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Discussion Starter #1
What is the maximum safe boost for our 6.6 Dmax?


For you guys with the Attitude monitor, where do you have your boost alarm set at?
 

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IIRC the attitude won't read much more than 25 pounds of boost. You can see 28 pounds measured at the wastegate pretty easy. With my stack I have seen as high as 34 pounds on mine. If you fiddle with the wastegate some have seen around 40 pounds but you will grenade the turbo if you keep hitting that level.


I don't think that you will hit an "unsafe" boost level with the wastgate working on the stock turbo. I have heard rumors that with the twins on the ATS truck that the stock heads were holding at 50 to 60 pounds of boost without a failure but who knows how long the top end will hold up to that abuse.


I did hear that they bent a conn rod on their engine but I have no clue as to the veracity of the statement or what caused the bottom end failure.Edited by: BMDMAX
 

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Discussion Starter #3
BMDMAX said:
I don't think that you will hit an "unsafe" boost level with the wastgate working on the stock turbo.




Cool, that sets my mind at ease as far as that. Thanks
 

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be very very careful about wastegates, i grenaded my turbo at 37lbs of boost..... very noisy, very expensive, and BD blew theirs up at 40# of boost, same results.


Anyone who totally disables the gate and barks their turbo can expect a nasty suprise.... i know from experience






BTW that was 37lbs PSIG after the intercooler!


Edited by: Got Juice?
 

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I regularly see more than 30, but less than 35. I'm running TST's comp box and their "calibrated leak" I guess you could call it in the boost sense line so that my boost is turned up but the wastegate will still function, just at a higher boost. I don't think I've ever barked my turbo, but I don't chop the throttle at high boost either, I back off gradually like 1 or 2 sec to fully off.
 

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Discussion Starter #6
Guys, I definately am not looking for that kind of power. I have a stock wastegate and intend to keep it that way.





Thanks for the replies though
 

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Hey guys, I'm new to the site but have been around others for a while. With an intake and only a 70HP comp tune with a stock turbo what, if anything, can be done to raise boost pressure with the stock wastegate?
 

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Tank said:
Hey guys, I'm new to the site but have been around others for a while. With an intake and only a 70HP comp tune with a stock turbo what, if anything, can be done to raise boost pressure with the stock wastegate?

If I had a 70hp tune, and wanted more power, I would just upgrade to a higher tune, and leave the wastegate stock. If you still think you want to modify it, you can put a restrictor into the vacume hose, but make sure you have a boost guage, and don't go too far.Edited by: Amric
 

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Thanks, I think for now it can wait, but hopefully before too long (this summer), she will get some more HP.
 

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40+ psi will not hurt the stock turbo at all unless you plug the wastegate actuator line off. If you unhook or plug that line off I have seen them blow anywhere over 35.
 

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CPMac said:
40+ psi will not hurt the stock turbo at all unless you plug the wastegate actuator line off. If you unhook or plug that line off I have seen them blow anywhere over 35.

I don't think I understand. Let's say one bleeds off boost and the turbo produces 35psi. How is that 35psi different from 35psi created from a turbo with a disconnected/blocked wastegate? I'm assuming both are measured at the same location in the intake.


Either way, the wastegate is not opening and the turbo is making more boost.


R, Steve
 

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socaldmax said:
CPMac said:
40+ psi will not hurt the stock turbo at all unless you plug the wastegate actuator line off. If you unhook or plug that line off I have seen them blow anywhere over 35.

I don't think I understand. Let's say one bleeds off boost and the turbo produces 35psi. How is that 35psi different from 35psi created from a turbo with a disconnected/blocked wastegate? I'm assuming both are measured at the same location in the intake.


Either way, the wastegate is not opening and the turbo is making more boost.


R, Steve

When the throttle is closed all the way with the WG disabled the exhaust energy is trying to spin the exhaust side of the turbo(without the saftey valve W/G), unfortunately (for me) the engine cannot ingest the air as the engine slows down. then you get a reverse pressure wave returning to the turbo stalling the compressor side.... and at 170,000 rpms that wave causes and eddy current that rapidly slows the turbine down while at the same time the exhaust energy is still trying to drive the turbine. a mild instance will produce a high pitched 'woofing' noise a major instance will woff several times before the shaft on the turbo distorts from the 2 opposing twisting forces, impellers then hit the housing, both shatter, sending pieces into the ic core/engine. If the worst case scenario happens shut truck off immediately otherwise it will feed off of the hp oil line to the turbo and you will have a runaway engine (like mine did) very scary stuff. I wish i coulda taken pics of my turbo, i saw it before it went away. I've blown other turbos, G-laders and roots chargers before, but this was TOTAL carnage!Edited by: Got Juice?
 

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"When the throttle is closed all the way with the WG disabled the exhaust energy is trying to spin the exhaust side of the turbo(without the saftey valve W/G), unfortunately (for me) the engine cannot ingest the air as the engine slows down. then you get a reverse pressure wave returning to the turbo stalling the compressor side.... "


Are you thinking of a throttle plate? There is no throttle to close. We step on a pedal which has a spring, 3 resistors and a couple of wires that send the signal to the ECM which controls fuel pump, fuel pressure, injectors, timing and pulse width. The intake tract is wide open all the time on a diesel. On the EGR equipped models there is a plate in the intake, but it is used to recirculate exhaust gasses, it's not connected to the throttle pedal.


