Diamond

what about the 2.5l I6, 4.4 and 4.8 l v8s?

swajames

yep, there's no magic in .5L per cylinder, just the configuration. Irrespective of cylinder capacity or total displacememnt, a V8 engine quite simply can't be as naturally balanced as an I6, although the specific angle of the V does indeed have an impact on smoothness. The actual volumetric capacity of the cylinder won't in itself have much impact on balance.

The horizontally-opposed Flat-6 (as in a Porsche) and the V12 are the only other common configurations that have naturally perfect balance.

krusir

Yes, I personally feel I6 is more smooth then V8. I came from a 4.4 V8 540i ... Compare with current I6 3.0 TT... This I6 engine produce about the same power (more HP, little less torque ) with more nimble and smoothness. I feel it run like a DC electronic Motor when I push my pedal.

Richard in NC

I haven't driven the Nissan 3.7 V6 but the Nissan 3.5 V6 is quite coarse sounding and feeling at high RPMs. The BMW inline 6 is quite smooth and liking to rev, even at 6k-7k RPMs. Note that in 2001 BMW had 330hp from 3.2 liters and in '95 had 340hp from 3.6 liters (in the E34 M5). Nissan can't match that normally aspirated hp/liter 14 years later.

swajames

And in fairness, Richard, BMW can't currently match the 485hp (and reputedly the car is actually making well over 500hp) that Nissan gets from just 3.8 liters and 6 cylinders in the GT-R. In your examples, you're bring the best that BMW offered at that time (it's I6 and V8 M engines) to the table, whereas the VQ engine has always been deployed in Nissan's low to mid-range cars. The new VQ in the 370Z is getting 332 bhp from 3.7 liters which is a pretty respectable output for a car that is very competitively priced against a comparable BMW.

einstein57

In the horespower to displacement race, the s2000 has everyone beat. I'm sure if BMW wanted to make a twin turbo inline 6 with over 500hp they would have no trouble doing so and keeping the same engine block as the N52. Just look at the numbers horsepower freaks is getting from the S54. I just wish BMW would toss some ITBs on a 3 liter inline six with an aggressive tune and a sport exhaust. That should easily put down 300 whp. Perhaps a second gen 330i zhp or a revision to the Z4 3.0is

swajames

It's only 107 bhp per liter...

The 911 GT3 gets 435 horses out of 3.8 normally aspirated liters (nearly 115bhp per liter)

einstein57

The original 1,997cc s2000 had 240hp. (120hp per liter). I guess the newer ones were weakened with emissions restrictions. And obviously we are ruling out rotary and motorcycle engines.

BMWPower06

Depending on which ur were referring to, it was based off the 3.0L I-6

The 3.0L I6 is BMWs bread and butter for two reasons:
The smoothness of the I6 and the .5L/cylinder displacement

Richard in NC

There is a big difference between n/a hp/liter and forced induction hp/liter. The Nissan is f/i so it certainly should do better than a n/a motor. Which BTW, the Dinan 380hp upgrade to the 3.0 TT is more hp/liter than the Nissan GTR. I don't know how far the Nissan motor can be taken but I guarantee you'll have warranty issues.

Second, displacement makes a big difference. Its far easier to get 100+ hp/liter from a 2 liter than it is from a 4 or 5 liter. One reason is the reciprocating weight limits RPMs and engine design. Second, the emissions levels are the same. The 5 liter M5 can't produce any more emissions than the 2.0 Honda. Therefore it's far more restricted. Bottom line, 500hp from an n/a 5 liter is far more impressive than 240hp from a 2 liter. At least IMHO.