boostard

First of all, the two cars which were dynoed (for an MT vs ATX side by side) weren't even of the same year. 2007 vs 2007... in 2 years a lot of variables can happen to a car, including but not exclusive to the volumetric efficiency of the engine(s)... read: this can be a BIG factor. Secondly, I dont see any dates or times on the dyno charts in question. Now Ill give it that they were probably done at the same place, but who is to say these weren't days, weeks or even months apart from each other? And of course we are talking about two different versions of the VQ engine (G35 vs G37) as well as different transmissions.

I really dont see anything to fully conclude the previous statement in question.

Mike

iTrader: (1)

You keep emphasizing time. Time doesn't make a difference in the dyno results with proper correction. HR vs HR, the only difference is the transmission, which is what you were asking for... both engines are VQ35HR.

Volumetric efficiency is not a measure of engine efficiency.... Going under the assumption that "there are a lot of variables between two engines of the same model", again, shouldn't all dynos NOT be comparable?

I still stand by my statement that any two cars dynoing on the same dyno with the same set of calibrations can be compared, if the same set of corrections are applied to both cars.

KAHBOOM

iTrader: (4)

Again... The 2nd from the last chart was for a 2007 AT HR engine as well as the DE MT. The last one was for a 2007 MT HR engine. Those are the two I'm comparing not the DE engine

Additionally this is a dynapack with correction factors included so even if they were done at different times, they wouldn't be that far off.
The data is the data accept it or not.

KAHBOOM

iTrader: (4)

Another set of dynos- these were done at different times but done on same machine with correction factors for a G37 coupe MT and AT.
https://www.myg37.com/forums/2314623-post1.html click the attachment in the post

https://www.myg37.com/forums/2481407-post8.html

Perhaps it is coincidence that each comparison of results done on the same machine with correction factors are so close?

Any other forums you look at- when correction factors are done properly for other cars- you can clearly see the difference between the MT and AT. I dont doubt that there is less drivetrain loss in the 6MT but the gap is not as wide as what is typical nor does it appear to be significant.
Thus further evident in the results mags achieve- such close times when testing the ATs and MTs in the G. Members have furthermore posted timeslip indicative of the fact th the two transmissions deliver remarkably similar power to the wheels.

iguess

iTrader: (1)

I thought HP rating was lowered because exhaust set up like sedan, with 2 mufflers.

According to this video, its set up same as coupe.

http://www.nicoclub.com/articles/vid...ottle-blip.mov

KAHBOOM

iTrader: (4)

hard to tell in that video but there is prabably a different bend or two that makes the difference.

iguess

iTrader: (1)

I turned the brightness all the way up on my monitor. It looks like the midpipe is similar (possibly smaller diameter???), but the rear muffler looks smaller. I would assume it'd have to because the hardtop needs alot of space, and the spare tire well would have to be lowered?

KAHBOOM

iTrader: (4)

That would sound like a reasonable explanation.

SantiagoDraco

The hard top itself is pretty much all above the frame/exhaust so I doubt that it has anything to do with the exhaust changes. However the structural reinforcement done to the frame/chassis is the likely culprit as they have to strengthen the frame when you have no integrated top.

JonfromCB

My guess would be Nissan is still "playing" with the fuel economy numbers on this
specific model in order to achieve the highest "fleet mileage" possible. CAFE standards
don't give the manufacturers "wiggle room" to manipulate HP ratings for the
sake of marketing any longer. I can think of several manufacturers who were forced
to advertise decreased HP ratings by as little as two HP over the last decade.
When a manufacturer says "at least" they mean it. Once they optimize the
mechanical components of a given model to the real world CAFE tests, they will provide a specific HP output for that model....that's ONLY ONE reason you see variances betweeen two exact displacement engines in two different models.

WildcatG

From 2009 Infiniti G37 Convertible - First Drive Review - Auto Reviews - Car and Driver

"The sonorous 3.7-liter DOHC V-6 carries over from the coupe, with peak output of 325 hp coming in five fewer than the hardtop’s, thanks to some exhaust changes."

It doesn't talk about it in this article, but I thought it had to do with re-routing the exhaust because of some of the structural changes needed for the convertible.

The G

+1000000

JohnnyCham

iTrader: (1)

its from the exaust. its wayyy quiter than normal, my 04 G35 rumbles when u drive with the windows cracked or down, did the same with my vert and i could barely hear the usual "roar" they make at 2500-3000 rpms. looks like my 1st mod is definitly gonna be the exaust for this car, then the spoiler cause i cant stand that damn short antenna.

djkmac

all this for a couple of hp??? for real??? How do I get pulled into these off topic post of mad scientist going at it on these boards lol.