i want to increase the efficiency under the hood.

ive been thinking of ways to increase miles per gallon while maintaining or even increasing performance.

these were the first things that came to mind, and i would like some help from somoene who knows what they are doing.

1. new pleneum
2. intake
3. underdrive pulley
4. lightweight rims ( stocks weigh 25-28lbs, decresing that weight will drastically increase gas mileage, thats for sure)

and please, i kno this a HPV and i shudnt bitch about gas...but i know it can be improvved with very little effort and the problem is the inefficiency of the vq.

can someone please reply with other engine mods that will improve feul efficiency while still maintaining/improiving performance.

 

Sorry for a useless response, but don't you think that if, as you say, it can "be improved with very little effort" that Nissan would have done it from the factory to make the car more competitive?

The car is what it is. I've been reading here for over three years and have yet to read about a modification, performance or otherwise, that does anything to significantly increase fuel efficiency.

The best mod I know of is a lighter right foot.

 

The four points of interest that you listed are primary ways of increasing efficiency. However efficiency can be analyzed in forms i.e. thermal, chemical, electrical, fluid and volumetric.

I am not certain what year your G35 is so I would like to point out that some of the potential modifications that you listed may effect your warranty.
I) To maximize volumetric efficiency you would need a new intake as well as pleneum, headers and exhaust with high flow cats.
II)Underdrive pulleys have reduced rotational inertia therefore requiring less power to operate ancillary devices such as AC.Underdrive pulleys are susceptible to warping and premature failure in high load and long duty cycle situations.
II) Light weight rims will reduce rotational inertia i.e. the force required initialize rotation and stop rotation. Rims such as the TE37, CE28N and Gram Lights are some of the best racing rims available. The above mentioned rims can be found on various Japanese SuperGT, Time Attack, Drift and Togue cars.

 

with those mods or most any engine mod your right foot will tend to be extra heavy on the go-pedal and will negate any attempts to improve fuel efficiency...

best thing to do in another way of saying to lay off the go-pedal is to stay below 3500 rpm....

 

i have an 04 g sedan, and the main reason why i was inquiring is because of the fact that the 05 has increased hp (04)260 - (05)280, at a better EPA.

 

[QUOTE=renegadestorm]The four points of interest that you listed are primary ways of increasing efficiency. However efficiency can be analyzed in forms i.e. thermal, chemical, electrical, fluid and volumetric. QUOTE]


What does volumetric efficiency entail? Air/ Fuel?

also I have the factory warranty 3yrs/ 36,000
and I purchased an extended warranty 6yrs 60k for 1,000 bumper to bumper.(great deal btw)

it seems like the best mod that I can go for is the Intake and Rims... i was considering SSR competitions. thanks for the input renegade

 

Why does spending $3,000 on light wheels/tires for the sole purpose of MPG fail my logic? Let's say you gain 2 mph with this mod. You know how long it would take to break even?

 

i completely agree on that point. first off, it would be more than 2mpg saved more like the ranks of 5, but that is besides the point. The lighter wheels would change the entire feel of the car, come out of corners quickly, more power faster, etc. It would be more for a performance bonus than for the fuel eff. Its just that much better though, that I can squeeze out better gas mileage, not have to fill up as much, and get a nice set of wheels. but as far as breaking even, no arguement.

 

IMHO, in order for you to actually FEEL the difference in handling, you probably have to spend even more than that.

I ran both the Z forged track edition 18s and the normal heavy Z tourings on my old maxima. Other than a very slight diff in accel, I couldn't tell much if any difference. Not in normal driving anyway.

I mean, if one IS going to buy some wheels/tires, by all means search for some good light ones. This is why I run the forged coupe 19s.

 

[QUOTE=aum003]I don`t know that your extended warrenty was such a good deal The factory warrenty is 4 years/60,000 miles, not 3/36. I won`t comment on the mods, because I`m one of those fools who will tend to use any additional power, and negate any fuel mileage increase made possible by increased efficiency!
Good luck.

 

I'd have to disagree that light weight rims are going to improve MPGs by 5. That's over an 20% improvement in mpg. Years ago on my Maxima I had a set of 36lb 16" lightweight rim combo in place of my aftermarket 17" combo (46lbs). Overall, the mpgs improved by 1 in city/highway driving and on the track I saw a .1 and 1mph improvement in the 1/4 mile with the lighter rims. That's with a reduction of 10lbs in unsprung and rotating weight. I'll admit that handling, braking, and initial acceleration did feel better with the light rims, but the mpg improvement wasn't there.

I think you'll be hard pressed to find a 17 or 18" combo that will reduce weight by 10lbs over stock because 17-18" tires are heavy and sub 20lb 17-18 rims are expensive. Also, most people end up going with wider rims and tires which increase rolling resistance.


As for the UDP, I'd have to disagree again. With my old VQ30, I had a UR UDP (80% lighter than stock) installed for about 1.5 years and it didn't improve MPGs at all. It didn't do anything for performance either.

And the intakes...all the aftermarket intakes remove the natural pressurization of the OEM intake tract at speed. The OEM setup is designed for optimal performance, driveability, and fuel mpgs. All the aftermarket intakes introduce additional engine heat into the intake tract because which does affect MAF readings and causes richer part throttle A/Fs to cool the combustion chamber. I'm not saying the intake is going to cause a major decrease in MPGs, but I doubt it will improve MPGs.

 

Sorry to threadjack, but I had to mention some rims. I purchased rims that I find attractive and didn't pay much of a weight penalty back in November, so I'm not exactly in the market for new wheels. However, I found these on tirerack:
http://www.tirerack.com/servlet/Call...filterSpecial=

They're 19 inch, forged, are slender(at 7.5"), and weigh only 18 pounds. I called tirerack and spoke with a dude named Kyle, to ask about other sizes. The same wheel can be obtained in a 17x8 at 15 pounds, and a 17x7 at 14.6 pounds. If you get the 17x7's, coupled with goodyear eagle GSD3's, sized 235/50/17 (which weigh 26 pounds), you're looking at a savings of aroung 8 pounds a corner, depending on the source and oem wheels/tires. At the same time, you've added 20mm of tire at each corner.

Not bad at all.

 

I was thinking of this the other day. My company car is a Grand Prix and has a 3.8L V6, at 70mph it is doing exactly 2K rpm. The G does a lot more than that (can't recall as I write this). What would really work is a much higher 6th gear. Heck, this car will do over 130 mph in 5th as it is, why not make 6th the "economy" gear? Is it even an option IF you had the chance to tear into the tranny? The plain truth is, this motor is geared way low for performance and it hurts economy big time.

 

^^^ You could always drop down to the 3.3's. ^^^

 

Yeah, but then I would lose that nice pull in the first 4 gears.