ApeXX

How badly do 3.73 gears affect top end speed? I've been told multiple times that this is a necessity for the V6 Mustang to improve low end acceleration, however no one really mentions if there is a significant decrease in top end max speed/acceleration.

The only source I found was a comment made on American Muscle, where some guy points out that with the 3.73's his engine is running at 3500 RPM on the highway cruising at 65 MPH, which doesn't sound healthy for the engine or his top-end performance (which is minimal in a Mustang to begin with, especially with the V6).

Thanks for the info!

945LSTANG

since when did top speed matter?


the difference is minimal and won't really matter anyways. your car is speed governed.

boomee

top speed matters alot i am wondering the same infor mation its nice to have down low power but i like a mix of both ya know. i am wondering the same thing

cominus

Its only a little, say top speed was 122, its now probably 118 or something, doesn't really matter seeing as how the US doesn't have an autoban.

ApeXX

Sorry I think I was a little vague. I meant (assuming the AM comment was accurate) that 3500 RPM at 65 meant much higher engine stress if I cruise at say 85 on the highway, or if I need to pass someone at highway speeds. My concern wasn't so much top speed as it was acceleration at those speeds.

Smokin04

Since your car comes stock with 3.27's a switch to 3.73's wont yield too bad of a difference as far as cruising rpm is concerned. There are several calculators out there that can calculate the exact rpm change. Just google gear ratio calc. and input your numbers. You will need to figure out your tire diameter in inches though. A 255 40 17 is around 26". So 25-26" is a good ballpark number to use if you aren't sure.

For that guy to say he was cruising at 3500...he might have had 20" rims on the car. You never know.

Also your car doesn't produce enough HP to reach the top end of the MPH spectrum with 3.27's...the 3.73's will actually yield better top end results for you. I checked for you and the difference if you have a 5 speed is only 394 rpm at 65 mph in 4th gear. So 2801 rpm for 3.27's will be 3195 with 3.73's...keep in mind that's 4th gear...NOT overdrive.

Buck268

When I went from stock 3.27 to 3.73 in my '94 Crown Vic I actually ended up gaining city mileage. Would get pretty much 20mpg around town or freeway driving as long as I kept the speed around 65-70mph. IIRC I would hit the 2k rpm around 60mph, but thats taxing the memory (been a couple years).

You can always calculate this stuff out, shoot me a pm/email and I'll send you a little VB program I made back in the day for that.

Jfsram

You will have to either try it or talk to somebody who has done this with a combination similar to yours.

Deeper gears almost always increases acceleration but in a V6 like yours it may not be true.

I carpool with a dude who has a V6 Mustang. It's not too bad at full song when he first mashes the pedal to pass but as the engine nears redline, it's just reving and making almost NO power. It gets most of it's acceleration from torque.
Basically for a high rpm, peaky engine. Deep gears for sure.

USMC1775

373s revving to 3.5 a 65? Somethings not right there...

ApeXX

Wow, thanks for the very helpful reply! It will still provide a decent low-range pull increase though, right? I'm just trying to justify the $300 installation, which will likely be even higher because I'll get the t-lok installed at the same time.

Hmm.... I did the calculations myself though and I got slightly different numbers. Keep in mind that I'm not totally sure what transmission is in the 2000 V6, but I believe it's the T-45? Anyway assuming that's correct, with my 15 inch (getting replaced soon) 205 width tires I would be making 2751 RPM in 5th gear running at 65. Did I calculate something wrong?