Any feel like having a tuning discussion?

[ChevyHighPerformance]

Originally Posted by Hal

Feel free to give those of us who are interested, but by no means experts, links to any refrences where we can learn more about this stuff.

Keep the info coming, I like this topic

Like I always run premium gas, have a 5-speed and live in a hot southern climate... I never thought about optimizing an engine for things like this.

Here is a link to LS1TECH that has other links about tuning.
http://www.ls1tech.com/forums/showthread.php?t=287094

I really haven't read through the stuff listed here but it came highly recommended.

[ChevyHighPerformance]

Just an update. With the new increase in low end torque, I modified the auto tranny shift speed table. This table shows at what MPH and throttle position you want the tranny to upshift or downshift for each gear. I lowered the MPH at which the tranny up shifts and I moved out where the tranny down shifts - I added more hysteresis. So when you are doing 60 MPH and you press on the throttle slightly the tranny doesn't down shift to 3rd right away. I get into 4th gear much quicker now and the acceleration in 4th is fine for small-medium grades. If I need more acceleration, I just blip the throttle more and the tranny will downshift. The stock shift tables can cause you to downshift (4th to 3rd) if you increase the throttle by as little as ~12%.

For low throttle positions I upshift quicker for better (hopefully) MPG. When you need the acceleration the new shift table doesn't hold you back.

[ChevyHighPerformance]

Another update. I've tweaked the tranny shift table several times. Not very scientific but - now it feels like the H3 floats/coasts. Before it always seemed like I always had to press on the throttle just to coast around town (as if I was dragging something behind me).

Also, in my plan the speed limit is 25 (lots of kids) and my plan is pretty hilly. Before I had to press the throttle to climb a hill but to keep speed going down the other side I would just let off the gas and I would maintain speed. Now, I have to press the throttle less to climb the hills and when I go over the peak, I let off the gas and I accelerate down the hill and have to use my brakes.

I know its not scientific, but now the H3 seems "lighter".

[wpage]

Originally Posted by ChevyHighPerformance

Another update. I've tweaked the tranny shift table several times. Not very scientific but - now it feels like the H3 floats/coasts. Before it always seemed like I always had to press on the throttle just to coast around town (as if I was dragging something behind me).

Also, in my plan the speed limit is 25 (lots of kids) and my plan is pretty hilly. Before I had to press the throttle to climb a hill but to keep speed going down the other side I would just let off the gas and I would maintain speed. Now, I have to press the throttle less to climb the hills and when I go over the peak, I let off the gas and I accelerate down the hill and have to use my brakes.

I know its not scientific, but now the H3 seems "lighter".

CHP Good Thread! Kindly monitor your MPG closely as you probe these tests. You are on to potentially significant info. Please continue to share your findings.

[DURAMAX TIM]

I use EFI LIVE for my dmax and it does a great job, hoping that they will work on the H3 soon.

A lot of guys on another forum use it and we trade files, plus my vendor sent me a 500+ RWHP race tune for my truck once the tranny gets upgraded.

diesels are much easier to play w/ AF doesn't matter really.

I've got a tune right now that gives me 60hp and 4 mpg better fuel mileage as long as u stay under 72mph.

It gets addicting playing w/ the tuning to see what u can do, the speed limiter and redline was the first things to change plus calibrate the speedo.

[HOKIE W/HUMMER]

CHP,
I'm really interested in your programming results, so keep the updates coming. So where would an owner search for a reputable programmer that we could trust to develop a "custom" program for our H3?
Hokie

[DURAMAX TIM]

Originally Posted by HOKIE W/HUMMER

CHP,
I'm really interested in your programming results, so keep the updates coming. So where would an owner search for a reputable programmer that we could trust to develop a "custom" program for our H3?
Hokie

do it your self?

[ChevyHighPerformance]

Originally Posted by HOKIE W/HUMMER

CHP,
I'm really interested in your programming results, so keep the updates coming. So where would an owner search for a reputable programmer that we could trust to develop a "custom" program for our H3?
Hokie

Alvin from PCMforLess is tuning the H3's now. Typically you pay a deposit for a loaner PCM (which is sent to you first) and tuning. You remove your PCM, install the loaner, and send your PCM to them to tune. Then exchange the stuff when they ship your PCM back to you.

We use the same tuning program - so they sent me one of their tunes electronically to check out. I'm going to evaluate the tune in 3 stages:

1) Look at the actual tune - what and how tables were modified,etc. - This lets you gauge how the tuner made improvments, the tuner's philospohy, etc.

2) Install the tune and run a few tanks of gas through. SOTP testing, MPG testing, etc.

3) If I have time, I'll do a before and after dyno.

I plan on posting the results here as well as how my own tune is coming along.

[ChevyHighPerformance]

Originally Posted by DURAMAX TIM

I use EFI LIVE for my dmax and it does a great job, hoping that they will work on the H3 soon.

A lot of guys on another forum use it and we trade files, plus my vendor sent me a 500+ RWHP race tune for my truck once the tranny gets upgraded.

diesels are much easier to play w/ AF doesn't matter really.

I've got a tune right now that gives me 60hp and 4 mpg better fuel mileage as long as u stay under 72mph.

It gets addicting playing w/ the tuning to see what u can do, the speed limiter and redline was the first things to change plus calibrate the speedo.

I know what you mean. I keep tweaking and tweaking when I'm probably way beyond the point of diminishing returns. I'm having fun - I'm a nerd.

[H3.007]

F5 - Are these tunes legit? If so, why wouldn't GM be offering them? I just happened to see a show the other day where an ASE Tech Inspector witnessed an HP test at GM. It was really cool how they did it... Glad to know that such tech claims are third party regulated (kinda like a UL for the auto industry and no offense to GM). This keeps everyone honest...

[wpage]

Having worked for several major Tech Companys. R&D has deadlines and comitments on projects. Often they do not own or have significant interest in products in the pipeline. They kick products out the door. Under the Just in time banner, ready or not. GM has great people however my moneys on CHP to tweak this thing since he has ownership and apparently commitment.
The H3 is still young and has some growing to do...Its a great machine but like the 55 chevy there still may be some tweaking to discover and have fun with!!

[ChevyHighPerformance]

Originally Posted by H3.007

F5 - Are these tunes legit? If so, why wouldn't GM be offering them? I just happened to see a show the other day where an ASE Tech Inspector witnessed an HP test at GM. It was really cool how they did it... Glad to know that such tech claims are third party regulated (kinda like a UL for the auto industry and no offense to GM). This keeps everyone honest...

I know you didn't ask me, but I feel the tunes are legit. I just loaded Alvin's tune (from PCMforLess) and the idle was very smooth and the low end torque boost is impressive (it was much better than my custom tune). Throttle is very responsive down low.

[H3.007]

CHP - how long did it take you to complete this process?

[DURAMAX TIM]

Originally Posted by H3.007

F5 - Are these tunes legit? If so, why wouldn't GM be offering them?

GM and others are after emissions stuff 1st and reliabilty/warranty 2nd (maybe).

got to keep the epa happy.

that's why they have so much torque management off idle, save parts I'm sure.

I know on the diesels it used to be u had to roll out black smoke to make power but w/ EFI we can make more power and very little smoke.

stock Dmax (LLY) is close to 600 rwhp or more w/ tuning and diesel only.
year ago 500 was really tough to get.
but an allison will only handle 350-400 though w/o upgrades.

[ChevyHighPerformance]

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).