Random thought about the engine bay layout

meep · Post by **meep** » Tue Jan 09, 2007 8:40 pm

Has anyone else noticed this?

Whilst removing the alternator to replace its brushes (yes, I realised I could've left it in situ

), as with anything I do to the engine, I had to remove the inlet tube going across the front as usual, and the two hydraulic pipes just underneath weren't helping access either...

Why didn't Citroen put the air flitter and the hydraulic reservoir the other way round?

Then you'd just have a short bit of ducting to the intercooler, and a couple of short pipes to the pump, it would be loads neater and easier to get at things.

If I had the time, I'd swap them over...

Kitch · Post by **Kitch** » Tue Jan 09, 2007 11:55 pm

Because on the multi point petrol injection models, the air intake and throttle body is on the NS. All other petrols have the intake in the middle above the carb/SPFI unit, yet none have it on the OS.
And its cheaper to maunfacture one base plate for the air box to suit all models.

With the except of the Mk1 models, and the TU engined cars, which have round filter boxes mounted on the engine rather than the shell.

Vanny · Post by **Vanny** » Wed Jan 10, 2007 9:59 am

Kitch wrote:
With the except of the Mk1 models, and the TU engined cars, which have round filter boxes mounted on the engine rather than the shell.

and the early diesels with the round airbox mounted in between the rad and the engine! THe injection madels came in quite late didn't they, so i wonder if the engineers had thought that far ahead or if there where other driving factors? It doe though make sence to have them over there, i doubt on the 16v you could turn the plenum around and pass over the alternator/cambelt to the other side!

I guess the other solution would be like a Xantia with engine mounted pump, airbox over the engine and lhm tank on the O/S.

jeremy · Post by **jeremy** » Wed Jan 10, 2007 11:49 am

Somehow when the BX was first designed I doubt if the designers had in mind the numerous permutations of engine etc that would be fitted.

You must also remember that the thing is assembled in stages from a number of sub-assemblies. For example the FDV and regulator are difficult to remove - but of course are easy to attach to an engine out of the car.

You can't bolt something to a part that hasn't yet been fitted!

meep · Post by **meep** » Wed Jan 10, 2007 12:19 pm

Hmmm, well I have only been exposed to a '91 TZD, so I don't know about the many engine or Mk1 variations...

I assume (from reading here about Xantia conversions etc), that all BXs have the hydraulic pump on the camshaft, to the left of the car (or nearside)?

So... ignoring the air filter variations, it still would've made sense to have the reservoir on the L or n/s, which would've saved a couple of feet of hydraulic pipe per car?

As I understand mass production theory, saving a bolt here and a clip there is generally a good thing?

My other theory is that a BX designer had a serious pipe fetish

DavidRutherford · Post by **DavidRutherford** » Wed Jan 10, 2007 2:03 pm

meep wrote:I assume (from reading here about Xantia conversions etc), that all BXs have the hydraulic pump on the camshaft, to the left of the car (or nearside)?

Nope. Most petrol BX's have the HP pump roughly where the injection pump is on a Diesel, thus the tank is ideally placed for it. (The feed pipe is fairly short)

Look at a MK1 BX19 and the layout it fine. It's only when things had to be modified for later engines that the layout becomes a bit haphazard

meep · Post by **meep** » Wed Jan 10, 2007 2:57 pm

ahhh... now it starts to make sense... it's an evolutionary thing and not being able to see into the future

So... if the hydraulic pump was more or less where the diesel pump is now, then you could swap these two over (bolt the diesel pump to the end of the cam), and voila! you've only got one wheel to time up when you do a cambelt

DavidRutherford · Post by **DavidRutherford** » Wed Jan 10, 2007 3:00 pm

meep wrote:So... if the hydraulic pump was more or less where the diesel pump is now, then you could swap these two over (bolt the diesel pump to the end of the cam), and voila! you've only got one wheel to time up when you do a cambelt

*cries a little*

Post by **docchevron** » Wed Jan 10, 2007 3:02 pm

Such wisdom! Car designers take note!

Cheers
Chris G

Kitch · Post by **Kitch** » Wed Jan 10, 2007 6:13 pm

jeremy wrote:Somehow when the BX was first designed I doubt if the designers had in mind the numerous permutations of engine etc that would be fitted.

That maybe, but he was refering to the TZD model, with the square airbox. And the reason its there is because MPFI models have the box there too due to the plenum location, seeing as the first MPFI car came out in 1986....before any of the TD's.

Stewart (oily!) · Post by **Stewart (oily!)** » Wed Jan 10, 2007 7:24 pm

Modern vehicles tend to be "designed" and come to us freshly created, vehicles that have a relatively long model life sort of evolve, the BX was initially only available with carburettored petrol engines (though the diesels were doubtless very close behind given the popularity of diesels in europe even then) but everything else came after, combine this with peugeot supplying the engines and you get the interesting layouts we know and love.
Stewart

tom · Post by **tom** » Wed Jan 10, 2007 7:28 pm

The BX was probably in the design stage before Peugeot had even bought the rights to the XU series of engines. Remember that they were originally Simca's design, about the only asset left of the Chrysler/Talbot company worth having.

Kitch · Post by **Kitch** » Wed Jan 10, 2007 7:29 pm

Probably also had something to with the fac that most early BX's had the HP pump near the alternator, requiring only a short hose from the res to get to it.

Ironically most later ones had the pump on the gearbox, meaning it had to have a big long hose awkardly stretched across the front of the block.

Stewart (oily!) · Post by **Stewart (oily!)** » Wed Jan 10, 2007 7:35 pm

My Xantia has the pump and tank on opposite sides of the engine bay too perhaps they were going for weight distribution or something? I read somewhere that early golfs had all ofthe moveable heavy bits on the right hand side to offset the drivers weight (left had drive) which resulted in them needing handed springs for the UK market
Stewart.

Kitch · Post by **Kitch** » Wed Jan 10, 2007 7:59 pm

Mercs are the worst.

To find the correct coil spring for a Merc (and I got asked, alot) you start with the chassis number and enter it into the lookup.

The car starts with a random number of points.

Then, you find out all the options the car has fitted, like Air Con, towbar, sunroof etc

Each part is worth additional points. AC was 2, sunroof was one....there were loads.

Then you add it all together and you have 7 groups.

For points totals "X-Y" choose this part number. For "Z-Y" choose this part number.....and so on.

So thats why whenever a Merc owner used to ring us asking for a spring for their 4 year old tat wagon, we'd simply just tell them to go to a dealer....they're just not worth the hassle!

Well sometimes, if we didn't like the customer we just sold them the basic springs and waited for them to come back with one end decked