Can I get Better MPG from A supra Trans

[sc40v8]

Question Swapping to supra trans can i get better MPG with a 5 speed instead of a 4 ?
I have a 1993 SC400 and my trans is shifting hard when going from Park to Drive. The trans shifts perfect in all other gears.I was told to not change the trans fluid because it could cause the trans to start to slip, is this true, or is there something else i can do to make the trans not shift hard when going into drive. When i purchased the car the previous owner had bought a Toyota Supra trans and had not got around to installing it. So i have this trans problem my questions are can i do a trans flush and change the filter to solve my problems or i also was told to install a shift kit to make it shift in to drive the normal way.

Another Question i have is if i install the supra trans in my car will it improve my MPG since i will another gear to cruise in, cause at 80mph im almost at 3000 RPM and cruising at that RPM is killing my mpg on the highway since i travel to work about 30 miles a day. If i install the trans would i need any other parts to make it fit smoothly?

Let me no what u guy's think please right back other forums i have posted this on haven't replied back for about 3 weeks and i think this is a very good question to ask about gaining MPG from this SWAP.

thanks Jeremy

 

[Lextreme II]

You might be better gas mileage if you swap out with the 1998-2000 sc400 or gs400 tranny along with diff.

 

[sc40v8]

yah i think so doesnt the 1998 sc 400 have a 5 Speed auto instead of a 4 speed ?

 

[Lextreme II]

Yes and the diff ratio is gas friendlier..

 

[spf_lexus]

Hey david, do you know the final drive for the 1st gen SC versus 1998 SC?


I have been thinking about the same thing for my swap. I would rather have a slightly higher final drive and the extra top gear with the 98+ auto.

 

[Lextreme II]

I dont have the number in my aging mind but it is a friendly ratio for gas.

 

[stevechumo]

Question Swapping to supra trans can i get better MPG with a 5 speed instead of a 4 ?
I have a 1993 SC400 and my trans is shifting hard when going from Park to Drive. The trans shifts perfect in all other gears.I was told to not change the trans fluid because it could cause the trans to start to slip, is this true, or is there something else i can do to make the trans not shift hard when going into drive. When i purchased the car the previous owner had bought a Toyota Supra trans and had not got around to installing it. So i have this trans problem my questions are can i do a trans flush and change the filter to solve my problems or i also was told to install a shift kit to make it shift in to drive the normal way.

Another Question i have is if i install the supra trans in my car will it improve my MPG since i will another gear to cruise in, cause at 80mph im almost at 3000 RPM and cruising at that RPM is killing my mpg on the highway since i travel to work about 30 miles a day. If i install the trans would i need any other parts to make it fit smoothly?

Let me no what u guy's think please right back other forums i have posted this on haven't replied back for about 3 weeks and i think this is a very good question to ask about gaining MPG from this SWAP.

thanks Jeremy

Most of the time when you flush your old tranny fluid, the tranny will shift better. I never saw it slips after that. The only time that it slips is when the wrong ATF is used. The old tranny fluid with ground metal that's stuck in the torque converter can kill the tranny. Also, try to adjust the tranny cable and the throttle cable. Loosen them up a little bit, so they can shift smoother.

Major tuning the car will effectively increase the MPG. A 5 speed manual tranny will save you gas, but thinking about the cost and time that'll be involved, that'll be years of saving gas. I believe Supra auto tranny is also 4 speed.

 

[Thermactor]

Think about it this way,
you will gain 1mpg at best from the 5spd trans,
you will NEVER, in a dozen lifetimes, get the money back from gas savings,
your fuel economy can be improved by swapping in a same-year LS400 auto trans OR adjusting your driving patterns.

 

[sideshow]

1uzs are not really very economical engines compared to others these days

if u went to a manual 5 speed u will prob gain abit mroe fuel economy
thats if u originally had a 4 speed auto
well its not really a 4 speed
its a 3 speed with overdrive

anyway another prob is yr enigne ecu will not drive the 5 speed auto
u would have to buy an aftermarket auto ecu
so basically whole job might cost u 3 to 5 g if u get no problems

i would go to a 5 speed manual box
it would make the car go fatser too and also be bit better on fuel
we had 2 hiluxes pretty much the same with 1uzs
one was manual one was auto
manual one got 30 to 50 kms extra per tank on city driving

 

[spf_lexus]

Try tightening your kickdown cable a couple turns. City driving will improve 1 or 2 mpg. It keeps your trans put in the high gear, requiring a larger % of throttle input to drop gears.

My dads supercharged Tacoma used to get 15MPG city and once tightened down it raised to around 17mpg. With the tq from the blower or 1uz, the trans does not need to drop gears every time 50% throttle was present.

After 2 or 3 turns, any more will cause the trans to "slam" into drive/reverse.