M3 v M4 VBOX Comparison

[Boss330]

Originally Posted by Jockey

So based off of that logic and using S65 DJ numbers of 340-365 whp (360-385 HP), that means the S65 was overrated.

I will sort of agree with you that a NA engine is probably going to pull more timing in a hot dyno garage over a F/I motor (since the F/I has some ability to control IATs over it's NA brethren), it's still not going to pull 60-70 hp worth of timing to see the deltas we are seeing between the S65 and S55 on dynojets.

That is still the one thing NO ONE has been able to explain.

That delta is a very interesting part here, no doubt

I think the truth might be somewhere in between the 340-365whp and 12-18% DT losses. But this is something I don't have much basis to make strong claims on. I haven't really followed the S65 dyno scene and debate. Ignition timing is one factor here, that can influence measured power.

But, we have seen the S55 dyno as low as 394whp on a Dynojet, while we have seen 365whp on a S65 (is that correct for the S65?)

Dynojets seem to be notoriously inconsistent, so it's probably a fools errand to compare different results. At least we will have large uncertainties it seems.

But, for lack of anything else that I know of:

Let's say that a Dynojet 365whp is a result that is as good as it gets, with no ignition timing issues etc. Let's also assume that the 396whp Dynojet result is a better/best match with what a MAHA records as crank HP.

-365whp is 414hp with a 12% DT loss.
(This means that the Dynojet of 365whp actually seem to make some sense?)

-396whp is 450hp with a 12% DT loss
(actually just 3hp less than the MAHA 460PS result)

I think many of us believe that the S55 might be underrated by around 14-24hp, in order to achieve the current 118,6MPH trap speed average.

396-365 = 31
(the delta between a good S65 and a S55 Dynojet that seems to correlate well with MAHA results)

This gets us to a delta of 31whp between the S65 and S55. We should only have seen a 11hp delta at the crank. But if we start looking into the amount of underrating that seems likely at the moment, we get:

-11hp claimed delta
-14-24hp in likely underrating on the S55

As you can see, this actually correlates pretty well as:

11+20 = 31

So the delta here is down to 11hp difference as per official specs and add on the 20hp as per likely underrating on the S55...

Of course the above has some assumptions and "leaps of faith". But on the other hand, 365whp and 12% DT loss ends up at 414hp at the crank for the S65. And the 396whp and 12% DT loss ends up at 450hp at the crank for the S55. Makes both of those Dynojet results seem reasonable and a good base for comparing the two.



Regardless of analysis or interpretation, we have two Dynojet results that only have a 31whp difference between the S55 and S65.

Problem is that the Dynojet have 340-365whp for the S65 and 396-425whp for the S55:

425-340 = 85whp delta
396-365 = 31whp delta

This illustrates the obvious flaws of the Dynojet and blindly comparing dyno results... I believe that the 31whp delta probably is pretty close, but the 85whp delta has to be a poor S65 dyno result compared with a inflated/happy S55 Dynojet... Not Apples to Apples

[Black Gold]

Boss,

You clearly don't understand "pulling timing", and how to determine it, what it looks like on a dyno, and how much of an effect it has.

1) a car that is pulling timing / has detonation events will show a wobble / dip on the power and torque curve. When you see the flat line / extremely smooth curve that the stock e9x m3 shows, this shows that there are NO significant timing pulls

2) you have provided ZERO proof of any timing pulls, and examples of dynos that show timing being pulled

3) I have personally data logged my old e9x and 4 other m3's, and NONE of them pulled timing. The results were still all within the range of every other stock e9x m3 at around 330-350 whp.

4) you have not incorporated this website, which I even told you about. This shows tons of stock m3's that have been dyno'd with correction factors, conditions etc.

http://www.bmwdynodatabase.com/DynoD...ype=1&dynoID=2

What you will find is that almost all e9x m3's dyno between 335-355 whp, with the highest SAE car dyno'ing at 357whp.

Go ahead and apply a 12% drivetrain loss to the highest performing car, and what do you come up with? 399.4. Apply it to the average power of 345 whp and you get 386 hp.

So, it doesn't take much to realize that either the s65 is overrated, or the 12% drivetrain loss assumption is incorrect. I would say its probably drivetrain loss, and a number more like 18% is more likely.

If you take the average dyno number of around 345 whp and add 18% drivetrain loss, you come up with 407 hp which is pretty close to advertised.

SO, either the s55, which dyno's on average around 390-400whp, is overrated, or has less drivetrain loss, OR a combination (most likely imo).

