MPG questions for higher efficiency
08-15-15, 09:50 PM
#1
Driver
Thread Starter
MPG questions for higher efficiency
Is it possible to have a z30 with a 2jzge gain MPG by placing a 3.27 or 3.76 ar in the differential?
Im not sure if this is the best way to gain MPG but I think Toyota 0w20 won't be bad on a non turbo motor.
Also dropping the chrome 16s for some alloy 16- 17s may help as well as nitrogen filled tires. Aside from doing the proper minor tune up things and running Denso Twin Tip SparkPlugs.. i have not thought of much else.
Truly I do not mind going slower if the MPG increases
. Im trying to get about 20+ in the city. Pitch me ideas fellas. Ive been kicking the idea of a A650e around some.
Im not sure if this is the best way to gain MPG but I think Toyota 0w20 won't be bad on a non turbo motor.
Also dropping the chrome 16s for some alloy 16- 17s may help as well as nitrogen filled tires. Aside from doing the proper minor tune up things and running Denso Twin Tip SparkPlugs.. i have not thought of much else.
Truly I do not mind going slower if the MPG increases
. Im trying to get about 20+ in the city. Pitch me ideas fellas. Ive been kicking the idea of a A650e around some.
08-17-15, 03:21 PM
#3
No, do not go outside of the stated oil weights outlined in the Toyota/Lexus owner's manual. Unless you have gone to the trouble and expense of having a 2JZ turbo engine custom built and the BUILDER specifically recommends different oil weights from stock... do not change to an oil weight not specified in the TSRM/manual. One of the hallmarks of the 1JZ and 2JZ's longevity is the oiling system. That's one of the big reasons they last so long.
Change the wheels all you want. Use nitrogen all you want. Though I think 17" rims and LS400 front brakes are a far better tradeoff than a smidgen better fuel economy. Also, I would NOT recommend any "low rolling resistance" tire in an SC since they already need all the traction they can get.
Finally, you could use a 3.916, 3.769 TT Auto ratio or 3.266 GS ratio with your non-turbo engine... but you'd quickly tire of the lack of ability to keep up with normal traffic as your tradeoff. This is coming from someone who gave up perhaps 1mpg at most on the highway going from 4.083 to 4.272. And I have a spare 3.769 ratio waiting to be installed when I swap my engine but right now without a turbo it would not be very beneficial.
To have a smidgen better highway economy and not be a dog to drive you'd need to combine a lower ratio with a turbo engine build or GTE engine swap. You'd probably have your best luck with city fuel economy by using a 1JZ-GTE VVT-i engine (you'd go from non-turbo 3.0L to a 2.5L turbo with low end torque) and for the most part driving it moderately. The engine will not have to work as hard to get up to speed with the VVT-i.
There is also the JDM only (and automatic trans only) 2JZ-FSE non-turbo direct injection engine. Same power output as our USDM 2JZ-GE's. To my knowledge, no one has bothered to swap one of those into an SC let alone tried to tackle the ECU and harness pinouts but that was Toyota's last big R&D effort to improving the fuel economy of the JZ series. They were originally only available in select Toyota sedans and wagons. For the expense of buying one, figuring out the wiring and getting it all in, plus sourcing some ignition and fuel parts from Japan when services are due, you'd be better off with another car or a turbo build for your SC.
Also, the A650E requires a specific engine ECU to control it. For a JZ engine application you'd need a USDM 2JZ-GE VVT-i engine and the ECU from either a 1998-2005 GS300 or 2001-2005 IS300 Automatic.
Really, for the trouble involved I wouldn't recommend going down this road if you are not planning to turbocharge your car. It will be a lot of effort for very little gain in fuel economy.
Change the wheels all you want. Use nitrogen all you want. Though I think 17" rims and LS400 front brakes are a far better tradeoff than a smidgen better fuel economy. Also, I would NOT recommend any "low rolling resistance" tire in an SC since they already need all the traction they can get.
Finally, you could use a 3.916, 3.769 TT Auto ratio or 3.266 GS ratio with your non-turbo engine... but you'd quickly tire of the lack of ability to keep up with normal traffic as your tradeoff. This is coming from someone who gave up perhaps 1mpg at most on the highway going from 4.083 to 4.272. And I have a spare 3.769 ratio waiting to be installed when I swap my engine but right now without a turbo it would not be very beneficial.
