Just curious, what type of gas mileage are you guys getting out of your jdm itr transmission setups?

I'm taking a look over at the regular Integra forums and some of those folks are netting mid thirties highway. I know that their USDM non-ITR 5th gear allows for lower RPM at cruising speeds, but I was wondering how much of a difference the jdm itr 5th will cause.

 

It has been proven that Honda 4 cylinders love cruising at higher RPM. Think it takes less throttle input to achieve a speed or stay at that speed with a higher final drive. I average 30MPG but I have done 34MPG.

 

it's not the trans, it's the pig rich p73 ecu that's your problem. if you actually had a good tune done with less fuel in the map mpg would go up and it would create less soot in the engine

 

Odd thing is that I already had a tune.

I thought I was running extremely rich due to the smell of gas in my exhaust fumes (no cat as of right now), but that was because of a faulty PCV valve.

I fixed the PCV and now the exhaust fumes are minimal.

The only other problem is that I could potentially be running rich, but from my limited spark plug reading experience, my last plugs didn't look as if I was running insanely rich (they had a light gray dusting, no brown from what I can recall).

I'll take another look when it's bright out.

Either way, I think I'm due for another retune.

 

I don't see why u wouldn't get 30+mpg. Both my USDM setuos get 33+ at 80mph cruising averages....with some around town driving mixed in. Probably like 34ish-35ish pure highway.

 

What RPM do all you drive at...

 

JDM 97 B18C-R, IHE, Stock Trans (same as US R gears), 94 Civic CX (yeah it's lighter), 205/40/16, Kenji Chipped ECU, 91 octane. Typical 34-36mpg. Worst was 28mpg when I went to the drag strip. I cruise @ 70mph, but still hit the back side of 8k rpm at least once each time I drive.

At a true 70mph (your speedo reads high), I'm at 3800rpm. M-factory has a gear/speed calculator so you can see before & after changes for tire sizes, final drives & gears: http://www.teammfactory.com/gear-calculator

I recently adjusted my valves, and there is definitely more power and the engine note has changed considerably now (all 16 were loose). I don't think that will effect anything but WOT mileage though, but only time will tell.

 

OP, do a search on 4.92 final drive. You'll be surprised at the amount of info on gas mileage with lower geared trannys you'll find. Excellent reading material.

 

80MPH...so like...4300? 4500? Something like that.

 

Well I have a 4.9 and I don't get that great of mileage because I have my vtec crossover set at 4500. So cruising at 80mph I am in 5th in VTEC the whole time haha

 

Of course more air needs more fuel=less fuel economy.
Not sure what you have your car tuned with but if it's S300 can't the VTEC be made throttle sensitive to so it doesn't cross over?
I know with my old S200 my R was SC'd and had to be at least 3K rpm's and 4 psi to engage the cross over. I could feather-pedal it all the way to the rev limiter and never get on the big lobes if I wanted.

 

Well it's all in the tune. Just because it's on VTEC doesn't mean it's consuming more air at a given mph. It takes "X" amount of power to go "Y" speed. Both are constant. Even though the rpm is higher, your load is the same. Therefore your throttle angle should be less to keep the vehicle going the same speed, thereby consuming the same amount of air & fuel (maybe a tiny bit more for increased friction).

The difference comes from the ECU. His setup is running more rich at that given load/rpm. Essentially wasting fuel to produce the same amount of power. You could tune it to run less rich at light load.

 

awesome thread....

 

See, I do that but the best highway I can get is like 29...............you ever seen the way I drive? I've got a heavy foot.

 

In my '97 with track day weight reductions, my stock USDM motor with USDM ecu gets 35+ mpg on the highway with my Euro E3E ITR trans (same gears/FD as 98 spec JDM).

 

I just pulled the same thing, practically 95% freeway. 29MPG, nothing to be proud of considering I tried to accelerate like a granny and coasted as much as possible.

Back to the tuner!

Do ya'll think that with the addition of ethanol to our gas that our MPG ratings have decreased over the years? I know that the gas station by my place uses up to 10% ethanol.