The speed is limited by the ecu, it stops accelerating after reaching the RPM limiter on top gear. I have heard that the HKS speed limit defenser can override the ECU, but have not tried it yet. i hardly ever reach speeds past 130mph, so not really on my mind to really get it.

 

To some extent it is. However, when you swap out the gear ratio, your NEW top speed is not limited because of limitations imposed by your gearing but because the computer "thinks" that you are doing 149MPH while in fact you are doing 121MPH with the 4.27 or 135MPH with the 3.76. The speed limit defenser removes the limitations set by your ECU but the limitations imposed by the laws of physics still remain.

 

So does it make my spedometer off by any value? Cause does'nt read the value off the wheel sensors? Or is that just the milage sensor thats on the wheels?

 

Speed is not affected by a gear ratio change, only a change in tire diameter affects the speed.

 

How does the car feel (compare) now since you switched out the 3.76 to the 4.10 gears? Also, what is your top speed if you know?

 

I'll make this quick and dirty....

Drove over to KAAZ and had my SC300 pumpkin put on today. Ray and Sajee swapped my KAAZ LSD out of the 3.92 pumpkin and into the SC300 pumpkin which has 4.27 gears.....no issues with fitment at all and bolted right up to the GS4.

While the install was being done, I asked the guys if I would feel a difference going from 3.92 to 4.27 as I had some doubts if I would even notice the difference because I've had the 3.92 gears on for awhile. Please note I am NOT a mechanic. They both responded that I would defintitely notice the change and explained why in great detail.

Well they were right....the initial low-end acceleration off the line with just minor throttle is amazing. The 4.27 gears and PI TC combo is money. I then did a WOT and noticed the car pulled ever harder off the line. I did not have rev limiter issues (remember I'm on 20s) which was nice but I only did WOT a couple of times on the way home.

Update: Freeway speed of 80 mph produced RPM level of 3400-3500.

Start searching for those SC300 pumpkins!!!

 

Do you have any before / after 0-60 or 1/4 mile times.

This is the only way I will belive this gearing will actually improve performance.

I have no doub't that the low end grunt will be something awesome, but I don't think you will have enough traction using that gearing, without using drag radials. I am talking when launching from a standstill. Most of us with with every NA mod available and the 3.76 gearing can still melt down the tires from a standstill. My biggest problem at the strip is tire spin. I have 295's on 11 x 20 rims, and I still don't have adequate grip.

Lastly, you will definitely be in atleast second gear by the time you reach 60mph. If you don't have a high stall TQ and a valve body mod, I can almost guarantee your 0 - 60 will be slower, cause you will lose time in the gear shift.


If you got a TQ, vb mod and drag radials, I'd say the 4:11 may work quite well.

 

4.27. oh man talk about freeway cruising and the gas mileage that comes with it

 

yeah no hard evidence here as i dont track my car...waiting for S&S install and FI someday

like you said, just in it for the low-end grunt

I thought it would be cool to try it though because KAAZ headquarters is so close to me and I stumbled upon the SC300 pumpkin on craigslist.

 

Have fun doing smoky burn outs at will and probably spinning the tires while going 10 to 20 mph by just romping on it.

You will probably scare a lot of people out of a race if you do that.

 

now get some stock 16s with drag radials and go to the track.

 

oh yes my friend......

I love when you get the question, "Wow......that thing is a Lexus??"

 

someday and I will post numbers just for you chuckb

 

Hey guys, I have the 4:27 gears but I haven't installed them yet. I'm going to the track next weekend with the SELOC clan. After that's all said and done then I'm going to install the gears and plan to go back to the track that same weekend. Then I'll have some evidence of the improved performance for you skeptics .

A friend of mine had a 5.0 with 3:55 gears and he would take a lot of other stangs with similar setup minus the gears. I also drove his car and it was quick, once you get the hole shot down with out spinning the tires.

 

I have the 3.76 gears (approx) and I raced another GS with almost the same level of mods and we both dynod our cars at 2 different times and were within 5 hp/tq of each other.

At the strip I usually got the jump off the line, but I would also pull away at each gear shift. We did this about 10 times. Even when I was slow off the line and he had a half car length on me, my car contiued to pull through each gear, pass him and keep going away.

The ONLY key difference between our 2 cars being I had the Supra LSD with the 3.76 gearing and he had the TRD version LSD with stock gearing. The fact that I pull further on each gear appears to prove that my motor is at a higher rpm at each shift, which so happens to be closer to the power band of our engines.

So going too high in the gearing, over 3.76 is just going to take you out of the powerband and slow the car down on the top end. As far as the bottom end, I already remarked that with the gearing I have, it is still difficult to manage traction even with 295 tires on 11 inch wide rims. My launch rpm at the strip was a sad, sad 1200rpm. Any more and the car would just stand still off the line. Granted the track was way too slippery, I still have traction issues on the street where I can launch at much higher rpms.

So you see I have scientific evidence of my remarks. I'm not being skeptical, I'm just stating the facts.