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BOV on a TDI
by
superman293
on 14 Jul, 2006 18:13
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Is it possible to have a blow off valve on a turbo charged diesel
thanks
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#1
by
DVST8R
on 15 Jul, 2006 00:25
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Anything with enough $$$ is possible, but since the air is not throttled or controlled and when you sundenly let off the throttle just the fuel is reduced, the air flows in the same as always the turbo isn't restricted and doesn't surge (for all you people who like to nit pick, yes I am aware that there is a point with really high PR that a case could be made for one, but anyone who has built a diesel to that point would not be here asking that question). So in this case there is NO point.
If you just want the lame sound, burn it on to a CD and play it to yourself in the car :roll:
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#2
by
Holeshot
on 29 Nov, 2006 16:18
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#3
by
OM617
on 05 Feb, 2007 05:14
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Diesels don't need a BOV. Anyone who knows how diesels work will be laughing their butts off at someone with a BOV on their diesel.
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#4
by
GTD.
on 05 Feb, 2007 07:39
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I saw a few ads on Ebay.co.uk for TD/TDI/HDi dumpvalves kits which were basically a very expensive sliver box (housing a change over solinoid I believe) a micro switch, some wires a bit of tube a few fittings and a dumpvalve with T for around £300>. I decided to see if one could be done on the cheap using parts easily found in a scrap yard.
A mate of mine had a bailey motorsport piston dumpvalve with a t-piece lying around his shed off a petrol turbo project so that was the start of the project.
Firstly you need a source of vacume as a diesel doesent hve a throttle plate (well except on a ford transit diesel with EGR) simplest way is to use the vacume pump for the brake servo so using a check valve with two take off of an old 88 Golf 1.6 auto im braking I then had my vacume source.
Now I needed a way of turning this vacume on and off when the throttle comes to rest. I found an EGR switch that fits on the LDA off a Passat TDI, and I also used an EGR solinoid off the same Passat.
I fitted the LDA mounted EGR switch rigged it to a continuity meter and tested it by pressing and letting go of the accelerator and found it did the opposite of what I wanted, it closed the circuit when the throttle was pressed and opened it when the throttle was at rest.
So I started wiring and plumbing in the dump valve using a change over relay as a "not gate" by using the normally closed (57a) terminal of the relay
I once fitted I took it down the road to test it and found although when the the throttle returned to rest the dump valve would open as there was no boost in the pipe operating the dump valve it would be forced open by boost from the turbo resulting in a leak of boost.
To rectify this I added a second EGR solinoid valve off a VW TDI that was tapped in to the manafold to LDA pipe and connected this to the normally open (57) terminal of the relay the used a T connector to connect the "Vacume" solinoid and the "Boost" solinoid to the dump valve.
Once again I took it out on the road to test and found it worked, and cost me a few pounds in parts.
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#5
by
RabbitJockey
on 05 Feb, 2007 17:13
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this is pretty interesting, could you draw some sort of a circuit to help show what all your creation does, and how it works, it's hard to understand, heres a little td controller thing i came up with, it's really not that useful, but just to give you an idea of what i am asking for from you
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#6
by
RabbitJockey
on 05 Feb, 2007 17:24
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also, does it only work when you let competely off the pedal?
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#7
by
RabbitJockey
on 05 Feb, 2007 17:52
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correct me if i'm wrong but this is your setup here?
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#8
by
RabbitJockey
on 05 Feb, 2007 18:02
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ok i see why my drawing wouldn't work, it's more or less your first setup, i don't understand what you changed though
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#9
by
GTD.
on 05 Feb, 2007 20:06
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Plumbing diagram
Wiring diagram
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#10
by
RabbitJockey
on 05 Feb, 2007 21:27
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ok i get it now
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#11
by
RabbitJockey
on 05 Feb, 2007 21:28
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buy really the vacuum is not needed
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#12
by
RabbitJockey
on 05 Feb, 2007 21:48
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the thing i still don't get is what is the lda switch on? and what makes it the lda switch go on and off
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#13
by
GTD.
on 06 Feb, 2007 02:59
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buy really the vacuum is not needed
So whats going to quickly snap open the dump valve?
The pressure of the boost on the piston?
Nope that would would only open a little bit, I didnt loose that much boost with the first version I made, you would end up with a quiet pffffftt noise rather than a PETUSSSSSSH.
the thing i still don't get is what is the lda switch on? and what makes it the lda switch go on and off
The "LDA" switch is the throttle switch thats mounted on the lda (thinking about it really I should call it a throttle switch or EGR switch) its fitted to EGR equiped cars.
pic "borrowed from one of VWRacer's posts
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#14
by
RabbitJockey
on 06 Feb, 2007 15:39
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you don't need vacuum because anytime there is more pressure on in the intake line than in the "signal" line the piston opens, i'm sure the vacuum helps to open it much mroe quickly , but i don't really see it being completely necessary