Rear end ratio for Supercharged cars

discogodfather · September 25th, 2009, 03:41 AM

I have a 3.27 read end with a roughly 400rwhp vortech supercharged setup. I know 3.27 is a little high, and I never really go 150mph+ and don't care about top speed.

Was thinking about 3.73 or even 4.10's to get some more low end acceleration (which is all my driving style cares about), but something tells me the 3.27's provide a little more traction at launch in 1st gear. First is very useful on my ride. Many fellow S/C modular dudes have told me their 3.73 or 4.10 makes 1st useless- too much wheel-spin and no hookup.

What do you guys think? My perfect setup would be fast off the line, without making 1st gear useless of course, and I don't care much for fuel economy or top speed. What's my best bet ratio??

DickH · September 25th, 2009, 04:44 AM

Do suspension work, launch in higher rpms. What suspension work do you have done?

Eagle2000GT · September 25th, 2009, 09:23 AM

What tires are you running on the 18" wheels? Tire size affects the way that gears perform. For example, 3.73 gears will behave more like 3.55 gears (it actually calculates to 3.59) if you have 245/45-18 tires because of the larger diameter of the tire (fewer revolution per mile). 3.90s will behave more like 3.73s (3.75).

Conventional wisdom says 3.73s for a supercharged car but it really depends on your horsepower and suspension. Sometimes 4.10s work and sometimes 3.73s are too much. I prefer 3.73s because my car is a daily driver with minimal suspension mods. With my set up I cannot go WOT in first even if I'm already rolling at 25 mph and if I hit second wrong I'm bouncing off the rev limiter going nowhere fast. I would not have been happy with 4.10s.

dcook_14 · September 25th, 2009, 09:55 AM

If you're worried about traction then you need to get better tires (DR or extra wheels with slicks) and do some suspension work. I think with my centri blower i'm gonna get 4.10s when the time comes, just because I don't make boost in the lower rpm range so I wanna get into the higher rpms quicker. Either that or I'll go 3.73's and just pulley down for more boost.

Rear end gears can easily be compensated for by changes in tire size. If you get 4.10s and they are too much, run a taller tire. If 3.73s aren't enough go to a shorter tire.

03_StangGuy · September 25th, 2009, 10:08 AM

I have 3.73s, stock suspension and 285 tires. Above 4000rpm in second the tires start spinning. Oh Im putting down about 420whp. A lil suspension and Ill have traction. but I wouldnt go with any other gears.

06RedfireGT · September 25th, 2009, 11:02 AM

Originally Posted by 03_StangGuy

I have 3.73s, stock suspension and 285 tires. Above 4000rpm in second the tires start spinning. Oh Im putting down about 420whp. A lil suspension and Ill have traction. but I wouldnt go with any other gears.

You're only making 420hp with 14psi on a 5.0 stroker???

03_StangGuy · September 25th, 2009, 11:38 AM

Originally Posted by 06RedfireGT

You're only making 420hp with 14psi on a 5.0 stroker???

That was with a brand new motor and gears. I was expecting more. I am still on the stock heads. Im goin to a dyno day October 4th, my fingers are cross that the motor and gears and broken in and the power is up.

September 25th, 2009, 03:41 AM	#1
discogodfather Newbie Join Date: Aug 2009 Posts: 22 iTrader: 0 reviews	Rear end ratio for Supercharged cars I have a 3.27 read end with a roughly 400rwhp vortech supercharged setup. I know 3.27 is a little high, and I never really go 150mph+ and don't care about top speed. Was thinking about 3.73 or even 4.10's to get some more low end acceleration (which is all my driving style cares about), but something tells me the 3.27's provide a little more traction at launch in 1st gear. First is very useful on my ride. Many fellow S/C modular dudes have told me their 3.73 or 4.10 makes 1st useless- too much wheel-spin and no hookup. What do you guys think? My perfect setup would be fast off the line, without making 1st gear useless of course, and I don't care much for fuel economy or top speed. What's my best bet ratio?? __________________ 2000 Factory Roush Stage 2 405whp Alcon /18" wheels Roush Stage 2 susp 3.27 LS MM roll bar Roush shaker 90mm MAF / 42lbs injectors / Focus SVT pump V1 S-Trim 3.125" @12psi /air-water IC / 928 Impeller DF Commando self-tune

September 25th, 2009, 04:44 AM	#2
DickH MM Fanatic 2003 gt 5.4 32v on the way Join Date: May 2007 Location: Omaha Posts: 4,191 iTrader: 2 reviews	Do suspension work, launch in higher rpms. What suspension work do you have done? __________________ 2003 Mustang gt - usual mods - slowly working on 5.4 swap 2004 srt4 - Stock DD/winter beater Click here for your tuning needs Before asking a gearing related question click THIS link and enjoy all your saved time.

