Place your bets please

MikeT · Unread post by **MikeT** » 04 Sep 2007, 10:48

Would anyone be interested in placing bets (sportsman or cash) on what will happen after I install Nitrous Oxide in my car (if it last that long!)?

The car is not in the best of shape and I don't even know when the cambelt was last changed so it wouldn't surprise if something major failed.

Having said that, I've been thrashing the car and upping the fuelling in my quest for more power and it seems to be taking it all in it's stride.

At the moment, I have at least three leaks. Mild coolant loss (green patches on rad), mild fuel (95% vegetable oil) pump leak and exhaust leak both near the engine and at the back box. The engine or gearbox mounts are a bit loose, as is the steering.

However, it has not used a drop of (cheapo Tesco) oil since last change (3K miles ago).

Although I won't be installing the NOS just yet, initially I'll be running a 30bhp jet and depending on how much extra fuelling I can provide, hope to go as high 150bhp.

Any takers?

p.s. The clutch may on it's way out too

Village · Unread post by **Village** » 06 Sep 2007, 13:22

there will be more noise.

whether its from the nitrous or from an engine blow up, the jury is out.....

best of luck, I'm looking forward to the results!!

AndersDK · Unread post by **AndersDK** » 06 Sep 2007, 14:34

My bet :

You will have lots of fun - for quite a while

I have a feeling that somehow your engine will survive - I cant say why.
Maybe its because I think that after a while you have tasted the blood, and then wants something with serious grunt.

Then your Xantia gets abandoned or sold.

The peugeot 205 was appearantly born for this

(though the ZX is much cheaper and share the same drivepack parts)

MikeT · Unread post by **MikeT** » 06 Sep 2007, 15:41

Please don't be diplomatic or tactful, I won't be offended, it's all good fun, say what you really think - I know I'm mad but what the hey.

AndersDK, you're welcome to revise your opinion as I'd be more inclined to get a motorcycle for ultimate power. I couldn't afford the increased fuel costs of a superfast car for instance, let alone the insurance etc.

This car however, runs on half-price fuel while thrashing it doesn't seem to affect consumption noticeably and adding nitrous should not increase the insurance by much, if at all.

The only way I'll abandon this car is if the engine melts, the gearbox disintegrates or the MOT repairs are too much.

Xaccers · Unread post by **Xaccers** » 06 Sep 2007, 16:48

I'd try and get a cheap mechanical only bosch pump, TehAgent reported an increase in oomph when he swapped his out, and it would remove one of your leaks.

MikeT · Unread post by **MikeT** » 06 Sep 2007, 17:25

I'm on the lookout for a spare one as you suggest.

Seems there's more to just the smoke screw, diaphragm and max power that can be adjusted

and I can service it at my leisure too, perhaps mod it to provide enough overfuelling in tandem with the N2O activation.

Care to make a prediction Xac?

Sturdybloke · Unread post by **Sturdybloke** » 08 Sep 2007, 18:53

You did ask for opinions, so brace yourself -

This idea worries me

You have a car that has coolant leaks & the injection pump is leaking, not to mention that you have said that the cambelt was changed back in god knows when (and I would worried with that one = dead engine), aswell as this -

Mike T wrote:The engine or gearbox mounts are a bit loose, as is the steering

So you want to shove much more power into a car that can just about handle as much as it has already? Get the problems on it sorted and give it a well earned service and it may last a while with NOS fitted, in the state its in that kind of wooly steering you describe sounds fu***ng dodgy (keep it well away from my family)

So in answer to how long it will last, not very long by the sounds of the way the car has been, or is looked after. It all depends on how much you paid for the car /versus\ pa(id/ying) for repairs. If it goes bang you would just buy another and transplant all your gear into that in todays throw away age

. That steering does concern me though you should get that sorted ASAP.

You did ask for opinions.......

A self opinionaited git - Craig.

MikeT · Unread post by **MikeT** » 08 Sep 2007, 20:45

Hi Craig,

I hear what you're saying about the steering and you made a very good point that I have overlooked. I shouldn't drive it until it's safely sorted.

Maybe I exaggerated the condition(s) to get my point across - I'm not accurate in my expression - and it is only recently that I sensed this steering/handling vagueness as I've grown accustomed to how the car drives and felt confident enough to give it a little more stress.

Ditto for the engine/gearbox mounts - most people probably wouldn't even notice it but I consider myself to be hypersensitive to the smallest of niggles.

I don't consider the minor coolant or fuel leak a safety issue, nor do I think the possibility of engine/gearbox failure any more risky than normal driving though I'm always willing to be further educated.

The car was cheap and I've probably spent more on DIY servicing already which is why I'm happy to leave the cambelt for a more opportune moment.

Thanks for your advice, I do appreciate it and your opinions. I don't consider you a git for saying so (I did ask for it!), quite the opposite in fact. It's been constructive criticism and helpful.

