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Discussion Starter #1
Can someone explain the boost cotrol should be hooked to the pot switch. Is it one wire to the lowest position, and the on wire out of the middle connector or join the middle connection with the end conector. Please any appriated
 

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Cut wire to B (boost signal).


Clockwise potentiometer terminal wired to B.


Center pot terminal to wire that was on B.


Counter-clockwise pot terminal wired to A (ground).


Fully clockwise is factory stock setting,


1/2 rotation CCW increases Boost level.


Full ccw rotation (ground) gives Boost Sensor DTC.


CW terminal to A, ccw terminal to B for clockwise Boost increase Edited by: gmctd
 

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Discussion Starter #3
Lost me. I bought a radio shack 10k ohm pot. I cut wire B from map. I spliced wire from map B to pot terminal one. I spliced harness wireto pot terminals 1 & 2. Is this wrong. Sorry I did not understant your instrctions. Please help.
 

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Is it a single turn pot, or a ten turn pot?
 

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Hey Ruben,








The single connection wire is from the MAP. The split wire goes to the wiring harness. Did you get a knob?
 

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In QM's picture, the terminal on the right goes to B


The termiinal in the center goes to the original wire from B


The terminal on the left goes to A
 

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Discussion Starter #7
I dont know what I am doing wrong just dosent work for me. I have BD PCM, 4 inch exhaust , 3 inch down pipe, spesrco intercooler. I am seeing 15# of boost same as always. It will boost 15# then drop to 11# to 12# of boost. I dont know how many pounds of boost it should hold , or if I just dont get it,and just dont have it hooked right any help appriated.
 

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It doesn't always work with a 'chip', Ruben.


What it is trying to achieve is about 15psi with the oem chip, which is factory limited to ~7-8psi.


Your 'hot chip' possibly sets that up internally, such that the PCM will allow more boost to develop.


Anything over 15psi is useless, anyway, because of turbo design restrictions, but 12 - 14psi is safe, with good power and response at 12psi.


If you list your truck year and model, and any upgrades it has, in your signature, forum responses can be more specific to your truck.


Check mine, for example - tells people it's a 1989 one ton, four door, four wheel drive with dual rear wheels, has a 6.5L, and it's heavy.


Heh vee, not Humvee (Hummer)
Edited by: gmctd
 

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Discussion Starter #9
I dont have a chip. I have the BD PCM. It was done for me by Jerry from BD. Jerry does all my PCM chips we get for the shop. So I guess reason Im not getting more boost is because of program. I talked to John Kenedy He says that its the switch. He told me to buy his and I will really se a differece. I guess Im just used to my Dodges. The GMC is my wifes she uses it to pull her horse trailer and all around family vehicle. I drive it and want more.Edited by: Ruben
 

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Excellent, Ruben - now I can see you have OBD-II, which requires PCM reflash , rather than 'chip'. You did mention that, but sometimes folks confuse terminology, if new to Diesels, and all.


John Kennedy's chips and reflashes are very aggressive, compared to the others.


Have you talked to anyone at BD, for more information on their setup?


For a little more performance from the stock engine, the only option left is a larger turbocharger - the GM-8 is a 12psi limitation, as is the 21.5:1 compression ratio, but you have all the goodies for about 240hp.


Next step is the 18:1cr 300hp street motor, from Peninsular Diesel, and others, which is the engine John Kennedy used to develop his chips and reflashes. His truck was unbeaten in pull-offs - 15000lbs, 6% grade, 1 mile, from dead stop to max speed achieved at top, iirc.


You can check it out at his site, if you're interested, and at Peninsular Marine Diesels. Several other shops are offering the 18:1 motor, but Peninsular did the research in cooperation with GM, also iirc.


It's not an inexpensive upgrade, but if 'she who must be obeyed' likes her truck, the improvement will be most enjoyable, and worth it .
Edited by: gmctd
 

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Ruben,


Your truck is reacting normally, I have all the same bells and whistles as you maybe a few more, but even with JK's boost control I peak to 15 boost but back down to about 7-8 cruise empty, and 10-12 heavy tow cruise, peaking back up to 15 if the hill I'm climbing warrants it.


