Engine/Transmission (1998.5 - 2002) 3.55's vs 4.10's 1/4 mile et's

[59Turbo]

Has anyone done a test between 3. 55's and 4. 10's on 1/4 mile et's? I recently swapped out the 4. 10's for 3. 55's and acceleration seems sluggish compared to the 4. 10's. Is this just a "feel" thing or or it really slower? I did the swap mainly to lower rpm on the highway and for economy, I just hope I didn't kill accleration too much. Anyone? Thanks for the help.

 

[pkelley]

My 01 2500, 4x2, reg cab, 5 speed has the factory 3. 54 and it works fine for everyday driving. I towed a 6,000 lb trailer with it and still got 22 mpg with the a/c on. My truck only has diesel and a/c as the only options so it's as light and as cheap as I could get it. As far as it being slower, yes I think it is. But I'm not really complaining with today's gas prices.

 

[jkidd]

4.10-->3.54

Iam sure it will sound slower as you are not going through the gears as fast and you will not hear the engine rev out as fast.



With as much power as you have I would think that it would hardly be noticable, but I don't know.



BTW how do you like the new gears, I was thinking of doing the same.

 

[jkidd]

you can buy a cheap 1/4 miole time estimator on ebay for like $30. It is called a G-tech pro. It will do 0-60, 1/4 mile, lateral G, Braking,



not totally accurate, but consistant ... ie off by the same amount/ percentage, so you can tell the differences of mods. I have the 6 spd and have to shift from 2----6 and I am not very consistant though

 

[59Turbo]

you can buy a cheap 1/4 miole time estimator on ebay for like $30. It is called a G-tech pro. It will do 0-60, 1/4 mile, lateral G, Braking,



not totally accurate, but consistant ... ie off by the same amount/ percentage, so you can tell the differences of mods. I have the 6 spd and have to shift from 2----6 and I am not very consistant though

Ya, I wish I'd have thought to but one of those G-tech pros then I would have known but oh well. I took it to the track last year but that was before the mach4's so I wouldn't be comparing apples to apples.

 

[J.BURCHFIELD]

I replaced my 4:10s with 3:55s and noticed no difference in fuel mileage or pulling power. reducing the RPM from 2200 to 2000 at 70 MPH was great. At 70 I kick in the gear vendor and drop 500 RPM to 1500 rpm and it really quiets things down. There was no difference in fuel mileage after I put in the gear vendor. The only thing I did that made a difference in fuel mileage was when i put in Marine injectors. they increased the mileage 3 mile per gal while towing but no change not towing. I know it does not make sense. There must be a formula somewhere that shows the greater the RPM the easier it is to pull the load and the lower the RPM the more you load the engine. My 98 12v is supposed to give peak torque at 1300 RPM. When I am traveling down the highway at 70 and see 1500 rpm it makes me think I am right in the ball park. REGARDS, -- email address removed --

 

[jkidd]

brake specific horsepower

brake specific horsepower is the term, for peak power per amount of fuel



I read that it was 1600rpm for 12v



1900rpm for the 24v If I recall correctly