3.15 R200 LSD with 2JZ-GTE and 5spd R154?

[ShaggyZ]

I posted this in "Drivetrain" a few days ago with no response and decided I'd probably get better results here.

 

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I recently acquired a 3.15 LSD R200 from slow_old car for more money than I should have spent on anything extra I knew I wanted to go lower than the 3.7 LSD, which I bought for $500 with CV's a few months ago BEFORE finally settling on the 2JZ over the L28ET or 4G63 of the GS-T Eclipse.

 

AFTER agreeing to buy it, I finally did research on what a 3.15 final drive ratio will do to my overall gearing and speeds. Aerodynamics, tire stretching, and skidding aside (ha!), at 7k RPM I could hit 208MPH. Of course, I'd have to be making at least 800HP, no doubt; but that's not up to discussion right now as there are so many factors involved there.

 

I really just want to get your thoughts on: how "livable" and streetable will it be, including traffic?; is the gap between gears going to be too great to keep me in the powerband?; will this be sucky for 1/4 mile racing? will this suck for possible road racing I may do in the future?; anything else I need to consider. I fully intend to drive this thing fairly regularly, which is one HUGE reason I went for the 2JZ over L28 - reliability at those power levels.

 

I've just seen too many Z's with too little (read "short") gear through 1st and 2nd, making them completely useless - 1st doesn't even get a chance to load up the engine and turbo. Obviously, a good, sticky, wide tire (at least 245mm) will be in order and the LSD is going to be helpful.

 

Notice that the R154 gearing with reasonable height tires (245/40/17) and the 3.15 rear end is fairly close to the stock Supra setup with its 6spd and taller (stock) tires and similarly geared rear; however, that is spread across 6 gears instead of the 5 of the R154. Also, the Supra weighs in at a minimum 500lbs more than my 280Z (assuming a ~2600lb weight) and I've heard upwards of ~3400lbs for stock twin turbo, 6spd Supras, which makes it ~800lbs difference.

 

I plan on sticking with stock twins for now and will shoot for low 400HP at the wheels minimum and possibly aiming for low 500's eventually. I'll likely upgrade to a T61 or the much-loved-as-a-street-turbo T67 before long.

 

Pay particular attention to the gap between shifts (assuming 7k RPM redline). Lets also assume that the 2JZ can make just over 200HP by 2500RPM and hits 400HP by 5500RPM and the torque isn't far off. I really need to get a dyno graph out - I'm mostly gaging off of dyno vids of Supras, Clifton's powerband, and various other, uh, things.

 

 

3.15 LSD R200 with R154 gearing (if link dies, ratios are decipherable in link)

http://www.car-videos.net/tools/speedrpm.asp?Car=Select&Num1=245&Num2=40&Num3=17&AxleRatio=3.15&Ratio1=3.25&Ratio2=1.955&Ratio3=1.31&Ratio4=1.&Ratio5=0.753&Ratio6=&Ratio7=&Redline=7000&Increment=500&B1=Recalculate

 

Stock MKIV Supra Twin Turbo (specs taken from here: http://mkiv.supras.org.nz/specs.htm)

http://www.car-videos.net/tools/speedrpm.asp?Car=Select&Num1=255&Num2=45&Num3=17&AxleRatio=3.266&Ratio1=3.827&Ratio2=2.36&Ratio3=1.68&Ratio4=1.312&Ratio5=1.1&Ratio6=.79&Ratio7=&Redline=7000&Increment=500&B1=Recalculate

 

 

For reference, here's the speeds for the 3.7 LSD R200 with R154 in the Z.

 

http://www.car-videos.net/tools/speedrpm.asp?Car=Select&Num1=245&Num2=40&Num3=17&AxleRatio=3.7&Ratio1=3.25&Ratio2=1.955&Ratio3=1.31&Ratio4=1.&Ratio5=0.753&Ratio6=&Ratio7=&Redline=7000&Increment=500&B1=Recalculate

[speeder]

The 3.15 with R154 looks good IMO-

 

My IS300 has a 6-speed with 3.13 rear gears and, to me, has the most perfectly spaced gears possible. There's a lot of shifting going on, however.

 

Given the much lighter weight of the Z, You could want some longer ratios in the lower gears of the R154, but I think you will like it.

 

Your turbo motor will love that 3.15.

[ShaggyZ]

The 3.15 with R154 looks good IMO-

 

My IS300 has a 6-speed with 3.13 rear gears and, to me, has the most perfectly spaced gears possible. There's a lot of shifting going on, however.

 

Given the much lighter weight of the Z, You could want some longer ratios in the lower gears of the R154, but I think you will like it.

 

Your turbo motor will love that 3.15.

Thanks for the feedback. I forgot your IS300 is turbocharged - is it a turbocharged GE or GTE?

 

If you get back to this thread, could you tell me what a comfortable cruising speed (with RPM) is for your IS300 in 6th gear?

[speeder]

My car has the Lexus GE with GTE rods and pistons.

