toyota cressida turbo aiming for 30+mpg

[mx73]

i have a turbo 86 toyota cressida. right now getting 18.5 highway. driving easy. have fried differential bearings. very bad!.
im hoping to get beyond 30, while having 400hp available.
i have a programmable ecu so it should be easy

[Sven7]

Welcome! Cressida's are not the most common thing nowadays. If you look up top for the hypermiling tips and efficiency mods you will find many ways to increase mileage. 30mpg will be tough but it's possible. Good luck!

[mx73]

ya its not such a heavy car. so i should beable. my friends stock got 27 on highway. epa rates its 22. but its not true.

18.5mpg is my best while driving slow, mostly highway. but i know i have a bad differential, in the middle of rebuilding it. pinion bearing is making tons of noise. fluid is actually boiling and frothing out of the top vent.

[cleanspeed1]

I had one of those! Same year!

People who have bought the rear mount STS turbo systems for Vettes and other V8 musclecars are experiencing mpg increases after the install and remapping of the efi system, so doing the Cressida should not be that much of a stretch. You did not say if you had an auto or a 5 speed in the car, but either way I believe 30 mpg is attainable.
I have been out of the import scene for a minute, so locally I don't know who is a reputable tuner with a proper chassis dyno. I do know this though; get yourself a J&S Safeguard knock controller and optimize the ignition timing. This thing will allow you to run a more aggressive timing curve for best power and mpg without rattling the old girl; you know those old 5M and 7M engines love to push the head gasket. Add water/meth injection as another level of safety.
I recently saw a Cressida done old school style: lowered, either Enkei or BBS rims, JDM location side view mirrors. Beautiful machine.

[mx73]

Originally Posted by cleanspeed1

I had one of those! Same year!

People who have bought the rear mount STS turbo systems for Vettes and other V8 musclecars are experiencing mpg increases after the install and remapping of the efi system, so doing the Cressida should not be that much of a stretch. You did not say if you had an auto or a 5 speed in the car, but either way I believe 30 mpg is attainable.
I have been out of the import scene for a minute, so locally I don't know who is a reputable tuner with a proper chassis dyno. I do know this though; get yourself a J&S Safeguard knock controller and optimize the ignition timing. This thing will allow you to run a more aggressive timing curve for best power and mpg without rattling the old girl; you know those old 5M and 7M engines love to push the head gasket. Add water/meth injection as another level of safety.
I recently saw a Cressida done old school style: lowered, either Enkei or BBS rims, JDM location side view mirrors. Beautiful machine.

its a factory 5 speed.

[cleanspeed1]

That's hot bro! Murdered out and stock ride height. Looks good! Did you do a Supra Turbo swap or did you just add a turbo to the existing engine?

If it were mine, and I do like to spend other people's money, I'd work on the tune and gearing in the beginning to slow the engine down at cruise speed. It's the off boost performance that you have to focus on, and a lot of times the timing curve is the deciding factor, and that is why I suggested the J&S Safeguard. The unit has been around for a long time, the technology has been proven. After that, some high torque camshafts that broaden the powerband and boost the torque where you drive it most of the time. I am not talking about something as extreme as truck cams, since you probably like to get on that thing and let it run, but someting that will have the current advances in cam technology. After all we're talking a 20 plus year old combination.
My Cressida was a silver automatic that a friend gave to me, and it had the typical top end problems. Went through oil like a sift. My thought at the time was to do a 7M turbo out of a later Supra and lower it, but except for the exhaust, look stone stock. This was before we had to deal with what we are dealing with now.
Just thought about this: adjustable cam pullies. Do some loops adjusting the intake and exhaust cam phasing to see how she'll respond. It's tedious, but it can yield results and if you go to the upgraded camshafts you'll be ahead of the game.

[mx73]

Originally Posted by cleanspeed1

That's hot bro! Murdered out and stock ride height. Looks good! Did you do a Supra Turbo swap or did you just add a turbo to the existing engine?

If it were mine, and I do like to spend other people's money, I'd work on the tune and gearing in the beginning to slow the engine down at cruise speed. It's the off boost performance that you have to focus on, and a lot of times the timing curve is the deciding factor, and that is why I suggested the J&S Safeguard. The unit has been around for a long time, the technology has been proven. After that, some high torque camshafts that broaden the powerband and boost the torque where you drive it most of the time. I am not talking about something as extreme as truck cams, since you probably like to get on that thing and let it run, but someting that will have the current advances in cam technology. After all we're talking a 20 plus year old combination.
My Cressida was a silver automatic that a friend gave to me, and it had the typical top end problems. Went through oil like a sift. My thought at the time was to do a 7M turbo out of a later Supra and lower it, but except for the exhaust, look stone stock. This was before we had to deal with what we are dealing with now.
Just thought about this: adjustable cam pullies. Do some loops adjusting the intake and exhaust cam phasing to see how she'll respond. It's tedious, but it can yield results and if you go to the upgraded camshafts you'll be ahead of the game.

it's a upgraded supra turbo. i rebuild the engine from the bottom up so no leaks no worries. alot of custom work. new computer/engine harness..

issues im having are the rear bearings. currently rebuilding my differential, i have 3.73 gears. its the highest gearing they came with. i used to get 23mpg, my friends got 27hwy stock. i think my blown diff has been losing 10mpg, plus my rear wheel bearings are probly shot too. , im going to cover the entire undercarrage in abs plastic. or alum/fiber plating. it needs to be aerodynamic on the bottom for fuel and racing. 160 on the track. \

right now i dont even have a under engine tray, probly losing fuel there lol.

i have the ecu tuned pretty good.im running pretty lean afr's too, i've tuned every aspect of the engine with my laptop. its over 300hp on 7-8psi, when off boost the ecu changes timing to save fuel. its map sensor based., my compression is a little lower than stock too. 8.5:1 vs 9.2 stock.

[cleanspeed1]

I read some of the overseas mags and one of the best tuners out there is the guy that put the Emerald standalone computer together. One of the things that he was saying is that a lot of times when folks are mapping ignition curves, they don't add enough timing during cruise conditions and that can affect the mpg quite a bit and dulls the throttle response. You might be leaving a lot of power and mpg on the table and not even know it. Might be high time to get that thing on a chassis dyno and see where the old girl is at. By the way, you have a wideband O2 sensor on her don't you?

Big props on your Cressy. Brought back some fond memories. What differential do you have in it?

[mx73]

Originally Posted by cleanspeed1

I read some of the overseas mags and one of the best tuners out there is the guy that put the Emerald standalone computer together. One of the things that he was saying is that a lot of times when folks are mapping ignition curves, they don't add enough timing during cruise conditions and that can affect the mpg quite a bit and dulls the throttle response. You might be leaving a lot of power and mpg on the table and not even know it. Might be high time to get that thing on a chassis dyno and see where the old girl is at. By the way, you have a wideband O2 sensor on her don't you?

ya wideband. its a full standalone computer, usb port. every sensor is new.only 80s technology is the frame/mechanical part of the motor. converted to distributorless ignition. 100% modern technology, on a 80s engine. it's pretty quick. i datalogged everything.. it's easily a high 12sec car right now. on the lowest boost setting ;-), since ur in chicago maybe u'll get a ride one day.

[cleanspeed1]

I'd like that. What side are you on ( northside, south, suburbs )? Staying in the city right now. Those old school twin cam 6s are no joke. Maybe an E85 tune and a ton of boost?
You won't have a driveline left in that car!

Time for a Ford 9" or an 8.8" Thunderbird/MN12 centersection so it can free up the gear choices.

Nothing like having 1000hp capability at the end of a keystroke