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Supercharged W/4:10's


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So, i'm doing a little homework here guys and would like feedback. I'm wondering if anyone is running an S/C (any flavor) WITH 4:10 gears? I KNOW it may seem a little crazy to run such a setup, but i'm guessing that some brave souls may be doing it and would covet any feedback, information, love/hate input you might have. If you've done this setup and went to 3:73's I'd like to know the "noticeable" difference between the two. I have 4:10's on my N/A, but wondering if I REALLY have to give up the gears IF I go S/C? I've really gotten used to the gears and really enjoy them.

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I've had the same question and even thought about going with the Paxton over the WHipple since the Paxton takes a little time to boost allowing me longer use of first gear. I talked with Josh and Glenn at QP and they said the Whipple is a better way to go and these cars run really nice with the combo. That's probably what I will be doing since these guys have been dead on about everything else and I trust them.

Right now at WOT with the 4:10's it shifts exactly where it's supposed to IMO. I can't imagine it with another 150 horses...

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It really depends on what you want to do with the car. If you just want to run around on the street, keeping the 4.10's is no big deal. If you want to go to the dragstrip you might run out of rpm's with 4.10 gears at the end of the track. 3.55 or 3.73's are your better choice in that situation. Since you already have the 4.10's just try it and see if it works for you and if you have to change, you have to, but you can decide after the supercharger is added.

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I have a KB SC and the std 3:55 gear....Unless you just like to buy tires (I gave that up when I turned 18), you can't changed gears fast enough. Why not get a 4 speed since your going to loose 1 gear by going to 4:10. If you want to spend money, buy a SC, not a turbo, and build up the bottom end of your 4.6. 10 PSI is at the limit of the std engine 4.6L (500-520hp at the engine) and you only hasten failure time if you push it more than that. Most of us who drive on the street really want the torque at the bottom end (2000 rpm) to get the car going and not have to push the engine to 4200 rpm before the power comes. I have a car (2500#) that makes 500hp (396ci) that had to have the 3:73 changed to 3:27 to even have a usable first gear. My 7L (2400#) car is 680 RWHP and uses a 3:77 with a 2.58 1st gear---0.62 5th. It is at 110mph from 2nd to 3rd gear shift point.

IMO...if you Supercharge stay at 3:55. If you are stock you may want to go to3:73. If your into only driving 1/8th or 1/4 mile the only limit then is the stock bottom end of the FORD 4.6L engine.

If you can, drive a SGT/SC with 3:55. Fact--The car outperforms my GT500.

Thanks for reading

Regards

Grady

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I am glad someone asked this question because I was wondering the same thing. I have 4.10's in mine and plan on supercharging it. I guess I will just see what it is like when I get it done. If I need to I can always go back to the 3.55's. Thanks for the info guys.

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As others have said it depends on how you drive and what you want to do with the car. I run 4.10's with the Shelby Paxton SC kit pushing 450+ RWHP and it's a very steetable (and fuel efficient) daily driver since at lower RPM's (under 2500) the Paxton is not producing any significant boost. It's also a very good setup for a ¼ mile track.

 

With 26" drag tires and a 6200 RPM shift point the car comes across the ¼ mile trap at 121 MPH and right at ~6000 RPMS so that is an excellent combination of HP, torque, RPM, gearing, and tire size. Note that at a drag strip you launch at 4000-5000 RPMs so you are well into the power curve of the Paxton blower and the low RPM advantage of a twin screw roots blowers is pretty much canceled out. Different story on a road course, the roots systems may have the advantage there.

 

If I were to beef up the bottom end and add another 100-200 RWHP via more boost, fuel and/or spray I would need to change to 3.73's or 3.55's (or change tire size or transmission gearing) to get the same results.

 

I agree that with the steep torque curves of a Whipple or KB the 4.10s would not be as good of a option for the street. There would be more power at low RPMs and you would not be able to get the extra power to the ground on street tires.

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With 26" drag tires and a 6200 RPM shift point the car comes across the ¼ mile trap at 121 MPH and right at ~6000 RPMS so that is an excellent combination of HP, torque, RPM, gearing, and tire size. Note that at a drag strip you launch at 4000-5000 RPMs so you are well into the power curve of the Paxton blower and the low RPM advantage of a twin screw roots blowers is pretty much canceled out. Different story on a road course, the roots systems may have the advantage there.

 

I'm trying to grasp this comment because you have a pretty sweet setup and are obviously experienced. So with the Paxton at a 4000-5000 RPM launch, it's producing it's power. If you were able to produce the same power at a lower RPM's with a Whipple, wouldn't that basically be the same? You just wouldn't launch so hard. Or is it necessary to launch that hard at the track? (says the guys who has never done it, yet).

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I'm trying to grasp this comment because you have a pretty sweet setup and are obviously experienced. So with the Paxton at a 4000-5000 RPM launch, it's producing it's power. If you were able to produce the same power at a lower RPM's with a Whipple, wouldn't that basically be the same? You just wouldn't launch so hard. Or is it necessary to launch that hard at the track? (says the guys who has never done it, yet).

 

Hey Stump - What I was trying to say (probably not very well) is that assuming both cars are relatively equal (weight, tires, gearing, suspension, max RWHP/torque, driver skill, etc…) the better low RPM performance is not much of a factor in a drag race.

 

Yes it is true that a Whipple or KB can produce higher torque at lower RPM's compared to the Paxton but if you try to launch at 2500 RPMs versus 4000 RPMs your sixty foot times would suffer due to bogging down and the race might be over in the first 330 feet.

 

In my opinion, regardless of which brand is used, most supercharged cars at the drag strip need to launch hard at higher RPMs so that they can get in and stay in the top of the power band all the way down the track. In general you want to launch as hard as you can without spinning the tires (or breaking something).

