1/8 th mile racing. Suppose you have an engine that makes maximum HP at 7000 and continues to make about the same HP at 7100, 7200, 7300. Here’s the question. Would gearing the car to cross the 1/8 at 7300 be more consistent than gearing to cross at 7000 or same? What say you.

I think it depends on how good the car works because you are adding more SLR to the car, unless you do what I had considered doing. That is pulling gear out of the trans and adding to the rear. My car is only 2000lbs so I was looking at putting a 1.58 gear set in and adding rear gear to get the finish line rpm I wanted.

I think would be faster using all of you engine's power curve, just not sure whether it would add consistency. It would force a converter change also, if your converter is correct now.

I set my car up to be at about 6500 at the finish (estimated weight by hp) for which I needed a set of 5:23 gears. After I got my gears setup and was talking with a very experienced local who told me I would light 'em up at the start and it was more important to gear for a good launch.
Mechanical issues have prevented me from running so far, so I don't know if I'm good or not.

quote:

Originally posted by markemark:
1/8 th mile racing. Suppose you have an engine that makes maximum HP at 7000 and continues to make about the same HP at 7100, 7200, 7300. Here’s the question. Would gearing the car to cross the 1/8 at 7300 be more consistent than gearing to cross at 7000 or same? What say you.

A typical SS car the engine peaks at 74-7500. They go through the lights at 8800... IMO a race car makes all the ET in the first 1/2 of the track. Gear is your best friend and ET maker.

quote:

unless you do what I had considered doing. That is pulling gear out of the trans and adding to the rear. My car is only 2000lbs so I was looking at putting a 1.58 gear set in and adding rear gear to get the finish line rpm I wanted.

If you haven’t already, you might consider looking at the price of that planet. It’s extreme and carries extra clutches…… but I know little about transmissions.

I’m already at where you are considering on going being geared strictly 1/8 with a 1.56 planet and 5.14 diff presently.I have new 99 and 101.5 RO tires on the floor and a 5.00 gear set on the shelf. I'm trying to decide which way

quote:

Originally posted by markemark:

quote:

unless you do what I had considered doing. That is pulling gear out of the trans and adding to the rear. My car is only 2000lbs so I was looking at putting a 1.58 gear set in and adding rear gear to get the finish line rpm I wanted.

If you haven’t already, you might consider looking at the price of that planet. It’s extreme and carries extra clutches…… but I know little about transmissions.

I’m already at where you are considering on going being geared strictly 1/8 with a 1.56 planet and 5.14 diff presently.I have new 99 and 101.5 RO tires on the floor and a 5.00 gear set on the shelf. I'm trying to decide which way

Yes, I know the cost. I decided not to chase that set up but not because of the gear set price. Right now I go through at 6800 and if I wanted to optimize I needed to go through about 7500 and just decided in the end I'm just bracket racing. I don't need to chase every hundredth, plus I'm a pretty quick Footbrake car.

Another thought about gearing. The engine power curve is an important factor to consider. Many of our common bracket-race engines don't carry the power well beyond peak. If you gear to the point where the engine is nosing over, you have gone too far.

Kind of a parallel to Larry's comment above -

Most racers like to be the chasing car in bracket racing. Is quicker ET more important, or is higher finish line MPH more important?

Maybe consider whatever gearing maximizes MPH

My two cents:

Considering the cost of changing the gearing in either the differential or the transmission, (and it won't be cheap) first ask yourself if it's worth the expense. Either way it's expensive and the benefit is usually minimal unless you are considering running a specific class and can't cover the number. Shoe polish is cheaper.

This change also limits you to 1/8th mile tracks, and usually doesn't make the difference you had planned on finding. One last thing to consider is the change to your starting line ratio and how you intend on dealing with the potential new problem it will create, ie: traction.

Buy a blue bottle if "Faster" is really important, it's a ton cheaper and doesn't care if it's 1/8th or 1/4 mile, it'll be a lot faster everywhere.

Sorry for the intrusion, it was just my 2 cents:

Bob

quote:

Originally posted by SlyFox:
Kind of a parallel to Larry's comment above -

Is quicker ET more important, or is higher finish line MPH more important?

Yes

The question was about consistency bracket racing strictly 1/8 mile. If I wanted faster I’d increase the size of the 388 I presently have.

I prefer slightly less SLR to aid when track conditions become poor even though it gives up some ET. Leaving wheels down is also more appealing to me.

A loose converter is more consistent than a tight one. So I’m wondering is running an engine at it’s peak hp longer (7000 -7300+) in the same distance (1/8) more consistent than achieving only the initial peak (7000).