Have you ever tuned a Honda?

Apparently not if you think you cannot find mpg's


Honda made the motors efficiency parts-wise, not tune-wise.

All that extra fuel is to keep the motor running cooler and smoother for when a sensor or two eventually go bad and wreak havoc.

Point is, leaving only the ignition coils, crankshaft sensor, and coolant temp sensor plugged in, you can still drive across the country doing nothing more then getting worse gas mileage.

I think you need to google search mista bone on d-series.org and look for his crx thread. he gets nearly 50mpg with a very basic setup, the same setup that got him approx 41 untuned.

Of course, we Fit owners will NOT see more then 2-3 extra mpg's tuned since we are 600-700 pounds heavier then that crx of his

 

There's room to get more mpg with tuning, but again, it's the last place to look for it. I think you need to google search 13fit on FitFreak:

That weight he mentioned that would cripple possible gains from tuning? That's one of the places I mentioned to look at before trying a tune. Instrumentation, technique and tire pressure have me averaging almost 50 mpg on the stock tune. I've got more mods on the list before altering the tune would make any sense at all for mileage.

 

If people were truly serious about getting a lot more mpg's, we would go for a longer 5th gear and a very small turbo setup.


a longer 5th would almost be constantly lugging the motor. The tiny turbo setup would give just enough power to push through it. Plus, if you did not intercool it, the hotter air does atomize better for a more thorough mix

 

Yeah, a taller 5th would be great! I'm against turbos for efficiency, though. Little turbo engines do a great job on the EPA test and also do a great job helping regular drivers fail to burn a lot of extra gas, but if you're actually working on mpg then they'll hurt- both in mpg and by having more parts to fail down the line.

 

you are making the false assumption that a turbo will negate any positives.

When properly setup, a turbo is a great addition for improving engine efficiency.

Obviously there are THOUSANDS of different sizes of turbos.

The ones that work well for gas mileage will be smaller ones, that do not create a bunch of heat, and do not use up much exhaust power to function.


There are plenty of factory vehicles out there that are turbo'd and get better gasmileage that way, rather then traditional all motor.

Diesels are the truck example. Mazdaspeed6 gets over 30mpg and is a turbo 4dr sedan that is supposed to be very sporty. Cobalt turbos got better gasmielage then the Cobalt superchargers. Minicooper turbos also got better gasmileage then the supercharged ones.


You, my friend, need to research a bit on engine efficiency. Turbos are awesome for fun, but they can help save your wallet when matched to your needs! Even Honda used this theory with the Honda Beat in the old days, a 3cylinder car.

Suzuki did this with the older Swift as well

 

I would just get in touch with Johnny Tran and turn a couple of SR20's. Then hit the NOS and BOOM awesome MPG.

 

Obviously we have a character here.

Its pretty simple with gas mileage.

you either have a small motor with minor forced induction or you have a bigger aspirated motor.


EX a 1.5 turbo will probably get the same gas mileage bump as if we just threw in a k20 and tuned it up a bit. The K20 would get better mpg's in our car then the standard civic SI or rsx because of vehicle weight change

So if the bigger motor is struggling LESS, how about that small turbo mounted on our small hamster?

Seriously, if you guys think turbo's are ONLY for wasting gas and having fun on the track, you know nothing of what a turbo even does (its only goal is improving volumetric efficiency)

 

The key here is "When properly setup, a turbo is a great addition for improving engine efficiency," and that's incorrect. A turbo is a great way to pump more gas into an engine, getting more power out of an otherwise efficient engine.

Why do car companies do this? So they can use a small engine that can get a good score on the EPA mileage test and still manage, if you live in the other end of the tachometer, to have fun power. I love fun power. It's awesome. But the moment you say "and I'd also like the chance to get good gas mileage," ditch the turbo and look for the fun power with your gearbox.

You're right that even Honda tried it- and then they stopped. Because you can build an engine that is capable of hitting a good sounding horsepower number on one test and can show good mileage on a different test, but you haven't built an engine that can do both on the same run. You've earned a couple sound bites for your commercials and pissed off a lot of customers who used the power and didn't get the mpgs.

 

I think the part your missing is that when not in boost a turbo motor is usually a really low compression engine. Thus great gas mileage when driven gently.