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Note that I am not saying one brand is better than the other, just different. So let's not start that debate (again). At the time I purchased my SC from SAI (April of '07) the Shelby Paxton kit was the only SC option available so it was an easy choice.

 

In terms of installation the Whipple and KB are MUCH simpler to install than the Paxton. I also think the twin screw roots design is better in many applications.

 

Having said that, if I had it to do over again I would still go with the Paxton strictly because of the old school Shelby Paxton heritage. The fact that all of the SC options can produce more power than the stock bottom end can handle makes them all somewhat equal in that respect.

 

I still think they are all good; it's probably more of a personal preference than a performance discussion when you consider how close they all are. I don't think I have heard any TS member say they have regretted the decision to add the SC regardless of brand/style.

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Thanks for the responses so far. I think I will stay with the 4:10's and see how it goes. My bigger fear is merely taking a corner (overpass or something like that) and laying in the throttle too hard and watching my tail end become my front end. Straight line launching i'm not so concerned about unless it becomes laying down a small patch of Goodyear everytime I take off. However, I've gotten so use to the 4:10's now that I think maybe with a little time and familiarity that maybe I'll be alright in the s/c application. Worst case scenario I notch it back to 3:55's/3:73's.

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Thanks for the responses so far. I think I will stay with the 4:10's and see how it goes. My bigger fear is merely taking a corner (overpass or something like that) and laying in the throttle too hard and watching my tail end become my front end. Straight line launching i'm not so concerned about unless it becomes laying down a small patch of Goodyear everytime I take off. However, I've gotten so use to the 4:10's now that I think maybe with a little time and familiarity that maybe I'll be alright in the s/c application. Worst case scenario I notch it back to 3:55's/3:73's.

+1 I think I will stick with the 4.10's as well and just see how it goes. Like you said we can always go back to 3.55's or 3.73's if we need to.

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I actually just received my shelby/kenne bell supercharger kit today. I will be installing the kit with ford racing 4.10 gears the beginning of next week. If you would like, I could post how it all turns out after the install.

 

 

Please do, much appreciated!

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I have a a paxton SC w/3:55 stock gears and was wondering about gearing it down to a 3:90 ratio, which I hear very little about. I've driven a Bullit with the 3:73 and really liked that gear but didn't know if it's worth it to change from 3:55 to 3:73...I was hoping a 3:90 would be a good compromise. I am not planning on any other powertrain mods or "official" drag racing, so maybe after all I've heard here I should just keep it stock.

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I have a a paxton SC w/3:55 stock gears and was wondering about gearing it down to a 3:90 ratio, which I hear very little about. I've driven a Bullit with the 3:73 and really liked that gear but didn't know if it's worth it to change from 3:55 to 3:73...I was hoping a 3:90 would be a good compromise. I am not planning on any other powertrain mods or "official" drag racing, so maybe after all I've heard here I should just keep it stock.

 

 

I heard the 3.90s whine like a mofo cause there arent Fords.

Thats why I went to 4.10S.

 

and loving it!

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I heard the 3.90s whine like a mofo cause there arent Fords.

Thats why I went to 4.10S.

 

and loving it!

I agree 390 whine not frpp gaers!!

I have a paxton s/c 12lbs boost making 503 rwhp on 100 oct and 489 rwhp on 93 oct. on a mustang dyno.

I tried 373, 390, now i have 410s perfect, with 26" et street though traps at 6100 rpm on old tune 468rwhp.

What ever s/c you go with, at launch 410 you will have to drop the clutch at min 5k or the car will bog on drag tires.

I'm thinking of 430s with my new 295x45x17 mt drag radials 27.5 dia..

I'm replacing my ram tob/spec 2+ ( 2k miles) and installing a Mcleod RST twin disk clutch, stock slave so I can feather out the clutch at launch.

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  • 2 weeks later...

Almost everywhere I've seen 4:10's for sale, they mention something about not recommended for boosted cars.

That's my .02 on that, but I've never driven an SC'd car with 4:10's.

How much does labor on a gear ratio change typically run anyway? I've seen the actual parts for sale everywhere and they're not expensive at all.

 

Ken

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So, i'm doing a little homework here guys and would like feedback. I'm wondering if anyone is running an S/C (any flavor) WITH 4:10 gears? I KNOW it may seem a little crazy to run such a setup, but i'm guessing that some brave souls may be doing it and would covet any feedback, information, love/hate input you might have. If you've done this setup and went to 3:73's I'd like to know the "noticeable" difference between the two. I have 4:10's on my N/A, but wondering if I REALLY have to give up the gears IF I go S/C? I've really gotten used to the gears and really enjoy them.

I have a 08 GT500 that I have had it pumped up a little. It has 644RWP and 656RWTQ and I was in the same mind set as you. I went with the 4:10's as I only drive the car for fun anyway. Worked out great and I am glad I did it. Mileage went down some but I expected that . Car is fast and is fun.

 

Veteatr

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I picked up the FRPP 4:10's yesterday and made a date with the ring & pinion shop to get them installed this Friday.

The gears were only $165 and the labor will run me $375.

I'm really excited to feel the difference!

 

Ken

 

That's a good price on the gears! You're going to LOVE them!

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I drive it almost daily and couldn't imagine it any other way....

 

By the way... check out what the UPS man brought me today!!!

 

Edit: And yes, I bailed on my desire to stay N/A and go head/cam!

 

Awww, man, that is NICE!!

 

edit - this one is noted as having 4:10's, and he is a member on the forum. There's another post somewhere about this.

 

http://www.dragtimes.com/Ford-Mustang-Timeslip-17596.html

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