Changing Gear Sets [Merged 11-7] transmission drive ratios

[poonman]

How the hell are you ppl getting like 35-40mpg?? I have never seen more then 25mpg on my car and thats 500 miles on a tank highway devided by 19.8 galon tank.

 

[GVR4592]

How the hell are you ppl getting like 35-40mpg?? I have never seen more then 25mpg on my car and thats 500 miles on a tank highway devided by 19.8 galon tank.

They aren't.

 

[poonman]

i didint think so, I may not be in rocket science but i can do math and math dont lie when done right

 

[SpoOLxExO]

Its possible to get 35MPG, but only if you know how to tune, and edit your EPROM for a 15.1:1 Lean burn code under NO boost. As soon as any amount of boost hits, its back to 11.8:1.

My Co-worker at F1Dyno was getting 42 MPG in his 60-trim B16 Hatch, using the same lean burn code.

Why am I not a Wiseman yet?WTF

 

[jeharrisonjr]

dont know what SpoOLxExO is really talking about, I think he means with DSM link and I think he probably should be a Wiseman if he is correct.

The best gas milage I have seen is 26.9, but thats all interstate driving.

 

[GVR4592]

Its possible to get 35MPG, but only if you know how to tune, and edit your EPROM for a 15.1:1 Lean burn code under NO boost. As soon as any amount of boost hits, its back to 11.8:1.

My Co-worker at F1Dyno was getting 42 MPG in his 60-trim B16 Hatch, using the same lean burn code.

Why am I not a Wiseman yet?WTF

I have my car tuned for 16.5:1 cruise, 15.5:1 idle, and if I don't boost it at all, I can get about 26-28 mpg combined city/highway, real world mileage, not cruising down hill in 5th gear at 1500 rpms trying to get 35 mpg.

I've been trying EVERYTHING I can to get it to a real world 30 mpg and it's just not going to happen with this car. I've set my fuel cut for 2 psi and a 3500 rpm rev limiter, I've set my check engine light to come on over 35% throttle. I've played with tire pressures, alignment settings,and a lot of tuning, out of all of that I went from 20-22 mpg to 26-28 mpg.

That might seem like a lot but remember that's with no power. I just changed it all back except for the lean cruise and idle, and that only gives me 1 mpg increase, I might as well just buy a Geo Metro.

Honda's are a completely different story. I have my brothers built B18C EF Civic tuned for a lean cruise and idle, it gets 44 mpg average and he beats the crap out of it, 9500 rpm shifts at least once a day.

 

[GVR4592]

Another thing I forgot to mention, if you guys are getting your mpg numbers from just one tank of fuel that would explain a lot. To be accurate you should take the average for 6-10 tanks of fuel. It's easy to make a run down the highway at 55 mph and get 30 mpg, but how many of us actually do only highway driving and no stop and go driving?

 

[jeharrisonjr]

I do mostly interstate driving so my real world milage is 24- 26MPG. I guess from what you are saying I am doing pretty good.

 

[RallyEclipse98]

I seriously doubt you'd see that much mileage increase. You might get another 3MPG out of it. For one thing, he's FWD instead of AWD, so he both has a higher final drive and less parasitic drag.
I don't believe his claims for that mileage, either.

Exactly! Don't believe what you read on ebay. He also said in that ebay listing that he only drove the DSM to work and in one of his pictures it has a nice chalked number on the window. Haha, I even know where he races...

 

[D_Eclipse9916]

it all depends on your driving, around town, untuned I get around 10-12 mpg, on the highway I regularly do trips to VIR, 253 miles away according to mapquest and ive headed out two or three times when the gas light came on and the gauge read E. Filled up 7-9 gallons and have always gotten there with a little bit of fuel left approximately .5 to 1.5 gallons. Who knows? the thing is so innacurate, but if I can make it there on only 8 gallons, I know im somewhere very close to 30-33 on the highway. BUT ONLY on mostly highway, and I do mostly city, so I only get averaged around 18-19 mpg total driving.

 

[SpoOLxExO]

I have my car tuned for 16.5:1 cruise, 15.5:1 idle, and if I don't boost it at all, I can get about 26-28 mpg combined city/highway, real world mileage, not cruising down hill in 5th gear at 1500 rpms trying to get 35 mpg.

I've been trying EVERYTHING I can to get it to a real world 30 mpg and it's just not going to happen with this car. I've set my fuel cut for 2 psi and a 3500 rpm rev limiter, I've set my check engine light to come on over 35% throttle. I've played with tire pressures, alignment settings,and a lot of tuning, out of all of that I went from 20-22 mpg to 26-28 mpg.

That might seem like a lot but remember that's with no power. I just changed it all back except for the lean cruise and idle, and that only gives me 1 mpg increase, I might as well just buy a Geo Metro.

Honda's are a completely different story. I have my brothers built B18C EF Civic tuned for a lean cruise and idle, it gets 44 mpg average and he beats the crap out of it, 9500 rpm shifts at least once a day.

Whats your part throttle, and total timing?

