Help me improve my 1/4 Mile times please - Lexus IS Forum
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post #1 of 5 (permalink) Old 02-22-2015, 05:21 PM Thread Starter
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Help me improve my 1/4 Mile times please

It was my first time ever at the track and I had a 3/4 full gas tank, dirty air filter and leaking a litle oil hehe. Don't know how, didn't do a burnout, launched at 3000rpm, dumped the clutch, shifted at red line, tires deflated to 30psi (idk everybody was doing it)...

2002 is300 5 speed Non lsd
Mods: k&n air intake, obx headers, obx y-pipe, coilovers, everything else stock.
Tires: 215/40/r18 front 225/40/r18 (on 18x8 and 18x9 wheels)
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60' ft 2.4


Is this a decent run?

How can I lower my 60'ft ?
What rpm should i launch?
When to shift gears?
Would a burnout help?
maybe wider rear tires?
Any driving/launching advice, technique?


Mods coming up sooner or later: 225 and 255 tires (respectively), 4.3 gears with lsd from a mk3 supra diff, bc stage 2 cams and apexi safc2 (with black box for ecu untunning problems).
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post #2 of 5 (permalink) Old 03-03-2015, 07:33 AM
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First off congrats on running your car.

That is a decent run and seems to be on par. I have an 02 5spd and when I ran my times were between 14.98-15.3. This was on a cool night at maple grove raceway. Track was sticky and I launched between 4500-5200. I had zero wheel spin and clutch slipped a little but hooked hard. I think my 60' was around a 2.2-2.3. It would be hard to do much better on stock setup. My only mods were k&n drop in filter and a Megan y pipe. Stock wheels with 225/45 bfg kdw2 tires. I shifted at 6k and bounced rev limiter across the stripe.

Are you spinning off the line?
A burnout would get the water off your tires if you drove through the water box (burnout area)

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post #3 of 5 (permalink) Old 03-03-2015, 08:41 AM
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I feel like this is a duplicate thread...
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post #4 of 5 (permalink) Old 11-04-2015, 03:28 PM Thread Starter
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I went back to the track and again I ran 15.4 as my best time. Now, what I am noticing (more than before) is a hesitation. My mechanic told me to change coil packs, spark plugs, spark plug cables and broken connector clips, so I did but the hesitation is still there. When I watch the video of my best run, you could clearly see the hesitation of the car, it lasts maybe one second but it is noticeable. I read on this forum that the stock is300 injector gave random misfire codes. I also notice other members saying that, that is the reason why token solutions designed the plug and play injectors for the 2jzge. I will consider getting the token solution pnp 420cc injectors and replace them when I do the 80mm throttle body conversion and I will control everything with a safc (I have the o2 delete black box). When I do, I will report back and take it back to the track to see if I improve my time and if the hesitation is gone.
Another member told me that my wheels might be afecting my times too, since they are pretty heavy (24 lbs front and 25 lbs rear).
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post #5 of 5 (permalink) Old 11-18-2015, 05:21 PM
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buy maf cleaner spray at your local autoparts store and clean your maf. Also, reset your ecu. These are cheap/free solutions that may or may not fix your problem, but the ecu learns as it goes, sometimes altering performance. A dirty MAF can also cause hesitation. Be careful when you clean it, and be sure to watch some videos on youtube; there's a bunch. By the way, congrats on staying on the na path with future plans for the cams and 80mm throttle and all that. For some time i lost my faith in NA 2j'z but i learned more about how to mod them, and they're really great engines. The is300 has a certain feel to it that not every car has and the engine is the heart of the car and plays a big role in that. It has character. A 5 speed running that time in miami's fall-transition weather with the mods you have seems low. I'm inclined to think the root of your problems is the hesitation and launch. Once in a stock auto with an open diff, I managed a 1.4 60 foot because of the lack of power. After the launch, it was slow af. Maybe it wasn't recorded well, but a second lower 60 foot= 2 seconds lower in the 1/4 and that has been tested. That means your car is abnormally slow off the line and makes up for it with a strong run afterwards. 15.4 is what id expect stock open diff auto car with 150000 miles to run in hot weather. You have coils which have stiffer springs than factory. That increases load transfer to the tires which causes loss of grip. This can make you hook worse, increasing your time. I suggest you make them full soft in the rear if they're adjustable when you drag race. The open diff can make times longer too. If you fix the hesitation, add an lsd, and soften your suspension, you 60ft should be noticeably lower and so will your quarter time. Considering you want the 4.3 diff, your car will launch and accelerate much faster. You'll encounter a traction issue until you upgrade your tires (from a 225 to 255 is huge and u can launch at a higher rpm) with the shorter ratio, but the car will make up for it in the rest of the run because the car will accelerate much harder. It's an excellent mod. Good luck. By the way for your ignition system if you haven't finished replacing it yet, I'd suggest ngk iridium ix plugs, ngk wires, and check out napol performance replacement coil packs. Supposedly better than typical aftermarket coil replacements and they're cheaper ($150 for a set vs $60-80 each for regular aftermarket replacemnts) you can find them on amazon. The plugs come pre-gapped, but check the gap anyways, and have fun taking the intake mani off. GOOD LUCK!
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