What drivetrain loss would it have to have if the car is not overrated at all? Based on 395whp, it would have to be 8%. This is extremely unlikely imo. I would suggest its closer to 15%. At 15% drivetrain loss the calculated hp would be 455 hp, which imo is likely and also matches your beloved MAHA dyno.

If you use 18% losses it shows a power of 466 hp. This is probably too high as there are a few reasons to believe the f8x is more efficient at putting power to the ground.

Regardless, the dynos are useful because they indicate the amount of power the car is actually transferring to the ground, which is more valuable than just knowing crank power.

The results of the trap speeds and racing the two cars indicate a big gap in power, and lo and behold that's what we see on the dynos.

Bottom line is that your posts include a bunch of random disorganized thoughts and speculation on things in which you do not understand.

You don't see me talking about simulation techinques because this is not something I have a firm grasp on. As its clear you don't know anything about timing pulls and how to apply or understand drivetrain losses, perhaps you should refrain from commenting on those subjects until you do.

[Boss330]

Originally Posted by KennyPowers

Boss,

You clearly don't understand "pulling timing", and how to determine it, what it looks like on a dyno, and how much of an effect it has.

1) a car that is pulling timing / has detonation events will show a wobble / dip on the power and torque curve. When you see the flat line / extremely smooth curve that the stock e9x m3 shows, this shows that there are NO significant timing pulls

2) you have provided ZERO proof of any timing pulls, and examples of dynos that show timing being pulled

3) I have personally data logged my old e9x and 4 other m3's, and NONE of them pulled timing. The results were still all within the range of every other stock e9x m3 at around 330-350 whp.

4) you have not incorporated this website, which I even told you about. This shows tons of stock m3's that have been dyno'd with correction factors, conditions etc.

http://www.bmwdynodatabase.com/DynoD...ype=1&dynoID=2

What you will find is that almost all e9x m3's dyno between 335-355 whp, with the highest SAE car dyno'ing at 357whp.

Go ahead and apply a 12% drivetrain loss to the highest performing car, and what do you come up with? 399.4. Apply it to the average power of 345 whp and you get 386 hp.

So, it doesn't take much to realize that either the s65 is overrated, or the 12% drivetrain loss assumption is incorrect. I would say its probably drivetrain loss, and a number more like 18% is more likely.

If you take the average dyno number of around 345 whp and add 18% drivetrain loss, you come up with 407 hp which is pretty close to advertised.

SO, either the s55, which dyno's on average around 390-400whp, is overrated, or has less drivetrain loss, OR a combination (most likely imo).

What drivetrain loss would it have to have if the car is not overrated at all? Based on 395whp, it would have to be 8%. This is extremely unlikely imo. I would suggest its closer to 15%. At 15% drivetrain loss the calculated hp would be 455 hp, which imo is likely and also matches your beloved MAHA dyno.

If you use 18% losses it shows a power of 466 hp. This is probably too high as there are a few reasons to believe the f8x is more efficient at putting power to the ground.

Regardless, the dynos are useful because they indicate the amount of power the car is actually transferring to the ground, which is more valuable than just knowing crank power.

The results of the trap speeds and racing the two cars indicate a big gap in power, and lo and behold that's what we see on the dynos.

Bottom line is that your posts include a bunch of random disorganized thoughts and speculation on things in which you do not understand.

You don't see me talking about simulation techinques because this is not something I have a firm grasp on. As its clear you don't know anything about timing pulls and how to apply or understand drivetrain losses, perhaps you should refrain from commenting on those subjects until you do.

Whoaaa...!!!!

Did you even read my posts? You just repeat what I also pointed out as regards DT losses. Only difference is that you seem to think that 18% is ok for the E9x but suddenly feels that 15% is correct for the F8x... Please provide your evidence that supports that fairly big change in DT losses...

And who has talked about a 8% DT loss? I have REPEATEDLY said that I believe the S55 to be underrated by around 14-24hp. This also correlates very well with MAHA and INSORIC results as well as the latest Dynojet run at 396whp...

2. I have indeed showed dyno graphs and charts that show ignition timing being pulled

See here: http://f80.bimmerpost.com/forums/sho...3&postcount=87

The dynodatabase has a 370whp SAE E92 with only mod being a cat back exhaust. Ran on 93 octane fuel:

http://www.s65dynos.com/showDyno.php...ype=1&dynoID=2

The rest of your post and previous posting history means that I don't see any point in commenting your personal attacks and insults. If you feel the need to use insults and personal attacks in trying to win the argument, that says more about you than it does about anyone else

[Black Gold]

First of all, maybe it was too strong. My aplogies

Second of all, let's not act like you haven't don't the same by calling otjers "biased" and accusing p1 motorcars and calling them out.