 

[Gregory]

Don't forget, your gas mileage depends a lot on how fast you are driving. Theoretically, on a N/T car, you should get best gas mileage going as slow as you can in final gear. Now, with us turbo guys, we have the third aspect to worry about, boost. But generally, you save major gas by drive 50mph instead of 60mph, or 60mph instead of 80mph, and so on and so forth.

 

[dsm-onster]

Oh, it is definately possible. I got over 33 mpg for 3 and 1/2 tanks in a row using just the easiest of pneumo's techniques: How To Save Gas.

A while back I got consistant 33-32 mpg on several tanks of gas just by staying out of boost after i had just installed my cam upgrades.

Highest gear possible to get what you need to get done, lowest speed possible to get what you need to get done. This is a good rule. and will save you the most gas from my experience.

 

[GVR4592]

Whats your part throttle, and total timing?

I have no idea, it's been a long time since i looked at my timing map. It's probably a little advanced compared to a stock 1g map in those ranges.

 

[GVR4592]

Oh, it is definately possible. I got over 33 mpg for 3 and 1/2 tanks in a row using just the easiest of pneumo's techniques: How To Save Gas.

A while back I got consistant 33-32 mpg on several tanks of gas just by staying out of boost after i had just installed my cam upgrades.

Highest gear possible to get what you need to get done, lowest speed possible to get what you need to get done. This is a good rule. and will save you the most gas from my experience.

I tried that and it only improved by about 2mpg combined city/highway. Do you do mostly city driving or highway driving?

 

[dsm-onster]

When I got 33 mpg cosustantly afte rI got my cam swap done I was running in the burbs of Hampton Roads, Virginia. Very cityish. No lights, but stop signs galore. I do not live there but I traveled there to build my parents house. So, that's how I racked up the city mileage.

Recently, I've recorded my mileage here at home. VERY rural. But these back roads are NOT forgiving. VERY twisty. Not like texas where there's no traffic/civilization but at elast the property lines are square . It's twisty, bumpy, and otherwise a pain on the brakes and steering (unlwess you feel frisky enough to let your car drive for you). Still, . . .

1. controling the braking and acceleration when you know you have a stop coming (BIG ONE!!!)
2. staying out of boost
3. raising tire pressure
4. getting into the highest gear early
5. running at the highest gear possible at the loweest speed (AONTHER BIG ONE!!!)

. . .has done wonders for me.

It's very boring. It downright sucks. and I HATE it! I dispise driving this way! but it still gets me the best mileage.

 

[SpoOLxExO]

If its possible, one can tune their off boost timing a few more points up, to get the car motivating w/o pressing the gas pedal in so much.

This is also a big factor when going for maximum mileage.

Think of a BMW with an MPG guage, the more you press the pedal in, the less mileage the car will return.

 

[Defiant]

Think of a BMW with an MPG gauge, the more you press the pedal in, the less mileage the car will return.

That's only an update on the old vacuum gauges marked for mileage. Now, on a turbo engine, at what point is the vacuum/boost best optimized for efficiency? How much load does the exhaust turbine put on the engine through exhaust restriction?

 

[SpoOLxExO]

One would think at no boost at all would yield the best result.

Since the FPR goes 1:1 in boost, this would mechanically add more fuel when its not really desired.

The BMW analogy was only an illustration for pedal effort required for maximum mileage.

And because of the turbo, exhaust scavenging in the engine is more efficient. Thus when going up a hill requires not nearly as much pedal effort as an N/A car.

So if you never boost, keep the pedal mashing to a minimum, and have a "MPG tune" under no boost, its possible to get into the 30's.

Now, the Honda mileage takes credit from its ridiculously efficient cylinder head design.

Its because of this why stock 4g63's can't make those (40+MPG) numbers happen

 

[terminaltsi]

i found 36mpg on the freeway on a300 mile trip in my old 92 fwd. i had pte 50 trim, 272 cams, 650 injectors, etc. and a good tune. cruising at 75 mph. the cams and the larger turbo help becuase the cams increase efficiency and the turbo keeps you from hitting boost as quickly, thereby keeping fuel consumption down.
oh yeah, just remembered my old 92 6/4 AWD with teh same cams but a b16g returned 30 mpg.
makes me think the cams really help in more ways than one.

 

[hubz91talontsi]

Ok so my fuel mileage sucks, so i want to do this. Where can i find taller 5th gears i can not locate them. Thanks

 

[DBordersX]

TRE

I think this is the site but I can't get it to load right now.

It's 10% taller if I remember correctly.

www.teamrip.com/GENUINE_FACTORY_AWD_PARTS.html

 

[JWoodley]

28-31mpg @ 75 mph for me. I highly recommend Jon @ TRE.

 

[FORMONTOYA]

You can get a taller 5th gear from just about any reputable DSM tranny shop (TRE, Shep, etc.).

But really the only true way to get better gas mileage is to be lighter with the right foot.

But then again, that's not why you purchased a turbo (AWD)...is it?

 

[hubz91talontsi]

Yeah but when i say bad its like 16, maybe 20 on a good day.. nah its never 20