Fuel Economy with a GTM TT kit!!!
 

Hey Guys,

As some of you know I bought the TT GTM G37 that I was help selling for a buddy of mine. And I know some of you remember the STI I had purchased before that. Well I sold the STI and bought the G37 mainly for a few facts...

David needed to sell his car quick
The STI had the worse Gas mileage of any car I ever owned!!!


Now when I first bought the G37 TT I figured that the car would be about the same if not a a little better than the STI well I will let you guys judge for yourself if you think TT is bad on Gas mileage:

STI City: 12-16mpg
STI HWY: 14-19mpg

Stock 370z City: 17-19mpg
Stock 370z HWY: 23-27mpg

GTM TT G37 City: 17-25mpg
GTM TT G37 HWY: 27-38mpg

I have been recording my mileage since I bought the car and I will say it is the best and most fuel efficient car I have ever owned. I can set the car to cruise control on the hwy @ 80mph and get 35-38mpg all day long. 55-65mph is even higher!!! Whoever, says going TT will ruin your MPG is full of it!!! I have pictures of my results that I can post if people want me to. I cannot speak for SC'ing your car but if you drive your car normal you can get hypermileage results! :excited: This last 19gal tank of gas should get me around 600miles with combined city and hwy!!!

That's insane! I never would have guessed that. It would be cool if you posted pics :tup:

Best I've gotten out of my Z was 30.1 mpg driving an hour from VA to MD after getting my exhaust installed.

i dont know how you guys get such good gas mileage.

everytime i look at the MPG meeter, and i see it over 20mpg...i know im not having enough fun.

i can't get my G over 15mpg lol :D

Hahaha econ!

If I wanted I could make it get 5mpg but that would mean I would be doing 140+mph everywhere! You wouldn't believe how fast a GTM TT kit really is! 70-140+ in 6th gear takes just a few secs!!! The car keeps up with 1000cc motorcycles all day long. I have stomped on corvettes, Mercedes, muscle cars, 600cc bikes and so on... I missed my opportunity the other day to play with a Lamborghini but that's another story.

so bigger injectors/pump and increased power from two turbos = higher fuel mileage, got it.

whaaa?

The only explanation is that you're typing this from the inside of an air tight location while dynoing the white dragon.

Incredible! Keep up the good work!

Are these calculations based on the on-board computer, or based on actual fuel-usage figures (e.g. fill up and record mileage and gas usage)? I can see a scenario where the on-board computer would miscalculate gas mileage on the high-end. For example, if the on-board ECU used injector pulse length to calculate fuel use, but you had larger injectors, then when cruising the injector pulse would be shorter because the injector is larger, but you are probably using the same or more gas. I just have a very hard time believing that a TT sports car is rivaling hybrid gas mileage on the freeway.

i can barely make 300 miles highway driving only on GTM S/C. about 17-20mpg. can it be our pissy 91 octane robbing us? lol

I believe it does it exactly that way. I've watched my fuel closely since adding my turbos and it definitely hasn't increased even though the on board computer says different. The larger injectors trick it. I drive mostly highways and am pretty conservative and I normally get 300 miles to the tank now. Here's an example of my gas mileage according to the car. I keep telling people I have a hybrid lol. The last picture is what I was getting before the turbos.

i really need to go forced induction asap.

someone loan me like $5k...thats all i need.

Sell a kidney!

Exactly this. The trip computer is estimating fuel economy based on "stock" injector pulse width, the trip computer numbers are meaningless.

Fill to fill measuring the number of gallon you put in the tank by the number of miles driven is the only accurate measurement.

if you're getting 38mpg highway in the Z you are either going down a steep hill or being partially towed.

:iagree:

You are 100 % correct the bigger injectors trick the stock ECU.

Yep. Now we just need to figure out how to fix that...

interesting

Guys I am doing my figures from pumping gas (I filled up 19 gal yesterday and drove 300+miles so far and I still havent reached 1/2 tank) and I am using info from the trip computer. both are correlating really closely maybe off by 1-2 mpg... still it does not negate the fact that at an increased hp level the car is under less strain to hold a given rpm...

for example:

maintaining 75mph in 6th gear stock required about 30+% throttle position...
maintaining 75mph in 6th gear TT'd required about 22% throttle position...

