Hey guys I have a turboed AP1 pushing 512whp and 334ftlbs wtq, and was wondering if there will be any benefit from changing gears and what kind to change to if there's any point. I've heard before that as you run higher boost and higher hp then your need for gearing goes away. Just curious what yall think.
Thanks.

 

There's a few ways to do this, and I'll do my best to explain. But I'm by no means a pro at this, just done a lot of research in the past little bit.

You can change gearing in your transmission, or your rear diff.

Rear diff is obviously the easiest of the two options.
If you run 4.10's still which I'm guessing you do, your way to improve would be to switch to a 3.90. Possibly a 3.77 but I wouldn't go that low with 500hp.
As the number in the gearing goes down, I.E. 4.10/3.90/3.77 etc etc you are going to gain top speed but lose acceleration. Beneficial for you because it slows down your revs a bit and keeps you in boost a bit longer. Not as quick as shifts. Better gas mileage via lower RPMs in the highway in 6th.
As the number in the gearing goes up, just the opposite happens. This is more beneficial for the NA guys cause if gives them quicker shifts and better acceleration. Hence why you see NA guys running 4.44 and 4.77's that do a lot of tracking. I've never rode in one of these cars but I'm willing to bet it is pretty awesome. Down side is your RPMs are gonna go up on highway cruising speeds and gas mileage goes down.

Now if you are like me and plan on beefing up your trans to hold the power of your engine... Most likely you are looking at a V160 or T56 option. I stuck with 4.10 gears in my 8.8 because I plan on going T56 at some point. The gear set that comes in the transmisssion I want has gear ratios of:
1-2.98
2-1.99
3-1.35
4-1
5-0.86
6-0.73

Where as OEM (AP1)is:
1-3.13
2-2.05
3-1.48
4-1.16
5-0.97
6-0.81

As you can see when you compare the two trans gear ratios the T56 I have chose has a lower ratio in each gear. This gave me very similar results as to running the OEM trans with 3.90s. But we all know the OEM trans insn't the strongest so I decided to go that route instead.

If you want to play with the ratios, here's a little calculator that will help you see what your top speed (mathematically not actual) will be in each gear:
http://www.tremec.com/calculadora.php
Axle ratio is your rear end
Tire height is well.. look up your tire and find its overall diameter... should be close to 25 inches

Hope that helps you, pretty sure I got that all right but if a pro has a couple other tips and tricks or advantages maybe they can chime in. I'll leave that up to you if it's worth it for you to switch you gearing if its something you want. This shouldn't require a retune or anything by the way.
Cheers
Blix

 

Wow that's a lot of info, thank you very much for that. I don't know if I'm going to, I really like the fast acceleration I have because of the turbo but I can see the benefits of lowering them so I'm in boost longer and lower RPMs for cruising. Going to mill it over and see what I'm going to do.

 

Very good information blixhavn

RZA, the 3.90 is the way to go you will get more use out of the power you make

 

I think I'll do this! Where can I get those gears? If anyone could help with locating some that would be awesome! In other words will someone tell me what I need to do to change the gearing. Like what diff

 

thanks for the kudos boys

Where you get your gears, will depend on what kind of diff you have in your car.
If its OEM, puddy can help you out. If it's stock you might as well get his stage 4 kit well you're at it cause you're gonna need it with 500hp. I will personally vouch for Puddys products, I never had a single issue with my stage 2 kit other than I passed it's "rated" hp capacity. He makes a great product and stands behind his name!

 

Thank you!

 

You are welcome to send me a PM for information on differential information and options