Firstly, I am a complete BMW newb. The only thing I know about them are that they require significantly more maintenance than our Lexus. No, I'm not a hater, so no flames please.

In any case, I recall a member mentioning that the whole point behind the M-Series is to be naturally aspirated. But I know the M's are FAST; I think the M3 had 420HP.

So my question is how is it possible to have such high power output if it is naturally aspirated? Sure, it has a significantly higher redline and HP figures are actually peak HP usually at an RPM near redline, but that does not constitute an extra 170HP over our 4.0L V8s, so what piece of knowledge am I missing?

 

BMWs more than anything are known for fantastic engines. I know mechanics that swear by them. You are correct, to make that much power, they need higher redlines. Similar to Hondas, high HP at high RPM and lower torque than the competition.
Now understand you are comparing a brand new state of the art engine in 2007 with one that was state of the art in 1992.

15 years a lot of time.

 

Engine makes power through air, ignition, and fuel. Those are the basic components of combustion. The idea is to maximize efficiency by balancing everything.

There are wayyy too many things that allows the BMW to achieve a good amount of power. Consider compression ratio, air flow, etc.

I *believe* the M3's engine has a larger bore but shorter stroke than the 1UZ-FE engine. That alone allows the M3 engine to rev higher, while moving the powerband up higher (notice low-end torque isn't spectacular).

A lot of engineering can take place in a decade.

 

Higher RPM's, compression ratio, overall efficiency. Look at F1 cars, they have 2.4 liter engines that make over 700hp, all naturally aspirated. Of course this affects reliability, and most of BMW's high output engines have been extremely unreliable, especially the last gen M3.

 

I agree with most of you post except the reliability portion. Though one person I know who had an earlier model of the E46 M3 having engine problems, the rest have had fantastic reliability with the M3. It's understandable with the earlier models of the car but that's the same with all cars. Toyota's recent fall with the new V6 camry is a prime example.

The later models of the E46 gen have had good reliability numbers.

 

The M motors are engineering marvels. Don't believe the hype about reliability. Check the bimmer boards & folks who own the cars for info.

 

Thanks for all the response guys, definitely appreciate it. Although I'm still not quite satisfied. I understand the high power output isn't only due to one aspect. But in terms of higher redline, I don't think that an extra ~2700 would be able to give so much more power.

1SickLex mentions that it was a state of the art engine in 1992 and still state of the art in 2007, but wouldn't the 1UZ be much in the same situation as well?

@GSteg, I just did a quick bit of research and noted that the compression ratio is about 12.0. So lets take our 1UZ as a point of reference, I believe it has a 10.5 or 11.0 C/R, so how much extra power would it make if it was boosted up to 12.0? Your last point about the bore and stroke was really helpful, definitely learned something! That is one thing about the 1UZ, it has an amazingly flat torque curve.

@Och, I definitely had no idea about the F1's, but don't the engines redline at approx. 18,000 RPMs? Is that the only way they make so much power?

@BrianGS430, I completely agree with your point about early-generation models being unreliable. When I mentioned "required more maintenance than our Lexus", I basically refer to the reputation of each company, I'm sure both Lexus and BMW have both had their share of unreliable models.

@DASHOCKER, so when you mention the hype about reliability, do you mean the sense of low reliability as conveyed by most individuals? I know that sometimes whenever a company screws up on ONE thing, then we automatically consider them to be a failure, regardless of their efforts to correct it, and the idea seems to linger for quite some time and in turn becomes the reputation of the company. I certainly believe that nowadays, the technology is relatively advanced and there isn't anything really critical that can go awry.

 

the main ways for a N/A engine to make more power:

higher engine revolutions
higher compression ratio
high flowing cylinder head / intake / exhaust systems

yes F1 engines run to 19000 rpms, their stroke is very short which enables the engines to rev very high

 

I think it is safe to say that you guys are forgetting transmission. Gear ratios, differentials all make a difference in HP and how fast the car can actually go.

 

Transmission does not effect engine output. It does however make it effect how it hits the pavement (wheel horse power).

 

Oh of course, but I was trying to make a statement about overall power.

 

If you were to throw higher compression pistons on your car right now, you will gain very little, if any at all. You need to consider air-flow and cam duration. In 1996, Lexus increased the compression ratio of 10.2:1 to 10.6:1 for the SC400. In the end, they gained 10hp at the crank.

 

So basically the compression has very little to do with the high output then? So just by straight ratio calculations, a 12.0 (using 1UZ as a base), would only yield about 35HP then. What else is there?

@4TehNguyen, great list! Is there anything else that would be able to yield higher output? I understand that those 3 aspects can only give so much, even in conjunction, their effectiveness is limited.

Also, another question is why is there no other engine that is able to even match power output of the M's? Lexus spent $400M USD back in the late 80's, so why haven't they been able to produce even close to that much power? And I'm sure the M engine isn't some black art that is exclusive to BMW, I'm sure Lexus could figure something out something similar and work that into their engines too.

Again, I don't know that much about cars, but I do know a fair amount, significantly more than the average person. But I'm sure you pros can fill me in!

 

Then quit using the term power when you mean vehicle performance. Gearing can make a big difference in things like 0-60 time but it has absolutely no effect on the power generated by the engine.

Engine power is about design. Forced induction is an option and it helps move more air and fuel through the engine - good things for higher power. Turbocharging, supercharging, and combinations of both have been used quite successfully. Getting power NA takes a bit more work but it isn't impossible. Rather than look at F1 take a look at NASCAR. Relatively primitive stock block engines with carburetors that can make 800hp and spin the better part of 10,000 revs - although not for long. What is impressive about the bimmer motors is that they generally haven't resorted to pure cubic inches to make their power. Oh, and as an aside, to me if bimmers are known for anything it is suspension/handling, not motors. In fact I never quite understood the reputation of the bimmer straight sixes. They were nice pieces but not that nice.

One of the problems with high specific output, getting a lot of hp out of small displacement, is that often the power band is quite narrow, not to mention they have a nasty tendency to get torque peaks quite a ways off form the hp peak - another discussion, which does bring you back to those nasty gears in both the tranny and rear end and your desire to do a lot of rowing with a manual box or have an automatic that will do a lot of shifting. Most reviews you will read about M models will always say that the average driver has no idea what they are driving because they never get it up into those higher rev bands. Shifting an M at 3 or 4K will not let you enjoy that power. And another thread would be why the high tech diesels with such (relatively) low hp ratings are not at all sluggish on the street because of their prodigious torque at low revs. A second issue with high specific output is compression ratio, which has been mentioned. Back in the day you could drive your Z28 or L88 or hemi (anything) and pump in 113 octane Sunoco 260 for 30 cents a gallon. Higher CR will require higher octane which is defined by its anti knock properties, or the electronic nanny will retard the spark and the power. Here in Cali we are lucky to get 91 octane premium. I am not sure what octane bimmer tests its engines on but anything with a high CR is going to need the appropriate octane to go with it or it won't generate the power. Just a sophisticated area, not one that you can totally understand in a web site post.

There are some good books on this topic and generally there isn't an auto mag in the bin that is very good at talking about this. Most of the automotive "journalists" spend their time trying to come up with amusing one liners to show you how clever they are and actually disguise that their big claim to fame is that they're the one who gets paid to drive cars, not you. Sorry for the rant.

 

Compression can give you a good amount of power if done right. Running higher compression could possibly mean the need to use higher octane gas. Lexus could have given you a crazy high compression, but then that would mean you need to run your car on at least racing gas. Lexus considers the mass buyers out there. They didn't increase the output by 10hp because that's all they could have done. You need to factor in reliability/quietness/smoothness/etc.