Boost Pressure

[iannotts]

Just the job!

Like mine and most (but not all) diesels, it should NEVER go into the vacuum section of the guage.

The only diesels that should do that are the ones with throttle valves across the air inlets to make vacuum for servo brakes, or for some crazy anti-pollution reasons.

Any Boost at all is good, and more is better, but you do want to limit the maximum boost to some sensible pressure so you don't cook your engine.

You'll be interested seeing the boost pressure and what makes it rise.

High boost, high gears and light throttle (a delicate balance to achieve!) makes for best fuel consumption usually. But you will need enough revs so that the turbo gets enough exhaust to begin working, which means some speed between 50 and 55 in 5th gear in most Discos. Any more and the airdrag rises too much and uses up power, and any less means the motor isn't making enough exhaust to do the business.

My TD5 Disco on cruise control at about 55/56 mph can easily top 42 miles per gallon on a motorway run. Not bad for a sleek streamlined lightweight.
Fantastic for a two and a half ton 4x4 shaped like a brick!
CharlesY

CharlesY

42!!!! I am lucky to get 28 - 30 at a steady 65 in my disco1 with 200 engine I know the larger tyres would drop it of a bit but...

 

[RAZ8550TDI]

hi charles, dont worry i used a boost gauge when i turned it up i just havnt fitted it into the dash yet, am not that soft gone up to the recomended 16psi and left it at that, aint been out in it yet but am getting a more distinct sound out the turbo so far. cheers for yer help bud

 

[CharlesY]

42!!!! I am lucky to get 28 - 30 at a steady 65 in my disco1 with 200 engine I know the larger tyres would drop it of a bit but...

That's no good at all!

We used to have a 200tdi that regularly took four of us and a stack of kit from here to Bisley (Surrey) and back .... and it ALWAYS managed to give us 35+ to the gallon cruising 70 - 75 all the way.

You need a trifle more BOOST and a trifle less BOOT!

Seriously though, you might see a decent improvement if you had a go at perfecting the injection timing , setting the injector spring pressures as specification, and generally "setting up" the engine to run its best.

You won't have an EGR in a 200 tdi will you?

CharlesY

 

[RAZ8550TDI]

not in 200s charles not as far as i am aware.

 

[Disc300Series]

Adjusting the Boost Chop as the boost has increased and smoke screw

 

[CharlesY]

Adjusting the Boost Chop as the boost has increased and smoke screw

Slob,

Translation or interpretation required ......

By the way, did your pies arrive yet?

CharlesY

 

[slob]

ah think it means the sprocket valve foo foo ring seperator differenshall gudyin pinion level set screw is over adjusted to the point of making no sense what so ever.

 

[Pikey]

ah think it means the sprocket valve foo foo ring seperator differenshall gudyin pinion level set screw is over adjusted to the point of making no sense what so ever.

Aye that's what I thought as well.

 

[HybridGirl]

PIKEEEEEEEEEEEEEEEEEEEEY! Where yer bin?

 

[Fox]

Thanks for all the replys, but i think it is a bit above me doing this myself, can anyone help me with the name of someone in the Coventry area that would be able to do this work.

Thanks again
Trevor.

 

[iannotts]

That's no good at all!

We used to have a 200tdi that regularly took four of us and a stack of kit from here to Bisley (Surrey) and back .... and it ALWAYS managed to give us 35+ to the gallon cruising 70 - 75 all the way.

You need a trifle more BOOST and a trifle less BOOT!

Seriously though, you might see a decent improvement if you had a go at perfecting the injection timing , setting the injector spring pressures as specification, and generally "setting up" the engine to run its best.

You won't have an EGR in a 200 tdi will you?

CharlesY

Hi charles, Normaly use as little boot as possable, crusing at 70 -75 only get 300 miles before light comes on. Been told I have little smoke from exhaust under normal acceleration. The motor has got 170k on the clock but uses little oil don't know if this will cause this. Would a new air filter increase MPG? The one that is in dont look bad on outside . As for boost I was understanding that more boost = less mpg. From what you are saying this is wrong. Do you recommend the 16psi that is mention for a 300 on a 200?

Could you point me in the direction of perfecting the injection timing. When I changed cam belt the timing hole lined up perfectly to the dowl hole in the engine. I havnt touched the spring pressure whilst I have owned the car from 133k.

Ian

 

[CharlesY]

All diesel engines work efficiently because the compression ratio is high. More BOOST increases the effective compression ratio = good.

There will be magic speed where the engine is running fast enough to make some boost, with very light throttle, and that should be good for economy. In my TD5 Disco about 55 - 56 mph on the motorway does the job, even with a big trailer on the back. That's just over 2,100 rpm, fast enough to be running well, slow enough to give the fuel TIME to burn well.

There are a number of threads quite recently about touch-tuning injection timing, and in a 200 tdi it would be well worth trying.

CharlesY

 

[iannotts]

cheers I will do a search

 

[CharlesY]

quote:
As for boost I was understanding that more boost = less mpg. From what you are saying this is wrong. Do you recommend the 16psi that is mention for a 300 on a 200?
unquote:

Don't confuse cruising on the flat with foot-to-the-boards POWER!

For full POWER we need maximum fuel delivery and full BOOST.
Raising BOOST alone will help only a little, but if MaxFuel is also raised, we can make a significant improvement. MaxFuel delivery may need adjusted, but in some setups it may automatically follow the increased boost.

Foe CRUISING the ideal is LEAST fuel but most BOOST. There's a balance to be struck. It will probably optimise round about 2,000 rpm in a 200tdi, maybe 2,250.

Any more means the car goes faster, and air drag rises quickly.

CharlesY