The car is a 99 TA w/ 346 cube cam only on a 200 shot, TH350, 4:10 gear, 26x10 ET Drags, about 3350lbs w/driver

Put the car on the dyno last weekend and tested out the nitrous system. Only made one nitrous pull and ran into some fueling issues but I also noticed that I was running out of gear fast. I pulled to 7000 RPM and it was right about 125MPH. The motor can handle up to about 7500 if it has to (still increasing power at 7000), but I don't know how much MPH I can get out of another 500RPM. With the fuel issues, it put down 550hp through an unlocked TH350. With the issues worked out, we suspect closer to 600hp, so I figure a trap speed near 135mph?? (someone correct me if I'm way off here).

The way I see it I'm clearly going to run out of gear on the bottle. So would I be better off going to a taller tire or going down in gear??? I haven't run it at the track with the TH350 yet, but I figure the more gear the better, considering its 2.52 1st gear. If I go taller on the tire, how much taller? Or how much less gear?

Thanks guys.

 

Put a 28 inch tire on it. I ran 4.10's to 140 mph with a 28 and the car was just about at 7000, depends alot on your converter's top end effeciency... if it's not slipping much (less then 7%) then you should be fine.

 

Like ^^he said! 28s should be about right!

 

I would step up to a 28" tire.

 

Ok, I've also been considering going from bias ply tires to radials. I've kind of felt that the ET Drags are a little overkill with me launching only on the footbrake. I've seen some very fast cars running on M/T radials lately and I'm sure they're much more stable at the top of the track. The car is also not making much torque (I think that's mostly to do with the Victor Jr intake), so do you think I can make it off the line on a set of 275/60/15 ET street radials without going up in smoke?

 

Radials are gonna take alot more suspension tuning time then a slick will. Guys hit that radial hard enough to 60 foot in the bottom 1.2x range in the 275x class... so it's doable, just gonna take more setup time.

 

the good thing about a slick is they will grow on the top side, radials won't grow like a slick will.

 

And to add to that, once you blow the tire, on a radial you cannot recover a run. So the "Hit-or-Miss" situation starts.

The reason you want more tire as you will gain in sidewall flex and contact patch will matter more then gearing it down. When you gear down, it will effect all your trans gears. BUT getting out the hole requires a steeper ratio BUT only if the tire/suspension can hold it so there is your fine line.

I have said this ever since I started racing that Gearing and Converter choice are always the last thing to pick and you may end up with 10 different set ups due to the fact that every car is different and you can see multiple track conditions when you go.