

It's the same percentage that I've heard the guys from Integrated Engineering quote too.

[Oldgixxer]

I've used this calculator for years just for shits&giggles..if you know the exact weight of your vehicle w you in it,plus fuel(in other words,race-ready) it's been pretty accurate for me.
I used it all the time when I was drag racing my bikes and it was always close to the dyno rwhp

Gives you a ballpark figure,and you can calculate drivetrain loss. It's not scientific by any means and YMMV

http://www.wallaceracing.com/et-hp-mph.php

[TacosRule!]

Originally Posted by FastRedPonyCar

APR (big in the porsche, Audi, VW scene)

And they make awesome exhaust systems. Wish they would do us as well...

[stoked335d]

Here are Dinan numbers from a 2020 model X3MC.

https://x3.xbimmers.com/forums/showthread.php?t=1897657

[Kevin_The_Clean1]

Originally Posted by stoked335d

Here are Dinan numbers from a 2020 model X3MC.

https://x3.xbimmers.com/forums/showthread.php?t=1897657

I remember seeing this too. What's interesting is that Dinan_Engineering posted the same stock power figures for both 91 -AND- 93 octane. Hmmm. I wonder which one is correct... ?

[Dinan_Engineering]

Originally Posted by TacosRule!

And they make awesome exhaust systems. Wish they would do us as well...

You do realize that APR & Dinan share the same campus and many of the same resources, right? Just serve different markets.

Originally Posted by Kevin_The_Clean1

I remember seeing this too. What's interesting is that Dinan_Engineering posted the same stock power figures for both 91 -AND- 93 octane. Hmmm. I wonder which one is correct... ?

Stock measured horsepower on those charts is always based off of 93. Usually its labeled that way for all the octanes except 93 but for some reason 91 wasn't on that particular application. If you flip to 100 octane though as an example it shows the same stock numbers with the 93 octane qualification. That callout on 91 likely just got inadvertently ommitted in the creation of the chart.

For the original topic of this thread -- drivetrain losses are not static and increase at higher loads but for the purpose of general broad stroke calculations, modern RWD BMW's are in the 12-15% DT loss range whereas AWD platforms sit in the 18-21% spectrum.

[Kevin_The_Clean1]

Originally Posted by Dinan_Engineering

You do realize that APR & Dinan share the same campus and many of the same resources, right? Just serve different markets.



Stock measured horsepower on those charts is always based off of 93. Usually its labeled that way for all the octanes except 93 but for some reason 91 wasn't on that particular application. If you flip to 100 octane though as an example it shows the same stock numbers with the 93 octane qualification. That callout on 91 likely just got inadvertently ommitted in the creation of the chart.

For the original topic of this thread -- drivetrain losses are not static and increase at higher loads but for the purpose of general broad stroke calculations, modern RWD BMW's are in the 12-15% DT loss range whereas AWD platforms sit in the 18-21% spectrum.

Dinan_Engineering Thank you for the clarification. If you happen to know what the stock 91 Octane numbers are for this early production S58 that lives in our pre LCK X3 MC's, please feel free to share that with us. In Northern CA 99% of the pumps around here only offer 91. So it would be nice to see those figures.

[omniphil]

Originally Posted by stoked335d

Here are Dinan numbers from a 2020 model X3MC.

https://x3.xbimmers.com/forums/showthread.php?t=1897657

542 whp for a stock car?
Those look more like crank hp numbers to me...

I guess that's the problem with dynos, they vary widely and can be manipulated by the tuners to show what they desire.

[stoked335d]

Originally Posted by omniphil

542 whp for a stock car?

I guess that's the problem with dynos, they vary widely.

508 BMW advertised HP is definetly under rated. I don’t think Dinan’s Dyno is off since they are in the hp business.

[strohw]

Originally Posted by stoked335d

508 BMW advertised HP is definetly under rated. I don’t think Dinan’s Dyno is off since they are in the hp business.

Those aren't wheel HP numbers on that chart. This forum has a large history of tuning companies posting their stock dyno numbers for this vehicle which include MP, Protuningfreaks, IND, etc. No one has dyno numbers that high. Most dynos put the non-comp at 450-460whp and the comp at 490-500whp.

Plus, the "508 HP" is the "under rated" part. Since BMW doesn't seem to want to use the SAE bhp standard that most other manufacturers use, them claiming 508 HP and putting down 490-500whp, makes them look under rated. When in fact, they're just choosing to rate their vehicles differently.