We told you those 20s were killing your cars performance

A 9.55 in the 1/8 equates to about a 14.80. Considering the conditions at the strip according to wunderground.com, the density altitude was ~1,600' which isn't horrible. The DA conditions would impacted the 14.80 1/4 mile run by ~.15 seconds so that means you're looking at 14.65. That's respectable. Put the 17s on the front and get the 60 foot into the 2.1 range and you're looking at 14.4s in the 1/4 or 9.2s in the 1/8. That's quite a change for 9.9-10.0. You might think those 20s looks great, but they kill acceleration, handling, braking, suspension response, and MPGs. That's a lot of compromise just for a look.

 

Unless you get a Shift Kit - then you can shift fast enough not to miss the 1-2 every time

 

Yes, 3.7 will make you spin a lot more. If you want traction you need better tires. What rubber you got on those rims right now?

 

So I went to the track on my 20's to compare apples to apples but change my launch from VDC ON to VDC OFF. To make a long story short- first run I screwed up and left VDC ON- but I ran:
60' - 2.302
330' - 6.392
1/8- 9.694
mph- 74.16
** Sat night due to the volume of people I had to roll thru the water before lining up. Did no burn outs and launched with VDC ON to avoid the tire spin. On Wed nights typically less people and they will let you enter through the center and avoid the water. So no water on my tires for this run. No pre-race burn out.

Second run with VDC OFF start in MM2 and shift manual to 3:
60- 2.302
330- 6.444
ET 9.765

Third Run VDC OFF start in MM2 slap to D during second
60- 2.337
330- 6.448
ET 9.763

4th run- Red lighted RT: -.073
2.413; 6.507; 9.811

Then I ran home and put 17s on the back only:
First 17 run was my fastest overall run of the night, but not by much.
VDC OFF - no water no burn out start in MM2 slap to D after 2

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

Next race- VDC OFF - no water no burn out
MM2 manual to 3
2.269
6.351
9.638

Next race- VDC OFF - no water no burn out
no 60 split
333- 6.368
ET- 9.66

next race - VDC OFF - no water- Burn Out attempted (not very good) MM2 manual to 3
2.402
6.482
9.769

Last race - VDC OFF drove thru the WATER & Serious Burnout from MM1 thru MM2- just reving and spinning at will.
Launched in MM1 slapped to D after hook
2.254
6.340
9.635

 

I know!! Had to compare apples to apples to gauge the upgrades. 20s weigh in at a whopping 59.8 lbs each (wheel and tire, no lugs) 245/35ZR20

17s I ran last nite in the rear are from a 350z, tires are 225/50. Weigh 48.6 lbs each.

Yes, I do think they look great!! With those black rubber bands wrapped around the 20's, they actually handle corners awesome!! Note, I have a G/Z-Track set up, with 350z Track sways F & R. Unless you spent a couple grand on coilovers and aftermarket sways, its a hard set up to beat, especially for the money. Got the Z Track 4 springs and both sways for $40. Approximately 20k miles on the stuff. One man's junk is another man's treasure!!

Well in theory yes, but the 3.7 is posi-traction!! Maybe lightweight 16s with 225/65s in back?

Maybe for straight drag racing I should weigh the back down? What else can I do to prevent excessive tire spin?

Thanks guys. We will get this old beater down into the high 8s soon!! Keep the suggestions coming!!

 

I can assure you that if you did an auto-x event, you'd quickly find out those 20s won't stick and handle corners like you think. The lack of sidewall gives the tires absolutely no chance of displacing the contact patch, either for handling, braking, or acceleration.


As for the 3.7 gear set, you'll kiss your cruise control goodbye if you do the swap. You can run the 3.54 swap without CC issues, but the 3.7 swap will impact your 03's CC operation. A typical LSD does not improve off the line traction assuming both tires are on the same type of surface. The advantages of LSDs are in the corners, especially slow off-camber turns where inside tires tends to get lit up and acceleration is lost. Most LSDs only do a certain percentage of torque transfer. The OEM VLSD only can transmit about 30% of the torque to the non-slipping wheel. It's not capable of doing a 50/50 split or greater. It also takes a split second to operate. This is because the LSD device has numerous clutches in a sticky fluid and slippage is what warms the fluid and engages the clutches.

 

Here's what I'd do.

Either find some lightweight 16's or just use your 17's

Buy a pair of drag radials. They are steet tires, but softer compounds for dragging. They require heat, so a good burnout is necessary. Get em hot and they should stick like glue. I've dumped the clutch on these and barely get a chirp.

