adlitem

Hey everyone. I just got my ride so I'm new to the forum. It gets up to 3k when I hit 70 mph and was wandering if that's normal. When I go 80 it gets up to 3.5k. I called my mechanic buddy and he said it's probably b/c it's a high performance vehicle. Is he right? I don't know much about cars but I assume this probably affects the gas mileage.

What kinds of ranges do you all see?

Thanks a lot

TroySC300

iTrader: (1)

That's not a very helpful response.

Welcome to the forum, and yes that seems normal.

5sp_jzz30

iTrader: (2)

yeah thats normal.

i have a diff out of an sc300 auto. higher gearing. its even worse. need to swap in the lower geared sc400 rear end to help gas mileage.

scfocus

iTrader: (3)

Throw in an LSD, that will help with higher speed cruising RPM's quite a bit

TougeSC3

iTrader: (2)

80mph 3k rpms on 215/60/15's

scfocus

iTrader: (3)

Really? Thats pretty low.. I'm also hitting 3k at 70mph but on 17's

OneJay

iTrader: (14)

I'm hitting 3k at 70 on 255/40/18

lexforlife

iTrader: (7)

soarer r154 matched to supra auto ttlsd 3.76 and 305/25/20 tires = 80mph i am at 2900 rpm

5sp_jzz30

iTrader: (2)

please dont misinform people. next thing you know this guy goes out and buys an lsd. 1000+ dollars later the car cruises at the same rpm.

lsd=limited slip differential

vehicle speed and rpm are related to the gearing of the differential. you can have a lower or higher geared and it can be either open or lsd diff. you have to change the gears in the pumpkin to change the gear ratios. most people change gearing by switching out the whole differential housing(pumpkin).

mtnrat

iTrader: (1)

Agreed. To get better cruising RPMs for my W58 swap I am putting 3.26 gears into the 3.77 auto TT lsd. I calculate 75mph at 2500 rpm compared to 70 mph with the Stock SC400 3.92 diff and auto tranny.

wickedsc3

iTrader: (3)

Yep that about right, i too found it to be a little high after comming from a 00 grand am that would cruz under 2k. Also on this note i was wondering if the year has anything to do with the rpms that car run at. Because here in michigan back around 93' the speed limit on the expressways were only 55 and now it is 70 so anyone know if that has anything to do with it like maybe that 55 is the speed they tested the lexus to run at back then. I just always kinda wondered about that if anyone knows

5sp_jzz30

iTrader: (2)

the gearing has not changed from year to year.

adlitem

Ok thanks. I originally posted this question because my other car does about 2.5k at 70. I realize there are a lot of factors that go into RPM and I thought the Lexus was running a little high. But, if it's in the normal range I'll stop worrying about it.

Thanks again.

StiCk3

iTrader: (5)

higly doubt they would change gearing due to a speed limit.

Our cars have some short gears, so they aren't friendly when it gets on the highway. That's kinda one of the nuisances that i have about this car. One extra gear could've changed this

evileagle

im about 78mph (logged via GPS as well) @ 3k on a 95 5spd with 255/35/19's and 275/35/19's.....