Increasing turbo boost pressure... discuss

Post by **woody1977** » 11 Sep 2006, 16:54

Simon Baxter wrote: You also won't achieve much if you try to adjust the boost pressure because the blow off valve will just release the extra pressure, so that has to be overcome too.

my car has a turbo and as far as i'm aware, the bov releases the pressure when you take your foot off the pedal.. not when you are accelerating.?

just by me putting a grainger valve in and upping the boost i can get good gains... but then my car was set up to overfuel from the factory as a safe guard. so there is good room for manoeuvre and it has an intercooler.

Post by **Simon Baxter** » 11 Sep 2006, 17:04

You are talking about a Dump Valve, they are designed to release pressure like you say, but on a vehicle with a throttle plate, of which a Diesel does not have.
The blow off valve is just a safety valve, it releases when manifold pressure reaches a set level.
like I say, you are talking about petrol engines, what you say is valid for petrols not Diesels.

Post by **woody1977** » 11 Sep 2006, 17:39

damn thats a shame.. would have been so easy otherwise.

Post by **airhead** » 12 Sep 2006, 00:45

Thanks for the wee debate there guys. It does help clear things up on my end. But yeah Woody, Simon is right. Ive done some homework on these things. Diesel and petrol turbos are chalk and cheese in so far as theyre adjusted totally differently. Ive got a guy whos going to get me a grainger valve anyway. Ill try it short term. Its not much hassle. I wont crank it up much. Just enough to see if its worth pursuing further.

Im inclined to try and get an oil cooler first anyway to be on the safe side. Im going to see if I can go the easy route and get one that takes the oil from the filter fitting. Ill mount it, eh, somewhere. Not sure yet. Ill probably put a second oil filter in as well for the added filtration.

One more question though. Is smokiness going to be a problem? I dont want to bother if the engines going to be pumping out smoke like a mad thing. Its OK now, as standard. Like any other mechanical injection diesel really. Its not an old worn out engine. Its well looked after with low mileage.

Post by **HarryMann** » 12 Sep 2006, 12:36

Not sure yet. Ill probably put a second oil filter in as well for the added filtration

I wouldn't bother with that unless its added capacity you are really after, don't forget the pump has to shove it around a big circuit anyway if you're going to put the cooler upfront.

As far as smoke is concerned, as long as you are matching more fuel with air, no extra smoke, but...

in practice, just increasing the overall fuelling using the main fuel screw means that untill the turbo is spinning well, about 2000 rpm, if you have your boot down, there will be more. Using a modified LDA boost enrichment pin and making other adjustments can offset this to a large extent.

Also, when going for power, its de rigeur to supply more fuel than the air needs, as in an air breathing engine you want to use all of it. Then there's lack of combustion efficiency and usinmg fuel for cooling which both mitigate towards towards supplying more fuel than necessary.

Max power diesels do smoke quite a bit, especially during initial pick-up and acceleration.

Post by **airhead** » 12 Sep 2006, 13:45

Im thinking I might have to recruit the help of someone who knows diesel engines better than me. I mean what is an LDA boost enrichment pin?

I tend to find nobody wants to touch diesels as far as tuning is concerned. If I get the grainger valve how will I know without the aid of a boost gauge how much pressure is being generated or if Im even overdoing it?

Post by **woody1977** » 12 Sep 2006, 14:14

you have to get a boost gauge fitted.. you wont wanna risk it, for the sake of a £30 gauge

Post by **HarryMann** » 12 Sep 2006, 16:16

Any pressure gauge reading up to about 20 psi gauge (eBay) and a length of plastic tube of the same bore as the tube that connects the inlet manifold to the diaphragm on the top of your injection pump (LDA thingy, maybe I've got theat Acronym wrong?) + a 'Y' or 'T' connector, a good one is to nick one off the difflock system of a syncro (VW still sell them, a quid or so)..

Then, as a starting point, you will know if your turbo is working well and if so, what pressure the wastegate valve is set to, which should eb circa 7.5~8 psi.

Here's one...

Pressure gauge

Post by **Simon Baxter** » 12 Sep 2006, 21:32

airhead wrote: I mean what is an LDA boost enrichment pin? I tend to find nobody wants to touch diesels as far as tuning is concerned. If I get the grainger valve how will I know without the aid of a boost gauge how much pressure is being generated or if Im even overdoing it?

There is no LDA pin on your engine, the 1.6TD has it's LDA laid on it's side.
a LDA LaderDrucktAneroid or something like that, it's the thing on yor fuel pump that senses boost pressure and adjusts fuelling to suit, sadly on a JX you can't really mess with it unless you do as Oettinger did and start welding bits on here, filing bits off there, moving pivot points la di la..

Don't even think about fitting a grainger valve without a boost pressure gauge, and ideally a EGT meter, of which incidentally I have ordered today from VDO, and if I managed to pick the right one I may start selling soon.

Remember, like I say, you have got to do things in order, or when it goes pop you will be sorry.
Buy the guages, buy the oil cooler, get the charge cooler and only then think about turning screws and chopping turbo pipes up

Post by **airhead** » 13 Sep 2006, 01:32

So the pressure relief valve goes in the pipeline that goes to the LDA, am I right? Or are you about to say "Ross you should really consider getitng someone else to do this for you"? I mean where else could it go? What other rubber hoses are associated with the turbo?

Post by **HarryMann** » 13 Sep 2006, 09:38

No, the simple bleed valve (or a more sophisticated pre-set pressure release valve) goes in the turbo's wastegate feed line, that is, in the pipe between the turbo compressor outlet and the wastegate pressure (diaphragm) valve. Crawl underneath and look for a thin black pipe that meets the above description. Either cut it in half and insert the valve at a sensible place or pull one end off, fit the valve and connect it up with another length - [provide support for the valve if it seems to need it.

Post by **airhead** » 13 Sep 2006, 13:18

So final question... wheres the wastegate? I know the LDA is on the fuel pump, blowoff vallve is on the manifold and the engine is in the back of the van where it belongs but in my exploratory missions of all things JX Ive never come across the wastegate. I dont even know what it looks like. For ages I thought that was it on the fuel pump.

Post by **HarryMann** » 13 Sep 2006, 14:55

An integrated wasetgate is on the turbo itself... an extrenal can be anywheer in the exhaust manifold. the JX turbos have an integrated wastegate.. as I said, just get under there and take a look at the turbo, take a torch and a hat so you can lie down copmfortably and go to sleep... Oops! I meant lie back and enjoy it, Oops! I meant take a good long look

Post by **airhead** » 13 Sep 2006, 18:27

So given that it has an integrated wastegate, will there be a hose going to it? I usually lie under my van with mud falling in my eyes trying to undo the biggest most rusty nut imaginable before ot rings, the spanner flies off and cracks me square in the forehead, then the expletives start flying. It has happened, believe me! Trying to crawl out from under the van covered in muck from the van and blood from my bleeding forehead is a real challenge, especially when you cant see and sit up too early, belting your head once again on the sill!

Post by **HarryMann** » 13 Sep 2006, 22:20

Cap, torch, goggles, camping mat to lie on, a jack isn't necessary on a syncro to get a good look at the turbo, yes, the tube runs a round the turbo from the manifold to the pressure diaphragm that has an adjustable length rod sticking out of it (to operate the wastegate). Don't alter the length of the rod (whatever you read), yet.