Thanks, I found that my best was shifting as soon as the needle hit 6.2. It's was the smoothest 0-100 I've done.

 

Agreed. Perfect analogy. For those following along at home- that means that a 22 lbs wheel tire combo might be faster than a 20 lbs wheel tire combo of the same size, due to the weight distribution of the wheel itself. If a wheel carries a lot of excess weight around the outside rim vs. nearer to the hub it will perform worse that a wheel of the same weight with a distribution of weight nearer the center. So you cannot gauge the results solely on overall weight. Engineers: Is there any way to easily figure out the weight distribution? I said "easily", as in "I am mathmatically challenged and a bit of a moron."

I do not disagree with anything you said. I am not an engineer, just an idiot with a G (but I did stay at a Holiday Inn Express last night). I was not intending to race Sat night, I was at a car show earlier in the day (hence the 20's) (okay, it was a kegger at a speed shop- fun combo!!)- and got talked into going- My first run was after midnight, I got 4 runs in before I left at 1:30 am. I used the VDC "ON" because "spinning tires always results [sic] in slower times". I can light up the 20's pretty well and I did not want to do that. I had felt that my previous trip to the track i had way too much tire spin so I was trying to minimize the spin.

BTW, for the engineers out there, a "kegger" is a party where beer is served out of a keg, usually resulting in irrational behavior by those who partake- be careful, oftentimes hot women are present at keggers which may result in your inability to speak or you may break out in hives, etc.). *My father is a retired mechanical engineer- (OSU- Go Bucs!), masters, phd, college professor and the "proto-typical" old school engineering nerd- I have seen pictures of him with his belt mounted holster slide-rule thingy on and looking damn proud of it. White dress shirt, pocket protector from hell, black tie and eyeglasses to complete the look. Just like the other 12 engineers in the pictures.

But seriously, I love talking with engineers about these types of issues due to their logical reasoning and scientific method way of solving a problem. I never got past college algebra in mathematics and still use my fingers and toes for cypherin' so you engineerin' fellas do come in handy. Sorry about picking on you guys during the middle school years!

I'm glad my post received such great input and feedback and I will update the thread with data after further racing and testing. Maybe I'll start a new "De-Bunking the Myths" thread or something. Please all you engineers and racers (drag racers for now), chime in.

I am not here to advocate the use of 20's at the track. I thought it was a given that my 17s would out-perform the 20's at the track, but now i'm not as sure. Jury is still out on that for now, I am going to do further testing with the 20's first and change my launch method back to VDC "OFF" before I slap on the 17s and go for low ET. I will try the various methods like starting in MM5, starting in D, brake torque/ no brake torque, etc. I will get all the info together and post as well as my previous two that we have been discussing. I may mount my little HD video camera on the inside to show the gauges (OK tach and speedo) and what I am doing- not necessarily what I am seeing.

I had planned on going back to the track to check my mods and I planned on running for a low ET using my stock 17s. however, in retrospect, it worked out well, because the only other time I had raced my car on any track, and it was the same track, I was also on my 20's. If I swap to my 17s now it will render my previous data useless.

I was not concerned about speed when I previously went to the track. It was just a father son bonding thing. I surprised my (then 15 yr old son) with a few runs down the track for him. It was going to be the first time he ever drove a car wide open thru 75+ mph. I told him he could keep going past the 1/8th finish line and top 100 if he wanted to. Then I got in the car for a few runs myself (I was praying that my car could do better than the 12's he was pulling down - turns out he thought he was supposed to lift on the gas in between his "manual" shifts- and he hit the rev limiter a few times in first gear). I pulled 1 sub 10 sec run. Rt lane- VDC "OFF" w/ med brake torque- MM1- slap to D after hook. Other runs were consistent 10.1- 10.2 ETs


For daily driving I just leave VDC "ON", but when i'm feelin' it, I turn it off. No doubt about it- it will always be "OFF" at the track from now on- unless testing for some reason.


no offense, but I don't give a crap what any "die hard" drag racers thought of me. I wasn't there to try and impress them or anyone else- well maybe just my son a little. this was a $10 "run what you brung" where stock Kias will line up against a pro stock car getting dialed in for "real" races.