Mike

Sturdybloke · Unread post by **Sturdybloke** » 08 Sep 2007, 23:07

Evening Mike,

Re-reading my post it did sound a bit self opinionaited/know it all git. Let me explain a bit more -

Mike T wrote:At the moment, I have at least three leaks. Mild coolant loss (green patches on rad), mild fuel (95% vegetable oil) pump leak and exhaust leak both near the engine and at the back box

You should get the coolant leaks sorted. If you shove more power through your Xantia then the cooling system will suffer first as a start. You could think about a manual operated switch to operate the cooling fans when you are giving it heavy beans (I use one I fitted, occasionaly on my Rover when I tow heavy things). Plus try to get the fuel leaks sorted. Bikers wont like spilt diesel on the road

Mike T wrote:Ditto for the engine/gearbox mounts - most people probably wouldn't even notice it but I consider myself to be hypersensitive to the smallest of niggles

Have you thought about those poly type mounts & suspension bushes. They realy make a difference. Your dodgy clutch could be causing a lot of these symptoms though. I know what you mean about dodgy clutches, my Rover (that has a XUD) is on its way out with a very snatchy/juddry clutch ATM.

Mike T wrote:The car was cheap and I've probably spent more on DIY servicing already which is why I'm happy to leave the cambelt for a more opportune moment

I would change it. I've spent a fortune rebuilding a Xantia head with a XUD fitted just like yours and it has cost a fortune (to do a good job). For the sake of say 50 quid I would do a service and you may get 100K out of your Xantia with a NOS system fitted.

For some reading......

I bought a Scirocco a number of years ago, that had a home made turbo kit fitted from a Janspeed kit for a Datsun 280. It was a crude instillation on a car that originally had 85 HP that ended up with circa 130 bhp. Long story short the car melted a piston

. Due to having inadequate turbo cooling (intercooler) after me playing about with boost settings/wastegate controlls and upping the power drastically / to a very heavy (fast & hard ) driving style. Cooling is of upmost importance when you intend to shove a 1/3 more power through the car.

Get the cooling problems sorted, change the clutch and give the car a full service and get your steering sorted and it will make a very interesting project

Sturdybloke's thought for the day wrote:Infact I am quite interested in what sort of max power a XUD will safely handle without going bang!

I am toying with getting a test engine and seeing on what power it can handle (have to get the MOT sorted first)

Mike, I wish you all the best with your tests, but best to get your Xant in A1 condition first before you boost power.
Let us all know what you decide to do

All the best - Craig.

MikeT · Unread post by **MikeT** » 09 Sep 2007, 00:02

Craig, seriously, I appreciate you being a "self-opinionated know-it-all git" if that's how you want to refer to yourself!

Maybe I am being overly exaggerative.....
I'm a bike license holder myself and I wouldn't allow the car to foul the road in the way you're thinking. It drips at the rate of one drop per minute and shows no signs of getting worse.

But as for the cost of clutch, cambelt, exhaust, cooling system, mounts, etc, etc, etc, I'd probably do better buying another car that's already sorted.

Yes, I've read about the new poly-wotsit bushes and I'm extremely interested to experience them.

As for the added heat concern, N2O is a cooling agent too and this xantia actually gave me concern that it was over-cooling itself it's so efficient! The problem is either head gasket or radiator, in my opinion.

But don't worry, I've decided to bite the bullet and get the safety issues sorted first.

My logic is that I'd rather see if the car can withstand the N2O BEFORE spenging wads on getting it mechanically A1, it's just not worth it and better being recycled as spares. If you saw it, you'd probably agree

but it would make an excellent "sleeper".

MikeT · Unread post by **MikeT** » 18 Sep 2007, 18:06

For those interested in this "project" (some for, some against) it will happen but there is a postponement or two.

First, owing to the unfortunate death of my landlord, I have to vacate the flat I'm renting and find a new home. Secondly and more importantly, there are a number of repairs to be done to the car and will happen (hopefully) one weekend - after I've moved - with the kind assistance and under the leadership of a very experienced and highly skilled Citroen DIY'er and forum member.

Additionally the (used) N2O kit failed badly during testing and a number of problems were found and rectified. However, like most of my posessions, it's packed and now in storage.

I will be offline without internet for an unknown time but I will report back my findings as soon as possible.

In the meantime, I thought some of you might like to see this picture that depicts exactly Citrojims naming of N2O injection - "grenade" although this explosion didn't come from the engine, just the inlet manifold - see it? right there, that flaming lump blasting off into space....

http://competitionplus.com/index.php?op ... 8&Itemid=6

If that happened to my car I would be fascinated for sure but it ain't gonna happen. It can't. Mine's a diesel.

Unread post by **CitroJim** » 18 Sep 2007, 21:02

Thats a rather impressive picture

Later XU petrol engines have a plastic inlet manifold (in fact my Activa has) and these have been known to shatter because of a backfire. Nothing so spectacular as that though! There was a case once of someone who clearly had a bad manifold air leak and could not find out why. The manifold looked perfect from the top but underneth it looked more like a sieve!

