Drag/tranny gurus help explain gearing!!!

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Alright, this is kind of a dumb thread, but I need someone with more factual knowledge than myself to chime in on why shorter gears are better for “balls to the wall” drag cars.

I’m arguing with my friend’s boss about why shorter gears are better, regardless of the application. Shorter gears=quicker acceleration. There is no other way around it. But he is giving examples that I cannot answer anymore. Given this is a full out drag car (meaning comfortability and gas mileage do not mean shit), why are shorter gears better.

I say, the shorter the gears, the quicker you get to your peak power.
Ex…Say two cars make 300whp at 5000 rpms, which car is going to get to the peak power faster? That’s a given, the shorter geared tranny.

So he says, “Yeah, but you have to shift twice as much”

He also says, “in a higher boost level (12psi), you cannot reach full boost due to traction problems associated with shorter gearing. First and second gear mainly.” In other words, you’re having to shift so quick (b/c of traction problems) that you can’t “ride the turbo out” to reach full boost because you are spinning. He also states, "while you’re shifting, the other car is being able to hold out their gear longer, so they can pass you. That the longer gearing will allow you to “ride out the power band.” In other words, stay in boost longer.

An example he said, “Why do drag cars use 3 speed trannies? They shorten the gears, but lengthen the gear ratio’s.”

He believes, in an all motor application, shorter gears are best. But for boost, it’s the longer gearing.

I realize that this guy is using traction as the problem with shorter gearing. But I would think that it’s the driver/builders responsiblity to compensate for the power being put to the ground. I mean, isn’t that what we want? More power being transferred to the drivetrain?

He says, “there is a point at which too much horsepower/torque (like 1300+hp in a fwd.) causes an amount of traction loss that cannot be compensated for in any way or form.”

I just can’t put into words, a factual, knowledgable, argument to this guy. He is the owner of a decent repped tuning shop around here. Please, let’s not turn this into an e-war! ONLY post if you know what the hell you are talking about, as well as supported evidence and factual information.
Thanks,
Chris

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You can stay in the power band for a longer period of time with a taller geared tranny, but the issue I ebelive is falling OUT of the power band on shifts. Short gears will always get you to top speed faster, but traction is a different story. In a 100% traction scenario, short is always better.
A big part of picking a tranny is matching it to your engines power band, traction, and other characterisitics.

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Everything YOU said is correct…you are letting him change variables like traction and what-not which make him seem somewhat correct.

Keep all variables the same.

Same car
Same motor/setup
Same amount of traction
Same power

Shorter geared tranny WILL out-accelerate and longer geard tranny.

Racing trannies, 3 speed or whatever are built for racing (duh) and in most cases they are automatic (just hit the lever) so the speed of the shift and how much shifting goes on are irrelevant.

I was going to draw a picture but think of it like a Stock graph with raises and dips on a timeline. When you are accelerating the graph is going up, when you shift, it momentarily dips and then starts going back up as you accelerate again and on an on until you hit that 1320 mark.

With a shorter geared tranny, the space between dips is going to be shorter, the shift dips are going to be exactly the same (as we are keeping variables the same and the guy shifts exactly the same no matter which tranny). Graph it out and there is much more area under the curve which is what we are interested in with the shorter geared tranny, putting the power to the ground that you are making.

Do a search on Honda-Tech as well…there are much better explanations (arguements, bitch-fests) on there.

HTH

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Also, regardless of what trans/gear ratio combo you go with, you want to be going through the traps pulling hard at the top of 4th gear. This can be achieved with the correct tire size, how high you rev the motor, etc…For example, a 400whp car with a B16 trans will need to rev to about 8800ish and use a 24in tall tire to be in the “sweet spot”.

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This article from Car Craft deals with changing the final drive ratio, but the general idea is the same:

http://www.carcraft.com/techarticles/1007/index.html

And Xenocron has it, your friend’s boss throwing in other factors which should be ignored. All other things equal, shorter gears will out-accelerate taller gears. Another thing, unless you’re taking 5 seconds to shift gears, you shouldn’t lose much from shifting more often… and in a quarter mile, “more often” would be what? One or two extra shifts?

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Everything YOU said is correct…you are letting him change variables like traction and what-not which make him seem somewhat correct.

Keep all variables the same.

Same car
Same motor/setup
Same amount of traction
Same power

Shorter geared tranny WILL out-accelerate and longer geard tranny.

yea but he is talking about it from a real world way and you guys are talking from a no experience standpoint, how many of you have driven a 1200whp fwd car and are able to say that “traction” must remain a constant? well news for you it CANT! what this guy means is that in a real race with an all out 1200hp fwd a longer gear tranny might be a solution to the inherit disabilities of a fwd platform. again from the point at wich this guy is arguing about he is correct. this guy owns a reputable shop and seems that hes known some guys that have high-horsepower fwd cars.

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So throwing in the example of a 1200 Hp RWD car proves his point about Honda tranny gearing how?

Please elaborate if you actually can…instead of telling everyone what they dont know.

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im not trying to tell everyone there wrong, sorry if it seemed that way. im assuming that the cars would be fwd because he said the “same two cars” and naturally i assume he means his integra. all im saying is that if you dont make traction an equal factor and instead assume a real world situation where traction between two different gear sets is indeed a factor on a fwd car. then instead you might need a longer tranny just to manage the amount of traction. sometimes being able to hook faster and get on the throttle sooner is better then spinning your tires the first 150ft and then accelerating expecially in a car that has 1000+hp traction is there number one concern.

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So, the shorter answer would be, “depends.”

10

yes :iagree:

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I think if you have the power to roll through the gears easily (turbo) then the longer the better, but I’m not only talkin’ about at the strip. On the street I would enjoy longer gears with a large amount of power. Of course the shorter the better at the track, unless you’re having traction issues. None of this by far is the text book answer, just my opinion that’s all. There’s a lot of factors if you think about it, so It Depends is one of the safest answers.

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short or long gearing

How about this… In the VW world the 6 speed trans with closer gears is slightly slower in the 1/4 mile than the 5 speed trans. but the 6 speed is better for autorcross… :think:

so depending on powerband and whan kind of driving, shorter is not always better. just my 2 cents

and when my car is done I will take pics and tell you what trans I am using…

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all the high hp hondas that i know, they all use shorter geared trannies… to help with traction issues, they simply use a dual/quad stage boost controllers… oh and slicks help too… if youre contemplating between a ls trans and a b16/gsr trans, you dont want to do the ls trans. but like driftlover said, it all depends on how much power youre making and your powerband and most of all… the DRIVER

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Traction is not the only thing to consider when it comes to tranny deciding. Some ppl are faster or slower when they switch from a B16 tranny to an LS. It really depends on your trap speeds as well and your redline.

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Wow, I started this thread like a year ago. Haha…