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Procrastinator
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Discussion Starter #1
Well ill be rebuilding my rear end soon if everything goes well and im considering a gear swap. I currently have 3.73s in, but im thinking the extra mpg cushion that 3.55s will offer might make it worth swapping. Right now playing with all sorts of numbers, 3.73s look like they are the gear I should have. If all goes well with my 5.4 swap, ill make somewhere between 400-500hp NA and I have every intention on spraying on top of that. With 3.73s, ill be good to ~140, 3.55s will take me to 147. With spray closing in on 140mph is looking like its possible so im wondering if I should swap in 3.55s just so I don't have to worry about running out of gear. Any opinions are welcome.
 

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Procrastinator
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Discussion Starter #3
On a 1/4 mile track. I wont hit 147, but 140 might happen so thats my problem. I don't really want to fix the problem by adding revs and I dont want to have to buy different tires to fix a gearing problem.
 

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your not taking into account the mechanical leverage a drag car needs.

if your planning on staying N/A, 3.55 are out of the question, 3.73's would be a minimum.
 

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Discussion Starter #7
Is running a taller tire at the track an option? If so, I'd keep the 3.73s
3.55s are cheaper to get than a new set of taller tires and ill already be in the rear end so it wont be any trouble to change them. I see the taller tire solution as an easy fix for improper gearing. There isnt much of a difference between 3.73 and 3.55, maybe it wont be a big deal to add 200rpms. I really dont think ill clear 140, im just thinking 3.55s would be good insurance. Is there any advantage to having longer gears with higher hp cars outside of traction?
 

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Discussion Starter #8
your not taking into account the mechanical leverage a drag car needs.

if your planning on staying N/A, 3.55 are out of the question, 3.73's would be a minimum.
Well even without spray im looking at making more hp/tq than most of the supercharged 2vs running around on the forum, so with that power are 3.73s still a must?
 

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3.55s are cheaper to get than a new set of taller tires and ill already be in the rear end so it wont be any trouble to change them. I see the taller tire solution as an easy fix for improper gearing. There isnt much of a difference between 3.73 and 3.55, maybe it wont be a big deal to add 200rpms. I really dont think ill clear 140, im just thinking 3.55s would be good insurance. Is there any advantage to having longer gears with higher hp cars outside of traction?
a high horsepower N/A car needs rpm & a car as heavy as a new edge car needs mechanical leverage if your looking to get the most out of it.

I'd look in the area of 4.30's with a 28" tire as a starting point for comparison.

the gear will give you the leverage & the 28's will make it manageable.

with either of your gear choices & the power level your talking about, you'll never see anything near 140.
 

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Well even without spray im looking at making more hp/tq than most of the supercharged 2vs running around on the forum, so with that power are 3.73s still a must?
it really all depends on how serious you are about the track in general & et's in particular.
 

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Or the mpg that you so greatly desire unless being ever so diligent on the pedal. Expect $5 per gallon by Memorial Day.
 

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Do you know what kind of power you need to trap at 140mph? Some serious power and weight reduction. I would go with 3.73's. But even like casper said, 4.30's with 28" tires would be good.
 

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Discussion Starter #13
it really all depends on how serious you are about the track in general & et's in particular.
Trying to beat my brothers 750 so im not going to try to keep my car a DD. Car is going to be stripped, right now the debate on weight reduction is if I want to keep the AC or not, then any weight that can be removed within reason is getting pulled. The 5.4 motor im working on might very well sit above 450hp, and after that ill spray whatever is needed to beat my bros 9.8 @ 135mph. A quick glance at newedges with ~600hp that get a decent 60" and I see high 9s with 135+mph. Im not expecting a 145mph trap, I just dont want to get caught running out of gear.
 

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im not sure what i would trap in the 1/4 but with my crap driving i hit 101 in the 1/8th with 3.55's and a 26 inch tall drag slick on 630 rwhp and 571 tq. so i would say if your running na mid 400's with a big shot of spray 3.55's would work with a 26 inch tall tire. but running 3.72's with a 26 inch tire may run out if your not pulling enough rpm.
 

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Discussion Starter #15
Well beeing optimistic lets say the 5.4 makes 480, then maybe I spray a progressive 175 shot that goes as fast as traction allows. That has to put me close to 140mph, and I really want to avoid any more revs than needed.
 

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Well beeing optimistic lets say the 5.4 makes 480, then maybe I spray a progressive 175 shot that goes as fast as traction allows. That has to put me close to 140mph, and I really want to avoid any more revs than needed.
traction wouln't be a problem with that kind of power given the right tire & susp.

the problem (from my perspective anyway as a drag racer & since your stating your building a drag car) is why the 5.4 4v with your modest goals?

a 4.6 2v can do what your wanting to do with just a little bigger shot for way cheaper, lighter, more rpm capabilities, easier to work on, etc., etc.
 

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Discussion Starter #17
I wanted a motor that could go mid 11s NA, and was collecting 4.6 4v parts for a higher revving NA 4.6. I then got lucky and scored an aussie 5.4 manifold pretty cheap and figured I might as well go with the 5.4 for the added low-mid range. A little more time passed and I accepted the thought of my mustang being drag oriented instead of just a decent street car. I want to finish the NA 5.4 just to see how well it will do, then spray on top of that just to reach my goal. I know that for the money I have spent so far I could have easily hit 600hp with a turbo 2v 4.6, but a na/nitrous car just seems more appealing to me so thats what I want to go with.
 

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I wanted a motor that could go mid 11s NA, and was collecting 4.6 4v parts for a higher revving NA 4.6. I then got lucky and scored an aussie 5.4 manifold pretty cheap and figured I might as well go with the 5.4 for the added low-mid range. A little more time passed and I accepted the thought of my mustang being drag oriented instead of just a decent street car. I want to finish the NA 5.4 just to see how well it will do, then spray on top of that just to reach my goal. I know that for the money I have spent so far I could have easily hit 600hp with a turbo 2v 4.6, but a na/nitrous car just seems more appealing to me so thats what I want to go with.
makes sense, I was just curious.

5.4 4v's are usually a dyno queen/wallmart parking lot cruiser kinda thing, you don't really see them at the track for obvious reasons.

one other thing, with the talk of being hung up on something as trivial as keeping/deleting the a/c have you given any thought to the seriousness (or expense) of the chassis & safety equipment you'll be required to have with a nitrous car in the 9's(or any car in the 9's for that matter)?
 

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Discussion Starter #19
I have not looked into it in depth but I am aware that there is a lot id need to do. Thats why im looking at my 9 second pass as a one time thing, at least at first. Honestly im probably going to go get a few NA runs and then spray out of nowhere just to get the time slip. I will eventually get what I need I think id like to bracket race it NA but so far everything else is already expensive enough. Spray is just to be faster than my brother, and maybe to make me feel better about spending all that time and money on the motor to not clear 500hp.
 
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