Ok, so I am not even sure how to ask this...

if going from a 3.73 to say a 4.10/4.30 ratio in the differential will allow more "power" to the wheels and be easier for the engine to tow (I tow at arount 6k pound 30ft RV trailer with my 2005 e350 v10).

Does this change (4.1/ or 4.30 diff) then change the torque/HP curves?

I understand that the taller(?) gears have the engine run somewhat faster for a given revolution of the tire, thusly making it easier to put the engines torque to the road. Do I have this right?

I am wondering if it might be worthwhile to dyno my van b4 and after the gear change, If I did what do you guys think I should see..(if anything) in the power curves?

another question....
in electricity there is a direct relationship between volts and amps that is watts = amps * volts ... is there some equivalent type of equation combining horse power and torque?

For what it is worth I will go with 4.30 when the money comes in.

...Rich

 

Changing the rear diff does not change the HP or torque, it just makes it more useable.
As for relationship, horse power is torque x RPM.

 

Actually the equation is horsepower = (torque x RPM) / 5252

 

Soo... if my peak torque is supposed to be around 410 lb-fts @ 2750 rpm my horse power is 1127500? (edit.. /5252 = 214 which would HP be at 2750 rpm about on the chart curve )

the only chart I have seen for the v10 2 valve has Peak torque 410 lb-fts @2750 rpm and Horsepower 265 HP @ 4250 rpm.

Now these are likely numbers at the rear of the engine arn't they? I would assume losses in the drive train all the way to the pavement.

this is why I wonder if I dyno at the wheels before and after the gear changes, my curves would be different, that is better with the taller gears.

I thought I saw somewhere that what trans gear you are makes a difference too.

I am soooo confused! (edit .. alittle less!)

 

Yes and yes.

 

If you can get the engine above the torque curve, then as you slow you will have more power available to maintain your speed.
You don't want to go with too low of a ratio, since it'll just spin the engine faster with no gain. The 3.73s in that now should do really well, I tow far more weight with a 360 v8 and 3.73 gears with very good results.
Just keep out of OD and you'll be good to go.

 

As a whole, no complaints with the 3.73 ratio, would like to get going alittle faster on the hiway ramps, and really wish I had some form of limited slip for days like today (lots of snow/ice). I know limited slip is not the perfect savior but it always seems that I am 1 wheel slipping. Now to decide on a auburn, dana, detroit, the list goes on.

Assuming I am going to do the change to limited slip, I will change gears too.

Anybody know what a good price on a dyno run would be? I have several places here in Indianapolis to choose from and have no idea what an unreasonable price would be.