Alloy Wheels

[beachcomber]

DerekW

- "put the cat amongst the pigeons" [ your mission statement ] and then leave the coop when the debate gets lively? I was just warming up.

Why go there in the first place if you feel the topic is "not important and nobody's interested"? Seems a bit of a waste of your original posting to me.

As for not reading your posts carefully - I can assure you I did, and I thought you made your points quite clearly - as I think, were my responses.

Words in your mouth? I'm not certain what part of your arguments that could refer to - as you seemed completely clear in what you were stating - I just happen to disagree.

Ah well, jorgy9, you'll be glad to see this is a short post. Still - disappointed that DerekW didn't want to defend his ORIGINAL argument further as a good debate is often quite informative.

beachcomber

BTW - drove a 1997 estate V6 MANUAL yesterday and with the owner's permission put the pedal to the metal - 129 MPH MAX speedo reading. It's on my short list to buy. Come on all you V6 owners - what should I realistically expect from a V6 estate?

[jorgy9]

Haven't tried top speed on mine, just to say that official top speed for a 12 V6 manual hatchback was 136mph/222kmh, which was achieved at 5600rpm, exactly at the engine's max hp. I remember though that some old test I read achieved a somewhat lower top, rather nearer 131mph/215kmh. The 12v manual pulls really strong on 5fth once above 3000rpm. But if u fancy all that stuff then u should try to find a 24v PRV. That's the one on MY list...

cheers
George

[beachcomber]

Hi George,

Thanx for that info.

What age car am I looking at for a 24 valve motor? I did see mention of some LPG experts on the forum. I guess my ultimate would be a 24V with LPG conversion. LPG is silly cheap in Germany [ Saxony ] and readily avilable. I recently saw a conversion with a big cylindrical tank in the load area - any other solutions for the tank position?

I actually prefer auto cars - anyone with experience of the auto box's reliabilty behind the V6? As I previously stated - max speed [ real or imaginary ] are not as important as torque and the ability to maintain 120 mph 'ish for maybe a 1000 kms at a time.
Does anyone have real life experience of a comparison between the 2.5TD and the V6?

Diesel has become aggressively dear in Germany [ as in the UK ], so I am still erring towards the V6 / LPG route.

What cost per mile could I expect with the LPG conversion compared with a 2.5TD?

All advice gratefully received

beachcomber

[jorgy9]

The PRV 24v I refered to was produced between 1990 to about 1995, but not sure on the end date. That's the 147kw engine -manual only-. Supply of those is small but steady in Germany -that's where I bought my 12v, incidentally-. A couple of people here run those and have LPGd them, so they'll say more. Your other choice as u might know is the newer 24v, 140kw, a completely different engine -and car, apparently-, and I *think* comes only as auto, although I wouldn't swear on it. In the UK at least it was auto only. This was introduced at around '95-96.

The LPG 24v -either 24v- is my star, as well. Which one, I don't know. From what I read, the later is a really smooth, "accomplished" car, the former is described as "a beast". But what if the latter 24v comes in manual as well? It should be pretty fast too.

Anyway, the owners will tell u more...

George

[DerekW]

My assumption that nobody was interested was based on the lack of correspondence, I was also aware that Noz might pull the plug on us - the subject matter hardly comes under "XM matters".

I am overawed by your enormous experience - a design consultant even! Should we be addressing you as Dr Beachcomber?

Here are some examples where you seem to have misinterpretted my comments:
"LARGER TYRES?......you state wider tyres as a reason to keep your styling gimmick alloy wheels". No I didn't, I wrote that I was unsure (in plain English I didn't know) whether the steel rims, which were designed for 195 tyres, would accept the 205 tyres fitted as standard to my car.
"according to your thesis your handling will be more precise (with steel wheels). I never said that, I wouldn't say that, I don't believe that. What I did was to suggest that, as these light alloys have a lower stiffness (Young's modulus) than steel, the manufacturers might be using more material in order to bring the stiffness up to that of steel wheels and that this would account for their comparitively heavy weight. In other words they finish up as stiff, but heavier. Perhaps with your vast experience you could explain to us the effects of increased unsprung weight on the handling and comfort of a car?
"I presume you are referring to the V6 version of our favourite car". Of course I am, if you look at the info under my singature that should be obvious.

As far as performance is concerned, I was quoting the manufacturer's figures as I have no facilities to confirm or deny them. In any case, it's of academic interest unless you're a "highly experienced" police officer trying out his new Vauxhall.

