Re-gearing for Performance?

[Tyler James Inc]

Decided to follow [MENTION=148869]Lindenwood[/MENTION]'s lead, and try out no-5th-for-a-tank myself. My results were parallel to his- my MPG didn't seem to be affected. Maybe .5 MPG less than what it's been. Completely negligible.
18 MPG without using 5th. Speedo/ODO is dead-on with my Taco VSS on the tail shaft.

Very enlightening experiment.

 

[Tyler James Inc]

I'm having a hard time mathing today.
If:
4th gear is 1:1
5th gear is .838:1
R&P is 4.1:1
To find what R&P I am emulating, is it correct to divide 4.1(R&P) by .838(5th gear), and then multiply by 1(4th gear)?
That happens to give me 4.89; virtually 4.88.
If my math is correct, driving in 4th with 4.10's would be emulating 4.88's in 5th.

 

[theesotericone]

I'm having a hard time mathing today.
If:
4th gear is 1:1
5th gear is .838:1
R&P is 4.1:1
To find what R&P I am emulating, is it correct to divide 4.1(R&P) by .838(5th gear), and then multiply by 1(4th gear)?
That happens to give me 4.89; virtually 4.88.
If my math is correct, driving in 4th with 4.10's would be emulating 4.88's in 5th.

That math sounds close to what I'm getting doing at as a percentage.

1/.838=1.1933
4.88/4.11=1.1873
1.1933-1.1873=.006

So basically it's with in 1/2 a percent of 4.88's. I think. lol

 

[JZiggy]

I'm having a hard time mathing today.
If:
4th gear is 1:1
5th gear is .838:1
R&P is 4.1:1
To find what R&P I am emulating, is it correct to divide 4.1(R&P) by .838(5th gear), and then multiply by 1(4th gear)?
That happens to give me 4.89; virtually 4.88.
If my math is correct, driving in 4th with 4.10's would be emulating 4.88's in 5th.

I'd think about it this way:

Ratio of 4th/5th vs. ratio of 4.88's/4.10's

1.0/0.838 = 1.193
4.88/4.10 = 1.190

Same difference and yes, driving in 4th in your case would emulate 4.88's. That's a cool experiment to decide if you really like that ratio for top speed. I might try that sometime too!

 

[phattyduck]

I agree with the math on the previous 3 posts. :biggrin1:

-Charlie

 

[dbd6604]

Just a quick scan of this thread before I leave for work, but if I'm interpreting everything correctly: The tendency for our automatic 5vzfe equipped vehicles to romp around sub 3k RPMS was intended by the engineers for quietness/comfort, not maximum efficiency?

Edit - Should also add, I noted when I intentionally drove like a grandpa for a couple tanks of fuel, I got worse MPG than I did when I drive with a lead foot. Kind of makes sense now.

 

[gamefreakgc]

Just a quick scan of this thread before I leave for work, but if I'm interpreting everything correctly: The tendency for our automatic 5vzfe equipped vehicles to romp around sub 3k RPMS was intended by the engineers for quietness/comfort, not maximum efficiency?

Edit - Should also add, I noted when I intentionally drove like a grandpa for a couple tanks of fuel, I got worse MPG than I did when I drive with a lead foot. Kind of makes sense now.

Yeah peak torque on a stock engine is at 3600 RPM, that's where the engine is most efficient with air/fuel in terms of making power. O/D does save fuel though by dropping RPM's but makes it bog down low trying to turn huge gear ratios at 2,000 RPM. Higher ratio gears bring that number up so you're in the power band more often.

 

[octanejunkie]

Yeah peak torque on a stock engine is at 3600 RPM, that's where the engine is most efficient with air/fuel in terms of making power. O/D does save fuel though by dropping RPM's but makes it bog down low trying to turn huge gear ratios at 2,000 RPM. Higher ratio gears bring that number up so you're in the power band more often.

This makes me want 4.88s and 33s

The key is creating a combo that keeps the vehicle in it's powerband for Max efficiency and performance

 

[phattyduck]

Just a quick scan of this thread before I leave for work, but if I'm interpreting everything correctly: The tendency for our automatic 5vzfe equipped vehicles to romp around sub 3k RPMS was intended by the engineers for quietness/comfort, not maximum efficiency?

Edit - Should also add, I noted when I intentionally drove like a grandpa for a couple tanks of fuel, I got worse MPG than I did when I drive with a lead foot. Kind of makes sense now.

Best MPG is achieved with reasonable/strong (relatively - not full throttle!) acceleration, then cruising at a constant speed (or load, if uneven terrain). The sooner (in time/distance, not MPH) you can get to top gear (or 3rd if speeds are appropriate) with the torque converter locked, the better up to a point. Coasting to slow down, avoid brakes, all that, helps too. No need to slowly come up to speed.

I do think the 'normal' mode on the ECT is tuned to shift a bit too low in RPM for most situations. That would be hard to prove without a lot of equipment though.

-Charlie

 

[gamefreakgc]

Best MPG is achieved with reasonable/strong (relatively - not full throttle!) acceleration, then cruising at a constant speed (or load, if uneven terrain). The sooner (in time/distance, not MPH) you can get to top gear (or 3rd if speeds are appropriate) with the torque converter locked, the better up to a point. Coasting to slow down, avoid brakes, all that, helps too. No need to slowly come up to speed.

I do think the 'normal' mode on the ECT is tuned to shift a bit too low in RPM for most situations. That would be hard to prove without a lot of equipment though.

-Charlie

I totally agree. I keep ECT POWER on full-time, tightened my kick-down cable and installed a valve body kit all to raise the shift points on my transmission. It helped but once in a while it'll still bog down low if I ease into the throttle.

 

[Lindenwood]

I ran 150 miles each way on the interstate at 75mph. Relative to previous experiments, I saw essentially no change.
.
Some additional notes:
1) Regardless of gearing, you will get about 1.5mpg more by consciously accelerating down hills (say, up to 77-78mph) and allowing some speed reduction going uphill (say, down to 72-73mph).

2) It was about 1db louder in 3rd (74db avg) than in O/D (73ish db avg). However, you could only tell the difference by hitting the button (it didnt occur to me to test until shortly into the drive when I realized I couldnt actually hear the engine at 3300rpm...).

3) I think I might actually have 4.3 gears, based on all the RPM / speed measurements I took across the board. Still, in O/D, if I try to use cruise control, these rolling hills cause the torque converter to unlock about once per minute, with an aggressive downshift every 2-3 minutes. This is incredibly annoying. Driving in 3rd, on the other hand, allowed the cruise control to maintain speed without ever dillydallying with the the transmission and never losing more than 1mph when most traffic was losing 2-3 on the same hills.