Drag Racing Tech - 26" Tires with 3.42 vs 28" Tires with 3.91?

I am thinking about swapping rear gears on my GTO to try something new. I do a lot of 1/8th mile racing, and would like the extra kick out of the hole. How will 3.91's with a 28" tire compare to 3.42's with a 26" tire? I am not even sure I can fit 28's yet, but it is just a thought at this point.
BTW, the car is making 500/500ish, and has run a best of 7.15@96.

I would go with 3.91 and a 28. I assume you already have the spray on your car. More kick=bigger jet.

I would go with 3.91 and a 28. I assume you already have the spray on your car. More kick=bigger jet.
No spray. Magnuson mp122h.

id go 3.91s keep the 26 and if you the the limiter then switch to 27- 28

Is the car stick or auto? Stick= 28in. no doubt and a stiff wall at that.
Auto= It probably depends on your stall.

Is the car stick or auto? Stick= 28in. no doubt and a stiff wall at that.
Auto= It probably depends on your stall.
Auto
Fuddle 3200 2.1 str.

26" with a 3.42 would be where I would start. The tq from the supercharger will go well with the "wide" gear ratio. If the car overpowers those tires at the hit of the throttle, go with the 28's. A tire that tries to "roll over" itself while hooking at the same time is going to create wheel hop. A taller tire is less likely to do this, think of a NHRA Pro Stock car when they wheel hop.

I hope that makes sense.

I am thinking about swapping rear gears on my GTO to try something new. I do a lot of 1/8th mile racing, and would like the extra kick out of the hole. How will 3.91's with a 28" tire compare to 3.42's with a 26" tire? I am not even sure I can fit 28's yet, but it is just a thought at this point.
BTW, the car is making 500/500ish, and has run a best of 7.15@96.
Your suggested gear tire swap will net you right where you are now. I would do the gear swap and stay with the 26" tire. I run MT 26" drag radials with 3.73 gears and they stick, running off a t-brake with 4000 stall.

Your suggested gear tire swap will net you right where you are now. I would do the gear swap and stay with the 26" tire. I run MT 26" drag radials with 3.73 gears and they stick, running off a t-brake with 4000 stall.
Please don't take any of this as arguementitive. I am merely relaying what I know to be true on my car, and what I have used.

I am making over 450ft/lbs to the wheels from the engine alone. When I leave, I leave off idle, and flash the stall. I have been running 275/40/17 MT DR's for the last year. (been through 2 sets) I know these lack sidewall, but until the recent mods, they worked well.

That said, I just bought some 26x11.5x16 ET Streets (bias ply) and had them mounted on a set of salad shooters. I am hoping the more flexible sidewall, and increased sidewall height, will help me overcome my traction issues.

At that point, I am worried that the gear swap will introduce more traction issues. That is the reason I was asking about 28" tires. If I run a flexible sidewall tire, then at lauch the diameter should be smaller, allowing me to take advantage of the new gearing. But then, when I am past the 60' mark the tires should grow so the car will act like it does with the 3.42's and 26" tires.

Am I wrong in any of this thought process?

Personally, I would stick with radials on an automatic car. Unless you put skinnies on the front, you will have that dreaded "top end sway".

M/T is coming out with some more 16" radials, and M&H makes a 28" tall DR that fits a 16" rim.

Al

Personally, I would stick with radials on an automatic car. Unless you put skinnies on the front, you will have that dreaded "top end sway".

M/T is coming out with some more 16" radials, and M&H makes a 28" tall DR that fits a 16" rim.

Al
Yeah, I am going to have to learn what the sway is all about. I had tried to avoid it up to this point, but I now have the ET Streets.
The problem was the lack of selection in MT 16" radials, and I did not want to spend the $ on 15" wheels, as they would have to be welds, or bogarts. I got the salad shooters for free.:drive: