16v front pipe

Philip Chidlow · Post by **Philip Chidlow** » Mon Jan 21, 2008 11:53 am

I'm the proud (?

) owner of a venerable Phase 1 16v now... which'll be fine once I get it firing on all cylinders

and I will shortly be collecting a nice Phase 2 valver too. (Glutton for punishment).

A question: I hear talk of a seemingly mythical front pipe with splitter which adds magic to the engine allowing the power to be fully realised. Without one power and torque are down.

Can someone explain (and thanks to Kitch I'm not totally ignorant) what these look like (any pics?) and am I likely to ever find one if I don't have one? What is used in place of one - apparently the ph.2 doesn't have one.... as for the ph. 1 I have spent precious little time in it's company as it's down the road having a cambelt fitted... so I don't know.

What should I look for?

Phil

toddao · Post by **toddao** » Mon Jan 21, 2008 3:47 pm

Good work Phil! Sorry, don't have a clue about valvers but look forward to seeing the first pictures appear soon.
What's the price for a new cam belt fitted there ? I've just been quoted €400 and, seeing as I've got two to do, looks like I'll be getting my hands dirty

Kevin B · Post by **Kevin B** » Mon Jan 21, 2008 3:57 pm

The front pipe from a BX16v has a divider in it which seperates the exhaust gases from different cylinders (cant remember which) for a longer duration.

This works because the exhaust divider allows the front pipe to behave as a tuned length of pipe improving exhaust gas flow from the engine, much in the same way the inlet manifold and plenum on your BX 16v engine improve air flow into the engine throughout the rev range.

You will only find this feature on genuine Citroen BX16v and 8V GTi front pipes, as pattern part manufactureres deem it to be a nicety they can sacrifice hence making thier product much cheaper to manufacture.

If you look at the front pipe looking down the flange connection you will see a horizontal divider running the entire length of the first section upto the point where it connects onto the expansion box.

Philip Chidlow · Post by **Philip Chidlow** » Mon Jan 21, 2008 4:26 pm

toddao wrote: What's the price for a new cam belt fitted there ? I've just been quoted €400 and, seeing as I've got two to do, looks like I'll be getting my hands dirty

Just paid £80 cash and £15 for the belt.

I've now sorted the ignition problem with a new set of leads, although at the next service I have a spare (new) dizzy cap and rotor that I got for a very good price and a set of plugs that I'll fit.

The car runs OK now, a bit lumpy at idle and not quite as quick as I was expecting, but for a 20 year old 187k mile car I think that's to be expected

Radio works too!

Way2go · Post by **Way2go** » Mon Jan 21, 2008 4:53 pm

Philip chidlow wrote: Just paid £80 cash and £15 for the belt.

Sounds like you got a good deal there!

Philip chidlow wrote: The car runs OK now, a bit lumpy at idle and not quite as quick as I was expecting, but for a 20 year old 187k mile car I think that's to be expected

When you get the injectors cleaned, it will rejuvenate this!

Found out that this can be done on the same equipment as Lucas/Bosch, by post for £11.75/injector.

See link for full info, ordering etc:

http://www.injectorcleaning.co.uk/

Kitch · Post by **Kitch** » Mon Jan 21, 2008 9:51 pm

The downpipes are the same on all 16v models, with the exception of the DFW cat versions which obviously have a cat in, but the same divider system.
It's actually common on most Citroens and Peugeots, its like a metal divider to seperate the gasses to allow them to flow freely. The manifold system is actually an 8-4-2-1, with a port per exhaust valve. The "2" bit starts in the manifold and continues into the downpipe until the bend at the bottom.
The common misbelief is that pattern exhaust parts don't have the divider.....most do. The thing that isn't always the same is the length of the divider in the downpipe and how far down it goes....some cheap parts only have a couple of inches. Whether you'd actually notice a different is debatable.
Mines a Walker downpipe and comes complete with the divider at the right length. However I have problems in other areas with it, as the fit isn't perfect and it resonates quite badly now, although at first it didn't.

The best unit you'll get overall is a Genuine one, although I don't know which company actually produces these. I'd try and find a Bosal one personally, as they're good quality and good value.

tim leech · Post by **tim leech** » Mon Jan 21, 2008 10:56 pm

My valver is also lumpy, is remove the injectors much of a Job or do they just unscrew?

Way2go · Post by **Way2go** » Mon Jan 21, 2008 11:27 pm

tim leech wrote:My valver is also lumpy, is remove the injectors much of a Job or do they just unscrew?

It's an easy job!

Described well in Haynes blue book Chapter 4B*5 section 12.

Vanny · Post by **Vanny** » Tue Jan 22, 2008 12:45 am

which version of the Haynes? there is more than one!

Way2go · Post by **Way2go** » Tue Jan 22, 2008 1:26 am

Vanny wrote:which version of the Haynes? there is more than one!

I thought there was only one BLUE version for the BX by Haynes, which is the version later than the brown?

Anyway:

Haynes 0908
ISBN 1 85960 190 1

Kitch · Post by **Kitch** » Wed Jan 23, 2008 10:16 am

In honesty, I severly doubt the lumpiness is anything to do with the injectors, cleaning them will just be wasting money. Petrol is full of cleaning detergents anyway, and theres no reason for them to block up in a way that diesels kinda do.
Only speaking from my personal experience, and the three valvers I've owned have all idled in a lumpy fashion. So has a mate's 405 Mi16 and a 205 with an Mi16 engine in it.
You'd do far better to put that money on a decent cap and arm, and a decent set of plugs. It would also be worth making sure it's fuelling properly (you can adjust the mixture on the AFM.)

Way2go · Post by **Way2go** » Wed Jan 23, 2008 11:20 am

Kitch wrote:In honesty, I severly doubt the lumpiness is anything to do with the injectors, cleaning them will just be wasting money.

Well you can doubt it but the "proof of the pudding" as they say gives great benefits speaking from actual experience.
I watched over my cleaning and they do a fuel metering test before and after cleaning. Before gave unequal amounts of fuel from each injector and afterwards the fuel delivery was balanced.
Why be so cynical over something you haven't tried & has given proven results for others?

tim leech · Post by **tim leech** » Wed Jan 23, 2008 1:18 pm

That you told Kitch

For less than £50 for the lot if it makes any improvemnet im happy.

Kitch · Post by **Kitch** » Wed Jan 23, 2008 6:15 pm

Way2go wrote:
Kitch wrote:In honesty, I severly doubt the lumpiness is anything to do with the injectors, cleaning them will just be wasting money.
Well you can doubt it but the "proof of the pudding" as they say gives great benefits speaking from actual experience.
I watched over my cleaning and they do a fuel metering test before and after cleaning. Before gave unequal amounts of fuel from each injector and afterwards the fuel delivery was balanced.
Why be so cynical over something you haven't tried & has given proven results for others?

Well it would have told me, if I hadn't had four injectors ultrasonically cleaned while rebuilding my own car (hence why I have numerous spares).
I'm not trying to be some jumped up ego like we've had on here in the past, I'm just saying what I see and what I've learned in the past.

Incidentally, have you ever owned an XU9J4 vehicle?

Post by **docchevron** » Thu Jan 24, 2008 3:20 am

Valvers are lumpy, live with it.
They have very aggresive cams and the mapping is a bit old hat, ergo, they be lumpy, dont mean theres owt wrong with it.

As for the front pipe, getting pipes with splitters is getting difficult now.
The last two I've bought didn't have a divider at all, one walker, one bosal.
Easy enough to cut and shut the pipe with a home made one though!