If one disconnects the hose entirely from the WG, the WG sees no boost. Thus it never opens, never bleeds off exhaust and makes boost until equilibrium is reached between fuel, rpm and load.


If one cuts a hole in the hose, once again the WG doesn't see the boost (all or some of it) and if you're bleeding off enough for it to make 40psi, I think it's probably fully closed. Thus same scenario as above.


I've seen video of what you're talking about, "barking" a turbo. The engine was under tremendous load and the throttle was suddenly released. I can see how this can put huge loads on a turbo and damage it exactly as you describe. It just seems to me that the 40 psi, in combo with extreme engine loading (like sled pulling or stuck in the mud) and sudden throttle release are the real causes here. Not whether the boost is bled off or blocked off.


Maybe I'm missing something. Is there a way to make 40psi boost with a stock turbo without blocking or bleeding the WG hose?
 

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This is really cool stuff guys! I have 2 questions for the both of you .


I was stuck in snow and spinning my tires a little. I was trying to rock the truck. I would put the brakes on and slow things down and then put it in reverse. The engine made some funky woofing/whirling noises. Do you think this was hurting my turbo? . It was -30 windchill and I was not about to be stuck.


Second question.


What does a Banks Big Head Wastegate do?
 

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socaldmax said:
"When the throttle is closed all the way with the WG disabled the exhaust energy is trying to spin the exhaust side of the turbo(without the saftey valve W/G), unfortunately (for me) the engine cannot ingest the air as the engine slows down. then you get a reverse pressure wave returning to the turbo stalling the compressor side.... "


Are you thinking of a throttle plate? There is no throttle to close. We step on a pedal which has a spring, 3 resistors and a couple of wires that send the signal to the ECM which controls fuel pump, fuel pressure, injectors, timing and pulse width. The intake tract is wide open all the time on a diesel. On the EGR equipped models there is a plate in the intake, but it is used to recirculate exhaust gasses, it's not connected to the throttle pedal.


If one disconnects the hose entirely from the WG, the WG sees no boost. Thus it never opens, never bleeds off exhaust and makes boost until equilibrium is reached between fuel, rpm and load.


If one cuts a hole in the hose, once again the WG doesn't see the boost (all or some of it) and if you're bleeding off enough for it to make 40psi, I think it's probably fully closed. Thus same scenario as above.


I've seen video of what you're talking about, "barking" a turbo. The engine was under tremendous load and the throttle was suddenly released. I can see how this can put huge loads on a turbo and damage it exactly as you describe. It just seems to me that the 40 psi, in combo with extreme engine loading (like sled pulling or stuck in the mud) and sudden throttle release are the real causes here. Not whether the boost is bled off or blocked off.


Maybe I'm missing something. Is there a way to make 40psi boost with a stock turbo without blocking or bleeding the WG hose?

I know kennedy has a better technical explaination of what happens, i do know that diesels do not have a throttle plate, i just mentioned closing the throttle. From my own frightfully bad experience never ever block the gate. Using an 'boost fooler' is somewhat safer than a complete disable (depending on how much you boost you bleed off) as the wategate is still functional, to bleed off exhaust energy when the throttle is released (during a shift for example) or simply do its prime function to release pressure when the factory set limit is reached.. IIRC i believe the surge line for our turbo is in the 35-37PSIG range... someone correct me if this is wrong info please!


Cross the surge line and close the throttle (someone cuts you off in my case) and you will probably feel as sick as i did that day.... OMFG oil smoke on decel... then white smoke and tinkling sounds in the exhaust and the intercooler (both sounds courtesy of shattered impellers trying to find their way out... in pieces.)
 

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Bronco said:
This is really cool stuff guys! I have 2 questions for the both of you .


I was stuck in snow and spinning my tires a little. I was trying to rock the truck. I would put the brakes on and slow things down and then put it in reverse. The engine made some funky woofing/whirling noises. Do you think this was hurting my turbo? . It was -30 windchill and I was not about to be stuck.


Second question.


What does a Banks Big Head Wastegate do?


Bronco, you have barked (surged) your turbo.... stop it :)


Most A/M wastegated are better quality designs to fight 'boost creep' under load to prevent crossing out of the compressors operating map and into the surge area. They also tend to be more aggressive in not opening prematurely and allowing peak boost to be built earlier and maintained. Most HP applications of remote wastegates are for high boost applications where adjustability on the fly is a requirement due to temperature increases/decreases and the resulting loss/gain in air density.
 

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Don't those pieces destroy the heads?. The pistons actually rise above the block about .015" with the only thing keeping them from smashing into the head is head gasket thickness.
 

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hoot said:
Don't those pieces destroy the heads?. The pistons actually rise above the block about .015" with the only thing keeping them from smashing into the head is head gasket thickness.

I guess i was just lucky. The turbo was sent back to GM for 'failure analysis'
 

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What we have seen is that 35 psi seems to be the point at where the turbo's go by by. Some units will go higher but a general rule on the D-Max is keep it below 35. I have seen one that came apart at 32 psi so you takeing your chances any way you look at it. There are to many varying operating conditions that will cause the pressure number to be different when they explode so I donot recommend running the boost higher than 30 psi for those who want long term safety, but then there's those 1%er that I tell keep it below 35psi.
 

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The Banks Big Head WG does the same thing the stock WG does except the Banks part is adjustable. Also, it has a port to attach a boost pressure line for a gauge.


JP
 
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