BOV for TDCi?

AnthonyTDCi · 12-08-2008, 05:58 PM

can a blow off valve be fitted to a TDCi and would it be worth while?

if so how can it be fitted to the plastic plumbing?

Mullett · 12-08-2008, 08:46 PM

Short answer no. (unless modern, EFI turbo-Ds use a butterfly)

Usually, in a diesel motor, the power is controlled through the injector pump, so when you press the accelerator, you're letting more fuel in (where in a normal car, you're letting more air in). There is a chance that they've used a butterfly in some newer motors as a means to increase efficiency, but I'd have to look into that. So if there's no butterfly, there's no pressure spike, so BOV doesn't open, with no extra pressure to open it, and no vacuum line to create an imbalance of pressure.

Anyone who knows more about modern diesels, feel free to correct me...

RM.

AnthonyTDCi · 13-08-2008, 10:18 AM

well that makes sence. was just curious to see if it would work.

when i back off the throttle there is a slight noise from the turbo....so maybe this is the butterfly youre talking about?

BlackLS · 13-08-2008, 11:29 AM

More likely a wastegate.

Lanyi · 13-08-2008, 05:16 PM

Before I get in trouble - The whole purpose of a BOV is to eliminate compressor surge (that is to stop pressure build up in the intake system to travel back to the turbo's compressor wheel). Other than that... you're looking for a nice scary whoosh everytime you pull up behind a slow driver right?

Now the problem with diesel engines is that they don't have throttle plates to control engine speed - where as a petrol engine has a butterfly valve in the throttle mechanism (as Mullett pointed out). That just means that engine speed is controlled by regulating the amount of fuel injected into the cylinder during the power stroke. Also, I think modern diesel engines have the fuel injection electronically controlled. Btw, any modification that raises the amount of fuel and air put through a diesel engine will increase its operating temperature - might just mean a shorten life span on your engine.

Now, if you want to sound intimidating, you could go for a dump valve simulator... But like you asked, is it worth while? No, unless your showing off. Can a BOV be fitted to a diesel engine? No... sorry. Spend that money on another gift for your car.

Ives · 13-08-2008, 05:23 PM

Why would you want make your Focus sounds sssssuuutututuuu.... ssssssssssssuuutututu

Mullett · 13-08-2008, 07:22 PM

The sound you hear on lift off could be compressor chatter, because the engine speed is dropping, possibly the waste gate (the pressure will increase slightly when you lift off, which could open a mechanical wastegate), or it could be the exhaust wheel overspeeding, because the exhaust volume drops dramatically when you lift off. I'd hazard that that's the most likely. So yeah, BOV no-go for your car...for that matter, I'd be very careful of an exhaust too, diesels usually sound awful with an exhaust. Get some nice rims and some good suspention instead

On another note, most diesel engines don't have wastegates, because the boost pressure is regulated by the fuel delivery: you can't lean out a diesel engine

That being said, some of them do, so like BlackLS said, your car might have one.

RM.

AnthonyTDCi · 13-08-2008, 07:26 PM

thanks for the info man. very grateful!!

no way i would put an exhaust on my car...ive had sports exhausts on all of my previous and ive grown a bit thin on them..i like the quiet car now lol

as for rims....im working on it ;)

BlackLS · 14-08-2008, 07:05 PM

Quote:

Originally Posted by Ives

Why would you want make your Focus sounds sssssuuutututuuu.... ssssssssssssuuutututu

Dose it bro! VL style

(that noise is from having no blow-off valve on a engine that needs it) ;)

b2tf · 14-08-2008, 07:45 PM

Quote:

Originally Posted by AnthonyTDCi

thanks for the info man. very grateful!!

no way i would put an exhaust on my car...ive had sports exhausts on all of my previous and ive grown a bit thin on them..i like the quiet car now lol

as for rims....im working on it ;)

right so youll put a BOV on but not an exhaust, you didnt have a nissan for a previous car did you?

AnthonyTDCi · 14-08-2008, 09:31 PM

only wanted to know if the BOV would have benifits like a petrol car...im not too sure how EXACTLY a diesel motor works thats why i was querying it.

as for the exhaust....im not too sure how a diesel would sound like with a sports exhaust?

Mullett · 14-08-2008, 11:22 PM

sound...odd. Very gravelly, I'd think. For a start, diesels don't rev hard, so that wouldn't help, and the constant rattle of compression ignition would probably drive you insane...I've heard that a TDI focus will be quicker than a 2.0 petrol one in a straight line, anyone care to prove/disprove that?

RM.

AnthonyTDCi · 15-08-2008, 12:06 AM

imho i prefered the diesel over the petrol when i test drove them. i think it was the torque that pushed me to the diesel.

the petrol one revved heaps harder which was unreal comparing the two!

in a straight line i am unsure though.

Mullett · 15-08-2008, 01:12 PM

Yeah, if the price gap wasn't so dramatic, I probably would have gone for an oiler too, but for now I'll sit on this one until I can trade it for an XR5

RM.

Lanyi · 15-08-2008, 01:40 PM

Yep, sitting and waiting! As soon as the prices drop just a little bit more on the XR5....

b2tf · 15-08-2008, 10:53 PM

Quote:

Originally Posted by AnthonyTDCi

as for the exhaust....im not too sure how a diesel would sound like with a sports exhaust?

call into your friendly local John Deere dealer who will gladly give you a demo.

AnthonyTDCi · 16-08-2008, 09:29 AM

Quote:

Originally Posted by b2tf

call into your friendly local John Deere dealer who will gladly give you a demo.

hahaha yeah think ill definatly pass on the exhaust!

lol well put though!

BlackLS · 16-08-2008, 10:13 AM

Quote:

Originally Posted by AnthonyTDCi

hahaha yeah think ill definatly pass on the exhaust!

lol well put though!

Youtube "Focus TDCI exhaust" to help make up your mind. They make the TDCI have a nice burble, almost like a Subaru boxer engine.