mark98ls40

Thinking of upgrading & wondered if the LS430 with the 6 speed is much quicker in acceleration than my 98. Is the 1st gear in the 430 lower for better off the line thrust?

Kansas

Here are the accelleration specs from the Lexus websites for both. What does it matter what the 1st gear ratio is -- the 04 LS430 accellerates faster than a 98-00 LS400 and, from my limited experience, the 04-up LS430 with 6-speed seems much quieter while accellerating.

Nuckingfut

Splitting hairs IMO.

Amskeptic

A half-second acceleration difference in the real world is close to meaningless in my simple life of nowhere terribly important to get to. As for the difference between 130 and 149, I'd feel cheated not to get my 149, I PAID FOR IT.
Colin
(save your money and learn to launch more effectively and you'll blow the doors off the 430 and the 460 owners who just stab-n-go)

mcat

wow.

it's hard to keep my foot out of that power on my ls400.

mcat

j three

Yeah, these are deceptive cars. Especially from a roll at about 30 mph, and on the freeway! The first time I punched it after upgrading from my 91 I was like Danm!

JBrady

Clearly 149mph is FASTER than 130mph, so ALL LS400s are FASTER than ALL LS430s.

Now, the 2004-2006 LS430 is definitely QUICKER than all 400s including the 98-00 models.

That said I have made many sub 6 second pulls in my 99, although I bet I could shave 1/2 second of the 430s publicized times of 5.9.

In addition to the 6 speed (more gears for closer gearing) they also have the 3.679 differential ratio which combined with a 3.27 first gear ratio give 12.423 times engine torque vs 10.964 for the 98-00 5 speed cars. With 320tq that gives a multiplied 3975tq in first gear (less drivetrain loss) vs 300 x 10.964 or 3289tq for the LS400. Both cars are very close to 400lbs so the advantage is clear and one continues through the full gear ranges. The 430 engine also reaches its peak torque earlier than the 400.

Add insult to injury with a better Cd of drag (.26 or .25 vs .29 ) the 430 has less air resistance for faster accell. The 430 is NO slouch. Don't be fooled by the 2006 power rating of 278hp as that is a different measuring standard and is equal to the 290 horse rating from previous years.

LexFather

x2

Glad to still see you here!

JBrady

Thanks, back at you!

I need to correct my above typo. I meant to say that both LS400s and LS430s are about 4000lbs vehicle weight (not 400lbs).

So, a 4000 pound LS430 has 3975 pounds of torque (force) to accelerate with in 1st gear.

A 4000 pound LS400 has 3289 pounds of torque (force) to accelerate with in 1st gear. (5 speed models)

So, in first gear the LS430 has nearly 700 pounds of force MORE than a LS400 to accelerate. Big advantage. It maintains a substantial advantage in every gear.

First gear numbers:
430 = 12.423 x 320 = 3975
400 = 10.964 x 300 = 3289 ( 686 pounds of torque less)

Second gear numbers:
430 = 7.380 x 320 = 2361
400 = 7.120 x 300 = 2136 ( 225 pounds of torque less)

Third gear numbers:
430 = 5.081 x 320 = 1626
400 = 4.651 x 300 = 1395 ( 230 pounds of torque less)

Fourth gear numbers:
430 = 3.769 x 320 = 1206
400 = 3.266 x 300 = 980 ( 226 pounds of torque less)

Fifth gear numbers:
430 = 2.733 x 320 = 874
400 = 2.459 x 300 = 738 ( 137 pounds of torque less)

Add to this the aerodynamic advantage of the 430 and as speed increases more and more force is required to overcome the drag... the lower the drag the faster the acceleration with equal force... and the 430 is slicker and more powerful.

One way to make MOST cars more aerodynamic is to lower them. The 430 has a drag of .26 (vs .29 for the 400) UNLESS it has the air suspension that lowers the car and that drops its drag to .25

So, what is a self respecting 400 owner to do???

Make more power:
Headers, exhaust, intake, tuning. Reasonable potential 330-340hp.

Create more torque:
Precision Industries torque converter (or a less effective alternative)

Reduce aero drag:
Lower car, keep tire width at stock, wider tires create more aero drag and more frictional drag not to mention they are heavier.

Reduce wheel and tire weight.
Reduced wheel/tire weight is more effective than reduced weight elsewhere since it must be accelerated both linearly (direction of the cars motion) and rotationally (as it is rolled).

Reduce vehicle weight. Power to weight RATIO baby.

Change the gearing. Effective but creates other compromises that the above do not.

Get REAL serious...

Bigger engine. Swap in a 4.3 liter from the newer car! Build a stroker 4.7 or even larger.

Forced induction, supercharger, turbocharger and even nitrous.

Learn to drive your vehicle to maximize WHATEVER resources you have AKA... Driver Mod!

GRAND_LS 4

iTrader: (2)

Good luck blowing the doors of a 460. Im guessing it will have at least 8-10 car lengths on you at 100mph.

JBrady

Well, at these power levels you will get somewhere around 1 car length per horsepower BUT there are several variables including weight (460 is 300 pounds up on the 400/430s) gearing, redline, shifting speed and more.

Lexus factory rated the 99 LS400 at 6.3 to 60mph and 14.8 in 1/4.
Lexus factory rated the 04 LS430 at 5.9 to 60mph and 14.5 in 1/4.
Lexus factory rated the 08 LS460 at 5.4 to 60mph and 13.9 in 1/4.

Figure about 1 car length per tenth in the 1/4 and there are 9 lengths between the 400 and 460. Of course I ran a 14.2 so compared to a less than great 460 driver the results will be MUCH closer in the real world.

mark98ls40

Thanks for all the info. on this. Guess I'll have to drive an 04 although the 98 is great.
Although at a mile high altitude, (less O2 means less power) more thrust off the line would be extra fun.