Nick123

Dear forum members:
I shipped few btrand new RX350s to my friends overseas and they confronted me with this question, maybe anyone can help:
Some cars can go beyond 120 m/h, some don't. For those which don't: when the speed riches 120 m/h gas pedal sinks to the floor and speedometer stops. Other cars go 140 and beyond with no problem (apparently they use them for racing ).
I spoke with Lexus service, they say it's a computer program/microchp and it cannot be adjusted. When I asked them 'then why some cars go faster the others?' they had no clue.
My friends would like to have this limit removed (even via programming) but they don't know where to look to.
Help, anyone?

salimshah

Nick:

I would not question the sanity of trying to go beyond the speed governer limit (specially on a SUV) ... if cought on public street, it will surely land ppl in jail.

RX does not apply brakes to slow down, it essentially stops providing more fuel/energy to create more power. Newtonian Physics still applies and drag + terrain along with the tolerance (lack of precesion and calibration) gives you the spread.

You are correct, the limiter is contolled by the chip. I dont know of any replacement chip or a process to circumvent the limitor.

Salim

Lexmex

There used to be a V-Max chip from TTE for the RX300 that did what you are asking, I do not think they have come out with one for the RX330 or newer.

That being said, HKS has something called a Speed Limit Defencer, http://www.hksusa.com/products/?id=781

However, you would have to ask them if it could work on the given vehicle.

Yet, the tires on the RX can only support a given high rate of speed for so long, I am pretty sure none that I know of come with Z-rated tires new.

Second, I have taken my RX300 up to a GPS tracked 120.9 mph (above the 112 mph cutoff) by ramming it down a hill on a non-patrolled toll road not to far from where I live.

You have to be very, very proficient in handling an SUV at high speed, have it modified (lowered would be recommended).

Going in a straight line (like I do on a drag strip) is nice or even on a straight stretch of highway, but when a dog, wild driver or some other act of god comes into play, that RX will not handle like a car.

tfischer

I have not heard that there is a limiter on the RX, but if it's at 120 I would not be too concerned, as that's a little bit of a high speed for cruising in such a tall vehicle.

My SC has a limiter at 150 (the European versions hit 160 or so) and I have not quite hit that yet.

Isn't this all pretty academic? The RX cruises nicely at 90, but I would not be very comfortable runing it in the tripple figures.

. . . Unless, of course, you intend to be running from the law.

crosborne

I'm more interested in your shipping of these vehicles overseas. Where overseas? Why can't they buy them from where they are?

Lexmex

It is actually 112 mph with the cutoff, but the intertia going down hill meant the car was still accelerating afterwards to hit the 120.9...took me several tries to do this.

You can get away with a lot in terms of speed down here, but in the U.S. I take it very easy (no need to rush on those beautiful and open highways).

Nick123

Thanks to everyone who replied to my question, especially to Lexmex!
While I'm still trying to get to the bottom of it, to all who asked I can tell this:
i. SUVs were shipped and are being driven in Ukraine where no Lexus dealers available.
ii. I told them all (my friend and his friends) that they'll kill themselves on those beaten-up and dirty roads with such speeds. No avail - in order to understand "why?" you have to understand misterious russian soul, which I don't.
iii. I'd appreciate if anyone who comes accross a solution to speed limiter e-mails me at mytriptokiev@hotmail.com as I'm not frequent to this forum.
Thanks!

Battousai

I am not too comfortable with your question on taken out the limiter on the RX350. It sounded like to me that your friend maybe up to something fishy over there.

TunedRX300

RX350 sold in the US has the speed limiter set at 112mph as the fuel cutoff point because OEM tire is S rated, which is specified to handle exactly 112mph as the max speed.
Just use a better tire, RX should handle above 112mph in a controlled environment (such as a track) if not fuel controlled by speed limiter.

RX350's 2gr-fe is far more powerful than RX300's 1mz-fe, why would Lexus not up the limit accordingly? Is it because Lexus is so concerned of your safety? Then why would ES350, using the same 2gr-fe engine, has a speed limiter of 137mph? ES owners are more aggressive than RX owners or physically and emotionally better prepared to embrace higher impact in a high speed endeaver?
Another food for thought, is pushing 112mph any less crazy than traveling at 137mph? Or traveling at 105mph safer than going to 112mph?
The real reason is Lexus can reduce the cost of goods sold by using cheaper S tires, summer tires rated V such as those in ES cost a lot more. Lower cost means higher profit margin. It $, not design or concern of safety at the end of the day.