I realize you've been around and know the game, but you will slow down, and ultimately that is what i was alluding too, you'll see first hand in the next few months, so that's neither here nor there, it's gonna get slower. i have no doubt, and neither should you, that the good spring time air, cold track or not is what allowed you not stay where you were at for this first round of testing. Spring/fall weather is always good for at least a .2-.4 ET increase, then you get into what i call normal summer time weather and your right back to where your "typcially" at with summer time DA's in the 3300'+ DA's that i'm sure you run in also during most of the year. Maybe your 396 will carry on the BBC powa tradition of not getting affected too badly by minor changes like this, but i still believe it'll slow down from seeing it happen everytime a guy went to taller tires and the same gear unless they were waaay off initally gear wise and the taller tire made the combo better.

big tires are where it's at though, better traction, more consistant 60's, less burnout/longer tire life, etc....i'm axious to get my new gear installed so i can see what my car can really do...weather it'll get me back the .3 I lost the first time i went from 28-29" tires, i dunno, but i'd be a happy camper if it did

 

Engineer, you didnt trim the wheel opening to fit the 29's? I have 28x10.5 w's on mine and they are VERY close to touching.

David

 

Funny you should ask about that!

Yes they are trimmed, and I ended-up and did it myself. I cut-out the inside lip out of the rocker on the front with a metal cutting saw. Then, used some Bondo to fill-in between the inner and outer panels. I had some spray paint (can) mixed-up and repainted that area.

On the rear, I removed the flexible body part and trimmed the metal back. Then I slotted-out the bolt holes in the flexible panel, pushed the panel back (wedge between the slick and panel) and used some stronger ¼-20 bolts to bolt it down and hole it back. However, the 29” slicks have still rubbed the panel in the area. I also cut some of the inside lip off the flexible panel.

The 29" slicks are the way to go with out F-Bodies, most of the NHRA stockers and super stockers have 29s, or 30s (with the correct gears, I have 4.30s). Here are some photos of the finished work. My paint work isn't too great, but it gets the job done.

WD

 

Can you take some pics of the rear plastic and inside of the front of the well with the tire off? DId you tape off the fender and cut to save the paint?

How far up the front did you start the cut?

I have some 295/65 drag radials I want to use with the spray, but they dont fit. They are 30 tall.


David

 

I don't agree with that statement at all. They are one way to go with an f-body.
I used 275-60x15 Hoosier drag radials on 15x8 Prostars last summer. They are 28'' tall and I run 4.10 gears with a spool.
This is on a car that is a decently set up drag only car and I pull consistant mid to high 1.4 sixtys. All season I NEVER had a bad 60 and I run nearly the same numbers that you do.
The best part is that I didn't have to do any body mods at all. Bolt them on and run.

 

Anytime you can increase roll-out your car gets better and more consistant.

 

My statement was basically a compairson to using 28" slicks. However, I do believe (as do many others) the 29s with the larger roll-out will typically yield more consistent 60 fts on an average.

Your DRs could be one of the exceptions to the rule. Although, I'll stay with my 29" Goodyear slicks, as I've seen people at the track have problems with DRs (high 9, low 10 cars), while the traditional slicks didn't have any problems.

Also, I don't see any of the stock or super stock people running RDs at NHRA Lucas Oil events.

WD

 

Squeezing 29's in there was quite an accomplishment.... I had to do axle relo and bumper cover cutting with 28's. A buddy of mine needed a decent amount of body work to fit 29.5's.





You have to keep in mind the specific goals of the driver... you want extremely consistant performance for bracket racing. Others might be looking for the lowest possible ET, which can possibly be hurt by tires that are too large. It takes more energy to bring the larger diameter tires up to trap speeds. They not only weigh more, but the center of mass is farther from the axle.

 

Also people forget, the heavier the car the more tire thats needed to get the girth moving.


David

 

I want it all, consistent performance and lowest possible ET!

According to my 2006 Goodyear racing Drag Tire Data book; the 28" (PN: D2001) weight is 23.1 pounds and the 29" (PN: D2004) 23.0 pounds. Hey, that is what the book says, basically the exact same weight.

Now, I don't know if that is correct, or a mistake. Possibly the larger 29" have a thinner sidewall to keep the weight down. I weighed the 28s I took off and they were 20.5 pounds with more-than 50% of thread remaining. However, I didn’t weigh the 29” before they were mounted.

I also was surprised that I was able to get those 29s on my car without any extensive work. However, they are slightly rubbing the flexible rear bumper cover, probably mostly during the burn-out.

WD

 

Yeppers, I run a series called the Street tire shootout which as the title implies requires the use of DOT approved tires. I started out with bias ply ET streets then Hoosier QTPs. Last year was an experiment with the Hoosier drag radials and it's a winner. Extremely consistant at my 3340 raceweight.
I'm not trying to argue that either tire is better, just that there are other options out there that are largely overlooked.

 

Are these pics at stock ride height? If so its sits alot higher than my car.

David

 

That photo was taken on the trailer and I have a floor-jack under the rear-end (slicks are about 1 1/2 ” off the trailer), which makes it look really high. I had just put the new 29s on and as checking the clearance. But the wheel well open and the top of the slick relationship are correct.

Also, I have Eibach asymmetrical drag springs on the back which are very tall. As I recall, those springs lifted the rear almost 2” or more when I installed them. I have considered cutting one turn off to slightly lower the rear end. I've added another photo which provides a better view.

David, are you going to the LTX shoot-out? I’m already entered and planning on being there and running in Heads-Up N/A

WD

 

Everyone wants a wider tire. Wide isn't always a good way to go. It makes a wide contact patch that's only on the ground briefly.

A tall tire makes a longer contact patch on the ground. A spot on the tire stays on the ground longer for better traction.

Factory tire height is 26". Going to a 28+" tall tire even with stock width is more effective than going to a wider 26" tall tire. Of course, going to a taller tire also requires a gear change.

 

There is a pretty simple way to get a 30x9 slick under a 4th gen...I have seen it done at several chassis shops but its not something that gets told......And it does not involve hacking anything up.

I know a few guys running LT1 stockers.....the tall tire is the way to go for them. But not everyone.

I run a MT e.t. drag with stock rear springs and the tire is up under the lip of the fender about 1/2" or more......sits alot lower than the silver one. Does that have stock springs?