Power Losses

[Should be Working]

Hi Guys

Haven't been on the forum for a while, so apologies if you have seen this before. read an interesting article in Autocar the other week about actual power available at the wheels against quoted power. Audi RS4 seems to be the main culprit losing a massive 68 bhp (16.5%) throught the 4 wheel drive transmission. The BMW M5 loses only 7% as it is 2 wheel drive. Should make for an interesting comparison if the E92 M3 has similar losses to the M5.

M3 - 385 bhp at the wheels
RS4 - 345 bhp at the wheels

Sounds like it could be an ass kicking for the RS4 to me (unless it's wet!!)

[Smoltz]

Originally Posted by Should be Working

Hi Guys

Haven't been on the forum for a while, so apologies if you have seen this before. read an interesting article in Autocar the other week about actual power available at the wheels against quoted power. Audi RS4 seems to be the main culprit losing a massive 68 bhp (16.5%) throught the 4 wheel drive transmission. The BMW M5 loses only 7% as it is 2 wheel drive. Should make for an interesting comparison if the E92 M3 has similar losses to the M5.

M3 - 385 bhp at the wheels
RS4 - 345 bhp at the wheels

Sounds like it could be an ass kicking for the RS4 to me (unless it's wet!!)

There are a number of threads on here about WHP vs CHP. A few important notes. You CANNOT attribute differences SOLELY to drive train loss. This is evident from the fact that some cars are gaining HP at the wheels relative to their crank HP specification.

The other factor (which certain parties here in the past have failed to take into account) is that some cars power/torque numbers underrated (this is done for a variety of reasons).

It is also important to consider that there are variations from car to car even for a specific model. This means that they could have had a ringer for an M5 and a dog for an RS4, increasing the gap. Of course they could have had a ringer RS4 and a dog for an M5. It's just important to note that it's NOT a sampling. 10 M5s and 10 RS4s from a variety of production dates would be a more telling story.

-Adam

[ChitownM3]

Originally Posted by Smoltz

The other factor (which certain parties here in the past have failed to take into account) is that some cars power/torque numbers underrated (this is done for a variety of reasons).


-Adam

Hey guys, this is my first post here. I am currently on a waiting list for the new m3. Just thought I'd chime in. In America it is currently illegal for car companies to underrate their cars like they used to, so whatever HP or TQ numbers are posted by the companies, those are real. Chevy used to under rate their cars big time about 5 years ago. My car supposedly had 335 hp at the crank from the factory but when dynoed, it put down 330 rwhp with an automatic trans.

[Smoltz]

Originally Posted by ChitownM3

Hey guys, this is my first post here. I am currently on a waiting list for the new m3. Just thought I'd chime in. In America it is currently illegal for car companies to underrate their cars like they used to, so whatever HP or TQ numbers are posted by the companies, those are real. Chevy used to under rate their cars big time about 5 years ago. My car supposedly had 335 hp at the crank from the factory but when dynoed, it put down 330 rwhp with an automatic trans.

If what you see is the case, numerous manufacturers would currently be in trouble. I would like to see your source for this information.

Thanks,
Adam

[m_bazeepaymon]

Originally Posted by ChitownM3

Hey guys, this is my first post here. I am currently on a waiting list for the new m3. Just thought I'd chime in. In America it is currently illegal for car companies to underrate their cars like they used to, so whatever HP or TQ numbers are posted by the companies, those are real. Chevy used to under rate their cars big time about 5 years ago. My car supposedly had 335 hp at the crank from the factory but when dynoed, it put down 330 rwhp with an automatic trans.

I understand where you are coming from but Engine Horsepower is completely different from Wheel horsepower, and they are not quoting Whp.

All wheel drive always loses more wheel horsepower than rear wheel drive.

we'll just have to wait and see what happens in July (when everybody tests the E92)

[ruff]

Originally Posted by ChitownM3

Hey guys, this is my first post here. I am currently on a waiting list for the new m3. Just thought I'd chime in. In America it is currently illegal for car companies to underrate their cars like they used to, so whatever HP or TQ numbers are posted by the companies, those are real. Chevy used to under rate their cars big time about 5 years ago. My car supposedly had 335 hp at the crank from the factory but when dynoed, it put down 330 rwhp with an automatic trans.

Then BMW is guilty and needs to pay up or serve time. How many times on record has the 335 been dynoed well north of 300 hp? The government wouldn't even need a lawyer to win that case.