I will post everything as soon as I have some time.

The point of my post was to get help figuring out why the mods were not translating to the track. I had the same wheels and tires on the car for my previous runs (constant variable) made mods that I hoped would improve my ET (plenum spacer and cat-back). Same idiot driver (constant variable). same crappy track (I run faster in the right lane (lower ETs), but only left lane gives 60 and 333' splits so I try and run in the left for that reason. Similar atmospheric conditions (constant? variable). Essentially the same ET. I emphasized that I had changed one other variable and that was my method of launch- VDC "ON". I left it on intentionally this time because I had previously run with VDC "OFF" and had trouble with excessive wheel spin at launch (yes, I know, the black rubber bands I have wrapped around the 20's are to blame!!).

Yes, the engineers discussed the sidewall issue and you are right. I do not disagree with anything you said. However, given the fact that with VDC "OFF" I was spinning tires, my car was easily overcoming the excess weight at launch (Initial momentum is where the extra rotational mass impact is greatest and it declines with speed, eventually making it more difficult to stop). After overcoming the extra weight of the stationary wheels, the excess rotational mass is now working in my favor and could actually help the eventual hook. The consensious was they were not sure and with the weight distribution being an unknown, they were only offering educated guesses. They felt the two rotational mass issues would likely offset each other with maybe a nominal net effect. They were interested in testing the theory.

Yes, everyone was in agreement that 17s with larger sidewalls is a better set up for launch. Again, we are talking tire/wheel performance in 1/8th mile race with no need to turn or brake.

After looking at the 60' and 333' splits, it was apparent that my VDC "on" launches were significantly slower this time but I ended up with roughly the same overall ET. So post mods I was clearly closing at the finish. The VDC on explains the results perfectly. 1st race the spinning tires helped offset the extra weight. In the second trip to the track, by preventing the spin, the wheels became dead weight, like throwing out an anchor. So despite my best efforts to slow the car down (unintentional), it still managed the same ET. Not bad! Further testing to come.

BTW, I am going to have my car dyno'd at S&R, anybody else want to jump in and see if we can get a group discount.

I plan on going to Sunshine Speedway wed nite if anyone in the Tampa Bay area wants to hook up and race let me know.

 

Thanks, but that is not going to help me. My motor is still pulling hard when it shifts at redline. I need to get rid of the rev limiter. I'll let you know after the dyno how my power curve looks.

I'm cursed with the early ECU

 

20s will have a profound effect on 1/8 mile ET and MPH, especially 60 foot and 330'. If you were to run a full 1/4 mile, there probably wouldn't be a huge difference in ET/MPH between the 1/8th and 1/4 mile between the 17s and 20s with the reason being the 20s require so much more energy to accelerate them and most of the acceleration in a drag race is in the first 1/8 mile or less.

There isn't a ounce of doubt in my mind that the 20s are sucking out at least .3 seconds and 2mph in the 1/4 mile. I'd venture to guess it's closer to .4 seconds. That's basically like taking away 20 to 25 whp. Your mods are good for maybe .2 seconds and 2mph and they do not have synergistic effect. The reason you can easily spin the 20s is because they have a super stiff and almost non-existent sidewall.

 

Believe me, your VQ35DE is no different than any other VQ35DE. Power peaks at 6300 and then starts to fall off. I've seen VQ35DE's with extended limiters and power drops like an anvil after 6700rpms. Intake spacers, catbacks, headers, and other intake/exhaust related components WILL NOT increase the engine's ability to breath past 6300rpms. Power will always fall off at this point. The only way to increase breathing ability is to do one or both of the following things:

1) Cams
2) Heads

As for your ECU curse, Technosquare makes an ECU flash for our 03 cars. It's ~$500 and they will map it for your mods. They also increase the limiter to 7100rpms and change the throttle sensitivity. On a stock 03 sedan, it's good for around 10whp. I'm surprised you don't know this is available.

