Is 16.6 seconds a normal 1/4 mile time for a 1997 Auto GXE with 18" TSW Trophies, a 75lb speaker box, and no spare tire?

I'm trying to figure out if and why my Max is slow. I get code 0505 (everything's normal) when putting the ECU in diagnostic mode.

My mods:
Crappy homemade Pop-Charger (K&N Filter and adapter)
Warpspeed Y-Pipe

I also have a MEVI, but it was turned off when I ran.
With it on I ran 16.2, which I still think sucks, but is a nice improvement for 1 bolt on.

Could some of you more skilled mechanics give me ideas on what to look for? The car feels fine when driving.
No strange sounds or smells, no excess oil burn, exhaust is white sometimes when cold, but otherwise no smoke.

When I Dynoed a few weeks ago i was running a little rich, (Fuel/Air was 12.5, but not terrible.)

And I just did a tuneup 3000 miles ago:
Replaced plugs with NGK Laser Platinums
Cleaned K&N Filter
300Z Fuel Filter
Tranny Drain and refill with Redline Synthetic
Throttle body and entire intake is clean as a whistle from the VI Install.

I did not do the PCV Valve, however.

Thanks for your help.

IanS

 

I suspect that your catalytic converter is clogged. How is your gas mileage?

 

300 miles/tank. has been about that ever since I got the car at 32k miles. Also, the car's performance doesn't seem any worse than when I bought it, but of course, that could just be because whatever it is happened over time and was not noticable day-day.

IanS

 

You don't by chance weigh 400lbs?

 

I know that some mechanics temporarily remove the O2 sensor from the exhaust pipe ahead of the catalytic converter and look for a change in performance.

 

Those TSW aren't remotely as light as you think. The 15X7s weigh a whopping 19lbs. I can only imagine the 18s weigh close to 27-28lbs. That alone is worth .3-.4 seconds and a 3mph. That 75lbs of speaker weight is also killing you. 75lbs of weight will suck out atleast .1 and 1mph, probably more. Those two "weighty" mods are sucking out a soild .5 and 3mph. What did you run EXACTLY:

60 foot
1/8 mile and mph
1/4 mile and mph

Conditions: temp, humidity, baro (check www.wunderground.com for historical conditions of your area)

300 miles per tank is pretty bad (~19mpg) if you don't drive with a lead foot. Those wheels and stereo aren't helping things either.


Dave

 

Uh...no....190.

 

The best milage I've ever gotten was 360 on a tank on a long freeway drive for 400 miles on cruise.

Here's my slips.

http://www.cyberhub.net/intake/installed/timeslips2.jpg

IanS

 

Interesting...a few weeks ago I looked up the TSW Trophy 18's on the wheel weight (forget the URL) site...

It said they were 19lbs.

IanS

 

Ian, I'm as stock as you can get and my last track run was 15.62. This is with the stock intake, less than 1/4 tank of gas, no spare, no sub box (35 lbs) and stock 15's. Weight is your problem. You need to lighten your car.

 

Oh yeah, forgot to mention...car dynos at a peak of 155hp.

So I'm not 100% sure it's weight.

IanS

 

Do you have a Y-pipe? I forgot to add that my tire pressure was set to 22 pounds.

 

Guess I'm not the only one having problems at the track.


Did you go through the water box or did a burnout? I talked to a few people that told me doing a burnout on street tires isn't a good idea. I couldn't get much traction after doing that. I had my tires at 22psi front and 35psi rear. Next time I'll try not doing any burnout and keep the tire pressure at street level of 35psi all around. I could only get a 15.6 the last time I went. I have more mods than you though, so I should have done better. I also did all my 60k maintenance of fuel filter, knock sensor, ATF flush, but didn't change my spark plugs because they seem fine. I just recently replaced the PCV valve too.

Hope you can figure out your problem.

 

No, I steered around the water because I'm on street tires.

I also was at 32psi all the way around.

IanS

 

Dude, drop your tire pressure in the front to allow the contact patch to stay larger than it would if you ran at 35psi. When you jump off the line the front of your car wants to lift up and when that happens, your tire's contact patch is decreased. theblue helped me with that piece of knowledge and he's right. I just did my tuneup and I know my car's faster now. I can't wait to hit the track again.

 

Well that's weird. When I ran my best to date of 15.4, I ran with 35psi all around, almost full tank of gas, stock rims with crappy no grip stock tires, and with one less mod(Don's VB). I manually shifted all my runs that time.

I tried the tire pressure at 22psi and 25psi, didn't help me one bit.


One thing though, I'm unsure if my tranny is shot or not.

 

Wow, that kind of sucks in terms of mpg unless you only went down to a quarter tank. I can do 500+ miles and that is highway cruising from 75-85mph. Admittedly mine was across Kansas and Western CO so it was true highway; long, straight, flat, god-awful boring, and no traffic to play with.

 

The weight and rims are killing your times Ian... See if you can borrow someones rims around here and take that sub out next time you go to the track... Are they open on Sunday or Monday? If so, hit me up and I'll go with ya, you can use my wheels and I'll help ya out on the rest...

 

Every one pound of unsprung weight (in this case your front wheels) is equal to about 8 lbs. of dead weight (weight in your car). We will assume the tire maintains the same weight, although most 18" tires weigh more than 15" ones.

The 15" TSW Trophy weighs 19.0 lbs. We will assume your 18" wheel weighs 26 lbs, again giving you an advantage as they most likely weight more. Stock SE wheels weigh 19.6 lbs. That is a 6.4 lb. difference per wheel, or 12.8 for both wheels. Now to convert that to dead weight, multiply by 8 and you will find it comes out to 102.4. Add 12.8 lbs. for the rear wheels (as they are dead weight because they are not on the drivetrain), and 75 lbs. for the sub box.

This means your car has approximatley an extra 190.2 lbs. inside the cabin. Another you. Don't you think an extra person makes a difference in acceleration? A comparison of my best G-Tech 0-60MpHs should also show a difference.
Alone: 6.88
150 extra lbs: 7.31
250 extra lbs: 7.65
350 extra lbs: 8.82

So yes, added weight makes a big difference in acceleration.
-Cyrus

 

Very intersting breakdown. Don't forget, you just calculated the difference in weight between the larger rims and the smaller rims, but the difference is actually greater than what you calculated because when it comes to a rotating rim, it depends on the distribution of mass; 18's have more mass furthur from the center than a 16. So, the difference in weight and the effect it has on the car is a lot more than we think!

 

Very true as well! MR^2 you can do the math yourself! Big rims hurt performance, there's no way out of it.
-Cyrus

 

Yes, Bu I know people with sub boxes and 18's have gotten better times than I have.

IanS

 

Most people's wheels are lighter than yours though. Remember, each pound per wheel is equal to 8 lbs. in the car, and that makes a difference! Also do they have more modifications? How are their reaction times?