RKSTRAT

I am not tech savvy, but curious about the power ratings for the two cars. I am loving my new 2017 IS300 Fsport AWD,
but I never had a chance to drive an IS350 AWD, as they were very rare around here.
The dealer now has a 2018 IS350 AWD Fsport in stock, and I will take a test drive after the holidays.

But just looking at the specs I was a bit confused regarding where in the power range the
cars differ. Of course everything is identical except the tune. Here are the specs:

IS300 AWD: HP 255 hp @ 6400 rpm, Torque 236 ft-lbs. @ 2000 rpm
IS350 AWD: HP 306 hp @ 6400 rpm, Torque 277 ft-lbs. @ 4800 rpm

This earlier thread had the dyno comparison:
https://www.clublexus.com/forums/is-...o-results.html

As stated:
"As you can see from the dyno results, the IS300 is torque limited above 4200rpm."

If the torque is identical up to 4200 rpm, why is that not obvious form the specs where the IS300 Torque is
reported for 2000 rpm versus 4800 rpm? Does the dyno result mean that the main difference in the tunes
is not obvious below 4200 rpm?

arentz07

I'm pretty sure the IS 300 actually makes peak torque at around 4200, based on the dyno chart. For some reason the 2000 number is where Lexus decided to quote the max torque. So in practice, the 350 and 300 are going to feel the same in around-town driving. It's only when you explore the area above 4200 that you begin to notice the difference. It may very well be that the IS 300 does make 236 ft-lbs at 2000, but I don't think that's the actual peak torque.

skiracer

I actually notice a bit of a surge in power around 4000RPMish in my 2018 IS 350 F Sport.

Is this similar to VTEC effect?

ClubLUser

iTrader: (1)

Yep, Variable valve timing, basically the same concept.

dizlex

It's too bad that Lexus took the cheap and sleazy path to detuning the IS300. Since they were giving-up high-RPM power (and thus the need to breath most efficiently at those high RPM's), they could have re-profiles the cams to give it MORE torque than the IS350 in the low to mid RPM's. This would have made it arguably a better motor than the 350. I would gladly give-up 50HP in an RPM range that gets used 1 percent of the time (if that) for more torque down low.

arentz07

We can't have the lower-rung model be more fun to drive than the top-rung model, now can we?

I've heard with the RR Racing tune, the mid-range response is a bit better in addition to the peak power being equivalent to the 350.

RKSTRAT

I am enjoying the IS300. I am trying to get a feel for the personality of the car.
So, on the on ramp, in Sport Mode, it feels good. When I get up to speed (60 mph),
I find I have to be conscious of pushing the pedal, otherwise I am drifting down to
50-55 mph. For passing, I need to really push the pedal, but it smoothly can get up
to 75 mph. Seems like it is designed for smooth power.

jmull3r

iTrader: (1)