Regardless, my points remain the same.

Second of all, stock is stock. And the average whp is clearly 345.

[Boss330]

Originally Posted by KennyPowers

First of all, maybe it was too strong. My aplogies

Second of all, let's not act like you haven't don't the same by calling otjers "biased" and accusing p1 motorcars and calling them out.

Regardless, my points remain the same.

Second of all, stock is stock. And the average whp is clearly 345.

Point taken.

The S65 dyno scene/discussion, as I have also said before, is something I haven't followed.

[Boss330]

Originally Posted by KennyPowers

First of all, maybe it was too strong. My aplogies

Second of all, let's not act like you haven't don't the same by calling otjers "biased" and accusing p1 motorcars and calling them out.

Regardless, my points remain the same.

Second of all, stock is stock. And the average whp is clearly 345.

Here are some other interesting dyno results where it's argued that both the C7 Corvette and S55 is allmost spot on with factory ratings. Probably just goes to show that the Dynojet, Mustang and other dynos are notoriously difficult to rely on. Of course it's cool for the customer to get a big HP number, but is that the right way of doing business?

http://www.automobilemag.com/feature...heels-on-dyno/

http://www.motortrend.com/features/p...z51_dyno_test/

http://blogs.motortrend.com/1407_on_...eneration.html

[Boss330]

Originally Posted by KennyPowers

Go ahead and apply a 12% drivetrain loss to the highest performing car, and what do you come up with? 399.4. Apply it to the average power of 345 whp and you get 386 hp.



If you take the average dyno number of around 345 whp and add 18% drivetrain loss, you come up with 407 hp which is pretty close to advertised.

I would suggest its closer to 15%. At 15% drivetrain loss the calculated hp would be 455 hp, which imo is likely and also matches your beloved MAHA dyno.

If you use 18% losses it shows a power of 466 hp. This is probably too high as there are a few reasons to believe the f8x is more efficient at putting power to the ground.

As its clear you don't know anything about timing pulls and how to apply or understand drivetrain losses, perhaps you should refrain from commenting on those subjects until you do.

Kenny Powers,

Since you made such bold claims that I didn't know how to apply drivetrain losses you should make sure you know how to do it yourselves perhaps

You make several claims and calculations on DT losses in your post:

12% DT loss:
357whp (x 1,12) = 399,84hp
345whp (x 1,12) = 386hp

15% DT loss:
395whp x (1,15) = 455hp

18% DT loss:
395whp x (1,18) = 466hp

I think you might have done a "small" error here...

It seems you have calculated DT loss from whp and not fom crank hp...

This is how it is supposed to be done:

12% DT loss:
357whp/0,88 = 405,7HP
345whp/0,88 = 392HP

15% DT loss:
395whp/0,85 = 464,7HP

18% DT loss:
395whp/0,82 = 481,7HP

Drivetrain losses is calculated based off the crank HP, not the other way round...

When doing bold claims and accusations, it's best to make sure that it's not you that do the errors you accuse someone else of doing...

[Black Gold]

Very true, appreciate the correction.

But, the same point remains. 12% Corrextion is not reasonable for the e9x

[Boss330]

Originally Posted by KennyPowers

But, the same point remains. 12% Corrextion is not reasonable for the e9x

Why?

RRI.se, which P1 Motorcars quoted, measured 12%. Based on the 12% on the E9x, P1 Motorcars made a case for 10% on the F8x...

You might be correct, but many seem to be of the opinion that 12% is pretty much spot on for the E9x.

As you know, we have seen the S65 dyno as high as 361-370whp on various dynos (as per the database). If those runs are indeed true representations of a S65 under ideal conditions, then 12% is spot on...

We have also seen as low as 30x-32x. That would require a 25% drivetrain loss if we should believe them to be a good representation of the performance of the S65

To me, all of this just shows how inaccurate and unreliable dyno results generally are... At least they can't be taken at face value. That the S65 dynos from 312whp to 357whp on the Dynojet (or in fact as high as 370whp with just a cat back exhaust) clearly shows that dyno results is a questionable source for exact answers...

