99 tahoe 4-door 4x4.Flowmaster custom exhaust. dual in-dual out muffler. AEM intake. JET MAF sensor. Hypertech programmer.Just had new engine(5.7 vortec) put in 20,000 miles ago. 285/75/17 Nitto Terra Grapplers on 2007 tahoe LT wheels. Cranked to level torsion keys. Rear 2" blocks. I need to know what I can do next to get more power to the pavement? How much does changing the gear ratio cost? What gear ratio is best for that tire size?i may plan to put a lift in the future, but I use it as my daily driver and don't want to get under 10mpg. I get about 15 now. Thanks fo the help.
What's my next step?
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BattelWagun
Full Access Member
I would say upgrade the injectors if you haven't yet and get a blackbear tune. Gears will cost in the neighborhood of $1k, I would only get them professionally installed. What ratio do ypou have right now? Gears aren't really needed until you start running heavier rubber, I would wait until the lift for that unless you plan on towing and have 3.42's or something. And yes, gears will affect mileage. A lot or a little depending on what you get.
Also, if you're up to it, a mild cam would be awesome
Also, if you're up to it, a mild cam would be awesome
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ch4d
Full Access Member
Here is a picture from bowties post in the Lifted Supension - Z71 & 4x4
your running Metric to Standard Result: 285/75/17 = 33.8x11.2/17
so possibly if you wanted you could run 4.88 for more power but its your choice in all.
your running Metric to Standard Result: 285/75/17 = 33.8x11.2/17
so possibly if you wanted you could run 4.88 for more power but its your choice in all.
What exactly would I get out of the blackbear tune?whatd does it do?and putting in a new cam requires some money in labor and the cam. Because I don't want to cut corners when putting parts in my engine.What kind of fuel injectors?
purple 'hoe
Full Access Member
TUNE
Ditch that hypercrap tuner. Get a tuner from BlackBear performance. Here's a link for more information, or post in their sub-forum. Get all of your mod's done first before you tune.
http://www.blackbearperformance.com/
Gears/Traction
With 285's, I have factory 4.10 gears with the G80 in my Silvy (different vehicle, I know) and I have great power compared to one with 3.73's. So anywhere from 4.10's to 4.56's would be good for 285's. Even 4.88's but that seems like too much gear for that tire size.
To keep that power on the ground and keep traction, get rid of your G80 (if equipped) and get a Trutrac or similar traction aid for the rear end (can not install a locker in the factory IFS differential fyi)
Transmission
Depending on your transmission miles, I'd recommend a higher stall on your converter, shift kit, and a corvette servo. If you are rebuilding it at some point, go with my recommended upgrades along with better clutch packs and a "beast" sunshell
Engine
Along with your current upgrades, I'd look into headers (long tubes if possible), high flow cat's, ignition upgrades (plugs, coil, wires) and injector upgrades. Electric fans also for cooling, and a lower temp t-stat.
If you plan to go further into the motor, then start reading up on cam's and other internal parts. I had a homemade intake, coil, plug wires, exhaust and a built 60e with 3.73 gears and 285's on my 1995 (TBI however) 2 door. Power as okay for what it was. The 5.7's really don't make that great of power though compared to a LS motor. If I owned a OBS still, I'd be swapping to a LS based motor.
Ditch that hypercrap tuner. Get a tuner from BlackBear performance. Here's a link for more information, or post in their sub-forum. Get all of your mod's done first before you tune.
http://www.blackbearperformance.com/
Gears/Traction
With 285's, I have factory 4.10 gears with the G80 in my Silvy (different vehicle, I know) and I have great power compared to one with 3.73's. So anywhere from 4.10's to 4.56's would be good for 285's. Even 4.88's but that seems like too much gear for that tire size.
To keep that power on the ground and keep traction, get rid of your G80 (if equipped) and get a Trutrac or similar traction aid for the rear end (can not install a locker in the factory IFS differential fyi)
Transmission
Depending on your transmission miles, I'd recommend a higher stall on your converter, shift kit, and a corvette servo. If you are rebuilding it at some point, go with my recommended upgrades along with better clutch packs and a "beast" sunshell
Engine
Along with your current upgrades, I'd look into headers (long tubes if possible), high flow cat's, ignition upgrades (plugs, coil, wires) and injector upgrades. Electric fans also for cooling, and a lower temp t-stat.
If you plan to go further into the motor, then start reading up on cam's and other internal parts. I had a homemade intake, coil, plug wires, exhaust and a built 60e with 3.73 gears and 285's on my 1995 (TBI however) 2 door. Power as okay for what it was. The 5.7's really don't make that great of power though compared to a LS motor. If I owned a OBS still, I'd be swapping to a LS based motor.
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