[m_bazeepaymon]

Originally Posted by ruff

Then BMW is guilty and needs to pay up or serve time. How many times on record has the 335 been dynoed well north of 300 hp? The government wouldn't even need a lawyer to win that case.

again ther eis probably some loop hole they are using to be able to B.S. their hp's...

[Smoltz]

Originally Posted by m_bazeepaymon

again ther eis probably some loop hole they are using to be able to B.S. their hp's...

Or a far more likely scenario... there is no such regulation. I'm eager to see ChitownM3's references for this claim.

-Adam

[ChitownM3]

It looks like I am incorrect. I thought I had heard somewhere that all cars were SAE certified, but according to this article GM is the only one. http://www.sae.org/certifiedpower/details.htm I think all manufacturers should do it though, so we really know what we're buying.

[ChitownM3]

Well this article from edmunds http://www.edmunds.com/insideline/do...ticleId=108751 also states that the 414 hp in the new m3 is sae certified. If this is the case, then the car has 414 hp, period.

[swamp2]

I was under the (false) impression that BMW MT typically loses about 15% of crank hp. This is far less and a far more efficient drive train than I (most of us?) previously thought. 7% is impressive. I also thought (from various forums, etc.) that the 4WD Audis typically lose as much as 25%. Oh well wrong again, good to learn some new things all the time.

One other point to keep in mind is BER, if we don't get BER (rumored) it will put about 5-10 hp less to the wheels during acceleration compared to the EU cars. BER will obviously improve the 7% figure from the M5, but probably only by a small amount 1-2%.

Either way the 40 hp differnce at the wheels is quite impressive and this is the heart of what BMW means by "efficient dynamics" (not that BMW=2WD and Audi=4WD is anything new). This really highlights that the M3 should really smoke the RS4 on the Ring!

[jpan08]

i don't think BMW tapped the full potential of a V8, they probably could have gotten 500 HP out of it (fuel economy may be sacrificed) i think they are leaving so serious room for a possible huge leap to a csl

[ChitownM3]

Originally Posted by jpan08

i don't think BMW tapped the full potential of a V8, they probably could have gotten 500 HP out of it (fuel economy may be sacrificed) i think they are leaving so serious room for a possible huge leap to a csl

It is very hard at this point in time to get 500 hp out of a 4.0L v8.

[swamp2]

Originally Posted by ChitownM3

It is very hard at this point in time to get 500 hp out of a 4.0L v8.

NA state of the art for production engines is F430 and GT3 both around 115 hp/l. Even at 120 hp/l (quite an impressive jump) the M3 would only be at 480. I'd guess the CSL will be about 450-460 hp from the same 4.0l.

[jpan08]

If BMW is trying to compete with mercedes' AMG, they're not even close, the AMGs have around 500 HP even though they are a bit heavier they do manage to crank out 4.5 or less. and i hate to say it but the AMG looks a bit more exclusive and stylish

[2m3]

Originally Posted by bimmerwithholes

what would happen if they put C63AMG engine in the M3?

The M3 will understeer even more when entering turn

[maq]

Originally Posted by bimmerwithholes

with bigger brake kit...

besides is C63 engine that heavy?
anyway it'll recover faster after the turn.....troque

Bigger brakes are not the cure for understeer.

The AMG engine is not that heavy for what it is, but it is bigger. It can't be mounted as far back and as low as the M3 engine. As a result, the center of gravity and front-rear weight distribution will all change for the worse.

[jpan08]

but Mercedes pulls off some good handeling for a lot of weight, for a new car the M3 is a bit behind the curve

[lucid]

Originally Posted by swamp2

I was under the (false) impression that BMW MT typically loses about 15% of crank hp. This is far less and a far more efficient drive train than I (most of us?) previously thought. 7% is impressive.

I must say I am rather suspicious of this 7% figure, and would not believe it unless I saw it verified by other independent sources. 7% would be a mechanical marvel.

[2m3]

Originally Posted by bimmerwithholes

with bigger brake kit...

besides is C63 engine that heavy?
anyway it'll recover faster after the turn.....troque

We prefer not to brake coming in to the turn......it is all M3 is about

[2m3]

Originally Posted by jpan08

but Mercedes pulls off some good handeling for a lot of weight, for a new car the M3 is a bit behind the curve

Weight is still weight. The AMG handling gets lots of help from electronic stuffs.

I like E63 and still wanting it though if I can afford it, but for different purpose.

Ok back to original topic by the TS

[d3l0n]

I have always thought of this.. how come cars (Bmw's especially) kcik other cars ass with having less power than competitors... and this is the only reason i caould thing as to why! Great find man.. i wish i could get that entire article and see a list of all other top sports cars and their losses to the wheel