mtflyboy25

in 6th? i have video proof lol do the math...

http://www.coastdriveline.com/htmlfo...lculator2.html

Rear End is 3.73
Desired MPH is 176
Tire Diameter is 26 or bigger lol
OD ratio is .65 for a 2011 GT manual
Calculate and boom
shows 5514

so give or take a few hundred RPM yeah I had plenty of rpm to use...

keep in mind I was lowered and had bolt ons...

mtflyboy25

I have driven all 3.. My 2011 had 3.31s... With intake and tune I was almost dead even with my buddy with his 3.55s, he would shift and I would catch up and then he would pull, then shift and I would catch up etc...

I swapped to 3.73s and long tube headers and I blew him away in every gear on every shift from 0-150mph... I averaged better in city mpg with my 3.73s and still pulled 29 mpg off on the freeway in Denver on a 150 mile trip.

I would go with 3.73s or 3.55s. If you dont want it to be faster just do the 3.55s they are a happy medium.

Cruzinaround

When my 2011 5.0 was bone stock except for the exhaust I ran my Buddy's 2012 Boss 302 OEM equipped. Mine has 3:55's his came with 3:73's.... From a roll or a dig... he was embarrassed everytime. Rolling from 2nd to 3rd shifting at 4500 then Kept it in 4th to get the RPM's up in the sweet spot of 7000 then wined out in 5th .... And literally walked away every time. From a Dig... Hold a bit longer in the 5000 + before 3rd then the same thing.... Sometimes its the driver and how its driven. And the tire diameter and the power/torque. From a dig the 5.0 has more torque than the Boss. From a roll its a driver's game. Would I swap out to 3:73's? Nope...I just swap tire diameters to effect the overall ratios. I prefer to have the top end since I do a LOT more open road driving and exceeding 160MPH now and again is just .... normal. And on a long run... the lower gears just can't hang. Even with the 6th gear you're working your engine much harder to achieve higher speeds. If you get pulled up on by a CTSV or better...they'll embarrass you if you're on 3:73s and don't have the power to make up for it. Besides GT stands for "grand touring"... not "got trounced". And unless your life is 1/4 mile at a time.... well, the reality becomes wow your car is quick, but it certainly ain't fast.

MrSandman

Explain how the slight difference between a 3.73:1 and 3.55:1 ratio allowed you to "walk away." What do you top out at in 5th? 3.73s are better in a roll because you start closer to ideal RPM than a 3.55 gear. 5th gear with the 3.73:1 ratio is heaven on the highway.. But like you said, a 3.73:1 rear will hit the limit before a 3.55:1 rear.. but its only a few MPH.

I used the correct label of 3.73:1 because it is a ratio.. its a pet peeve of mine when "car guys" use 3:73 instead of 3.73... 3:73 makes absolutely no sense (the ratio is 1:1.. first number is gear, second is 1.. hence, 3.73:1.. the : means ratio).

Cruzinaround

It's actually a good point to refer to the ratio. the final drive ratio varies from 1st all the way through 5th and is not even applicable in a hgwy race when you're talkin about 6th. The final ratio in each gear is affected by tire diameter and traction is affected by the compound in the tires used....FYI... Pirelli's are not a match for grip Vs many other brands....I run on Cooper RS3-s...aka MIckey Thompson street comps...far better than the P-zeros, since they will stick and grip instead of spin and squeal. And again... The Boss 302 is less torque in the low to mid rpm band than a GT... both are a match for HP in the higher RPM band. ..A hard launch in the GT sticking hard to 5000+ then shifting 2-3 in the mid range puts your torque curve above the Boss. 4-5 Hold to 7000 then wind it out in 5th....and you're walking him every time. works like a charm. nowadays with modest bolt ons I can walk away on most of my buddies on 3.73's with minor bolt ons.

In the end it's a math game and statistics and... The chance that the other guy is so not as good with a manual. or even if he/she is.... Hope You're better.

the real fun is when they jump ahead on you...and you just creep on them and reel them in before you run out of road. while they look at you like WTF?

--

added...

BTW...the 1:1 ratio is typically achieved in 5th....at which point the power behind it will determine the outcome. So if you can imagine why a Cobra GT500 putting down 630+ HP at the crank can stomp on a Brembo GT with 430+ at the crank while it still only has a 3.31 rear axle ... it has a lot more ooomph at the same power band as the GT. Simple math. In the end its a numbers game. a few of my buddies went with Boss 302 intake upgrades and their torque suffered for it... Or they could have waited and went with the Cobra Jet intake and not taken a hit on their torque and added some more HP range for their rpm band over 7000. But they didn't. Most times when I'm getting pulled on nowadays....the other guy has some boost. So now I'm considering either a Vortech, procharger or maybe even...dare I say....nitrous. In the end. Its all about self expression and enjoying the ride as a DAILY DRIVER, while remaining somewhat practical. So by the time I'm considering some form of boost addition.... I might just start driving the EVO more and garage the Stang except for a Sunday drive.

and..

