I think you are going to like the tune. I just loaded Alvin's tune on mine. Idle is super smooth. Low end torque has a nice boost.

 

That's great news. He is also anxious to hear how I like it and wanted some feedback. I told him I'd give him a call and let him know how things feel. The Idle is definitely a good thing.

 

I had mine did and love it.

 

So, YOU are the mystery man/woman! What kind of a increase did you notice? Are you getting metter gas mileage? Please share with us

 

Here is some new fuel economy test data.

First, the goal was to test my modified tranny shift table versus the one supplied from Alvin in his tune.

There are two elements to fuel economy: acceleration efficiency and cruise efficiency.

CRUISE EFFICIENCY

For highway traveling, the goal is to maximize the cruise efficiency. For example, for a typical vehicle the amount of gas it takes to accelerate from 0 to 60 MPH is about the same amount required to keep the vehicle traveling 60 MPH for about a mile. So you can see that when you are traveling many miles the amount of gas used to accelerate you is very small compared the amount of gas you’ll use to keep you at speed for many miles. This sets up my first test for which everyone probably already knows the results. I ran the H3 at two fixed speeds (40 MPH and 44 MPH) in both 3rd and 4th gear and measured the rate at which the gas is consumed. (The gas volume was measured and since the temperature was constant for all tests the volume is reflective of the mass of gas used.)

3rd gear:

40 MPH - fuel utilization rate = 3.38u/s

44 MPH - fuel utilization rate = 3.92u/s

4th gear:

40 MPH - fuel utilization rate = 2.90u/s

44 MPH - fuel utilization rate = 3.05u/s

u/s is a scaled volume of gas used per second

The conclusion here is that if you are cruising you want to be in the highest gear with the torque converter locked. My guess is that even though the drivetrain efficiency is higher in 3rd than 4th gear, the higher engine parasitic losses associated with the higher RPMs in 3rd than 4th gear dominated the fuel rate utilization.

ACCELERATION EFFICIENCY

For city traveling, the goal is to maximize the acceleration efficiency. If you are starting and stopping every block then the amount of gas used to accelerate the vehicle will dominate the fuel consumption and MPG. The trick the hybrids do is absorb energy and store it during braking; then use this stored energy to accelerate the hybrid. This is why the hybrids do proportionally better in the city than the highway.

I ran the H3 at three different constant throttle positions (35%, 45%, and 55%) and measured the total fuel volume used when going from 20 to 50 MPH. (The gas volume was measured and since the temperature was constant for all tests the volume is reflective of the mass of gas used.) I ran this test for both my tranny shift tables and Alvin’s tranny shift tables.

My tranny table

35% throttle: time=28.8 sec, total gas used = 3583u total

45% throttle: time=15.8 sec, total gas used = 2945u total

55%+ throttle: time=13.1 sec, total gas used = 2567u total

Alvin’s tranny table

35% throttle: time=29.3 sec, total gas used = 3803u total

45% throttle: time=12.0 sec, total gas used = 2473u total

55% throttle: time=11.1 sec, total gas used = 2508u total

u total is a scaled amount that represents the total gas volume used

Because it was difficult to precisely hold the throttle in a fixed position there is some variance (maybe +/- 5%) about each time and total fuel used data point. There are two conclusions from this test: 1) Alvin’s table resulted in less fuel consumption than mine and 2) the more throttle you use to accelerate (within reason) the less fuel you use. This goes against the EPA’s advice to not accelerate fast when pulling out because you’ll waste gas. I think the reason why the higher throttle resulted in less total fuel being used is due to the lower pumping losses associated with larger throttle positions thereby increasing the engine’s overall efficiency. Basically, your engine doesn’t have to work as hard to suck air into the engine when the throttle body is open more.

I think the key is learning how to drive based on how the tranny tables are set up. I think my tables are better for cruise (highway) and Alvin's are better for acceleration (city).

 

I'm completely impressed right now. I love learning these new things. I'm like a black hole for this kinda stuff.

I think it's very interesting that you disproved an EPA theory, at least for this vehicle.

Secondly though, This really wouldn't apply to a manual transmission, would it? You would be controlling everything. Do you know what the odd thing is? I noticed these results with my manual and could never figure it out. Whenever I would give it more gas and shift at higher RPMs while accelerating to my final speed, I would get better MPG. I intentionally used a tank of gas and accelerated shifting on or below 2500 rpms, and got worse MPG, I'm assuming because it wasn't really producing enough torque at those lower RPMs to make the thing move very well. What you are saying makes perfect sense. I'm interested in finding out more of what you find with normal day to day driving.

I should have Alvin's PCM back hopefully tomorrow. You guys are getting me all geeked up about this stuff

 

God, Numbers, give me numbers..I love this kinda talk...gives me goose bumps[8D]

Anyway, excellent report and very enlighening...Just curious, How did you measure the fuel consumption actually? Was it a mathimatical result, based on MAF-Airflow and O2 emissions readings?...I assume you were plugged in with a lap-top while perforing these road tests...This is all very intriguing as to your test bed..Cool beans man!

 

I'm guessing this is James Nelson (by the user name)? Nice doing business with you, glad you love it.

He's not the only one - there is also Brent Richardson and James Knowles. I do not know their forum names.

So stepping away from the number analysis for a sec, how do you like the feel of it overall?

 

I've had mine in for a couple of weeks now and overall am pleased. Noticeable difference in low end torque and upper end when you kick it into passing gear. It doesn't seem to labor as much as it used to when taking off from a standstill.

Haven't noticed much of an improvement in mpg, I'm still getting 12 in town and 14 on the highway driving 80-85. It was nice last weekend being able to hit 110mph on the interstate though, no more speed limiter and the truck was very stable. This was on the factory 33" Bridgestones, not my 35" mudders. It doesn't downshift as much trying to maintain higher speeds either.

So that's my SOP opinions and I think it's worth the $ for the improvements.

Jim Knowles

 

Thank you for the feedback!!

We've noticed with some of our customers that it takes a few weeks to see an increase in gas mileage. Not because of the tune, but because they have been getting right foot happy with the new power