I am seeing an increase in motor efficiency and can sustain higher rpm's with less throttle input. Therefore, the motor is able to get higher fuel economy.

mike

btw rcz... I have been driving a TT G37 for 2 months now :tup:

btw at 75mph i am just under 3k rpm and barely touching the gas maybe 6% throttle... The mileage to empty jumps around on me so I am not using that as my basis... After 200miles yesterday it went from 395 to empty up to 495 back to 450 and so on depending on my driving. Also I believe the trip computer is taking calculations at 1 mile increments and comparing the avg fuel consumption to give you the est. range. If i lay into it for a quarter mile the range doesnt change until a mile or two later and if I am coasting it doesnt change either.

Mike

hmmmm.... I wonder if the wife will buy this logic! lol

... honey, the twin turbos are actually saving us money...!

lol my wife to be is all over it haha but her nickname at work is Turbo cause she loves turbo cars hehehehe

If a TT got better gas milage than a stock motor everyone would put one in...

http://planetsmilies.net/smoking-smiley-5437.gif

Must be that new math they are teaching in school...

Hey everyone said me and Semtex were applying ricer math when we quoted his exhaust, HFC combo on hp.... guess what we were right! My math is on target... I have been getting 500+ miles on a tank of gas when i drive it normal...

500/19=26mpg

550/19=28.9mpg

600/19=31.5mpg

so with my avg's being around 26-31 combined I should be right on target.

I have the same car/combination (essentially). I have to side with Bullitt, although I understand and won't completely trust the onboard computer (which reads around 29-27 mpg on cruise.) It just sips fuel when I'm not stepping into it.

That said, probably because of exhaust flow (no cats, straight out), the car is effortless at 70mph.

The new math: Having my cake and eating it, too. :D

Coop

ricer math FTMFW!!! hehehe

Turbocharged engines are generally considered to be more efficient than an NA motor of similar or slightly lesser HP level, but I've never heard of adding a turbo system to a car making it more efficient, although if the compression ratio is reduced then I guess it is theoretically possible.

Come on guys...the idea behind saving fuel with a turbo engine is that you can produce same power with LESS cylinders or LESS displacement when compared to another engine. Bullitt, could you please explain why the car is more fuel efficient now?

It's not like GTM needed more advertising to sell their S/C and TT systems.. hahahaha..

- Do you have a Z or a G?
- Are you having sucky gas mileage?
- The answer to your problem is Twin-Turbo!

IT WILL PAY FOR ITSELF WITH SAVINGS!

:ugh2::ugh2:

LMAO!!!!:bowrofl:


RCZ: its simple... the injectors are running a lower duty cycle at the same rpm... despite the larger injector size it could easily be using less fuel than the stock units. Since the 600cc are not that much larger than the stock units. Many of us are experiencing this with TT kits because we are staying low in boost where it is actually beneficial... if I was at 4k rpm and 30% throttle I wouldnt be getting these results...

Mike

If the exact same driving accelerations are used pre- and post- turbos with good tune, then you will get better gas mileage out of the turbo'd engines.

Engine Technologies

The thing is most people get turbos to accelerate faster and not for gas savings.

You don't honestly think that your engine requires less fuel than mine to reach a certain AFR because you run larger injectors, do you?

You guys must have magical turbo kits then. I drive mostly conservative and all highways and I don't get the gas mileage I use too. It surely isn't better either.

Alot of it has to do with tune also. Are you running slightly rich or slightly lean?

Good point, more on the rich side. I don't think it's a big enough deal for them to be getting double what I get though.

:iagree:

I average about 18mpg mixed driving now. Before TT I was around 22mpg mixed driving. I always write down the mileage in a small note book.

My trip computer is off by about 50%. My last tank it showed 27mpg but if you do the math I went 329.2 miles on 17.9 gallons. That works out to 18.39 mpg.

Still, not too bad after almost doubling the power but by no means is it better.

Again this is all dependent on your driving habits... When I am trying to save gas I drive completely different. I also like to have fun... Consider it hyper mileage if you want but it is possible. The difference between excellent gas mileage and having fun is paper thin...

Most cars tend to read significantly higher gas mileage after installing larger injectors because the PCM gets its MPG readout through monitoring injector pulse times. Obviously, larger injectors present a change in pulse times but the PCM cannot adapt and reads high due to larger injectors flowing the same amount of fuel as stock injectors but needing fewer pulses due to the larger flow rate.

Fewer pulses = higher MPG readout.

600 miles per tank??!? Um, no way. Did the previous owner change out the gears? If so, your speedo and milage will read much higher.