 

If you know anything about Tuning, or have Tuned, you would understand that you could achieve more MPG by leaning out the cruising Load/RPM cells...ive seen guys lean out their crusing AFR's to 17.5 or higher and achieve near 100mpg. The key is tuning ignition/timing , at such lean AFR's. Of coarse Aero and weight are also key factors too.

 

Fit Charlie, you are missing the point entirely.

A turbo is sucking gas hard when you drive it hard, just like any naturally aspirated motor.

A small turbo spins much more easily, thus allowing the motor to get air without wasting hardly any energy.

Honda stopped the majority of its turbo projects because they decided a tiny motor with a turbo was costing more money then a slightly bigger natural aspirated setup.

And if you think Honda stopped, no way. They are coming out with a 1.0, 1.5, and 2.0 turbo motors for the next generation of gas mileage and performance.

All three of those motors are expected to be beyond the 40mpg marker, with the 1.0l expected to get over 50mpg

 

When I turned mine I stayed about the same. I do however run a map on road trips which raises the VTEC point a bit so it's not going in and out over little throttle changes and definitely yielded me a few MPGs more on the highway. It's funny because it's more useful (better MPG) when I'm going 80 vs 70 hahaha. Haven't had time to tweak it to find the sweet spot for 70 yet tho.

 

I currently drive about 150 highway miles a day in my 2007 GD3 Fit and she is about to hiy 40K miles any day(luckily for me the old lady who owned it before me never drove it). Back to the point a taller 5th would help drastically my previous vehicle was a 2004 chevy cavalier and on highways doing 80mph's at about 3k rpm's I was still getting 30mpg's and that vehicle had larger fuel injectors and was tuned for additional HP. Doing 80mph's at 4k rpm's(way to high in my opinion) in my fit I get the same 30mpg's but was expecting so much more. I am trying to adapt a new driving style of 70mph's to see how much it helps the fuel economy but a taller 5th or even another gear would be great. Does anyone know if the new transmissions fit the GD3 motors?

 

Pretty sure the new 6th speeds don't really have any taller of a gear for highway anyways.. And taller gear doesn't necessarily mean better mpg, if at all. Honda knows what they are doing but it's no surprise 60-65 mph is best for mpg on the highway. Pretty sure we're in some kind of lean burn duty cycle on the injectors at highway cruising.. but supposedly vtec and 16 vales are enabled at over 70ish mph 2800+rpms? Perhaps like a previous poster said, raising the vtec engage point may help for highway. I'll play around and see what happens.

 

in stock form, 16valve mode is engaged past a certain speed on GD's

do some datalogging, GD flashpro owners, and report back.

Also, the 16valve mode kicks on under lots of engine load. even if you raise the rpm engagement, it will still engage if the engine is struggling too much.

On my GE I have smaller tire diameter, so im at higher rpms at the same vehicle speed as factory size diameter. My mileage has not dropped! interstate, I cruise at 75mph gps speedo.

 

Anything to lower the RPM's at higher speeds would be helpful not sure what would do it but if it is not possible I will have to get used to cruising at slower speeds. Not a big deal but the FIT would be so dreamy if it had a 6th gear and at 80mph it was around 2500 rpm that would be so idle and I am sure many would agree.

 

You are missing the point. If the Fit was spinning 2500rpms at 80mph, it would not be able to accelerate, and might not even be able to maintain that speed without alot of throttle, which would remove the whole point of lowering the rpms.

Honda has been playing with engine rpms and gear ratios for years. They had good formulas in the late 80s and early 90s, and since then have only improved the combination.

The noise reduction of having lower rpms would also be removed by the louder engine load noise.

Have a quick test. go 40mph, put it into 5th, and watch the mpg gauge as you try to maintain speed. watch how the mpg gauge stays below 20mpg as you attempt to maintain speed even up the slightest of hills. That seems about the rpms you want, right?

Now dont forget, at 80mph you are dealing with ALOT more air drag, any downforce will add "weight", and the fact you are more susceptible to any wind coming towards you.

conclusion is, let Honda do their thing. they weighed the pro's and neg's of their gearing choice. In the end they got a very good balance of mpg.

One final thought, if 5th gear was low enough to be 2500rpms at 80mph, how massive of a leap is that from 4th gear? you would need to be running in 4th for anything under 65mph or so, and that would destroy mpg. So you dont want honda to change 5th, you would want them to change 3rd and 4th as well, at least.