Kenne Bell Switch Chip in advance of Supercharger kit?

[SilVert99GT]

I have an automatic and I'd like to run 3.73's. However, since I plan on getting a KB 9 PSI blower eventually I'd like to avoid having to pay $400 for a Predator or chip to correct the speedometer since the KB kit comes with a chip.

Is it possible/practical to buy the switch chip (or the entire 90mm/Big Tube/cold air/throttle body kit) in advance of the supercharger and use it for correcting the speedo?

 

[narongc73]

Wouldn't 3.73's generate too much wheelspin once you get the KB supercharger?
If you're going to get the SC, I'd keep the stock gears.

 

[01MustangGT]

Wouldn't 3.73's generate too much wheelspin once you get the KB supercharger?
If you're going to get the SC, I'd keep the stock gears.

keep stock gear.
3.73gear bring the rpm to redline too fast, it's hard to keep up with the redline when u have the KB. i recommend u buy the clutch and flywheel first because mine is slipping badly, i hit the gas hard, boost jumps to 9psi immediately, rmp goes to redline but car didn't move. then the smell of clutch is all over my car. i need a new clutch badly but parts and installation is around 1G

 

[SilVert99GT]

Wouldn't 3.73's generate too much wheelspin once you get the KB supercharger?
If you're going to get the SC, I'd keep the stock gears.

I thought so too, but then I read on their website that 3.73's were optimal.
Kenne bell 2V tech tips

keep stock gear.
3.73gear bring the rpm to redline too fast, it's hard to keep up with the redline when u have the KB. i recommend u buy the clutch and flywheel first because mine is slipping badly, i hit the gas hard, boost jumps to 9psi immediately, rmp goes to redline but car didn't move. then the smell of clutch is all over my car. i need a new clutch badly but parts and installation is around 1G

I have an automatic.

 

[narongc73]

I thought so too, but then I read on their website that 3.73's were optimal.
Kenne bell 2V tech tips

Actually they said stock is good for the 4.6. 3.73's is good for the quarter mile, that doesn't mean it's driveable on the streets. If you use your car at the track and not an everyday driver, 3.73 is for you. If it's for mostly daily driving, it'd go with stock. I got my KB coming and my gears will remain stock. Or why not just ask KB? Save that 400 for new tires! You're gonna need em!

 

[BrightBlue00GT]

3.73's are the max you want to go, but you can use them to advantage if you clutch properly. Considering yours is an auto, I would stick with stock 3.27's though.

For speedo corrections, why not just use a SpeedCal anyway?

 

[SilVert99GT]

Actually they said stock is good for the 4.6. 3.73's is good for the quarter mile, that doesn't mean it's driveable on the streets. If you use your car at the track and not an everyday driver, 3.73 is for you. If it's for mostly daily driving, it'd go with stock. I got my KB coming and my gears will remain stock. Or why not just ask KB? Save that 400 for new tires! You're gonna need em!

I did email the question to KB and their email auto-reply says it may take up to 7 days to get answer so I decided to ask here as well. I was considering the 3.73's because I think my mustang is extraordinarily heavy and the KB supercharger is in most likelihood 6-8 months away.

Auto vert + CDC light bar + 12" subs + amps + chrome 18x9's + me (260 lbs.)= lbs.

3.73's are the max you want to go, but you can use them to advantage if you clutch properly. Considering yours is an auto, I would stick with stock 3.27's though.

For speedo corrections, why not just use a SpeedCal anyway?

SpeedCal is not an option for automatics.

 

[02blksunshine]

Guys I think you should reread that TechTips.pdf. With 3.27's at 5500 rpm you'll hit the max rpm for the charger. 3.73's might be way overdoing it. With 3.73's you'd have a max allowable engine rpm of 4826 for the KB. Let me know if I'm misreading that.

 

[BrightBlue00GT]

With 3.73's you'd have a max allowable engine rpm of 4826 for the KB.

No, we've proven that not true.

SilVert99GT - yea, forgot you're an auto.

 

[SilVert99GT]

Guys I think you should reread that TechTips.pdf. With 3.27's at 5500 rpm you'll hit the max rpm for the charger. 3.73's might be way overdoing it. With 3.73's you'd have a max allowable engine rpm of 4826 for the KB. Let me know if I'm misreading that.

O.K. after re-reading the GEARS section I've decided to stick with the stock gear ratio. 3.27 x 5500 = 17985 which is right at the supercharger's max of 18K rpm. Thanks all.