Mobil F1 0W40 oil on HDi engine?

rossd · Post by **rossd** » 12 Apr 2005, 14:20

<blockquote id="quote">quote:<hr height="1" noshade id="quote">The HDI turbo wastegate is vacuum controlled, so only the boost that is needed for a given throttle opnening is applied to the engine. The TD turbo is mechanically wastegated so it can (in theory) give full boost even when the throttle is closed, in any case it gives more boost than is needed to match fueling all of the time.<hr height="1" noshade id="quote"></blockquote id="quote">
I don't want to sound to pendantic or geek like, but only the 110 upwards is vacuum controlled, the 90 has the same manifold pressure type setup as the older XUD. "More boost than is needed" on a TD is a kind of misnomer, you only produce boost when fuel is added, so inject a small amount of fuel and you get a small amount of boost. I can see your point, but in reality it doesnt happen. My old 306 XUD turbo only gave full boost at full throttle when under full load, for example pulling in 4th from about 40mph upwards. Even then, adjusting the wastegate to give more boost didnt produce any more on the gauge, only after the fuelling was increased was any more boost observed.
Hence fuelling and boost are always matched in the HDi, they have to be for emissions reasons.
I do agree with your theory, but in reality it just doesn't really happen.

Kowalski · Post by **Kowalski** » 12 Apr 2005, 15:16

There are situations where the XUD produces way more boost than is needed, when engine breaking at high revs for one but that is probably a rare. I'd agree that boost does accompany fueling but the boost has to be there to allow fueling to begin with then more fueling creates more boost that allows more fueling again.
Older turbo diesels were notorious for emissions of nitrogen oxides because they put more oxygen into the cylinder than there is fuel to burn so the nitrogen in the air is burnt (oxidised) instead of fuel. Newer turbo diesels control fueling and boost more closely so less nitrogen oxides are created and they're cleaner, the emissions standards are tighter for diesels now than they were.

Post by **Thunderbird** » 12 Apr 2005, 15:47

The HDi doesn't feel at home with sport driving in what concerns to temperature.
Before tuning it wasn't elastic - really boring. After tuning it got more responsible (the RPM pointer goes up much faster when demanded) but when pushing instantly from 2000RPM to 4000RPM often, in a little while water will be at 100ºC.
On my previous petrol car (1.6 liter 120HP), I 'played' between 4000RPM and 7000RPM (bellow 4000RPM it had little torgue) and it stayed cooler.

rossd · Post by **rossd** » 12 Apr 2005, 15:51

<blockquote id="quote">quote:<hr height="1" noshade id="quote">I'd agree that boost does accompany fueling but the boost has to be there to allow fueling to begin with then more fueling creates more boost that allows more fueling again.
<hr height="1" noshade id="quote"></blockquote id="quote">
Yes to a certain extent, but thats why diesels smoke on acceleration, as the fuel injection volume increases to create the boost. Its common sense that no fuel = no turbo boost.
If 'boost' has to be there to allow fuelling to begin, then in theory these engines would never actually start... [:)]
NOx emissions are caused by high combustion temperatures and can be reduced by retarding the injection timing, which cools peak chamber temperatures, or the use of EGR which replaces some of the induction air with an inert gas (Exhaust gasses). But, as NOx decreases, other pollutants such as Hydrocarbons and particulates (smoke) increase, so in any engine, its a trade off between the two. Obviously, the better the injection system (eg pilot injection, post injection and higher pressures) then the efficiency increases and hence the pollutants decrease.
The XUD fuel injection pump, be it Bosch or Lucas, actually had an overrun cut off device, so where in your example boost was produced when braking at high revs, this was simply the air being pumped through the engine spinning the turbo. Exhaust emissions would be non existant at this point because injection would be cut and the engine would simply be an air pump turned by the momentum of the vehicle.
I'm an self confessed engine bore [:D], turbo diesels and how they work fascinates me, how manufacturers are getting ever increasing outputs fom smaller and smaller capacities whilst still keeping emissions under control is amazing.
Back on topic to the original poster, why not use the Quartz 9000 oil from GSF, its the same quality but about 3 times cheaper and is actually the Peugeot recommended oil.

