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DIESEL BLOW OFF VALVES!


BrUcE
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I got a 91' 200 tdi disco engine in my D90. It would be wicked if I could put a blowoff valve on it, but a mechanic told me it wouldn't work. I couldn't be the 1st person to try and do this but I have never heard of it before. Your thoughts, pics or instructions would be nice.PREFERABY INSTRUCTIONS WITH PHOTOS :)

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Waste of time and money................................

The boy racers here do it with a combination of fiddly microswitches and valves, just to have a woooooshing sound.

It gives no performance gains what so ever.

Grem

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Guest diesel_jim
Waste of time and money................................

The boy racers here do it with a combination of fiddly microswitches and valves, just to have a woooooshing sound.

Grem

My td5 does that anyway....my intercooler has split at one end! :lol::angry:

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I got a 91' 200 tdi disco engine in my D90. It would be wicked if I could put a blowoff valve on it, but a mechanic told me it wouldn't work. I couldn't be the 1st person to try and do this but I have never heard of it before. Your thoughts, pics or instructions would be nice.PREFERABY INSTRUCTIONS WITH PHOTOS :)

It won't work.

A blow off valve or dump valve is used on a turbo PETROL engine. A petrol engine has a throttle plate which blocks the inlet when you take your foot off the accelerator. When you do this, the pressurized air from the turbo has no where to go. Without a blow off valve, the back pressure causes the turbo compressor to slow or stall. When you try to accelerate again, the turbo has to spin up to speed again which creates lag or a flat spot.

With a blow off valve fitted, when the throttle is closed, the blow off valve vents the boosted air so that the turbo compressor does not slow or stall so that when you press the accelerator again, the blow off valve closes and the boost is there instantly because the compressor is still spinning fast.

A diesel engine doesn't have a throttle plate to restrict the inlet when you take your foot off the accelerator, so the turbo does not slow/stall anyway.

Therefore a blow off valve will not work on your tdi.

Regards,

Diff

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Isuzus have butterfly valves on them Diff - but its an emissions thing, ends up on the workshop floor and is never seen again :), Ive got a video somewhere of a Toy BJ with a BOV on it, I'll see if I can post it up

Thanks Jez,

I guess I should have said that 99% of diesels don't have butterfly valves and 99.9999%(roughly) don't have butterfly throttles which close off the inlet :D

His 200tdi is in the 99.9999% range though, so I am pretty confident it won't work. :D

Regards,

Diff

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Some will know, from my previous posts, that I tend to the serious and the practical, with no time for idle tiddle-taking or posting nonsense just to keep my post count up.

That hasn't changed, so without bothering to challenge anything that previous contributors have posted, I will just draw the original posters attention to http://www.zen19051.zen.co.uk/prod01.htm

Note that his prices say 'fitted', so what The Derv Doctor' will do when faced with an address in Kingston Jamaica is anybodies guess.

The Derv Doctor has been advertising in UK magazines for some months, long enough to have been sussed out if he wasn't paying his advertising account. Reader should also note that he doesn't say anything about a performance increase, just more noise. As a lot of money is spent on 'noise systems' be they radios or engine exhausts, I don't see the problem in going for this noise maker. It isn't for me, but neither is a lot of the mud and bull**** activities endorsed by other contributors on this forum.

Good Luck Bruce, the choice, as ever, is yours.

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Or alternatively, you can get electronic fake dump valves which play a dump back sound - no idea how realistic they are or how they're operated, but it would save monkeying with a perfectly good engine.

or if you cant afford that you can get ones that just release compressed c02

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Thanks Jez,

I guess I should have said that 99% of diesels don't have butterfly valves and 99.9999%(roughly) don't have butterfly throttles which close off the inlet :D

His 200tdi is in the 99.9999% range though, so I am pretty confident it won't work. :D

Regards,

Diff

Some diahatsu's have a throttle butterfly, and the throttle cable goes to it, not to the injection pump

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Some diahatsu's have a throttle butterfly, and the throttle cable goes to it, not to the injection pump

Hi Dan,

Surely you don't expect me to list all the millions and millions of diesel engine types (including the 200tdi that the original poster was asking about) which fall into the 99.9999% category I mentioned? :lol:

I assumed the original poster wanted a 'proper' blow off valve for performance as well as noise, in which case I stand by what I said - there will be no performance benefit if he fits one to his 200tdi :D .

Regards,

Diff

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Bruce,

What you need is one of your mates sitting in the passenger seat holding a CO2 fire extinguisher.

At the right moment he just pulls the trigger.

Everyone will think you have a blow-off valve from an oil-rig!

Suppose you could connect the trigger to your clutch pedal with a bit of string to automate it!

Si

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Guest diesel_jim
Bruce,

What you need is one of your mates sitting in the passenger seat holding a CO2 fire extinguisher.

At the right moment he just pulls the trigger.

Everyone will think you have a blow-off valve from an oil-rig!

Suppose you could connect the trigger to your clutch pedal with a bit of string to automate it!

Si

Or an ARB diff locker..... but just make sure you engage/disengage it on a straight bit of road!!! :o

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Finally somebody puts something humorous. Better stick to the advice and hold the jokes. Excellent job by Si i must add though. Anyhow I know theres no added performance but I think they sound great and there is no one I might add that is a member of this forum that can ever say that they had an abolute need for particular items on their trucks. Mine is a daily driver so I like to get some sort of everyday fun out of the car here, as my route to work is not exactly up a river bed. Theres no radio but I have a 1 gallon 2 trumpet air horn that scares the **** out of taxi men when they bad drive me (I highly recommend that). So maybe this time I'll have to sacrifice my wants and just settle for a can of whipped cream to do the trick. Thanks

http://www.airhornsoftexas.com/

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  • 3 years later...

I haven't fitted one myself but I used to own a Peugeot 306 and plenty of people on that forum fitted them to their diesel cars

You can pick up used kits on forums or ebay for around £60 or so. On a diesel they work using a microswitch on the throttle linkage so when you use full throttle and back off it releases some pressure from the inlet.

I'm not a fan as they actually reduce power for a small instance as you need to re-pressurise the inlet again, that and I think they sound gay on anything but a evo or similar car.

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