 

I wasn't so much concerned about the actual time as I was the lack of improvement. My 1st track trip 60' at 2.3/ 2nd track trip 60' at 2.6. .3 is huge at 60'.

 

Well there you go. That's why you're no faster in the 1/8 mile on your second trip out. Your 60 foots are way slow. You're .3 seconds slower off the line on your 2nd trip which is will basically as a .5 second impact on 1/8 mile ET when compared to your 1st trip to the strip. If you had provided us with your best 60' foot and 1/8 mile ET/MPH between your 1st and 2nd trips to the strip, it would have answered a lot of our questions. You're slower simply because you're a lot slower off the line. My wife's 165hp automatic Subaru Legacy GT wagon has pulled low 2.4 60 foots

 

I'm scared to go to the strip now since I got my g37s brakes, those things are heavy as hell and will slow me down a lot.

 

I think the oem G37 rotor is close to 30lb each. A stock 03 rotor is only 15lbs or so.

My dream setup is a oem brembo on 2pc racing brake rotors.

 

Damn that's crazy, plus its not including the extra weight of the calipers....

2pc rotors for g37 brakes are too expensive

 

Brakes are supposed to slow you down!!

 

As mentioned, get rid of the 20s.

A 2.6 60 foot vs. a 2.3 60 foot is a huge difference, and a 2.3 is still crap. It is important to remember DA as well. Don't go race when it's 90 degrees out and expect good times.

I have basically the same mods as you and I've been a 9.2, or something like that, with a 14.1x 1/4mi. The only difference is that I don't have huge wheels. Do you also happen to have a sub?

The OEM 17s are also crap, but they are SO much better than those 20s.

It hurts me to think you even took your car to the strip like that.

As Dave mentioned, leave it in MM "2" from the start, and shift from there on out. TQ brake a little bit off the launch, and go for it!

 

I'm assuming you meant for the track. I like the 20's, I think they look sexy as hell. They really aren't my style though. I want something less flashy. Seriously I would like to trade them for the 19" M- sport wheels. IMHO that combo looks the best on the early G sedans. Anybody want to trade?

Thank you captain obvious! Go throw my 20's on and see how you do!!

Uhhhggg, Hello I live in Florida. It's almost November and the high is 90 today. Yesterday's LOW temp here was 75 degrees. It is supposed to cool off. The LOW today is supposed to get down to a chilly 74, but the track will be closed by then. And then you have the radiational heat of the track from the sun, and the constant high humidity. C'mon down here and run your car in Fla. My 2.3 60' splits were in June - frickin' hotter (its actually the humidity) than you can imagine (with the 20's, uphill, against the wind, pulling a boat, in reverse, blindfolded!!)

no sub. It must be that you are just that much better at driving than I am.

I assume you are speaking strictly about for the track. My car is my daily driver. It is a delicate balance between performance and aesthetics. I have 17" 350z wheels that I intend to eventually use at the track when I go for low ET.

Dude?!?! Seriously? Well then for your own well-being i suggest you never, ever look at this thread again. I'm going racing tonight!!!! In the 20's again no less!!!!! I will dedicate my first run to you!! I would show you the pics of my car after my son wrecked it, but I don't want to send you over the deep end

For the rest of you, I will be running in my 20's tonight with VDC "OFF" and testing different launches. If I switch to 17s it will render all the previous data I already have collected useless. My baseline run was on 20s and I need to keep that variable constant for now (apples vs apples). If I put 17s on and run faster, I will not know what the mods did vs what the 17s did (apples vs oranges).

