Top Speed

I would definitely not focus on just lengthening the fifth but rather flatten the whole fives. Two hundred does not seem out of reach with your stage one.

First off, I'd lower the rear end drive ratio to 3.27:1. I know Ford reached 200mph at the Champ Car Fast Lap with a 325hp car. Changing this part should cost you $200 max + $150 for install. The bad part is that you won't be able to race your Stang before at least 500 miles break-in period lest burning the whole thing. That's a very delicate part.

Second, since you're going to travel at very high speed, a good cold air intake would make more sense than most of us not flying above 120mph ninety percent of the time. I don't think the Stage 1 includes this as a mod. From personal experience, the C&L Intake will provide you with at least 25hp over stock if you re-tune your PCM as well. Total cost with re-tuner is $600-$700 and you can do install on your own it's very straightforward.

Total cost 1K, this 500 mile break-in and you should be good to go.

You would want to change the gearing in the differential, not the tranny unless you spent the 5k plus to change over to a Tremec T-56 double overdrive 6-speed.

i would also mabey think about suspension and tires for stability at those speeds... Not sure what your stage one already has suspension wise though...

you can have all the power and gearing you want but you wont get over 143ish unless you remove the speed limiter, but you can do that with the same tuner you used to tune the computer for the intake.

Stang457 said:

I am entering a road ralley on the west coast and want to know the best way to increase my top speed. 143mph just isn't going to cut it. Ideally I would like to get it closer to 200mph. A s/c will be the frist step. Does anyone know anything about lengenthing fifth gear? How is this done? Any other ideas? My car is an 2005 Roush Stage one.

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your top speed is power limited (due to aero drag) not gear limited. without boosting your power dramatically, lengthening 5th will REDUCE your top speed not increase it.

it's because force to the wheel is a product of engine torque and overall gear ratio.

at 550rwhp you'd max at 187 at 5600 rpm (not even redline).

to increase top speed 1) increase your power and if possible 2) improve your aerodynamics to lower drag coefficient.

check out this top speed calcutor site for the 05+ mustang

http://www.speedshoppro.com/Downloads/GearCalculators/TopSpeed_Calculator.html

Just out of curiosity, why the need for xtra speed on a rally. Going out in the desert where there aren't many cops? Or is it a rally to get there fast...like a cannonball run?

maybe heading to this;
http://www.silverstateclassic.com/home.htm

It can certainly be done but it's not easy to go 200 mph.
Hopefully you are having a nice cage built.
To be as safe as possible you will need to do aero work, cage, fire system, suspension etc....
The HP part is obvious.

If you don't want to change your rear gear, I think the best alternative would be a gear vendor setup. http://www.gearvendors.com/
With that you could go 4th then 4th+OD then 5th, 5th+OD. The 5th + OD would be awefully tall though. Pricey too. Or just get a 9" rear and 2 gear setups so you can use one for drag/every day and throw the other gear in for really high speed stuff.

As for aero, you want the air to go over and around the car, not under so you need some sort of really low air dam in the front. I don't have much experience with 05- Mustangs though since I just got one.

Best thing to do is to find a shop that has experience with this and hook up with them as it's a serious undertaking from both a performance and safety stand point.

stormin29 said:

maybe heading to this;
http://www.silverstateclassic.com/home.htm

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Thanks........WOW......how fun.

or this? http://www.gumball3000.com/

Stang457 said:

I am entering a road ralley on the west coast and want to know the best way to increase my top speed. 143mph just isn't going to cut it. Ideally I would like to get it closer to 200mph. A s/c will be the frist step. Does anyone know anything about lengenthing fifth gear? How is this done? Any other ideas? My car is an 2005 Roush Stage one.

Click to expand...

I think you need to consult a professional. You are going about this entirely wrong and it does not seem like you have much of a clue about the requirements, physics, or even the basics of racing. You may want to look into the rules from the sanctioning body holding the event.

The last thing you would worry about in your quest for 200 mph is the engine and trans. Physics are a real bitch to overcome. You would only address the drivetrain after first fianlizing the chassis, safety, and suspension systems. All of that would likely blow your $20k budget.

Based on the questions you are asking I will assume that you have little or no racing experience. Do yourself a favor and attend, as a spectator, a few auto crosses, HPDE events, etc. Then, participate in a few of these. You will quickly learn just how reckless your current quest is.

If this "rally" is a legal event, you will likely never be in a class that would be any where near 200 mph. To enter the "unlimited class" in any of the high speed events (silver state, pony express, 318, etc) you need to possess a current professional racing license.

If this rally is one of the illegal "goonball" style rallys, then "reckless" would be a mild description of my opinion.

You have received some good pointers in this thread that I hope you look into. I am going to close this thread becasue I fear it may be a "goonball" style rally that has caught your attention. If it is a legitimate rally/event, then PM with a link to the event and a link to the sanctioning body rulebook and I will reopen the thread.