Why would BMW ever under rate their horse power on an engine especially an M3/4

[Thurman Murch]

Please show proof

Unless something was wrong with a tb or something in fuel delivery

I think it's a hoi polloi type of thing to fascinate/machinate about paying a premium price and then justifying the lack of worth then running to an economy minded car

The f8x will be more prone to atmospheric variables but I bet it will be faster in steep mountain ascents and have moments of abundance and moments of those hot, humid days where it just bogs

I do notice that certain fueling stations have better fuel but some seem to give better mileage like chevron and more power like a shell or in between at esso but this is more in application towards a turbo

NA cars seem less affected by fuel

[tomwac]

Originally Posted by CanAutM3

You come on an internet forum with an improbable story to attempt to justify your claim that BMW defrauds its customers with engines that are overrated. You then get upset because somebody calls you out

You're right about about one thing, time to move on

Really not much else to say ...
But ok...I'll bite...show me 1 (one, I'll spell it out as you obviously have trouble reading and/or comprehending) dyno report which shows a E46/E9x/E39/Z4M/E36 3.2 with power numbers according to BMW claims And post it here...full stock...
Not 1M, F10 etc as these do have claimd power (or even more in some cases)... Good luck and report back...
I guess you're just one of these folks who just can't stand when someone says something negative about your pride and joy ... relax, it's just a car...
And I'm right about about about more than one thing ... It just does not fit in your small minded brain ...

[tomwac]

Originally Posted by Alpine F31

Hyundai did too. My wife got a check from a class action suit against Hyundai because of overrating horsepower numbers.

"Hyundai Motor America, the United States arm of the automaker, admitted in September 2002 that it overstated the horsepower on the Santa Fe, Sonata, Tiburon and other models sold in the United States."


http://www.nytimes.com/2004/06/22/bu...ower-suit.html

I guess it is much easier in the US... These things never work here. Few weeks ago a guy sued Renault because his Scenic fuel consumption is a lot higher than advertised and even though some others owners followed, the court did not...
We don't even have something like your lemon law here... If you happen to get a lemon, you're on the dealers mercy...

But on topic, I really hope this new 3.0TT will deliver...I'll find out in October ... And even though I loved my E92, the mighty V8 screaming at 8000 rpm, I think it was the least exciting M I ever owned...here is hoping BMW listened to his (loyal) customers

[M4TW]

Originally Posted by tomwac

Really not much else to say ...
But ok...I'll bite...show me 1 (one, I'll spell it out as you obviously have trouble reading and/or comprehending) dyno report which shows a E46/E9x/E39/Z4M/E36 3.2 with power numbers according to BMW claims And post it here...full stock...
Not 1M, F10 etc as these do have claimd power (or even more in some cases)... Good luck and report back...
I guess you're just one of these folks who just can't stand when someone says something negative about your pride and joy ... relax, it's just a car...
And I'm right about about about more than one thing ... It just does not fit in your small minded brain ...

The 3.2 has been out of production for quite a few years. This discussion is more about what BMW has done with its TT FI engines beginning with the N54, which was repeatedly shown to make more power than advertised. The same can be said about the new M5, which more closely parallels the M3/4 engine.

Your own personal experience with the non-FI S65 sounds like an unfortunate factory cripple because the S65 does not have a reputation for having an endemic problem with overrated power.

Also, when you want to issue an ultimatum, try "full stop" instead of "full stock" as "full stock" can easily be misconstrued when you are using it with dynos and hp.

[tomwac]

Originally Posted by M4TW

The 3.2 has been out of production for quite a few years. This discussion is more about what BMW has done with its TT FI engines beginning with the N54, which was repeatedly shown to make more power than advertised. The same can be said about the new M5, which more closely parallels the M3/4 engine.

Your own personal experience with the non-FI S65 sounds like an unfortunate factory cripple because the S65 does not have a reputation for having an endemic problem with overrated power.

Also, when you want to issue an ultimatum, try "full stop" instead of "full stock" as "full stock" can easily be misconstrued when you are using it with dynos and hp.

Well, that is exactly what I'm trying to say and hope for... The S65 issue I had, might have been an isolated problem, the fact is BMW didn't do anything about it and I just stated that here, which is enough to be called a liar (without even knowing all the facts)... The thing is that I hear/read more complaints about NA engines not giving the promised power output, but apparently that is a sensitive matter here ...

Not really sure what you mean by your last paragraph, as I didn't give anyone an ultimatum (as I don't really care) but only wanted to see dynos from stock M3's... As English is not my native language, maybe that is not very clear...

[M4TW]

Sorry, don't worry about your English. You were requesting dynos "full stock" which could mean "fully stock" or more simply, "unmodified". The phrase "full stop" (which is what I thought you intended) is from the era of telegrams when a "full stop" was used for a period.