They would prob take care of your traction issues alone.

Also, don't keep the 20's on up front. Def go with a lighter smaller wheel...with a narrow tread.

Until then, other small tricks....

Overinflated your front tires to just under max pressure. This will decrease rolling resistance. Let the air out of your rear tires a bit to make them softer and less stiff. The track should have an air machine for this. Sometimes lowering the psi in the rear tires helps with traction. If stock pressure is 30 psi...try 20-25 psi.


Add weight over the right rear tire. Keep in mind this will slow youndown top end.

Typically, this is my technique with an automatic car at the track. Stage and mash the brake pedal with left, while revving up to stall speed on the converter with my right.

On the last yellow light, let off the brake, but do not floor it just yet. The car will begin to move forward. Now, because of the difference in speed inside the stalling torque converter, you have some time for engine speed to match trans input shaft speed...might be 1-2 seconds. Basically the car is going to catch up to the speed in which the rpm you were flashing the converter at the line at. At this point, feed in the throttle.


Hard to explain, but easy to perform. Basically don't mash the gas on the green. Two foot it, and let the car move against the stalling converter before feeding in the horsepower. You'll find this cures a lot of traction issues because you aren't shocking the driveline all at once. Let the converter absorb it.


FYI...if you plan onndoing this a lot, invest in more frequent retrains drain/fills and possibly a trans fluid cooler.

 

Just get stickier tires and practice launching. You will get it. Unless you are running ridiculously overkill tires you will never be able to mash it off the line and just hook without spin. The 3.7 with posi will help you. Yes you will be more prone to spin off the line but after you have traction the lower gear ratio is only going to benefit in addition to the benefit of a posi.



All good tips except I don't really agree with this one. It works very well for cars with straight solid rear axles. Its not really beneficial for independent rear suspension cars like these because of the way the differential mounts to the car.

 

Here are my 225/50R15 BFG DRs on the 9lb 9-spoke Mazda Millenia rims. The rim clears the rear calipers by about 1/8".

 

Agreed the 20s are not optimized for any other than looking sexy. I need all the help I can get in that department!! I really do want to get the M19" Sport Wheels though.


Are you sure I lose the CC with a 3.7? What if I crack the case and just swap out the internals? I need my CC!!

Looks like I might just go nitrous. Easier and cheaper.

I didn't really intend to keep the 20s up front- just had to hurry to get back to the track before it closed. My son had my Air Impact Wrench in his car so I had to do it by hand- arggg
next time I will have my stock G wheels up front and Z 17s in the back.

Got the staging thing down pretty well- I started drag racing at real tracks nearly 30 yrs ago. Also did SCCA road course racing. 1970 Datsun 240z- eat your hearts out!!!

Long story but on Wed nite I got waved up by Walt the one-arm wonder- water-boy (Sprays down the lanes and acts as a lane spotter. I'm going thru the middle to avoid the water and the other (more senior) lane spotter pounded on my car with his fist and started cussing me out. So I roll down my window and very respectfully asked what the frick his problem was. He cursed at me some more and told me to follow the rules and the spotters. I told him Walt the one-arm wonder- waterboy waved me up- he asked waterboy and waterboy admitted he waved my up. So pyscho spotter starts screaming and cursing at waterboy while I'm just sitting in limbo in the middle of the track. So I ask pscho spotter what the F he wants me to do now that I am lined up- does he want me to reverse it out or just make the F'ing run. he apologized to me and told me to run- I thanked him and politely told him that if he ever touched my car again I would get out of my car and whoop his *** in the middle of the track.

So I am making a solo run after all this drama. I stage, then I got the "Top Fuel" tree. RT: .741 If your not prepared for it, it goes by fast- it was green before I realized what had happened. waterboy was nice to me the rest of the night- but psycho spotter wouldn't even look at me again.

BTW, on my first run the tower didn't have my Car Info/time card yet. They introduced me as a "toyota, no mazda maybe, could be an acura- well folks I'm not sure what that is but it is a good looking new import"- I had to chuckle.

I mash to the floor at the 3d yellow- I'll try back off some on the throttle at launch- it won't feel right, but I'll try it.

It seems like bracket racing would be cake in an A/T. I'm trying diff launches and shifting and my times were relatively consistent. I'm thinking bracket, leave in D with VDC ON. Won't be my fastest ETs but I guaranty I can be consistent as hell and take home the money.