To have a smidgen better highway economy and not be a dog to drive you'd need to combine a lower ratio with a turbo engine build or GTE engine swap. You'd probably have your best luck with city fuel economy by using a 1JZ-GTE VVT-i engine (you'd go from non-turbo 3.0L to a 2.5L turbo with low end torque) and for the most part driving it moderately. The engine will not have to work as hard to get up to speed with the VVT-i.
There is also the JDM only (and automatic trans only) 2JZ-FSE non-turbo direct injection engine. Same power output as our USDM 2JZ-GE's. To my knowledge, no one has bothered to swap one of those into an SC let alone tried to tackle the ECU and harness pinouts but that was Toyota's last big R&D effort to improving the fuel economy of the JZ series. They were originally only available in select Toyota sedans and wagons. For the expense of buying one, figuring out the wiring and getting it all in, plus sourcing some ignition and fuel parts from Japan when services are due, you'd be better off with another car or a turbo build for your SC.
Also, the A650E requires a specific engine ECU to control it. For a JZ engine application you'd need a USDM 2JZ-GE VVT-i engine and the ECU from either a 1998-2005 GS300 or 2001-2005 IS300 Automatic.
Really, for the trouble involved I wouldn't recommend going down this road if you are not planning to turbocharge your car. It will be a lot of effort for very little gain in fuel economy.
Last edited by KahnBB6; 08-17-15 at 03:26 PM.
08-20-15, 04:32 AM
#4
A 3.26 is actually quite a bit better on gas over the factory 4.08 I had. I picked up in the 2-3mpg range despite the larger turbo. You basically will need a downshift every single time you want to pass or even speed up a bit which will get annoying in a manual. Without boost I think it would be unbearably slow. Automatic may be slightly easier to live wifh but there's less ratios for the box to choose from so I expect it would be constantly hunting for the right gear.
As an additional thought, manuals usually will give better mileage over automatics assuming similar gearing.
As an additional thought, manuals usually will give better mileage over automatics assuming similar gearing.
10-07-15, 01:32 PM
#6
If you don't care about creature comforts, shedding weight can help with city MPG. It won't do much for highway, but less weight to accelerate = less gas consumed to do it. Stuff like pulling the back seats, switching the front seats for non-power seats, pull trunk carpets, pull cabin carpets... there's quite the rabbit hole to go down, but it's not a particularly comfortable nor quiet hole.
10-07-15, 01:39 PM
#7
Driver
Thread Starter
If you don't care about creature comforts, shedding weight can help with city MPG. It won't do much for highway, but less weight to accelerate = less gas consumed to do it. Stuff like pulling the back seats, switching the front seats for non-power seats, pull trunk carpets, pull cabin carpets... there's quite the rabbit hole to go down, but it's not a particularly comfortable nor quiet hole.
"Oh you already had the back seats pulled out ? Lemme pull the **** out of this panel to see if you are hiding martians in your car"
I removed the CD changer that thing is a POS it stayed on after the key was pulled out.
Most I'd do at the moment is remove that dorky motorized antenna.
I would like some seats but it does not seem feasible to purchase a RHD and LHD non motorized seat for cheap. Any who I'll see how it goes with the 0W-20
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10-07-15, 02:24 PM
#8
Well, SC's aren't made for fuel efficiency. Just look at the final drive on an SC400. A car with a V8 and a drag coefficient of .31 running 2500+ RPM at 70mph? These were not designed with fuel efficiency in mind.
That said, playing with oil weights can cause their own issues. Once it gets too thin it'll probably still lubricate OK, but you can easily start to lose oil through seals. Which means either burning oil or leaking oil. Leaking is just messy aside from the whole being low on oil aspect. Burning oil can mess up the catalytic converter and give blue smoke on acceleration (or all the time if it's burning a lot.)
I would imagine that your best bets are the rear end ratio. Your first gear acceleration will suffer, but once you're in to second and above, while the shift points will change, you can always shift down when needed to regain the shorter gearing for acceleration. It won't be quite as snappy on the freeway and might shift down more often, as long as it can hold your speed on a moderate hill, you should get better mileage overall unless you're compensating for the lack of acceleration with judicious throttle and shifting action.
In general any time you can get the engine to turn a bit slower as long as you still have enough torque to keep you going you should be getting better mileage (within reason.) Many of our SC's run fairly high RPMs on the freeway, I know I wish my 5th gear (98 SC400) was a bit taller. I've been toying with the idea of swapping out the rear end.