I've hit 173MPH on the speedo and the GPS in 5th at maybe 7200RPM... I can still wind out to 7750RPM theoretically so I'm gonna guess maybe 179-180 tops.... I think the ratio calculators will call it 182 MPH. Do I really know...not.... just having been there and done that...it is what it is. But then again sometimes you run out of road and unless you wanna make a pact with the devil...you let off before you "hit the wall" so to speak. If I had to call it I'm at the limit of most bolt ons prior to boosting....so at the Crank...maybe close to 500....at the wheels definitely over 400. Never Dyno'd so I'm just guessing. My buddy has been dyno'd and he has lesser bolt ons and puts 420 to the rear wheels... So I'm just going on a hunch. Maybe one of my 3 son's will go the extra mile on it... hmmmm.

lawman1

No. there is theory and then there is practice. I have 28 inch tires (285/40/19) and 3.73s The car will not pull in 6th. I know. I tried. After about one mile and at 158-159 miles per hour I shifted from 5th to 6th. It was like a fat girl jumped in the trunk and invited her friends. Car just bogged down. I actually lost speed over a half mile. At that speed I am pulling over 500 whp and it still could not pull in 6th gear.

An overdrive of .85 might work but .65 is too big a jump. Just because some calculator says that it can be done does not mean it can be done. A 5.0 with a Roush Supercharger churning out 560+ to the wheels did 173 running on 3.55 and an automatic. Now lets see your video of a manual GT with 3.73s doing 173 in 6th gear with 2500 to spare. I doubt you had more bolt ons than me. Further check my video evidence of a dyno run. Pay special attention to the the rpm and the speed. 7700 rpm (hard rev limiter) on 3.73's with 275/40/19 tires gets you to 162-3 mph. (See bottom Y axis of graph last screen shot)

If my car won't pull in 6th, neither will yours.

Cruzinaround

I will second that...6th gear is not for speed its for cruising.... its effectively an overdrive gear that makes your final drive ratio theoretically "taller" than the rear axle ratio alone. So unless you're driving with an ENORMOUS amount of horsepower and torque to the rear wheels popping into 6th will always lose a road race for you since the car will bog down and you'll see the other guy pull away fast.


Let me add...

MTFLYBOy...


If you were in 6th then you would be there for an extremely LONG time and across maybe your entire state and still not get up to speed cruising in that gear with 400 RWHP or less. I can't see that happening...Unless your 2011 is running an engine swap from a Bugatti or maybe 2 of them, one for each rear wheel???? In 5th I can see hitting that speed.... and with 3.73's to 4.10's it would hit its RPM cap..... sooner at a lower MPH than the 3.55's or 3.31's or 3.15's. For a long run.... lower gears... not as effective. For a quarter horse setup...yep... but then like a real quarter horse... it's all over when the long distance ponies catch up....some sooner than others.

Rios04GT

To put it into perspective a stock 2011 5.0 with track pack and grippier tires run a 12.7 while a regular GT with 3.31s run a 13.2 I am not sure how much of a difference the tires make but closer gear ratios wake a car up since it gets you in the powerband a lot faster, problem is you have to change gears sooner.

here the 12.7 run
here the 13.2

Rios04GT

Assuming both cars are stock with the exception of gears top speed in the Mustang GT with 3.31s is achieve in 5th gear, 6th speed is useless. I am not sure about mustangs with 3.73s since the ratio of 6th in a mustang with 3.73 might be closer to 5th in a mustang with 3.31s. I am not too sure about this but this could be the case. So in the long run, the 3.73 gears might have an advantage since 6th gear might still give the car a higher top speed.

I have 3.73 gears in my car and my friend has 3.31s in his. his car makes 500 with plenty of bolt ons/boss 302 manifold included while mine is pretty much stock with the exception of an axle back. My car keeps up in the first 3 gears and after that his pulls away but mainly because his car makes much more power. Needless to say he is getting 3.73s soon. So yeah 3.73s do make a lot of difference performance wise.

Cruzinaround

Nope...same thing...6th gear is an overdrive. Renders your car pretty useless for pulling. As far as power band... The rpm range is the same to hit it for max torque and max HP... The peaks are different so launching you're seeking the sweet pocket for torque... Rolling you're aiming for max HP RPM band. Therefore top speed in your car....is lower. My buddy with the Boss 302 is typically a gear ahead when I'm still winding a gear below him. When he's in 5th I'm still in 4th raising my RPM's to 7500. A gear behind is always an effectively shorter ratio. Power add on's make getting there faster. Case in point...Your friend still pulls away on you in 4th and 5th with 3.31's. You keep up through 3rd. So if he just went to 3.55's OR CHANGED TO A SMALLER DIAMETER WHEEL/TIRE combo to effectively change his final ratios he'd walk away from you in every gear since he's already laying down more power and torque in every gear. If you're setup for being an effective quarter horse then... Okay, but a road race is a very different game and there's more than 1/4 mile out there. The taller gears have the advantage from a roll all the time between two vehicles otherwise setup similarly. And will likely be more fuel efficient to boot. Remember it's a Mustang GT aka "Grand touring". If you're setting up as a pocket rocket then your biggest competition will be the guys with Hondas. If you're going to be a driver of a performance vehicle....Then there's a reason a Shelby GT 500 is equipped with 3.31's to achieve breaking the 200mph wall...

And overall wheel/tire diameter does effect the final drive ratio. Keeping several wheel/tire combos is not unusual for guys that Autocross and Drag between regular driving. Changing tire diameter to change the overall ratio is a LOT quicker than swapping a ring and Pinion. Add stickier tires and that's always a game changer for any type of racing.