There is not a lot of risk of holing a piston on an N2O'd diesel engine as there is on a petrol engine due to the fundamental difference in the combustion processes. A petrol engine holes a piston either due to detonation (pinking), pre-ignition (usually caused by hot-spots in the combustion chamber) or a lean mixture causing very high combustion temperatures. Interestingly, a piston holed through detonation looks like it has had a bullet shot right through it

The point here is that a diesel detonates as a natural part of it's combustion process and the concept of a weak mixture does not exist. Pre-ignition due to hotspots is a slight possibility though. So, you'd be very unlucky to hole a piston.

N2O should help with a fundamental combustion problem in a diesel. Diesel combustion occurs in excess oxygen conditions and in fact to avoid smoke there needs to be something like 50% more oxygen present than is actually theretically needed. Black smoke comes about because of a shortage of oxygen. Although there is what seems like plenty of oxygen, combustion still only occurs when finely atomised diesel can mix with around 14 parts of air (i.e stochiometric) and this tends to occur in areas and patches and not all over the combustion chamber. In fact a lot of available oxygen (and diesel) is wasted because it cannot mix at 14:1 or because the air and diesel is in the wrong place. Banging a load of N2O in will make much more oxygen available and up the chances of more diesel being able to mix at the 14:1 ratio it needs and thus combust effectively.

This is the whole reason why diesel engines do all they can to make the combustion chamber air as turbulent as possible, to give the best possible chance for as much diesel as possible to ignite. The XUD uses indirect injection via a swirl chamber to achieve a very turbulent airflow and very good mixing with the finely atomised diesel. This turbulent, swirly air also helps to cool any hot-spots that may develop in the combustion chamber and thus reduce the possibility of dangerous pre-ignition. Petrol engines cannot take this route because all the turbulent and swirly air will blow out the spark

deian · Unread post by **deian** » 18 Sep 2007, 21:36

I reckon the engine should last more than you think it will. Diesel engines are built stronger due to the higher compression ratio, so mechanically wise I reckon it'll hold. But the other things may fail 'for' your engine... cooling etc.

I would say... it's up to you when you want the engine to break, but don't let the car break before the engine does, i'e bushes, mountings, steering etc, you are the boss here, not the car.

The engine may be one of those, thrash me forever engines... within engine types... i.e XU10, XU9, XU11, etc, there is what I would call a monday morning engine, and on the other end, a friday aftenoon engine, lets hope yours is a monday morning one, you will never know how hard you can push the engine until you try, I also think that some engines just WANT pain, and will still run regardless of the maintenance or lack of.

Why don't you get pictures and video of the whole thing. It should be interesting. Good luck.

Unread post by **CitroJim** » 18 Sep 2007, 22:00

deian wrote:I reckon the engine should last more than you think it will. Diesel engines are built stronger due to the higher compression ratio, so mechanically wise I reckon it'll hold. But the other things may fail 'for' your engine... cooling etc.

I agree on the cooling front Dei. The more power you extract from a diesel the more heat you'll dump to the cooling system so it needs to be tip-top. I'd be very inclind to reposition the intercooler away from the coolant rad to both make intercooling more efficient (helps power and reliability) and to ditch the aircon condenser which must impede airflow to the coolant rad even if the aircon is not in use.

In my view the 1.9TD cooling system as standard is only just up to the job and its deficiencies can be seen when doing heavy towing.

The general feeling amongst those that tune XU engines to within an inch of their lives is that the XU/D bottom end is easily good for about 200BHP with good reliability. Around 350BHP they start to throw rods on missed gearchanges apparantly

The cranks are fully counterbalanced and very strong. Standard head gaskets can get a bit marginal at high powers though and the metal laminate "repair" gasket is apparantly the one to go for. The only weak XUD was one briefly fitted to the 306 and I cannot recall its code now. It had a habit of breaking rods.

If you've ever had any XU engine in bits the bottom end looks very meaty indeed, even in my XU5 it's a heavy old beast, as are the conrods. It is remarkable how this allows the XU5 to rev quite like it does

By todays standards the XU family are big, heavy and over-engineered.

The main thing to bear in mind when tuning an XUD is to get maximum power at lowish revs. They don't much like going over 6000rpm it seems but by then you're into heavy pumping losses anyway so there is no point.

MikeT · Unread post by **MikeT** » 19 Sep 2007, 10:32

I feel fortunate to have this diesel car. Not only can I use SVO as an alternative fuel but there's no risk of leaning out the air fuel ratio as in a petrol engine - one of the biggest reasons N2O has such a bad rep.

I do expect more heat, how much is yet to be seen. Fortunately, injecting N2O will cool the induction gases by a wide margin and when it breaks down on combustion the nitrogen released will also serve as a cooling agent to the pistons. If heat does become an issue, I've been advised to install water-cooling sprays to the intercooler but I get the impression this will only be needed on massive boost levels.

As far as engine damage goes, if there's an inherent weak point, adding more power will stress that part further, obviously.