That said, playing with oil weights can cause their own issues. Once it gets too thin it'll probably still lubricate OK, but you can easily start to lose oil through seals. Which means either burning oil or leaking oil. Leaking is just messy aside from the whole being low on oil aspect. Burning oil can mess up the catalytic converter and give blue smoke on acceleration (or all the time if it's burning a lot.)
I would imagine that your best bets are the rear end ratio. Your first gear acceleration will suffer, but once you're in to second and above, while the shift points will change, you can always shift down when needed to regain the shorter gearing for acceleration. It won't be quite as snappy on the freeway and might shift down more often, as long as it can hold your speed on a moderate hill, you should get better mileage overall unless you're compensating for the lack of acceleration with judicious throttle and shifting action.
In general any time you can get the engine to turn a bit slower as long as you still have enough torque to keep you going you should be getting better mileage (within reason.) Many of our SC's run fairly high RPMs on the freeway, I know I wish my 5th gear (98 SC400) was a bit taller. I've been toying with the idea of swapping out the rear end.
10-07-15, 05:24 PM
#9
Driver
Thread Starter
Well, SC's aren't made for fuel efficiency. Just look at the final drive on an SC400. A car with a V8 and a drag coefficient of .31 running 2500+ RPM at 70mph? These were not designed with fuel efficiency in mind.
That said, playing with oil weights can cause their own issues. Once it gets too thin it'll probably still lubricate OK, but you can easily start to lose oil through seals. Which means either burning oil or leaking oil. Leaking is just messy aside from the whole being low on oil aspect. Burning oil can mess up the catalytic converter and give blue smoke on acceleration (or all the time if it's burning a lot.)
I would imagine that your best bets are the rear end ratio. Your first gear acceleration will suffer, but once you're in to second and above, while the shift points will change, you can always shift down when needed to regain the shorter gearing for acceleration. It won't be quite as snappy on the freeway and might shift down more often, as long as it can hold your speed on a moderate hill, you should get better mileage overall unless you're compensating for the lack of acceleration with judicious throttle and shifting action.
In general any time you can get the engine to turn a bit slower as long as you still have enough torque to keep you going you should be getting better mileage (within reason.) Many of our SC's run fairly high RPMs on the freeway, I know I wish my 5th gear (98 SC400) was a bit taller. I've been toying with the idea of swapping out the rear end.
That said, playing with oil weights can cause their own issues. Once it gets too thin it'll probably still lubricate OK, but you can easily start to lose oil through seals. Which means either burning oil or leaking oil. Leaking is just messy aside from the whole being low on oil aspect. Burning oil can mess up the catalytic converter and give blue smoke on acceleration (or all the time if it's burning a lot.)
I would imagine that your best bets are the rear end ratio. Your first gear acceleration will suffer, but once you're in to second and above, while the shift points will change, you can always shift down when needed to regain the shorter gearing for acceleration. It won't be quite as snappy on the freeway and might shift down more often, as long as it can hold your speed on a moderate hill, you should get better mileage overall unless you're compensating for the lack of acceleration with judicious throttle and shifting action.
In general any time you can get the engine to turn a bit slower as long as you still have enough torque to keep you going you should be getting better mileage (within reason.) Many of our SC's run fairly high RPMs on the freeway, I know I wish my 5th gear (98 SC400) was a bit taller. I've been toying with the idea of swapping out the rear end.
I figure every little bit helps. Im going to switch to 0w20 BUT it is for the winter and I do not race the motor so the oil wont be exposed to prolonged temperatures out of its efficiency.
I have seen few members here running 0W20 and on youtube however non have complained.?!
I also own an automatic so I think Ill have to deal with it really since swapping out to a lower gear is very involved I'd rather install a LSD for that much effort.
Thanks for your replies man!
10-07-15, 08:32 PM
#10
LEXOWINO, I'm going to reiterate again that it's not recommended that you use 0W20 oil or anything other than the 10W30 or 5W30 stated in the owner's manual. Some owners on youtube demonstrating that they've made it work doesn't say much. For how many miles has it worked for them? Have they sent in oil samples during changes to a lab to get analyzed so that they can prove they aren't causing unnecessary long term wear by veering from Toyota's recommended ranges?
I know you're looking for more efficiency but using the wrong oil weight/viscosity isn't the way to do it. matguy is right: SC's were designed in 1990 as luxury sport coupes when premium gas was barely $1/gallon. Their fuel economy for the time wasn't too bad. These days it's merely average to lousy. Consider the kind of car you're driving. Great fuel economy was never a design feature.