 

Cruising at 80 mph is almost 3000 rpm. Very comfortable except for the exhaust drone that will be fixed very soon.

[timbo1jz]

yah,

I am stressing on what rear end and gear ratio that I should run with my 1jz and a r154. I need to decide soon so I can get a driveshaft made ASAP. I have the r180 and their is no way that it will hold up.

[Quin]

Not to bust your chops, especially since I don't know what effects this being in a Z car versus a Supra is, but 3.15 is WAY, WAY too low for an R154, at least in the MkIII (very important) that it came out off. The ratios you're seeing in the neighborhood of 3.20 are from the MkIV that has Getrag V160 six speed, with completely different gear ratios.

 

For reference, MkIIIs with R154s had 3.73s and 3.91s. I think you may end up with an absolute dog here (very good for high speed runs, not very good for getting there)

[ShaggyZ]

Not to bust your chops, especially since I don't know what effects this being in a Z car versus a Supra is, but 3.15 is WAY, WAY too low for an R154, at least in the MkIII (very important) that it came out off. The ratios you're seeing in the neighborhood of 3.20 are from the MkIV that has Getrag V160 six speed, with completely different gear ratios.

 

For reference, MkIIIs with R154s had 3.73s and 3.91s. I think you may end up with an absolute dog here (very good for high speed runs, not very good for getting there)

 

With a 2JZ-GTE and very similar gearing to a 6spd Supra (utilizing the R154 and a 3.15 rear) plus the fact that the 280Z will weigh at least 600lbs less than the Supra (approaching 800-900lbs) and not being able to stick in as wide a tire, I think it will be just fine. First gear will be a little crappy at first, but better than completely roasting the tires, which I suspect will happen.

 

Still, I appreciate the input.

[Quin]

MkIIIs weigh 3500-4000lbs, for reference. I'm not catching what you mean by similar gearing to a 6spd Supra? Quite different, I assure you. The only similar gear is fifth to sixth, IIRC.

 

Also, it's not the width that matters, it's the diameter. Stock Z wheels are what, 15s with recommended sidewall around 50? MkIII Supra wheels are 16x55. Regardless, I'm fairly certain it'll be much too low. Seems like it'd be a complete dog off boost. I'll talk with ARZ (not sure what his name is on here, that's it over on Supramania) and see what he's using.

[RUSSJZ-ZED]

comparisons.

 

R154

This is a robust 5-speed transmission found in the MKIII Supra Turbo and Toyota Soarer (turbo) up to 2001.

 

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

 

Soarer tt final drive 4.083 to 1

Mk3 supra(r154) final drive 3.7 to 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

Applications:

 

final drive 3.266 to 1(Japan market)

 

1993-May 1996 Supra turbo

V161

Ratios:

 

First Gear: 3.724:1

Second Gear: 2.246:1

Third Gear: 1.541:1

Fourth Gear: 1.205:1

Fifth Gear: 1:1

Sixth Gear: 0.818:1

Applications:

June 1996-? Supra turbo

final drive 3.266 to 1 TT (Japan market)

( 3.769 to 1 - late model NA 6 speed)

 

 

This of any assistance? -lifted fron local Toyota site(they are pedants, so usually accurate.)

[Quin]

A forum member here running a 7M and R154 is running a 3.73 gear in an R200 diff. That data you posted looks correct, it is of note that MkIIIs also came with 3.91s. It was a pre89-post89 difference, but I cannot recall which is which.

[ShaggyZ]

MkIIIs weigh 3500-4000lbs, for reference. I'm not catching what you mean by similar gearing to a 6spd Supra? Quite different, I assure you. The only similar gear is fifth to sixth, IIRC.

 

Also, it's not the width that matters, it's the diameter. Stock Z wheels are what, 15s with recommended sidewall around 50? MkIII Supra wheels are 16x55. Regardless, I'm fairly certain it'll be much too low. Seems like it'd be a complete dog off boost. I'll talk with ARZ (not sure what his name is on here, that's it over on Supramania) and see what he's using.

 

If you're missing my meaning regarding "similar gearing," read through my original post again and take a look at those links I provided that show the actual calculated speeds per gear given their respective differential ratios, transmission ratios, and tire circumference.

 

The short of it is this: the tire circumference difference between a reasonable sized tire on the Z and the stock Supra makes a good bit of difference; and the gearing is similar in that the speeds each gear will take you to from 0 to 200mph is nearly the same except that the V160 is spread across 6 gears and the R154 is spread across 5 gears - I believe, as does Speeder, that the weight difference is the primary reasons this will be more than acceptable. I don't want to have a totally useless 1st and 2nd gear it'll go through so fast.

 

Besides, this is largely an experiment. Of note: Z-Gad is moving to a sub-3.00:1 differential in his 2JZ-GTE setup.

[Quin]

Also of note, another 7M + R154 guy is interested in moving down to a 3.54 from a 3.7. If you have a good bit of power coming from that 2J, you should be fine. Learn something new everyday!

 

My bad :embarrassed: