Duramax Intercooler tuning
07-17-2006, 02:18 PM
#41
Originally Posted by Manic Mechanic
I can't tell you about GM's torque management yet but I can tell you about supercharged timing curves. With only 13.5 (that's total right?) you're doing more harm than good. Your exhaust system is going to run really hot and burnt ex valves are a good possibility. Seeing as how your going to tow and want to er on the side of safety here's where I would go. From idle ramp up quickly to 25* total by 2,500 then slowy work in a little at a time as the RPM's climp. By your 4,800 shift have 28* in it. If you extend your shifts later keep adding a degree. Leave some timing retard in at shifts to cushion the blow. This would generate a power curve within 2% of optimal but with less tendency to knock. Remeber you're only running 6 LBS. of boost and that's intercooled. That's not much as far as pushing the detonation threshold is concerned.
On my supercharged race engine I mentioned earlyer I shifted at 6200, by then timing was upto 36* without issue.
Vernon
On my supercharged race engine I mentioned earlyer I shifted at 6200, by then timing was upto 36* without issue.
Vernon
07-17-2006, 02:40 PM
#42
Originally Posted by kbracing96
Vernon, I don't know what kind of motor your are working with, but there is NO WAY you can run that kind of timing with these motor naturally aspirated, let alone FI. You would have broken pistons faster then you could get out of the gas. GM designed these cylinder heads for high flow and a fast burn, so you run much less timing then in other types of motors. 13.5 is a little conservation for a boosted motor like this, but unless he has some race gas with the compression he has, he can't safely run more then about 18*-20* max on the street. EGT's aren't that bad with these setups.
Shewie.....man im glad to hear that, cause i couldnt find anyone running near that much advance. All i had heard was 13*-16*. I know I am a little on the conservative side, but i am really hoping to pick up EFILive this summer or fall and start programming myself. With it being so hot, and a few mountain drives in my near future....i decided to leave a little timing out of it for now. It felt strong with no knock at all....so Iam happy for now. KB, did you see this question.......
Also, what kind of KR do you typicaly see when no torque management has been removed from the tranny? I am semi-scared (even though now i can do it) to remove much if any TM due to the horror stroies i read on the diesel boards about guys killing thier Allison with little more than 150rwtq over stock. Does the KR increase during shifts based on the amount of timing thats added? What I mean is if i am seeing 1 degree of timing pulled during a shift at say 14*, will i see 2 degrees pulled at 16* and so on? Do you know what i mean?
I realize if this was "Actual knock", then the knock would increase as timing is added. However, since this is false knock brought on by TM, would it "also" increase as timing is added?
07-17-2006, 03:18 PM
#43
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Those timing numbers are for an older engine with inefficient combustion chambers. I'm assuming he must think the Gen III engines use the same cc's as the older Gen I SBC. Even if we're talking about a Gen I SBC, 36* of timing under boost on pump gas is asking for it.
Total timing is not something we have to worry about either. That is refering to an older distributor type ignition where you have to deal with mechanical and vacuum advance.
Total timing is not something we have to worry about either. That is refering to an older distributor type ignition where you have to deal with mechanical and vacuum advance.
07-17-2006, 03:37 PM
#44
Torque management is based on a calculated torque figure that the PCM comes up with. It calculates X torque = pull X timing to reach its calculated torque # to keep it "safe" during the shift and can vary depending on the conditions and load. It doesnt say "pull 4* on every shift" Make any since?, lol. I wouldn't be afraid to pull 40-50% of TM out of your stock trans settings. Your not making the kind of torque the big diesels are making. It also depends on how you beat on your truck. I've been running with no TM with the oem stock 4l60 with only a TG shift kit and vette servo for a year and a half, but I don't constantly beat on my truck, and I have tweaked a few thing in the setting to suit my driving style. The big thing in making a trans live is finding the fine line where your slipping the clutches just enough to where your not braking hard parts, yet not slipping them enough that they burn up.
07-17-2006, 04:44 PM
#45
Originally Posted by kbracing96
Torque management is based on a calculated torque figure that the PCM comes up with. It calculates X torque = pull X timing to reach its calculated torque # to keep it "safe" during the shift and can vary depending on the conditions and load. It doesnt say "pull 4* on every shift" Make any since?, lol. I wouldn't be afraid to pull 40-50% of TM out of your stock trans settings. Your not making the kind of torque the big diesels are making. It also depends on how you beat on your truck. I've been running with no TM with the oem stock 4l60 with only a TG shift kit and vette servo for a year and a half, but I don't constantly beat on my truck, and I have tweaked a few thing in the setting to suit my driving style. The big thing in making a trans live is finding the fine line where your slipping the clutches just enough to where your not braking hard parts, yet not slipping them enough that they burn up.
