Any feel like having a tuning discussion?
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Any feel like having a tuning discussion? - 10/6/2006 6:39:33 PM
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ChevyHighPerformance
Posts: 159
Joined: 7/5/2006
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I have HPTuners for the H3 and have been working on my own tune. I was wondering if anyone wanted to discuss tuning.
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RE: Any feel like having a tuning discussion? - 10/6/2006 10:13:36 PM
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HummerGuy
Posts: 6679
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Funny you should say this.
I received my "PCM For Less" loaner PCM today and will be installing it tomorrow morning. I am sending them mine and getting it tuned for 93 octane. The only mod I have is a K&N filter in a stock air box. After careful consideration I decided I will be driving close to 100 miles a day and do not want any extra noise that I would get from a new exhaust and CAI kit, considering the cabin is already very quiet. They have already completed one tune for a user here (I don't know who, Yet!) and this person they said is really pleased with the results. I will probably be the only person getting it tuned specifically for premium gas, so I may have different, hopefully better, results. We'll find out. I will hopefully have mine back by next Saturday, which also may be my first time off-roading with it.
I started a new thread that is documenting my progress and results. The next thing I'm going to do after I drive it for a few weeks is buy some Iridium spark plugs and see what that does, if anything.
< Message edited by HummerGuy -- 10/6/2006 10:16:03 PM >
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RE: Any feel like having a tuning discussion? - 10/7/2006 1:11:12 AM
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Jmm
Posts: 131
Status: offline
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morning HG.
I don't get your point abt. ''93 octane''.
Here, the only petrol available is either standard 95 octane or Premium 98 octane.
Last tank results :
315 miles= 83 liters 100 % city. the car has now 1583 miles.
I have tried using standard 95 octane on other cars and really, I did'nt notice any difference.Neither in power nor in MPG.
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RE: Any feel like having a tuning discussion? - 10/7/2006 1:30:02 AM
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Linus Gump
Posts: 960
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Here in the US we have the choice between 87, 89, and 93 octane gas. From the factory the H3 is designed to run on the 87 octane gas. Not all areas carry it, such as where HG is loacated, so he is opting to have his PCM reprogrammed to run best on 93 octane gas. All the octane rating indicates is the ability for gas to resist knock and detonation. The higher the number, the more resistant it is. It does this by burning slower. The only way more power or economy can be gained from using higher octane is if the timing curve of the injectors is changed to allow for a longer burn time before the piston reaches the bottem of its stroke. This is one of the things he is having changed.
I would assume since yours was imported to Europe that someone would have made these changes so it will run on your gas during the impotation and safety check process.
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RE: Any feel like having a tuning discussion? - 10/9/2006 6:12:27 PM
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SedonaBoundH3
Posts: 82
Joined: 8/8/2006
Status: offline
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quote:
ORIGINAL: Linus Gump
Here in the US we have the choice between 87, 89, and 93 octane gas.
Not everywhere. Here in the People's Republic of California, 91 octane is the maximum. 91 Octane "Premium"...what a joke. Its just an excuse to get an extra 10% on each gallon from those who'll spend it just in case it makes a performance difference. (After many comparisons in my turbo Audi, I'd say it absolutely doesn't).
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RE: Any feel like having a tuning discussion? - 10/11/2006 6:57:45 PM
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ChevyHighPerformance
Posts: 159
Joined: 7/5/2006
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Update. I just added about 15 gallons of gas. The MPG was 14.7. My driving is 100% city with trips less than 5 miles and hilly roads.
Previous MPG data:
1) With the modified aftermarket air box, ported throttle body, exhaust and a couple other little things I was getting a solid 13.5 MPG.
2) I faked the Inlet Air Temperature sensor (IAT) out with a resistor and added resistance in series with the Engine Coolant Temperature sensor (ECT) to get more timing. With the resistors, I would get between 14 (mostly) to 14.5 MPG.
The resistors were removed for the latest test since I had direct program control and I didn't need to "trick" the PCM.
During this 15 gal test run:
1) I modified the shift trajectory several times part way through. So the full effect of this is not known.
2) I made many wide open throttle (WOT) runs to check on timing, knock retard, and tranny shifting. The WOT runs hurt the MPG.
3) It's been colder so I idle more in the mornings before I pull out which hurts MPG.
The results are encouraging but this is just one data point.
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RE: Any feel like having a tuning discussion? - 10/13/2006 9:46:38 PM
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ChevyHighPerformance
Posts: 159
Joined: 7/5/2006
Status: offline
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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).
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