Post by **Thunderbird** » 12 Apr 2005, 16:11

Do you think that in a tuned HDi it would be adisable to replace Citroen air-filter by another one that allows more air to flow?

Kowalski · Post by **Kowalski** » 12 Apr 2005, 16:53

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by rossd
Yes to a certain extent, but thats why diesels smoke on acceleration, as the fuel injection volume increases to create the boost. Its common sense that no fuel = no turbo boost.
If 'boost' has to be there to allow fuelling to begin, then in theory these engines would never actually start... [:)]
<hr height="1" noshade id="quote"></blockquote id="quote">
Boost is there to operate the enrichment device which allows MORE fueling, base fueling is there regardless of boost. The engine is able to run without the turbo... i.e. it can run without any boost whatsoever, in fact at low revs the turbo doesn't do a whole lot, then you get your chicken/egg effect where the turbo does produce some boost, which allows more fuel, which creates more boost, this is what makes your XUD surge at 2000rpm.
With an older turbo you've got to make best use of the boost you have, you don't have a lot of choice in how much you get they are pretty crude devices really. With newer turbos the electronic controls can decide how much boost to give with electronically controlled wastegates and variable geometry etc.

jeremy · Post by **jeremy** » 12 Apr 2005, 23:01

Some people say that expensive after market filters help - but if they filter efficiently they cannot. If you think the filter is obstructive, remove the element, clean up the filter housing and inlet pipe prior to the filter and take it for a spin. If it improves what you really need is something like 2 standard filter assemblies connected as it were in parrallel not one after the other.
Someone will now tell me that a K&N makes their car go faster which may well be true but if you look at one you can see straight through it and so it only keeps the leaves out and tey wont do much damage anyway.
Ran many of my petrol cars without the filter without any apparent harm. Look at how little the things extract and then think that most of it would have been suspension anyway so what damage was likely to result in cold damp Britain. I always keep a good one in the TD as the turbo may get dirty and I don't want to get rid of it yet!
Jeremy

Post by **Thunderbird** » 12 Apr 2005, 23:13

It's decided then - I will keep the Citroen filter (my HDi has a turbo too), and will start using Mobil 1 0W40!

Kowalski · Post by **Kowalski** » 13 Apr 2005, 03:31

K&N Filters are an oil covered filter, it filters by making the dust stick to the oil. A paper filter filters because it has holes that the dust can't get through but the downside is that these get blocked by the dust.
For ultimate performance you probably want something like a Dyson....

Post by **Thunderbird** » 13 Apr 2005, 05:26

I will stay with paper air filters and change them every 10.000kms/6kmiles.
Driving in intensive traffic usually makes them get quite dirty.

Kowalski · Post by **Kowalski** » 13 Apr 2005, 14:49

I looked at K&N because as the paper filters get dirty I get more turbo lag and less low down torque. The paper filters are past their best after 6k miles and cost around £3-£4. A K&N filter would cost me £30-£40 so I'd have to do 60k miles before I reach break even point assuming that cleaning and re-oiling the K&N is for free.
Personally, I decided to stay with paper and change the filter coming up to an MOT or when I noticed performance was down, usually its only noticable in the hot weather.

jeremy · Post by **jeremy** » 14 Apr 2005, 13:23

some of the ancient oil bath type filters were probably quite effective and kept on working. I can remember cleaningloads of sludge out of some - far more than a paper element would trap but I don't know how long since they were last cleaned.
Filthy dirty things - usually you'd move it to get at something and put it somewhere you thought was safe and then find it tipped over spilling oil everywhere!
Jeremy

Kowalski · Post by **Kowalski** » 14 Apr 2005, 14:36

My Dad's tractor has an oil bath filter, its a small tractor but the filter is about the size of a bucket, tractors tend to be accopmanied by a lot of muck so they need good filters.
My Dads old JCB wasn't running properly at one point, so I had a look at the sight glass on the water trap. It looked like it had some muddy water in the bottom of it, so I opened the tap an nothing came out, I took it all apart and found that the water trap was in fact solid with mud. That JCB has 2 fuel filters in parallel and they were filthy too. Being filled up in the field from 45 gallon drums probably didn't help there.