I can say that on one occasion I was driving down a three lane dual carriageway. The usual scenario, inside lane nose to tail, centre (overtaking) lane with well spaced traffic, outside (second overtaking) lane nose to tail with no-one prepared to lose his place. I came up to this lot and joined at the back. After a few seconds a Mercedes sports car arrived on my tail, on three or four occasions when traffic permitted I moved into the centre lane so he could get past. On each occasion he declined so I eventually remained in the outside lane. Blow me down, he then overtook me on the inside! Ho, hum. It had the logo 500SL (might have been SEL) on the boot. A couple of miles later the road widened to four lanes, the traffic thinned and he was off, sticking in the outside lane. I moved to the third lane and went with him, keeping a distance of about 20 yards between us. We carried on for some seconds accelerating in tandem until, with traffic visibly building ahead of us, I backed off. I did not look at my speedo whilst this was going on but I do have a Garmin GPS12 satelite receiver (bought for my boat) in the car and, although a simple device it does show, amongst other things, the maximum speed achieved since last reset. It is also dead accurate as far as speed readings are concerned. At the end of my trip I was surprised to find it indicated 120mph. The point is that my car was still accelerating hard at that point and was performing effortlessly. The sidelights were still firmly in place.

Using the published figures for Cd and frontal area to calulate drag, and the generally accepted figure of 40N per ton per 10mph increment for rolling resistance, it would seem that, with 140kW available, 143mph is a little optimistic and 136 is probably more realistic. So if you are prepared to accept calculated figures then that's one up to you. This is of course in still air conditions and on the level, wind and gradient will either add to or subtract from that figure.

I assure you that the XM's appearance was not a criterion that I cosidered. I wanted space, comfort, that ride and the fact that it was a Citroen.

Similarly, as a pensioner without a day job, I can't justify spending money on an extra set of steel wheels. So although I think my Monacos are ugly, I can't see them from the driving seat and I've long ago stopped worrying about what other people think of me. And as I've already said, when they're spinning the onlookers can't see what they are anyway.

My original posting was made because I genuinely wanted an answer as to why people wanted wheels that seemed to have a number of disadvantages. I wasn't trying to score points off anyone. You have told me it's appearance that matters. OK, I have my answer.

Derek

This post has been edited by DerekW on October 16, 2006 09:09 pm

[DerekW]

Please excuse the misspelling of "comparatively", finger trouble.

Derek

This post has been edited by DerekW on October 16, 2006 11:51 pm

[beachcomber]

Welcome back Derek,

To be truthful I do have letters I could put after my name but sadly and alas not a doctorate. Instead I just spent 45 years at the sharp end of engineering design, and ended up as a moderately successful design consultant who is still in regular demand both in the UK and Germany. You may still call me Beachcomber, and no need to be overawed, I am quite happy to pass on my "enormous experience " to those less gifted - and yes, I could of course quite simply explain the effects of unsprung weight on the dynamics of a car, but it doesn't take any sort of expert to justify that obvious fact - does it?

As an engineer, I never expect anything to be obvious, but I was relating to "the" V6 version of our favourite car [ in the ludicrous 140mph PLUS claim ], and not "your" car - subtle difference.

However, you're quite right Derek this IS getting boring, as my initial intention was to pass on useful information to XM owners in response to a genuine query regarding alternative wheel fitment.

BTW, I'm sure everyone accepts the typo with "comparatively" - spelling is no big deal on an informal forum - by the way, did the same happen with piDgeon?

Beachcomber

[DerekW]

Bye bye

This post has been edited by DerekW on October 19, 2006 11:30 am

[citroenxm]

Beachcomber

I had a 12v PRV V6 for a short time.. I had 140mph from it.. It was however, an auto by birth, that was converted to a manual if that makes any difference. It was fitted with a 24v V6 manual box.. It blew the diff however.. so I got rid.

Got a V6 Auto, 12 v, and had 120mph at 4000rpm...

Putting my 24v V6 S1, 1990 car, on the road soon I hope. Have been down the road to test it though, and it looks like a 150mph machine!!! Manual Only gearbox, but have a Series Two V6 with the 60 deg unit and they are auto only.

In my opinion, the 90 deg is a nicer sounding machine..

Shall report top MPH on the 24v when I get there..

Regards
citroenxm

[beachcomber]

Thanx for that info. CitroenXM.

Do I take it with horror stories of auto boxes and diff's giving up the ghost that those components can't handle the V6 power?

Would I maybe be better off going down the Diesel Turbo route? Top speed is largely academic and a function of how accurate the speedo is anyway - as previously stated - I'm more interested in being able to cruise for a 1000kms at a time at a steady 110 - 120mph AND the ability to tow a reasonable load without effort.

I have to say that my Volvo 965 [ 3 ltr. 24V straight 6 ] does that task with ease - but it doesn't have the comfort of the XM and the petrol consumption at those velocities is horrendous [ what about the V6 XM ? ]. One possibility was to fit the Volvo with LPG. Although it has the "tow pack", which includes load levelling suspension on the rear, it is mightily inferior to the XM suspension. My V6 Espace [ auto ] is just a slug by comparison!
Diesel is still quite cheap in Germany, but LPG is way cheaper - especially if I nip over the border to Czech!