September 25th, 2009, 09:23 AM	#3
Eagle2000GT I Post Entirely Way Too Much 2000 Mustang GT 12.73@111.36 Join Date: Aug 2007 Location: Shelbyville, IN Posts: 5,311 iTrader: 1 reviews	What tires are you running on the 18" wheels? Tire size affects the way that gears perform. For example, 3.73 gears will behave more like 3.55 gears (it actually calculates to 3.59) if you have 245/45-18 tires because of the larger diameter of the tire (fewer revolution per mile). 3.90s will behave more like 3.73s (3.75). Conventional wisdom says 3.73s for a supercharged car but it really depends on your horsepower and suspension. Sometimes 4.10s work and sometimes 3.73s are too much. I prefer 3.73s because my car is a daily driver with minimal suspension mods. With my set up I cannot go WOT in first even if I'm already rolling at 25 mph and if I hit second wrong I'm bouncing off the rev limiter going nowhere fast. I would not have been happy with 4.10s. __________________ ProCharger P-1SC, 9 psi, STD 396/383; Uncorrected 388/375; SAE 383/370 Mods list in Garage. Last edited by Eagle2000GT; September 25th, 2009 at 09:30 AM.

September 25th, 2009, 10:08 AM	#5
03_StangGuy I Poop Entirely Way Too Much Blown 03 GT Join Date: Jun 2007 Location: Long Island NY Posts: 6,917 iTrader: 0 reviews	I have 3.73s, stock suspension and 285 tires. Above 4000rpm in second the tires start spinning. Oh Im putting down about 420whp. A lil suspension and Ill have traction. but I wouldnt go with any other gears. __________________

Threads Similar to: Rear end ratio for Supercharged cars
Thread	Thread Starter	Forum	Replies	Last Post
High End Cars	AMmuslGT	The Clubhouse	24	April 11th, 2009 05:34 AM
Stock rear gear ratio?	Ntv69	5.0 Mustangs	5	November 16th, 2008 09:14 PM
What gear ratio for a supercharged v6?	V6 Stalker	V6 Mustangs	40	March 31st, 2008 06:52 PM
rear end gear ratio	G.T. Rags	96-98	37	April 24th, 2007 12:31 AM
8.8 Rear end (What Factory cars have it)	GreenFaleen	V6 Mustangs	43	January 8th, 2007 11:34 PM

September 25th, 2009, 09:55 AM	#4
dcook_14 Banned 2004 Mustang GT 12.35@114.08 w/ 1.88 60' Join Date: Feb 2009 Location: Waterloo, IA Posts: 7,015 Blog Entries: 2 iTrader: 7 reviews	If you're worried about traction then you need to get better tires (DR or extra wheels with slicks) and do some suspension work. I think with my centri blower i'm gonna get 4.10s when the time comes, just because I don't make boost in the lower rpm range so I wanna get into the higher rpms quicker. Either that or I'll go 3.73's and just pulley down for more boost. Rear end gears can easily be compensated for by changes in tire size. If you get 4.10s and they are too much, run a taller tire. If 3.73s aren't enough go to a shorter tire.

Remove Advertisements Sponsored Links
Ford Mustang Forum Advertisement

All times are GMT -4. The time now is 01:12 PM.
Contact Us - Modded Mustangs : Ford Mustang Forums - Privacy Statement - Top
Modded Mustangs is ©2005-2008, All Rights Reserved, And is Not Affiliated with Ford Motor Company. Forum is powered by vBulletin ©2000 - 2012, Jelsoft Ent. Ltd. & SEO by vBSEO 3.3.2 ©2009, Crawlability, Inc.