[Black Gold]

Originally Posted by Boss330

Here are some other interesting dyno results where it's argued that both the C7 Corvette and S55 is allmost spot on with factory ratings. Probably just goes to show that the Dynojet, Mustang and other dynos are notoriously difficult to rely on. Of course it's cool for the customer to get a big HP number, but is that the right way of doing business?

http://www.automobilemag.com/feature...heels-on-dyno/

http://www.motortrend.com/features/p...z51_dyno_test/

http://blogs.motortrend.com/1407_on_...eneration.html

ran in 4wd mode when dyno'ing e9x and f8x. corvette run in 2wd mode. watch the vids, the e9x and f8x front wheels are spinning (4wd mode) and the vette front wheels are not (2wd mode)

[Boss330]

Originally Posted by KennyPowers

ran in 4wd mode when dyno'ing e9x and f8x. corvette run in 2wd mode. watch the vids, the e9x and f8x front wheels are spinning (4wd mode) and the vette front wheels are not (2wd mode)

Good observation (havn't checked the vids myself yet)

Do you know what impact, if any, this has on the measurements?

I believe some dynos can run the free rolling drums/rollers electrically at the same rate as the driven wheels in order to avoid ABS/TC issues on a dyno run. If so, that wouldn't impact power measurements would it?

If the rear wheels have to run the front drums as well, then that means more power is needed. But wouldn't the dyno know exactly how much it takes to spin the drums at any rpm and add that to the calculations showing whp?

[Black Gold]

Originally Posted by Boss330

Good observation (havn't checked the vids myself yet)

Do you know what impact, if any, this has on the measurements?

I believe some dynos can run the free rolling drums/rollers electrically at the same rate as the driven wheels in order to avoid ABS/TC issues on a dyno run. If so, that wouldn't impact power measurements would it?

If the rear wheels have to run the front drums as well, then that means more power is needed. But wouldn't the dyno know exactly how much it takes to spin the drums at any rpm and add that to the calculations showing whp?

I don't know the answer

But, it stands to reason it's a significant power robber

-because the e9x power is only 310 which is way off even the lowest 2wd stock dynos per the dyno database
-look at how the power trails off badly at redline for both cars relative to other dynos and bmws own claims

I would throw it out personally , and am not sure how to correct for the 4wd test or if it can even be reliably done

[Boss330]

Originally Posted by KennyPowers

I don't know the answer

But, it stands to reason it's a significant power robber

-because the e9x power is only 310 which is way off even the lowest 2wd stock dynos per the dyno database
-look at how the power trails off badly at redline for both cars relative to other dynos and bmws own claims

I would throw it out personally , and am not sure how to correct for the 4wd test or if it can even be reliably done

Agree that this factor needs to be understood/explained before we can be sure of this measurement!

[Jockey]

Originally Posted by Boss330

Regardless of analysis or interpretation, we have two Dynojet results that only have a 31whp difference between the S55 and S65.

You came to that conclusion using the best results from one (S65) and the worst results from the other (S55).

I don't think I need to say anything more than as to why your conclusion is wrong.

On the same day, on the same dyno, we saw a 60-70 hp difference. It doesn't get more clear than that.

[turbo8765]

S55 is MUCH faster. We've seen this in the real world.

The dyno's are moot.

[Boss330]

Originally Posted by solstice

Ouch for the naysayers your Vbox 122 mph just got confirmed by a 121 mph drag strip time slip

Originally Posted by gthal

Well, now the naysayers are saying that the driver of that car that trapped 121 at the strip didn't really turn off his JB4 and run stock

These are the days of our lives....

Originally Posted by solstice

Yeah, I'm ready to put them all on the ignore list soon. Too much excuses, denial and things that make little to no sense. I'd say this though, I would be surprised if this car wasn't running an ethanol mix to take full advantage of the JB4 and that should likely help some when running stock as well. 121 mph is very strong and likely at the top percentile of what we'll see from stock runs. But who knows.

Originally Posted by Jockey

Yep, there is always a way out. I will say they have a plausible excuse this time.

Originally Posted by gthal

Here's the link... http://f80.bimmerpost.com/forums/sho....php?t=1034476

The M4 has JB4... first run with it, second without. However, some are claiming that the owner of the F82 was lying when he said he removed his JB4 tune for the second run as they aren't buying the 121 trap.

Do you guys still believe in the 0,34MPH difference between stock and JB4 tune, after seeing these results:

http://f80.bimmerpost.com/forums/sho...1#post16636109

A whopping 5,2MPH increase in terminal velocity with the JB4 Stage 1... Going from 118,9MPH to 124,1MPH

If you still believe that the other guy ran with JB4 stage 1 off and got a 121,21MPH trap and only managed a 121,55MPH trap with the JB4 Stage 1, I'd like to hear the explanation...

[Jockey]

Originally Posted by Boss330

A whopping 5,2MPH increase in terminal velocity with the JB4 Stage 1... Going from 118,9MPH to 124,1MPH

If you still believe that the other guy ran with JB4 stage 1 off and got a 121,21MPH trap and only managed a 121,55MPH trap with the JB4 Stage 1, I'd like to hear the explanation...