ANyway thanx for the info - I'll keep looking

ATB
Beachcomber

[citroenxm]

Hi beachcomber

My V6 is on LPG!!

I can fill her with 30 quid at 38p litre, and do about 300 miles.

I worked it at an equivilent of around 40mpg!

Hence my signiture...

On petrol, though your looking at around 20 to 28 mpg...

Regards
citroenxm

[beachcomber]

You're the man I need to speak to then!!

Did you fit the system yourself? What is the approximate cost and is there a chance of a secondhand unit or is it XM specific?

What size and placement is your tank and does it cause much of a problem with load space?

If you have time to answer these questions and any other info. I would be grateful, as this is my preferred route over Diesel.
Thanx in advance
beachcomber

[jorgy9]

Beachcomber,

the Volvo's suspension and the XM's suspension, as I guess u know, are probably the two extreme opposites in the world of suspensions, on this galaxy...I presume it has a Panhard bar with a rigid axle and antiroll bar at the rear, doesn'it ? My father's 460 had the same typical Volvo suspension of that era...the whole car's configuration was so dull that it was impossible to drive it fast and get any pleasure...the car wouuld just not communicate...the steering was sooo artificial in feeling, u'd think it was connected to butter ...but if this just all makes a dull car, it was the rear suspension, with it's assymetric motion, was the potentially dangerous in extreme conditions! On one ocassion I rememeber being on summer holiday, my father driving at about 40mph on a straight line -nothing extreme there then- and the car passed over some large pothole-shaped unevennesses on the tarmac. The front passed normal, the rear axis though "jumped" sidewards to such a degree and speed that my -poor- father had to do counter-steer (is this how it's called in english?) to keep the car going straight !! The car was only good for going straight, on a motorway with perfect pavement....It was comfortable in certain types of bumps, but in others, or when a bit loaded, the rear would just violently indulate up and down -giving headache to me and my little sister who were the unfortunate rear passengers!-. People still bought Volvos though...

George

[jorgy9]

citroenxm,

I'm getting rather 19-24mpg on my manual V6 ,aren't u a bit optimistic there (28mpg? and an auto?) ? Or perhaps there's something wrong with my car?

On the XM-L yahoo there was recently a discussion on the effect of a bitron box related to the speedo, that seemed to feed speed info into the engine ECU. One person reported he had found many dry joints in that, and after fixing them (nothing was apparently wrong with car) his consumption fell. The role of the box feeding speed info to the ECU was not known to the discussants there -it was speculated that it could be to feed a richer mix when stationary, to reduce engine temperatures-. That's how the guy explianed his fall in consumption when he fixed it (ie his ECU was feeding a rich mix constantly beforehand).

Comments???

George

[beachcomber]

Hi George,

Now I would be the first to say that an XM is superior in virtually every department over a Volvo - but "dangerous"?

BTW - 24 mpg would be fine [ especially with LPG ] - 28 mpg and I'd be delirious.

Did you ever see the Volvo estates that wrapped up the touring car championship for 3 years running before the other manufacturers had them banned - because they were "Estate cars"? Admittedly the squiggy rubber bushings were replaced by poly versions - but never the less - the basic stock Volvo set up.

And Volvo have certainly moved on from your Dad's era - omigosh - they even have FRONT WHEEL DRIVE now!!!!

Ditto with the rear axle set up - I really have no interest in the history of Volvo - but I think it was in the late 70's that they realised that the set up you describe was a bit behind the times and went for an IRS system. It was actually quite sophisticated [ of its type ] - certainly more so than the Ford system of the same type. Like ALL automotive systems, it's biggest flaw came about as a result of that pesky "rubber compliance" [ still there DerekW ?] which allowed too much movement in an effort to compromise for a smooth ride. Now we all know that our favourite car can adjust between extremes of suspension and driving style, and is better for it - as long as various control bushes aren't out of thir brains.
My current Volvo is a 965 CD and has such a suspension system [ IRS ] AND it has a self levelling system - but as stated, doesn't compare at all with my VSX XM in that department.

Not that I am defending Volvo particularly - I have catholic taste in cars and take each one on it's merits for the job I have in hand. Neither will I defend "My" current choice of cars with a blinkered view and deny it has faults.

I have had Citroens since my first Light 15 [ early 60's ] and there's always been a Citroen in my stable since. But as my needs altered [ or tastes ] I have always had the "odd" car or two about me at the same time.

The most practical Citroens I have owned were my various CX's Familliales and Safaris - and STILL superior in many respects to my VSX.

All that said - my Volvo is for sale!!!!

Beachcomber