Anyway, back on point, I hope your M3 on order turns out to be a factory freak when it comes to HP to make up for your previous experience.

[tomwac]

Originally Posted by M4TW

Anyway, back on point, I hope your M3 on order turns out to be a factory freak when it comes to HP to make up for your previous experience.

I'm sure it will and honestly, I can't wait to sit in an M again after 1 year without one

[crabu2]

Originally Posted by CanAutM3

Further, I also seriously doubt that BMW says a 20% variance (+/-10%) on engine output is normal.

I'm bring this thread back from the dead!

1st it's still 10% from the baseline rating.. But when comparing one engine to another, it can be 20%.


I also believe there allow for a 10% variance. The reason for this is on Outboard boat motors, they allow this same percentage of variance.

Personally, I don't think BMW over or under rates their engines outside of the 10% variance. If they were, Mercedes, Audi and the others would too. Don't think for a minute that the competition doesn't test the engines of their competitors.

Also listed hp numbers sell cars because of bragging rights. That's why some companies have been busted for inflating numbers. Underrating can cause a spiral effect.. as in others start underrating then you have to underrate your engine even more... which makes no sense because when the average customer looks at a brochure, sees one car listed at 250hp and a competitor listed at 200hp.. They're going to think the 250hp car is quicker.

BTW, an allowance of 10% at the crank can make a huge difference by the time is gets to the wheels because of drivetrain loss...

[Sodhi16]

Dinan website says they dyno'd a stock m3 at 484hp when rated at 425 stock. Can't really argue with that

[CanAutM3]

Originally Posted by Sodhi16

Dinan website says they dyno'd a stock m3 at 484hp when rated at 425 stock. Can't really argue with that

Folks need to better understand how certified power ratings are obtained and how modern engines, particularly FI ones, behave in different operating modes.

Traditionally, certified engine power ratings have always been achieved by running the engine in steady state (constant RPM) on a bench dyno to obtain more precise and repeatable results. The engine is run in step increments (500RPM for example) for each power reading. Running the engine at constant RPM for a few seconds allows all the parameters to stabilize before taking the power reading. For many years, this method has proven to be to most representative and accurate way to obtain certified power ratings.

Things have changed however. With the avenue of advanced electronic control, modern engines, particularly turbocharged ones, can now produce a fair bit more power when in transient state (while accelerating) than when in steady state. This mostly happens at mid to high RPM (at low RPM, they tend to makes less power in transient). The SAE testing standards to obtain certified ratings has even been relatively recently amended to allow manufacturers to test in transient state to take advantage of this behavior, but ultimately, it leaves up to the manufacturer to chose how they want to test (steady state or in transient). This makes it very difficult to compare power ratings between FI and NA engines and between manufacturers (not knowing which method was used to obtain the certified power rating).

It seems pretty apparent to me that BMW has elected to remain with the traditional steady state approach to obtain their certified power ratings. Just looking at the power charts they issue is a good indication (straight lines connecting the testing points). This will certainly gives the impression thay BMW "underrates" their FI engines.

[crabu2]

Originally Posted by Sodhi16

Dinan website says they dyno'd a stock m3 at 484hp when rated at 425 stock. Can't really argue with that

That's nice, but if their testing method isn't the same, it doesn't mean squat. Even different brands of dyno's give different numbers. So unless Dinan used a testing method that has strict controls, which are the same that the manufacture is using, it means nothing.

If anything I'd think BMW uses much stricter rules when testing... like using non-pump gas made to a specific standard, with strict air temps and what not.

[horsepower_and_hounds]

Originally Posted by Sodhi16

Dinan website says they dyno'd a stock m3 at 484hp when rated at 425 stock. Can't really argue with that

484 stock? I don't think so....even at the crank. More Dinan ####

[Sodhi16]

Originally Posted by ehagerty

484 stock? I don't think so....even at the crank. More Dinan ####

Maybe they are chatting **** but was an article from caranddriver regarding the S1.

[horsepower_and_hounds]

Originally Posted by Sodhi16

Maybe they are chatting **** but was an article from caranddriver regarding the S1.

Oh I don't doubt it was said...... I was just just say'n

[Super Spartan]

well one thing for sure, my M4 doesn't *feel* like a 439 BHP car. I had more thrill in my 2005 Pontiac GTO with the LS1 engine which only had 328 BHP stock compared to my M4. That car made me shit my pants when I went full throttle.....with the M4, it's fast, but you don't *feel* it's fast if you know what I mean

[Professor///M]

All of you got it wrong. All of these posts for nothing. The guy that enters the data from the "real" spec sheet to the "internet" likes to see all of the commotion when people get more for their money... so he keeps on doing it. Every car has like 15-400 more horsepower then actually stated.