Okay, cool, i understand. Well the next time in, or when i get my own EFILive, i will probably do like you said and remove maybe half of TM and up the timing o about 15* at WOT. I think i should be safe at 6lbs of boost with an efficient A2A IC at 15*.
07-17-2006, 06:44 PM
#48
I would find out what the above-atmospheric 8.1 guys are using for timing, instead of everyone else. 13.5° might be all, since you are getting that quick flash of KR when you frst go WOT. I don't know how kbracing96 knows that it is torque management, I don't see that graph in the your screenshots.
The bigger the cylinder bore is, the more knock prone it is.
All that I'm saying is comparing your timing to mine is apples vs. oranges.
The bigger the cylinder bore is, the more knock prone it is.
All that I'm saying is comparing your timing to mine is apples vs. oranges.
07-17-2006, 06:58 PM
#49
Originally Posted by MikeGyver
I would find out what the above-atmospheric 8.1 guys are using for timing, instead of everyone else. 13.5° might be all, since you are getting that quick flash of KR when you frst go WOT. I don't know how kbracing96 knows that it is torque management, I don't see that graph in the your screenshots.
The bigger the cylinder bore is, the more knock prone it is.
All that I'm saying is comparing your timing to mine is apples vs. oranges.
The bigger the cylinder bore is, the more knock prone it is.
All that I'm saying is comparing your timing to mine is apples vs. oranges.
07-17-2006, 07:48 PM
#50
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Well you guys are either discussing timing advance past an initial setting of 10-15* or we're on two different planets. His graph shows him running timing at WOT and higher RPMS that big blocks have idled at for all of my life and before that actually many small blocks too. And sorry I don't believe the Gen 3 stuff is that much better, better yes but not that much. Also I just went and double checked the combustion chambers on my HP3 8.1 heads and they're still wedge shaped. No pent-roof chamber with centrally mounted plugs, no fast burn stuff. GM is doing away with the big block and going supercharged eight because the smaller bore/stroke and combustion chambers leave less unburned fuel to clean up. In other words bigger engines need more timing advance to be able to burn the fuel in time. Think about it, each one of my cylinders has more displacement than a whole GEO metro engine. That much displacement with only one spark requires a head start to burn the whole thing in a hundreth of a second.
The old days we had distributors and we had to worry about initial and total. We'll as far as I'm concerned we still do. After cranking there's really no reason to not have some timing advance when just idleing without any throttle. Lets say the spark fires at 10* BTDC and the engine purrs. That would mean you have 10* initial. If you add 20* at WOT then you now have 30* total. When I say total advance I mean actual degrees of crankshaft rotation from when the plug fires until top dead center. 13.5 at WOT isn't nearly enough for this or most engines in use today.
So perhaps my ignorance of how GM and or HP Tuners software shows timing advance is what the (my
) problem is. If the timing advance shown in the graphs is actually all advance (initial + advance for RPM & load) then it will always be my stance that he's leaving some power and fuel efficiency on the table, big time. If the graph shows only advance added for RPM & load and doesn't include the base advance that it started from then it makes more sence. It would make it harder to keep up with what you're doing but doesn't change the physics.
If there's something I'm missing please tell.
Vernon
The old days we had distributors and we had to worry about initial and total. We'll as far as I'm concerned we still do. After cranking there's really no reason to not have some timing advance when just idleing without any throttle. Lets say the spark fires at 10* BTDC and the engine purrs. That would mean you have 10* initial. If you add 20* at WOT then you now have 30* total. When I say total advance I mean actual degrees of crankshaft rotation from when the plug fires until top dead center. 13.5 at WOT isn't nearly enough for this or most engines in use today.
So perhaps my ignorance of how GM and or HP Tuners software shows timing advance is what the (my
) problem is. If the timing advance shown in the graphs is actually all advance (initial + advance for RPM & load) then it will always be my stance that he's leaving some power and fuel efficiency on the table, big time. If the graph shows only advance added for RPM & load and doesn't include the base advance that it started from then it makes more sence. It would make it harder to keep up with what you're doing but doesn't change the physics.If there's something I'm missing please tell.
Vernon