Swapping your SC400's 3.92 rear end for a GS 3.26 rear is the most drastic way to make a difference at the consequence of sluggish performance. Or if you have an SC300 automatic you can swap the factory 4.27 rear for an SC400's 3.92.
Contrary to what I said before about tires, if you are only rolling on a fully stock/OEM spec suspension on stock wheels then maybe give a more efficient tire design a try. Before I said that SC's need all the traction they can get and that's still the truth but most of us have a modified suspension that makes sticky tires with a good rain tread design prerequisite.
The most drastic modification an SC owner could do with an SC is to keep the suspension fairly stock with factory narrow tires, open diff, modern "efficient" tires that aren't that great for sport driving or pushing the car, a 3.92 SC400 diff swap and a JDM 2JZ-FSE Automatic engine swap with a custom engine harness. Then you might see a pretty significant jump from our stock fuel economy numbers. No one has done that because it would be exactly the same performance as with any other stock SC300 Automatic but at the cost of a 1JZ-GTE engine swap.
I know you're looking for more efficiency but using the wrong oil weight/viscosity isn't the way to do it. matguy is right: SC's were designed in 1990 as luxury sport coupes when premium gas was barely $1/gallon. Their fuel economy for the time wasn't too bad. These days it's merely average to lousy. Consider the kind of car you're driving. Great fuel economy was never a design feature.
Swapping your SC400's 3.92 rear end for a GS 3.26 rear is the most drastic way to make a difference at the consequence of sluggish performance. Or if you have an SC300 automatic you can swap the factory 4.27 rear for an SC400's 3.92.
Contrary to what I said before about tires, if you are only rolling on a fully stock/OEM spec suspension on stock wheels then maybe give a more efficient tire design a try. Before I said that SC's need all the traction they can get and that's still the truth but most of us have a modified suspension that makes sticky tires with a good rain tread design prerequisite.
The most drastic modification an SC owner could do with an SC is to keep the suspension fairly stock with factory narrow tires, open diff, modern "efficient" tires that aren't that great for sport driving or pushing the car, a 3.92 SC400 diff swap and a JDM 2JZ-FSE Automatic engine swap with a custom engine harness. Then you might see a pretty significant jump from our stock fuel economy numbers. No one has done that because it would be exactly the same performance as with any other stock SC300 Automatic but at the cost of a 1JZ-GTE engine swap.
Last edited by KahnBB6; 10-07-15 at 09:30 PM.
10-08-15, 12:25 PM
#12
^^ That sounds right for a V8. Anyone know if the 98-00 SC400's rev any lower @ 70mph?
On mine (4.272 ratio) it's right at 3,000rpm @ 70mph... 3,500rpm @ 80mph... 4,000rpm @ 90mph.
With the factory 4.083 ratio it was about 2,800 @ 70mph.
Whenever I switch to the 3.769 TT Auto ratio and 275/40-17 rears it should be at 2,600rpm @ 70mph.
On mine (4.272 ratio) it's right at 3,000rpm @ 70mph... 3,500rpm @ 80mph... 4,000rpm @ 90mph.
With the factory 4.083 ratio it was about 2,800 @ 70mph.
Whenever I switch to the 3.769 TT Auto ratio and 275/40-17 rears it should be at 2,600rpm @ 70mph.
Last edited by KahnBB6; 10-08-15 at 12:33 PM. Reason: Addition/correction
10-08-15, 12:38 PM
#14
matguy, that's odd. The A650E 5-speed automatic in the 98+ SC400's has a 0.753 overdrive fifth. Identical to the overdrive 5th ratio in an R154. With the factory 3.26:1 rear diff it should be lower than 2,800rpm. Maybe it was under partial acceleration in 4th at the time?
Yes, please confirm for us again when you can.
Yes, please confirm for us again when you can.
10-08-15, 01:09 PM
#15
Yeah, I'll have to double check. I remember thinking about taking it on my road trip to Vegas (from Seattle) in Feb and not being too happy with the high RPMs. I did some looking around to double check my memory before posting that and it seemed others were seeing similar. It's highly possible I'm over-remembering the number based on other (possibly inaccurate) accounts I was seeing recently.
Damn, now I want to get it back together so I can double check (well, and drive it in general.)
Damn, now I want to get it back together so I can double check (well, and drive it in general.)