[Ian1973]

Originally Posted by crabu2

I'm bring this thread back from the dead!

1st it's still 10% from the baseline rating.. But when comparing one engine to another, it can be 20%.


I also believe there allow for a 10% variance. The reason for this is on Outboard boat motors, they allow this same percentage of variance.

Personally, I don't think BMW over or under rates their engines outside of the 10% variance. If they were, Mercedes, Audi and the others would too. Don't think for a minute that the competition doesn't test the engines of their competitors.

.

Well actually Mercedes and Audi's have also shown to be underrated from the factory, so there goes that argument.

[crabu2]

Originally Posted by Ian1973

Well actually Mercedes and Audi's have also shown to be underrated from the factory, so there goes that argument.

Bingo! No competition is going to sit still and allow a competitor to make it look like they have some fairy dust that makes their cars go faster with less hp.

All this.. My Dyno shows x hp so I know BMW underrates.. It's a good argument, but unless you're measuring at the crank and under the same testing conditions they are ... and remember they're not using pump gas, they get gas made to their specs and it usually comes in 1 gallon containers ... you really have no idea what the engine is putting out versus your dyno numbers.

[radioman1980]

A lot of interesting speculation from the various replies -- some relevant, mostly not (you ever notice how when people don't actually know the answer to a question they begin talking about the most closely related thing they DO know something about?).

Underrated specs are coming out of the business department, not engineering. The more accurate question to ask is: Why does BMW INTENTIONALLY underrate their performance stats?

Ignore all the technical talk about turbos, dynos, altitude, and barometric pressure. Users mkoesel and miiipilot both said it best: BMW underrates their specs for the same reason many automakers do, so they don't cannibalize sales of the next best (in this case, quicker) car they're selling.

Car manufacturers conduct extensive demographic research on their target market. For example: we don't get any of the M-line "estate" vehicles (wagons) in the US because BMW understands we're a SUV and Crossover market; Europe often has several trim/engine options available well below our lowest (and slowest) because of fuel prices, freeway systems, speed limits. And it's this very line of strategic thinking that we see the marketing department "manipulate" specs bc they know a customer is less likely to fork out $115K for the M5 if the M550 has just 40 less HP or is 2/10's slower to 60mph (as one example). And obviously no car company is going to risk lawsuits by OVERRATING a vehicle as the customer WOULDN'T get what they paid for, but there's no harm in getting MORE than what you paid for, so that's the flexible variable.

It will never make obvious sense to us why some models or trims get underrated a lot, a little, or not at all because we don't see what's happening in the sales department and because we don't understand the targeted market, or both the external (Audi/Mercedes) and internal competition (5 series vs 6 series). But BMW has a very strategic reason and it's everything to do with pricing, sales, customer expectation, and ultimately their bottom line.

[JeffO]

Originally Posted by m2ruder

484 stock? I don't think so....even at the crank. More Dinan ####

I remember the HP from Dinan was more like 468 crank HP. When I was in his shop in 2013 I saw a chassis dyno without rollers, connects directly to the axles. He said that cars over 500 -600hp can no longer be reliably tuned with rollers due to tire slippage. His number is based on his dyno and correcting the drivetrain loss to crank with no tire slippage. The type of dyno he used was originally developed to dyno F1 cars many years ago. He also said he was the only BMW tuner that he knew of using that type of dyno.

[deeldoo]

They probably never underrated it, turbos depend on atmospheric conditions alot, they just used the lowest possible rating as a baseline so they don't get sued up their poopshoot.

That's why 90% of the guys dyno at 390-420 whp but you will find the odd one under bad atmospheric conditions who roles out a 370 whp.

Car under general condition non-zcp accounting for 10-15% drive train loss should be rated at around 450-475 at the crank, zcp at around 475-500.

[Dgleich]

They didnt.

If you look at the modern bmw dme (engine ecu) map, you will see that the car is not targeting specific boost. It is targeting torque i.e. horsepower at specific rpm.

A lot of dyno measurements report car power corrected for atmospheric conditions which is really wrong since the dme does that correction already to always produce equal power in all climates and elavations.
Also, when tested on steady state dynos, they usually dyno their expected 370-390 (base vs zcp) whp.

There is a great mainline dyno video talking about different dyno types and how they report horsepower differently:

My performance simulations also agree with the 370-390whp stock for S55 and their 100-200kph times.

I've seen some peoples arguments about 1/4 mile times as well, and the exit speeds which shouldn't be that high considering the horsepower. What people don't take into account when discussing that is the juicy power curve that the S55 has. Almost constant horsepower in the area that mattters the most.