Couple of silly questions.

1) why does the 350z only produce 287 hp. that's only 82hp/liter. why is that only Honda, BMW, and Ferrari can make cars that routinely produce 100hp/liter or more. heck a 1991 nsx produced 90hp/lt. u would think that a 2002 nissan could atleast match that.

2) why is the red line on the 350Z only 6600. I mean, its nice that it has 274lb-ft of torque but it would be nice to have atleast 7.5k redline to really use that fat torque/hp curve.

3) Final question. nothing to do with the Z. Why would a water cooled porsche box/911 require 11 quarts of engine oil. I can understand it needing 10+ quarts when they were air cooled, but not when they are water cooled.

thanks in advance.

 

1) HP/Liter is a misleading spec on the engine. Consider torque/displacement instead.

VQ35 - 78 lb-ft/liter

E46 M3 - 81.9 lb-ft/liter
F360 - 76.7 lb-ft/liter
F20C - 76.5 lb-ft/liter
LS6 - 70.2 lb-ft/liter

Based on some of the better engines floating around, I'd say the VQ35 is doing pretty good on power output. And since horsepower is just torque times rotational speed...

2) The VQ35 engine (or a variation thereof) is used in half of Nissan's lineup. It wasn't designed for sports cars so much as it was adapted. So there are many issues that may keep the redline down - reliability, inability to breathe at high speeds, etc. And it's also possible that Nissan wanted to avoid the negative perspective that the S2000 has gotten.

3) Good question I can't give you a hard answer, since the only people who know work for Porsche and probably aren't at liberty to discuss it.... but, I'd guess it was somewhat of a carryover from the switch to water cooled - would have required extensive redesigning/retooling of the car... And more oil never hurt... Just my theory on it.

 

1. Design point.. less stress on the engine, cheaper to produce, easier to drive.

2. see above.

3. Oil is still part of the cooling system and with more it does not have to be circulated at such high speed,

 

1) Agree with cdelena. It's a design tradeoff. And a bit of marketting. But yes, a higher hp (and torque) per liter of actual engine volume (not just cylinder displacement) and per kg of mass can have positive impact on handling, balance, accel.

2) Same. Note that it is all a compromise. If you design your engine and valvetrain for higher rpm, you usually sacrifice low end performance. VTEC is a somewhat expensive solution to this. Basically, cost is your answer to (1) and (2).

3) Don't know. Are you sure of the "more volume=lower circulation speed"? I would tend to believe that since heat removal=flowrate*specific heat*delta-T, the actual volume does not factor. Perhaps boxer engines just require more volume by design?? Maybe it's just a legacy (no pun intended!)

 

FCGuy - don't forget that if you double the volume of the fluid (from 5.5 quarts to 11 quarts, for example), you also double the amount of heat energy that can be stored by that body of fluid at any given delta T. So while the volume doesn't affect the heat removal rate, it does affect the delta T in that the oil never gets as hot. This would allow you to maintain a lower heat removal rate and not worry about cooking the oil if the engine was run extremely hot for a few minutes, on the assumption that the HRR would cool the oil back down during a period when the engine wasn't producing as much heat.

 

3) ok i have a stupid theory...in most cars we carry 4-6 quarts right? maybe the engineers thought if we can manage to dirty or use up 4 quarts, there is no way in hell you can do that to 11 quarts given the same time period..

i dunno, just what i thought since my mom's mercedes uses 9 quarts...