They say a "cold front" may be coming our way, so maybe I can get some runs in 60 deg weather.

 

Nice find. 9 lbs is crazy light!! What years will work? What does the tire/wheel combo weigh in at?

 

I believe they're rims that came off the mid-1990s Millenias. They're 15X7s. The entire wheel combo weighs in at around 35lbs, if I remember correctly. Super light compared to my OEM 17" combo which is something near 48lbs. I've only made two passes on the DRs and that was back in 2005 that very first time I ever ran the car at the strip. Running these shorter DRs basically change the 5AT rear gear from a 3.34 to a 3.55. The downside is it forces you to shift into 4th about 200 ft short of the finish and it hurts performance.

Conditions that day were in the mid 70s and my mods were a Z-tube. My best on the OEM 17s was a 14.49@97.6mph with a 2.28 60'. I held 3rd the entire run. With the 15" DRs, the car went 14.50@95.8mph with a 2.20 60'. With either the 17s or the DR, the car didn't spin. The DR improve torque multiplication off the line hence the better 60' and similiar ET to the 17s, but that shift into 4th negated any additional drop in ET and it sucked out some MPH.

Now I have the 3.54 gears out of the 6MT. Teamed with the DRs, the overall ratio would be closer to a 3.8. Obviously I'll have to shift to 4th again, but I should probably be a bit further out from the finish. I have no idea if this combo will make me any quicker or not. Hopefully I get this tested before the strip closes for the season.

As for the 3.7 gears, you will most definitely loose CC. There's no way to fix the issue either. It's not the old days where you'd exchange the speedo gear to correct for gear ratios. The CC on our cars get readings from the driveshaft and wheel sensors. The 3.7 gear through the CC reading way out of whack therefore it doesn't engage above 60mph or something like that. With the 6MT 3.54 gears, you'll have CC until around 80mph or so. The 04.5+ cars don't seem to be affected by rear ratio changes. IMO, a 3.7 gear seat is a bit too much gear for daily driving in a relatively low revving V6 like our VQ35DEs. If you had a Rev-up or cams, it would be a different story.

 

Well, you could figure it out...but not easily.

Actually scratch that. If i had an accurate model of the wheel and tire rendered in CAD, i could prob do it fairly easily. Of course making the model is another story, but i could prob ballpark it.

But you are 100% right. Take two wheels that weight exactly the same...one 15" and the other 20". Even though they weight the same, the 20" wheel will require more energy to spin vs the 15" wheel due to the majority of the mass being located farther from the hub than the 15" wheel.

Most of the wheels mass is in the wheel rim part which contacts the tire and seals the air inside. The spokes don't weight much depending on the design. The hub might have some weight, but it's close to the center of rotation.

 

I've come accross 19" tires that weigh 26-28lbs (RE050s) vs my forged coupe 19 wheels that weigh only 19-20lbs. IMHO, much of the weight is in the tire. Or at least as much as.

 

I have an early 03 sedan with the crappy ecu- so others with the similar ecu may want to take a look at my mods to get an idea of what the motor can do without an ecu upgrade or tuning.

I had the car dyno'ed yesterday for the first time ever. Done by Bobby at S&R Performance. Result on first and only pull was 255 hp at the wheels. I took a pic with my phone of the computer screen showing the results, but it didn't come out very well. It shows second pull on results, but the first was just calibrating and checking.

Don't know which mods are responsible for increase in hp over stock, but Bobby said he was impressed with the performance gains I had gotten out of my rather modest mods. He said it was the strongest running 03 he had tested without significant mods (i.e., turbo or supercharged).

I'm tempted to start unbolting and re-testing to see where the gains are coming from- then again- if it ain't broke- don't fix it!!


As I was imagining how ugly those Millenium wheels would look on my car, I kept thinking I had seen a set of wheels/tires recently that looked just like those. Sure enough, my son's stock 16" wheels from his 95 Mits 3000GT look nearly identical to the millenium wheels except the Mits wheels only have 7 spokes. they weigh in at 42 lbs each, 2 lbs lighter than my 17" 350 wheels and 16s should carry the weight closer to the hub than 17s. So off to the races on the ugliest wheels I own!!! The 20's weigh 60 lbs each.

Unless something unforeseen comes up, I'm going back to the track tomorrow night with the 16s (215/60r16- not ideal, but better than the 20s) all around. It should be significantly cooler so watch out- I'm feeling a sub 9 run coming on!!!!