Finally, some useful info. thanks. I will try Dave's suggestion and the others as well. i'm taking an engineer with me to help collect, organize and assess the data. Again, my first runs tonite will be MM 1 and slap to D after hook like pre-mod runs. I am trying to replicate the conditions of my 1st runs for mod performance assessment purposes. It's only an 1/8th track. Only the left lane gives 60' and 333' splits, but my ETs are consistently better in the R lane. Murphy's Law #9,034.

Lastly, the weight distribution of the vehicle and wheel spin. Anyone have data on amount of fuel to carry to maximize traction? I'm going with a quarter tank tonite- because that is what I had last Sat night. I don't know what I had in the tank my first trip to the track.

Are there any other shift suggestions people want me to try tonite?

I may try and get my wife to drive her FX loaded with my jack and 17s to the track. She is a bit of a diva and the track is a dump even by race track standards, so that may not work out for me. My son has youth group on Wed nites so he cant haul the crap down to the track tonight.

Anybody in Tampa want to volunter to be a pack mule for me? I'll pay for your admision at the track!!

 

If it were me, I'd scrap all runs on the 20s and swap the 17s to the rear when you get to the strip. With a standard jack, it takes all of 15 minutes to swap wheels. I've always left my wheels in the pits and no one ever touched them. There is a racers etiquette. I've never heard of anyone getting tools, wheels, etc. stolen from the pits at a track.

DO NOT put the car in 1st and the try to execute the 1-2 shift yourself. You'll be slower, believe me on this. Since you have an 03, put the car in 2 and manually shift the 2-3. Done deal.

When you roll up to the line, do the following:

1) Avoid the water box. Spin the the tires a little to get the crap of the tires. A burnout is not needed for radials.

2) Creep up until you set the pre-stage light, then creep ever so slowly until the stage just comes on. It's called shallow staging. This will give you about 8" of roll-out before the timers are tripped. It's basically like getting a rolling start. This alone can be good for a .05 second reduction and 1mph improvement in ET/MPH in the 1/4 mile. It hurts reaction time, but reaction time has no bearing the ET/MPH so who cares in this case.

3) Put the car in 2. Mash your foot on the brake. When the lights start to drop down, mash the gas to the floor while holding the brake. When you see the second set of yellow lights come on, release the brake. What you're doing to stalling the torque converter for about .5 seconds. You should come off the line around 2300-2400rpms and it should result in a low 2.2 or lower 60 foot assuming the tires don't spin much.

4) Manually the 2-3 and hold 3rd (if you running the 1/4 mile).


I usually always show up to the strip with around a 1/4 tank of fuel and I'll yank then spare and any loose items from the car like my tool bag, car seats, gym bag, all weather floor mats, etc. In my car, all this gear equals roughly 100lbs! I never understand why people choose to run their cars the way they on the street. You're at the strip you should do what you can to run a best. You only get so many runs.

Secondly, don't waste your money running when temps are above 75 degrees. It's just not worth it. For every 10 degree change in temp, it's basically .1 seconds. With my old VQ30 Maxima, the difference between running on a 95 degree vs a 50 degree day at .40 seconds and 5mph with absolutely no changes to the car, driving style, or 60'.

 

Thanks for the input regarding launch and shifting.

But you obviously don't understand my climate. I might get 3-4 days PER YEAR when the track is open to me with temps under 55 degrees. I ran tonight October 27 and the temp was 81 deg when I was running according to my G. This was after sundown.

Waiting for cooler temps is just not an option. We typically only get a couple months of cool temps per year. Even then the daily highs can be in the 70s. We usually go swimming on Christmas.

My car runs like a bat of hell on a cold morning when I first start running. - no way to measure the difference though. Hopefully I will get some cooler weather soon.

It's only $10 to run all night so its not breaking the bank.

Best run tonite:
R/T: .380
60' @: 2.239
330' @6.276
ET 1/8: 9.553
MPH 75.15

17s are still spinning too much. Next time I try with minimal brake torque at launch. Will a 3.7 rear FD just make my tire spinning issue worse?