The BD PCM is only a little better than GM 99+ factory, I tried it but sent it back swapped for the junkard 99 PCM $125 vs. $600 much better buy.


FYI BD doesn't flash PCMs (or at least they didn't) they sub out to an outfit called Z Industries that used to be the ONLY reprogrammer out there regardless who you bought it from.


I think JK has a "race" PCM a little hotter than the Z & GM 99+ factory, Bill Heath is also marketing a new program. Kennedy will pretty much tell you the 99+ GM PCM is as good as Z flash for the money. Jury still out on the latest offerings.


As far as boost control goes, once I set mine to desired boost output I never touched it, so a tunable pot really isn't necessary with a IC installed engine, a fixed resitor that gives about 80 kPa baro is really all you need. Those without IC will want to tune up or down depending on OAT to keep IAT in safe limit.Edited by: Turbine Doc
 

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TD is right,


With your spearco (big dollar) intercooler, a 10k resistor soldered in between the MAP and the B wire would do the same as full potential on your current switch.


But, I still don't know if you wouldn't benifit from both. With both and the switch off you would still have 10k ohms resistance or 80kPaG of barometer reading off your map sensor. Turn the switch up and MAP signal would drop another 10k ohms, or to about 60 kPaG.


This increase in resistance might help level out the boost readings in the lower RPM, but may do nothing to push them over 15psi maximum turbo output. (If the respose doesn't feel powerful, fuel might have been affected by too much resistance, but this is not the case at 10k ohms)
 

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I'm not advocating use of both; in an IC equipped or WMI engine, fixed resistor is sufficient. Variable resistr for non IC/WMI as you can adjust down boost as outside temps go up, to keep IAT in the green while having higher boost than factory program calls for.


The resistor variable or fixed, allows you to run up to 15psi boost & keeps you from throwing a code with stock PCM program, in a turbo master rig you can set spring length for higher boost but will throw a code plus get into high IAT if non IC/WMI.


The PCM defuels for high IAT non IC equipped, you can also defuel if algorithm of IAT vs , vs MAP(boost), vs baro, vs rpm isn't where PCM expects it to be; this is what Ruben & myself are up against now. My factory HD program and the BD/Z Ind modded factory program just basically add fuel they did not complete the picture.


It's a little more complex than just adding fuel, or boost, that is why the reflash or chip are required to account for all of this maintain driveability and provide desired power, throw in backpressure as GMCTD describes and what I also have seen on my gauge and it becomes a balancing act.


Right now there isn't a 1 program fits all setup, ideal would be a selectable box for economy, tow, or race power or multiple programs like DMax has. You can add fuel in form of propane, or hi pop/flow injectors, and incrimental gain with FSD resistor and computer is blind to that to a point, the algorithms(curves) are still present for timing, boost, baro etc, that is what is currenlty keeping from netting bigger gains.


Look at Dmaxes 6.6 vs 6.5; .1L delta in displacement should not be that big a difference, lower compression, and bigger turbo we should be able to take advantage of similar gains that Dmax enjoys from reprogramming. Now there is a limit to how much extra power the 6.5 can handle in sustained conditions, that is the real limit, how hard for how long do you want to max your engine out.


The Dmax was designed for more margin in that area, the 6.5 was a "We need to go to market now" design, with driveability, decent power & economy. It followed the 6.2 N/A engine also an engine with lots of potential if set up right, just a matter of how much money you want to pump into it.
 

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From what I understand about the Programming, there's a whole lot of variable being underutilized, but unless you're some kind of hacker, it's an encrypted hexcode genius puzzle. The only light in this tunnel is what the Thirdgen.org guys have been able to do with their programming in order to run turbos in non- turbo cars. The only veriable I'm missing is, of course, calibration. Without knowing which hex prarmeter controls what, you're lost. Yet the thirdgen guys where able to do it.


A mojor difference between the 6.5 and the 6.6 is the fuel system. Pilot injection and 25,000 psi fuel rails and dimesions to compression combustion. Propane in the fuel system isn't dissimilar, in that it should be combusting as the injection of diesel occurs like the pilot is combusting as the main injection occurs.Edited by: quantum mechanic
 
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