Diff Ratio

[datjas]

Has anyone changed their diff ratio in their everyday xr6t,Id like abit more off the line does feel like it could do with taller ratio,s.My car is an 04 ba xr6t auto.I have done cooler and piping battery relocation to passanger side and also pod filter,plans after this are to fit my 4inch dump I have the 3.5 inch x force rear half and twin outlet muffler to fit once I get my exhaust housing back from the fab shop and will do the mid section myself.Will also be doing the usual wastegate actuator with my properly ported housing and oversised flapper,springs,injectors,fuel pump and flash tune as everyone does,With all that done what do people with experiance think about doing the ratio's, Worth it or not?When the car is finally tuned if it makes 300kw ill be happy to leave it there for now with the auto.

[Benji_vs]

Taller ratios will make it fell more sluggish, I think your wanting a shorter ratio. Im not sure what the 4 speed auto diff ratio is but I think you might want to look at a 3.45:1 or 3.71:1 any shorter and you will be reving too hard when cruising.

I think Taller (I.e 3.08:1 to 2.73:1) increases top speed where as shorter (3.08:1 to 3.45:1) will increase acceleration but with the reduction of top speed.

[Ralph Wiggum]

Are you trying too get quicker acceleration out of first or a higher speed range?

Lower gear will make it accelerate harder but they will make it feel laggier. A taller ratio loads the engine up more and will bring the boost on quicker but may not be any faster

[datjas]

Sorry yes I meant higher ratio's as if it was 3.08:1 going to 3.45:1 seen a couple of 4.1 complete centers for sale.

[Ralph Wiggum]

stock 4spd auto rest is 3.43, a manual 3.73 will wake it up but 4.09's would mean a 17% increase in rpm for the same speed. would also mean bulk wheelspin.

Too low IMHO

[Henz]

My brother has a 4 speed and 4.11s, at cruising speeds doesn't seem to use much barely fuel, last time I drove it averaged 10.5 with hwy driving and a bit of traffic over a few hours. Seemed to rev normally at 100kmh.

[Jamsey]

3.9's would make first end at around 70. which is what the 5 speed manual xr6t's do in 1st. I dont think 4.11's would be over the top short. the 6 speed autos 1st gear top speed is comparable to the 4speed auto with 4.8 ratios.

Edited 14/04/11 09:13 AM by Jamsey