Rock-a-Lex

iTrader: (4)

Is there any way to increase the rev limiter only by about 200-300 rpm's in a GS400? If so how and what could be the negative effects of such. I'm getting ready (REAL SOON) to install my PI TC and 3.76 LSD combo and have been reading up about cars hitting the rev limiter a lot with this LSD...I want to try to prevent this...is there a solution?

gserep1

I don't think it is possible without a change to the engine programming. The limiter is protection for the engine. Excessive rpms put more strain on the drivetrain.

The most critical part is the timing of the pistons to valves. The valves are actually a mere fraction of an inch above the top of the pistons while driving. There is a notch in the piston crown to accommodate the valve coming down when open. That is why timing has to be spot-on. Engine overspeeding causes these components to operate out of time, and the pistons will bend the valves.....MAJOR REPAIR. the potential is there.

Toyota has designed this engine to operate safely at the current redline. To exceed it for any appreciable period of time is to invite damage. If the redline limit is raised, the driver will attempt to go higher. I would say that the fact you have the TC and differential is all the more reason the redline should be where it is.

All the torque is developed down low on this engine, and if it were not for that limiter at 6250, the engine would easily turn 7000 or more. It will not last at that speed for too long. You certainly wouldn't have reliability.

I do all I can to avoid the redline.... I just shift up a gear.

Good luck

slowdiver

iTrader: (10)

tiptronic....

ShaneC

the tiptronic to my experience is not that great on the GS. my previous car, 2001 Celica Automatic w/ tiptronic. it allowed me to stay in one gear as long as i wanted, just like a manual. allowed me to jump off the rev limiter if i wanted to. also if i was flooring it and wanted the car to shift early before it gets close to the rev limiter. it allowed it with out having to lift off the gas.


iono why i am mentioning this..i just thought i would just share.

GS FONZy

iTrader: (6)

if you want to prevent hitting redline, which is why i think you are asking, then maybe you can install a shift light. i does suck when you rev over redline, car starts to bog and loose power. however; sometime raising the redline can drop hp and other times can actually increase, but that's another can of worms that needs a lot of fine tunning and for our cars i have not heard of any ecu upgrades that will accomplish such thing.

macd7919

iTrader: (10)

If you want to up your redline the least expensive way would be to run a Haltech F10x. It is a fuel controller but also lets you set whatever redline you choose. It is going to be in the neighborhood of $1500 installed but on the bright side, no more bouncing off limiter and you will also gain some Hp as it is a standalone fuel controller and can be tuned for optimum output. It is also a great unit to use with FI if you ever chose to go that route. If you are interested in having it done pm me and I can link you up with a guy in your area. Hope that helps some.

Rock-a-Lex

iTrader: (4)

Thanks for all the help and advise guys. Yeah, I'm not really a big fan of the tip-tronic when racing on the straights (different story on the twisties). I feel that it leaves too much room for error if not shifted at optimal times whereas in "Drive" with "Power" mode on I feel that the computer does this effectively and efficiently consistently (very wordy); LOL!

Mac...I will PM you after I do a little more research on this Haltech unit; thanks again.

-Nick

GS FONZy

iTrader: (6)

cool to know. how much higher in RPMs do you think a 400 can go before getting in to the danger zone. how much more HPs do you think can be produced at a higher RPM from current redline.

macd7919

iTrader: (10)

Well, there is no way to put an exact number on safe rpm from speculation and I don't have the data on the springs etc... to calculate it. I wouldnt be too scared about going another 500rpm higher, that *should* solve your issue hopefully. As far as power increase you are going to be able to tune your AF without the factory computer trying to change things. The F10x is a standalone controller so it is independent of factory fuel control. For example, if you had a car with intake, exhaust, etc...basic bolt on's and no fuel correction I would say you could gain anywhere from 20-40hp and 30-40ft tq. 400/430's respond very well to proper tuning.

JeffTsai

iTrader: (1)

All cars are designed in mind to take more stress than the specification. The redline is where the engine can operate at an extended period of time without self destructing, granted the coolant and oil temperatures do not rise significantly. You can run the car at redline for a few minutes without too much of an issue. The redline is the "safepoint" so you shouldn't have any problems pushing another 500-700rpm's out of the motor. The biggest issue is that you're gonna start losing power because the timing on most cams will start to fall off around redline. Also, keep in mind the valve springs might not be able to support everything moving at such a fast speed.

Point being....you should be ok raising the rev limit a little bit without worrying about the engine going kaboom. It will fix your problems of bouncing off the limiter between shifts, just don't expect the engine to make more power

Rock-a-Lex

iTrader: (4)

Good to know guys...I would just hate if I have to ALWAYS use the tip-tronic during hard launches. I read somewhere that you can lose as much as .4 (maybe more) in the 1/4 mi by hitting the redline in every gear and when racing another car that's BIG and there goes the whole race! Hopefully I'm one of those lucky ones that don't hit redline with this LSD/TC combo...we'll see.

chuckb

there's no power there above redline anyway.

GS FONZy

iTrader: (6)

tip tronic is best in freeway/highway driving. my best ETs were on "D" if you realy want to speed your shifting, then you need a valve body. search, we have talked about this before, then you can get this installed when you do your TC.

if you realy want to run tip tronic then install a shift light, even if you raise you rev limiter, what's to say you won't hit redline then you need something that will let you know when to shift with out staring at your RPM gauge

LexFather

well no reason to go past redline on the GS 400, b/c peak hp is near the limiter...anything past that and your going out the powerband.....

There is no rev limiter remover I've seen.

Rock-a-Lex

iTrader: (4)

It's NOT that I want to speed my shifting at all! I want to just be able to put it in "D" and mash the pedal to WOT if I am racing without hitting the redline and boucing off the rev limiter. Some people here luck out with GS4XX with the TC/LSD combo and never hit the rev limiter. I have read that people actually hit the redline and for a split second it doesn't shift and bounces off the rev limiter all while in "D" <-----that sucks and that's how you lose the race. I'm not feeling the use of tip-tronic in a straight run as I think the computer can shift at more optimal times than that of a person manually...especially with the Lexus tip-tronic which isn't exactly "instant" response.