3:73's out 4:30's IN

[2003MYSTANG]

I was talked out of the steeper gear set and into 3:73 about a year ago. I was robbed!!!!! Live and learn and pay again. The 4:30's are the way to go with the mod motor. My tire size on the rear "315/35/17" is a little taller and led me away from the 4:10's. At 75 mph in 5th the rpm's are 2600. Right at the bottom of the power curve. 1st-4th snappy,snappy, snappy!!!!!!!!!!!

Now about that Twin Screw ????

 

[SonicB]

Glad you like it. That's alittle too much gear for me but it's all about having fun and what makes you happy.

That gear set and a twin screw would be interesting.

 

[WOT]

Sorry but 4.30's and a blower

Forget about it, unless you plan on running slicks all the time. I have 3.73's with a blower and I can tel you there is no traction at all.

 

[2000BLKGT]

I'm running a KB 6psi with 4:10s, and my buddy is running a 9psi KB with 4:30s...and it's a blast.

Keeps your right foot honest.

 

[Gunfighter]

must be a real neck snapper!

 

[2003MYSTANG]

I sure would like to try some boost with the 4:30's. The 315/35/17 BFG G-Force KD's sure hook up nice. I had to relearn how to drive the car when I installed them.

 

[underdog225]

i am at about 2700-2800 rpm at 65 with my 4.30s. i really want to get some slicks or d/r for the track only but am afraid that it will damage my rear end. but wow the 4.30s are fun!!!

 

[try2catchmy99]

4:30s all the way

 

[2kyellowgt]

I have 4.30's sitting a box, but I might not put them in since I just installed 100 shot of N2o. I dont want to run out of gear but the time I get to the end of the track. Shifting to 5th at the end would probably hurt my times.

 

[joshheat25]

Who has and Auto with 4.30's??

 

[joshheat25]

I wonder how an auto with 4.30's will run?

 

[hotmustang331]

^3K @ 65 LOL, now we are getting closer to how my 66 is taching LOL, but its 3K at about 55, no O/D and 3.80s. IMO when you get up ther you loose the function of O/D and i tell you what, it IS NOT COMFORTABLE in the 66 taching 3500RPMs at about 70MPH, and with 4.30s in an auto or a 99-00 your getting darn close. But hey I guess most of you dont have a weekend worrior to drive around...the GT is your "hotrod", see my GT is my daily driver that i want to feel comfortable in, so maybe thats why i am against anything above 3.90s LOL.... BTW I know 3.80s are not very steep for a car that can turn 7500RPMs, but its going to be S/Cd and I am planning on keeping it at around 650RWHP.Thats why those gears are in, that and mainly because theres no O/D for right now LOL.

 

[ghoststripes]

your wheels

What wheels do you have hooked up with those BFG's?

 

[5spd GT]

That is a "strangely" low rpm even for that tire size. I'm at 2600rpm at 75mph with my 373's...I think something is off on your car or you looked at the wrong mph

Is this is your daily driver? I'm assuming you have a "beater vehicle"?

 

[MidnightGT]

Sorry but 4.30's and a blower

Forget about it, unless you plan on running slicks all the time. I have 3.73's with a blower and I can tel you there is no traction at all.

Paxtons are centri type right? Wouldnt from you launch you be running minimal boost? I cant see how it would cause that much traction issues. A twin screw yes, due to instant torque...but centri I think youd be fine with moderate launches.

BTW: Im not saying bad about the centri type...I am hoping to get one by end of summer.... (Anyways TS types like KB are 2 expensive!!!)

 

[98blackstallion]

http://tchracing.com/tech/gearcalc....m&givenval=70&givenvaltype=MPH&selectedgear=5 that is a gear calculator that I used to make my decision.... I will be at around 2600 rpms at 70 mph

 

[MidnightGT]

played around with it
4.30s seem to be bad on gas mileage....especially if you have no rev limiter and dont know how to shift:
At 100 MPH in 1st gear, your motor is turning at 18,967.0 RPM

 

[TGJ]

Paxtons are centri type right? Wouldnt from you launch you be running minimal boost? I cant see how it would cause that much traction issues. A twin screw yes, due to instant torque...but centri I think youd be fine with moderate launches.

BTW: Im not saying bad about the centri type...I am hoping to get one by end of summer.... (Anyways TS types like KB are 2 expensive!!!)

IMO, 4.30's are the best N/A gear out there for a 4.6 auto, 4.10's are the best N/A gear out there for a 5 Spd. SC applications should be 3.55's/3.73's for a manual and 3.73's/3.90's/4.10's for a manual.

Now I used to think the same way, however I have been proven wrong. I know somebody that used to run a Vortech SC'ed TBird 4R70W with 3.73's IRS. I don't remember the stall speed but it was 3000 RPM or less. I have yet to see a Twin Screw or Roots SC Tbird out 60' his better 1/4 mile runs. This basicilly means that the car had to be making significant low end power.

The HP/Torque number's may not be as high in a Centrifugal SC in the lower RPM as a Positive Displacement SC but it is making more as compared to a similar N/A application.

 

[Tylerb59]

I run out of gear (top of 4th) at the track with 4.10s. I can't imagine 4.30 especially if you trap more then 105.

5th gear has no use (obviously), I've topped out 4th and continued in 5th and it just dies.

 

[hotmustang331]

^ exactly what my concern was. If you dont mind, what do you trap? With my 3.73s I SHOULD be going through the 1/8 real close to the top of 3rd, and through the 1/4 at about 4800 for 100MPH.It should help my trap out since I had to shift to 4th before the end of the 1/4 with the 3.27s. I shall see at the end of the month when i go to Fun Ford.