Threxx

Say you're cruising on the highway, not accelerating, not decelerating... just maintaining speed w/ cruise control over a long, straight, level stretch of road.

What RPM does your tach stay at? I won't say a specific speed because I'm sure some of you only remember your tach's RPM at a particular speed.

Like I know in my 00 Silverado (3.42:1 gearing, 4-speed 4L60E) I cruise at about 1900 RPM @ 70MPH... and I really love that.. I dunno why, but there's just something cool feeling about going that fast with the engine just barely having to rev.

I once rode in an LS400 (pre-98 so it only had a 4-speed auto) and noticed it was reving nearly if not right on 3k RPM at 70MPH... and although the engine was still smooth as silk, it struck me as odd that a V8 would have to be revved this high to cruise.

I'm in the market for a GS400, and I'm hoping with the power-curve benefits of VVT, and the extra gear in the 5-speed auto, that the GS400 might cruise a bit lower RPM?

So around the 55-85 MPH range, what does your GS400 tach at? Please list both speed and RPM.

babyboy

Threxx
I have found my Gs to tach around 2100 to 2300 rpm at about 70 mph.

rominl

iTrader: (4)

at 90mph my car is doing 2800

LOTC

Immpossible, the LS will rev about 2100-2200rpm going from 70-75mph. I drive to 85mph and it is only at 2800rpm

Threxx

Is yours a 98+ LS400 or a 97- LS400? The one I rode in was a 95 or somewhere around there... so it had the 4-speed, I'm thinking that may be the difference. But I'm positive it was right under 3k RPM at 70MPH... maybe 75MPH tops.

Maybe he had it stuck in 3rd gear?

Phillycat-24

I read this post earlier today and you made me think about it. I have a 99 GS 300. I went out driving got on the E-way and my RPM at 70 mph was at 2800. Now I do not drive the car everyday, maybe once a week. I am wondering because the weather is cold out that it is at 2800. Anyone can tell me why.

Threxx

Was the car fully warmed up when you did the reading?

Many cars will intentionally hold a higher RPM to warm the motor up more quickly until they are at or at least near their thermostat's prefered temp.

My truck does this too... normally in while accelerating normally my (auto) transmission shifts between 1500 and 2000 RPM, just depending on how quickly I'm accelerating (it's very torquey so the tranny is preprogrammed to shift early to take advantage of this). But when it's cold, for the first 3-4 minutes, it seems to refuse to shift before 2500 RPM even during the lightest of acceleration, and refuses to shift into overdrive on the highway alltogether... until it gets close to its normal temp and then everything goes back to normal. It's annoying IMO b/c I have flowmaster exhaust, and so everyone in my neighborhood thinks I'm speeding around when really I'm not even accelerating. But still, it's normal.

Phillycat-24

Was the car fully warmed up when you did the reading?

I had driven the car for about 30 mins. So I would say that it was warm. It fills alittle funny also I guess that I will have to start driving it more often.

meanboy

Sounds like it's normal to me. If you think it's high, maybe, your speedo or tach needs some calibration. But having driven mine on the freeway today, 2800 rpm at 70 mph doesn't seem out of the ordinary.

Phillycat-24

Oh ok thanks that makes me feel better. I thought it was alittle high.

Threxx

OK so some are saying ~2200 and some are saying ~2800, who's right here? Or is the OD gearing in the 400 a bit taller than the 300 in order to take advantage of the 400's extra low-RPM torque?

LOTC

I have a pre 97 LS400 4 speed auto Threxx. But for the GS300 they do rev higher.

I will try to take a pic next time.

JCHO

I have 99 GS4

65 mph 2200
75 mps 2400

rominl

iTrader: (4)

pretty much what i have too. at 90mph you would be at around 2800rpm

meanboy

I think both are right.