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#75 by 745 turbogreasel on 30 Jan, 2011 15:45
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I'm a fan of the get a bigger tranny, axle, whatever approach.
Braking mode ideally, you hit a momentary pushbutton to trigger it, and it closes the vanes to work as an exhaust brake, but opens them up at a light touch of the accelerator.
at a basic level, use the same strategy as any other exhaust brake
more advanced, you tap an up/down button to set desired speed.
From new Dmax literature...QuoteA new feature on Duramax-equipped models is an exhaust brake system. This driver-selectable feature uses the turbine control of the variable geometry turbocharger and the compression of the engine to generate backpressure, slowing the vehicle without applying the brakes. It is a smart system integrated with the cruise control feature and varies the braking to account for the grade and vehicle load.
The exhaust brake system allows for virtually effortless driving and towing, with seamless and quiet operation. It also helps prolong brake life and prevents overheating the brakes on long, downhill grades. -
#76 by regcheeseman on 31 Jan, 2011 03:40
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Not sure about the exhaust brake at all
Using a turbine as a brake seems to make little sense to me, but then using brakes at all is something I tend to avoid generally.
Adding both features would be very easy regardless. -
#77 by 745 turbogreasel on 01 Feb, 2011 00:42
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Not sure about the exhaust brake at all
Using a turbine as a brake seems to make little sense to me, but then using brakes at all is something I tend to avoid generally.
Adding both features would be very easy regardless.
The scenario;
You are coming down out of the sierras with a carload of treasures.
Coasting in 3rd gear, you are holding 66 MPH at 4000 RPM, 0 fuel is being injected, vanes full open(TPS=0). An upcoming turn recommends 45 MPH.
-you could press the service brake and smoke up some pad, but neither of us likes that.
-grab 2nd?
-Raise the boost to 14 PSI, now you compress lots more air in the compression stroke, and substantially increase exhaust back pressure. There is still no fuel injected, so the increased work the engine is doing can only slow it down. It is almost like you did shift to 2nd, you are slowed to 55 and make the corner without having touched the brake.
Rounding the bend, you come upon a truck in the slow lane belching smoke as he takes a run at the next uphill, what so you want to do?
a)Keeping fields green for the bunnies is important, you leave the brake on till you match speed 2' off the back of the trailer, and draft his sorry ass up the hill.
b)WOT Demons get the best of you, but since you are already pushing 1 bar, there is not a puff of smoke as you go to full fuel, and without hesitation leap past the evil rolling highway blockade.
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#78 by regcheeseman on 01 Feb, 2011 07:28
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or option 3...
ignore the 45 sign posted as that's for pussies and take it at the 66mph you are already at.
I understand the scenario, and the beauty of a micro controlled system is that with the simple inclusion ofQuoteif pushbutton = 1 then let Vp=255
end if
into the main routine then your wish is granted,
or you could haveQuoteif pushbutton = 1 and Tp<10 then let Vp=255
end if
It basically says that if the pushbutton is pressed and there is no throttle input (Tp) (or very little) then the desired vane position (Vp) is 255 i.e. closed
The servo motor which positions the turbo vanes has a feedback variable Sp (servo position) . The servo motor is contantly driven to make Sp = VP (wthin a small tolerance)
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#79 by rabbitman on 01 Feb, 2011 23:09
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Now that is cool!!
.
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#80 by rolo on 02 Feb, 2011 14:01
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nice one reg
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#81 by lord_verminaard on 03 Mar, 2011 09:03
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Congrats! Can't wait to hear how it works in the car.
I think the OEM keeps the vanes open while at idle to keep the restrictions as low as possible. So when you hit the throttle to go, there will inherently be a bit of a pause while the vanes close. I'd think this would be enough of a delay in boost.
Now launch control, I like that idea.
Brendan -
#82 by R.O.R-2.0 on 03 Mar, 2011 09:19
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when do we get to buy kits/finished products? i really want one of these bad boys!
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#83 by macka on 05 Mar, 2011 05:10
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when do we get to buy kits/finished products? i really want one of these bad boys!
ditto -
#84 by Rising on 25 Apr, 2012 12:50
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Any news on these bad boys? It's been over a year... And i just bought a vnt
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#85 by rodpaslow on 25 Apr, 2012 13:51
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DITTO
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#86 by keaton on 25 Apr, 2012 20:41