As some people read in a previous thread, I installed a PI TC and SRT intake/ecu a week or so ago. I had gone to the track with the car bone stock a week earlier. The best time I could muster then was a 14.99 @ 93 mph and my best 60' was 2.431, which is about as fast as getting out and pushing it off the line .

Anyway, that was then.....Last night I went back to the same track again. Unfortunately, we had some terrible conditions (rain, drizzle). It took 3.5 hrs to start the first car down the track, but finally at around 9:30pm they let us start running. As usual, I was the only Lexus running, but I went anyway. I ended up only able to run 3 times before the track closed at midnight. My best time tonight was substantially better. I ran a 14.6 @ 95.75 mph with a 2.204 60' time. I went 2-1 with the only loss by .09 secs to a turbo 280z.

I found something kinda interesting though. My first two runs, along with all my runs the previous outing, were done with the VSC on. When the car was stock, it really wasn't an issue since the tires wouldn't break loose enough to activate it. Last night however the first two runs they broke loose enough to activate it and I noticed that I ran almost identical times 14.9's. My last run I took it off and I had some wheel spin but ran my best 14.6????? Had this ever happened to anyone before? I figured that having the VSC on would help me by controlling spin and thereby getting me off the line quicker but it did the opposite. With the VSC on, my first 2 runs had 2.4 and 2.3 60' times....w/o it I had the 2.20???? Someone explain why the VSC acted kinda like a governor in the sense that when activated it netted almost identical ET's and 60's.??? I personally think the car is capable of 14.3 probably, with a good launch. Which is more than a half second with just two bolt-ons. Not the full second they advertise, but close. Not bad.

Sorry for the long winded disertation, but bottom line is that I'm happy so far with my mods. So I wanted to follow up with numbers for those who are on the fence about just exactly how much performance gains are with these two mods.

Let me know what you guys think.

 

Hmmm, aren't stock GS4's supposed to run about 98mph trap speeds?

 

J - your results with the VSC ON are exactly what I would have expected. There is no doubt it slows my car down when on because it reduces the power to the wheels (by metering the fuel flow I believe). VSC is not a device for performance, it is a device for safety.

When I'm lining up for a fast launch, I always turn VSC off. With just the TC and no LSD, you might have some wheelspin but practice will help with that... just have to figure out how to 'feather' the gas until you get fully rolling. Make sure you turn the ECT to Power and AC off as well (although it should cut out under full throttle anyway) as well.

 

According to?

 

I found out the hard way. I noticed that my 60' and ET's were almost identical, no matter what. I was either a heck of a driver on a very well tuned car OR something was causing the car to do the same thing over and over. I would have sworn that the wheel spin would be worse than no spin. In my other car, which is considerably faster than my 400, that's my biggest problem....traction. I thought the VSC was a solution, but I guess it's not.

Oh well, at least now I know how to get out of the hole faster. What really bites is that I should have gone 3-0 Fri night because had I had the VSC off when I ran the 280zx turbo, I would have smoked him too. That's what really bites.

 

DaveGS4 mentioned it, but an LSD is your next step. Then you don't have to worry about the traction, just the driving. Hopefully I'll be getting my TC and LSD installed in the next few weeks.

 

I know....I haven't read too much about that, as far as recommendations. Does anyone have any links?

 

This is a good question for a search. There have been several recent and many not so recent LSD threads. The usual choices are the TRD clutch and the Supra Torsen as well as some new options like the ATS Carbon.

 

I did do a search but there are a ton of worthless threads that have to be weeded thru. I'll keep looking.

 

I found a bunch real quickly with my search.

https://www.clublexus.com/forums/sho...threadid=74185

https://www.clublexus.com/forums/sho...threadid=77438

https://www.clublexus.com/forums/sho...threadid=14356

https://www.clublexus.com/forums/sho...threadid=75786

You basicially have two choices, TRD clutch type or Supra TT Torsen type. There is a new carbon-fiber one that Guru is putting in, but I'd personally hold off on that until we get some more input on how it works from him. The details about the difference between the two choices can be found in the threads above.

 

Traction control systems are the bane of drag racers. The only sort of traction control system that works is an AWD system. Any system that improves traction by slowing you down is no friend of mine (at least in dry weather!).

Instead of using VSC at the track, try using some VHT, which is a traction compound (sticky stuff) that you squirt onto the track in front of your rear wheels and roll over. While this might help your wheelspin issue, it may not make you go any faster. Depending on your torque curve, you might actually go faster with a little bit of wheelspin than none at all. Low ETs are attractive, but I pay more attention to MPH as a measure of actual performance in real life driving.

I'll take a car that does the quarter mile in 14.5 sec at 124mph anyday over a 12sec 115mph car!

 

Thank you. I had put in "LSD" and got a ton of threads just mentioning LSD not explaining the choices. Anyway, thank you. I think that I'm going to hold up on getting an LSD since it's over $1k just to start. I'm not going to be going to the track every weekend with the Lex. I just wanted to make it a little quicker than stock. I've got another car that I take to the track that helps me cut the craving for speed.