the 4.30 rear end with a w-58 runs at 3,500rpm @ 70mph and the 3.73 runs 2,700rpm @ 70mph.... is there Anyone Else out there who went from the 4.30 to a 3.73 and gained gas milage?
4.30 vs. 3.73 Gas Milage?
- Thread starter chris89
- Start date
Well, RPM from the crank position sensor is one of the primary inputs for injection duration. However, it isn't the only one. And driving habbits will sink your mileage as fast as anything.
3.73 might be too tall for the car. It weighs 3500 lbs, and has 180 CID pushing it. If you plan on a turbo later, that is different.
When I changed from 3.08 to 3.73, I gained 2 mpg average on my tank. Highway trips suffered of course, but around town went up. The engine wasn't as loaded as much to get the same acceleration.
3.73 might be too tall for the car. It weighs 3500 lbs, and has 180 CID pushing it. If you plan on a turbo later, that is different.
When I changed from 3.08 to 3.73, I gained 2 mpg average on my tank. Highway trips suffered of course, but around town went up. The engine wasn't as loaded as much to get the same acceleration.
It shouldn't suffer gas milage, it should help gas milage, Again this is on a Non-Turbo supra. But it will suffer acceleration.
With the 4.30 you'll get better gas mileage around town, but you'll get worse gas mileage on the freeway.
With the 3.73 you'll have worse gas mileage around town, but you'll get better gas mileage on the freeway. Not recommended for NA, you'll lose acceleration. 3.73 is best for people with big turbos/short powerbands that need longer gearing.
If you REALLY want to get rid of the 4.30, go with the 3.91 (Pre89 Turbo). The step down won't be as drastic and noticeable as the 3.73, and your RPMs on the freeway will be lower.
With the 3.73 you'll have worse gas mileage around town, but you'll get better gas mileage on the freeway. Not recommended for NA, you'll lose acceleration. 3.73 is best for people with big turbos/short powerbands that need longer gearing.
If you REALLY want to get rid of the 4.30, go with the 3.91 (Pre89 Turbo). The step down won't be as drastic and noticeable as the 3.73, and your RPMs on the freeway will be lower.
Fuzz420
Are U Here 2 take My Baby
I really don't care so much, i just want better gas milage, But the 3.73 should still be better in town as long ur off the gas since you'll constantly be at lower rpm than if u had a 4.30... I guess it is a pretty drastic jump, I wonder if someone has a video of they're supra with 3.73s... a gauge shot of WOT. Another thing is i hate having to shift all the time around town, I'de like to go faster in each gear so i don't have to shift so much, Plus it'll cruise better with the 3.73... since with the 4.30 i'm always in the powerband, 3.73 will give me less power so i should get better mpg.
Want better mileage, throw in a MAFT Pro and run a lean cruise and idle.
Swapping out the diff only makes an appreciable difference if at least half your driving is highway. I did see an improvement in my mileage when I swapped in a 3.91, but I think once I get my LC-1 installed with PT tracking running I'll see the biggest gains.
Swapping out the diff only makes an appreciable difference if at least half your driving is highway. I did see an improvement in my mileage when I swapped in a 3.91, but I think once I get my LC-1 installed with PT tracking running I'll see the biggest gains.
Nick M said:
Probably, it also takes longer at a specific elevated throttle position to reach a given speed on both highway and city street. My driving is at least half highway and my mileage did improve. Should get a bit better once I get my LC-1 installed and setup PTT.
I wish i could keep the 4.30 but have my 5th gear Widened so i get low rpm at Highway speeds, But have less load on the engine around town for best possible mpg.
chris89 said:
One of these days I'm going to try to get a hold of the folks at Marlin Crawler and see if they can accomplish that with either a W58 or a R154. I suspect that if anyone has enough experience with Toyota transmissions it's them.
chris89 said:
Ninja Edit or what? lol. I'm going to be switching to Speed/Density soon... either when I install my LC-1 or shortly after.
CRE said:
I noticed virtually no difference (on my turbo car) between a 4.30 and a 3.73, highway or city mileage.
CRE said:
LOL, yeah. haha. I just hate how the afm is so restrictive, I wouldn't mind spending $300-$400 On switching mine over to where i can use the ls1 afm 3". I could gain a little power and gas milage, right? What r u using now? Would MAP sensor ever be possible on the 7m-ge? that would be awesome!
chris89 said:
A MAP sensor is part of the hardware needed to run Speed Density. I'll be switching over to Speed Density in the next couple weeks. I've posted the wiring diagrams in my writeup. You won't notice any improvement in your gas mileage unless you install a wideband to take advantage of Part Throttle Tracking and tune your WOT AFR.
It'll cost more than $400. The MAFT Pro itself is $399. Then add the LC-1 for $200, MAP sensor for $70 and IAT for $12. Harness will be a little more, about $25, unless you make your own in which case it could cost a little more or less.
Back to the whole mileage gain thing, the difference really only comes in with highway driving. Even with the MAFT Pro and a lean idle and cruise set up you're only going to see a real difference when your driving at a consistent level for an extended period of time.
Well i'm very happy with my supra now that i have a good working afm, and so far i'm noticing about 20mpg City, which is amazing since my driving habits have not been good, I might be able to get more if i drive right. I really want long gears, i'm so sick of my Short gears.
Then you want longer gears. The 3.91 will be best for your NA. A local owner I know also recently changed out his 4.30 cuz he hated shifting so much through town.
We don't need to make 5th longer, we need a 6th gear. I love my 4.30 gearing I just wish I had a 6th gear for freeway, plus then my top speed would be like 200 :icon_razz
We don't need to make 5th longer, we need a 6th gear. I love my 4.30 gearing I just wish I had a 6th gear for freeway, plus then my top speed would be like 200 :icon_razz
AGlobalThreat said:
It doesn't work like that. 6th gear does not have to mean lower RPM freeway speed.
R154
Ratios:
First Gear: 3.250:1
Second Gear: 1.955:1
Third Gear: 1.310:1
Fourth Gear: 1.00:1
Fifth Gear: 0.753:1
V160
Ratios:
First Gear: 3.830:1
Second Gear: 2.360:1
Third Gear: 1.680:1
Fourth Gear: 1.310:1
Fifth Gear: 1:1
Sixth Gear: 0.790:1
Unless you want a double overdrive like a Z06.
Double overdrive, now that would be something.
Also explains why I see all Z06s like idling down the road at 50+MPH, LOL.
Also explains why I see all Z06s like idling down the road at 50+MPH, LOL.