Just curious if anyone else here has experienced or noticed a "lack" of top end power on the M273 V8, not that my engine isn't pulling strong or anything, but I've recently raced a 2013 S4 and a 2014 WRX Stage II and found that, surprisingly, they both managed to get ahead on the top end (80mph+) instead of off the line where I would expect them to have an advantage. I'm not particularly referring to the top end of the RPM range, but maybe it has something to do with gearing or even possibly elevation since I'm at 6000ft above sea level. I know the torque curve of the M273 is 391 lb.-ft. from 2800–4800 rpm which seems pretty broad, but maybe that's giving me a false sense of the engine's capability at low speeds. It's just a little odd since I thought a large displacement V8 would really shine when the little turbo/supercharged setups run out of steam.

As a side note, I think that the sweet spot of this car's mid-range acceleration is around 2nd gear at 3000rpm, what are your impressions?

 

Even with a tune I agree top end power isn't all that great. Then again I don't get much of a chance to WOT to 80-90+ as there aren't very much empty open stretches here.

 

A forced induction car like the two you ran will have an advantage at altitude. A large displacement V8 should pull harder on the top end but the folks I run around with hardly consider the top end to be 80mph. More like 110-130+. 80 mph is in that WRX's sweet spot. Thats likely in the meat of third or bottom of fourth gear for that car.

Note, when I say bottom of fourth I mean just shifted from tapped out third to fourth. Not 2k rpm in 4th.

 

Interesting you've noticed that too Lemon... I'm thinking it is due to altitude largely, especially because power comes from displacement and thus the density of air whereas with forced induction cars they lose quite a bit less power at altitude. You're probably right, I was just considering quarter mile times when it comes to "top end" when I raced the WRX and S4... I trapped 14.4 @ 97mph at my best so didn't really have time to tell what it would do at 110+ (it was 97 degrees that day)

 

Whew, 14.4 @97mph huh. Come try the 550 at sea level lol.

 

I've never had it at anything lower than 5280ft and it's heart breaking lol

 

a set of long tube headers will move the tq band a bit higher in the revs.

 

Interesting you say that I was watching a video from Summit Racing yesterday regarding long tube and shorty headers and that's what I took away from that video, a solution would probably be getting some Kleemann or Supersprint longtube headers. Thanks! Since I'm still trying to sell the car I don't think I'll do it but we'll see, for some reason I think longtube headers made for the E550 by Kleemann won't work on 4-Matic because of the all wheel drive hardware up front, but I need to look more into it.