Using the 118.9 as a "confirmed" stock trap speed, 121.2 (2.3 MPH difference) seems within the realm of possibility on a stock car especially after demonstrating a 5.2 increase from stock to JB4 Stg. 1.

Isn't 121 still at the ragged top of your +5% regulation? The 124 trap is definitely in line with what is being advertised as the HP jump to JB4 Stage 1.

We've seen stock Vbox results of 122 and a general rule of thumb is subtract 1 MPH to get a rough 1/4 mile trap.

So I still say 121 is within the realm (upper limit of that realm) of what we might see on a stock S55.

[solstice]

Originally Posted by Jockey

Using the 118.9 as a "confirmed" stock trap speed, 121.2 (2.3 MPH difference) seems within the realm of possibility on a stock car especially after demonstrating a 5.2 increase from stock to JB4 Stg. 1.

Isn't 121 still at the ragged top of your +5% regulation? The 124 trap is definitely in line with what is being advertised as the HP jump to JB4 Stage 1.

We've seen stock Vbox results of 122 and a general rule of thumb is subtract 1 MPH to get a rough 1/4 mile trap.

So I still say 121 is within the realm (upper limit of that realm) of what we might see on a stock S55.

Good point. It looks just as much or more maybe that the JB4 was disabled or non functional on the first run in that drag race than that it was enabled on the 2nd run...

[Boss330]

Originally Posted by Jockey

Using the 118.9 as a "confirmed" stock trap speed, 121.2 (2.3 MPH difference) seems within the realm of possibility on a stock car especially after demonstrating a 5.2 increase from stock to JB4 Stg. 1.

Isn't 121 still at the ragged top of your +5% regulation? The 124 trap is definitely in line with what is being advertised as the HP jump to JB4 Stage 1.

We've seen stock Vbox results of 122 and a general rule of thumb is subtract 1 MPH to get a rough 1/4 mile trap.

So I still say 121 is within the realm (upper limit of that realm) of what we might see on a stock S55.

Originally Posted by solstice

Good point. It looks just as much or more maybe that the JB4 was disabled or non functional on the first run in that drag race than that it was enabled on the 2nd run...

The 118,9MPH was a Vbox terminal velocity, NOT a trap speed. That's two different things!

Trap speed is supposedly as much as 1MPH lower than a Vbox terminal velocity... (as I just noticed you also wrote)

This means that the 118,9MPH would be around a 117,9-118,4MPH trap speed.

To me, it seems VERY unlikely that the 121,21 and 121,55 was on a stock engine (as those numbers actually are trap speeds from a drag strip). In order to compare those two numbers with the Vbox we will have to add the same 1MPH as we subtract from a Vbox to get a rough trap speed estimate.

That means the two 121,xx would be something like this on a Vbox:

121,21 + 1 = 122,21MPH
121,55 + 1 = 122,55MPH

These numbers are much closer to the JB4 numbers than they are to any verified stock number we have seen so far (highest verified Vbox is the 120,9MPH from the UK Magazine). I find it very unlikely that these numbers are on a stock engine (especially when he claims to have a JB4)

[Boss330]

Originally Posted by MRSSIIM3

im not sure what counts as vbox verified but my vbox data was 122 mph which according to you is really 121 which is way more than 118.9...

Verified as in using a magazine or other reliable source that tests under same circumstances and under a controlled and repeatable manner. The UK magazine tests at MIRA proving grounds in England, using Vbox equipment.

Your 122mph is certainly astounding, but hasn't been close to any previous or subsequent test results. And your 122 isn't a 121 trap speed, according only to me, but according to those that have looked more into difference between trap speed and terminal velocity (I take it everyone knows the difference between the two things?).

When we start seeing more 122mph Vbox results on stock cars, then your number would also be considered a representative result. As of know yours is a good 3-4MPH over the average trap speed, and more than 1MPH higher than the 120,9 from the UK. It's also more than 3MPH higher than the stock Vbox number in the OP here.

Again, your results are astonishing! But so far no one seem to be able to replicate them...

[Jockey]

Originally Posted by Boss330

The 118,9MPH was a Vbox terminal velocity, NOT a trap speed. That's two different things!

Trap speed is supposedly as much as 1MPH lower than a Vbox terminal velocity... (as I just noticed you also wrote)

Which is exactly what I said @Boss330!

But 118.9 is NOT a Vbox terminal velocity, it's a trap speed!

[Jockey]

Originally Posted by Boss330

It's also more than 3MPH higher than the stock Vbox number in the OP here.

No it's not. You're confusing a trap speed with a Vbox result.