Activa quirk?

Unread post by **CitroJim** » 01 Apr 2010, 09:18

Koukku wrote:The kick is probably the result of the two chamber intake manifold. It acts a bit like a variable length intake manifold, but without any moving parts.

Two chamber Koukku? Although I've not sawn one up to look closely inside, the ES9J4 manifold looks a pretty standard sort of plenum with tuned runners to me. I can't quite visualise the two chambers you speak of..

The nice surge of mid-range these engines give I would think would be the tuned runners coming on song and giving a nice increase in torque as they do their job

It's a very pleasant characteristic of this engine and it make you wonder sometimes why we bother with turbochargers

I do like my big normally aspirated engines...

Unread post by **Dommo** » 01 Apr 2010, 11:40

Is this what you mean at ~3:00 in this video? Worth watching the whole video just as a blast from the past to be honest.

http://www.youtube.com/watch?v=gppKvnfugnk

citrov6 · Unread post by **citrov6** » 01 Apr 2010, 12:32

Fair play about all the valves going, it is a good inlet system, whatever they have done. I had had a guess that they blocked of 12 valves because it behaved like a 12 valve at the bottom end, but 24 valves at top end. Sounds much better than a vvt too.

I agree Jim, I think they could of fit a short v8 in there if they wanted. This v6 though is very smooth, much smoother than other v6's can be torquey but lumpy.

There is more to the CoG thing, I did a project on it at university some time ago but I remember if the CoG does not change position you will not get weight transfer, if the car stays completely rigid this will be the case, but if it rolls for example in the tyre or by change in suspension on one side it will shift the CoG and there will be weight transfer.

I miss old top gear I wish it would go back to that style of actual reporting

Koukku · Unread post by **Koukku** » 01 Apr 2010, 12:43

CitroJim wrote:
Koukku wrote:The kick is probably the result of the two chamber intake manifold. It acts a bit like a variable length intake manifold, but without any moving parts.
Two chamber Koukku? Although I've not sawn one up to look closely inside, the ES9J4 manifold looks a pretty standard sort of plenum with tuned runners to me. I can't quite visualise the two chambers you speak of..

I have seen a drawing of it showing the innards... I'll try to dig it up. Here's what Peugeot said upon introduction of the ES9J4:

The variable volume air intake system, which consists of a two-part aluminum alloy intake manifold, is designed to increase response at all engine speeds. Both compartments are joined by two permanent links, one of which is long and the other short. The dimensions of these links are optimized to produce a change in intake behavior as engine speed changes. At low speeds, both chambers behave as separate air compartments, as if each one is supplying an individual three-cylinder engine. At high engine-speeds, however, they work together as if they were a single compartment, with an effective volume that is slightly smaller than the total of both, Peugeot said.

- http://www.allbusiness.com/transportati ... 892-1.html

Dommo, that is the older 24 valve V6, they never put that in a Xantia. I guess the idea is the same, but in ES9J4 there are no valves in the manifold.

Koukku · Unread post by **Koukku** » 01 Apr 2010, 12:53

citrov6 wrote: There is more to the CoG thing, I did a project on it at university some time ago but I remember if the CoG does not change position you will not get weight transfer, if the car stays completely rigid this will be the case, but if it rolls for example in the tyre or by change in suspension on one side it will shift the CoG and there will be weight transfer.

The physics of racing series that I linked to earlier explains weight transfer in rather good detail. The amount of weight transfer during braking, accelerating and cornering can be calculated without knowing anything about the type of suspension, or lack thereof.

Unread post by **CitroJim** » 01 Apr 2010, 13:11

Koukku wrote: I have seen a drawing of it showing the innards... I'll try to dig it up.

Well, well now that is interesting... A well'ish kept secret but it explains why the engine feels as it does...

If you could post that diagram, it would be wonderful Koukku

It is amazing what a plain-looking manifold casting hides!

Oh for TopGear to be like that again

It's actually rather sad to see how it's degenerated over the years. Clarkson has a lot to answer for and to think some would like to see him as Prime Minister

I often think it would be better if James May was the sole presenter and Clarkson and Hammond were relegated to a spot on CBBC (The BBC Children's channel). Top Pedal Car perhaps...

That episode of TG is old - "The new Peugeot 605"... 21 years in fact.

That one had the 90 degree PRV V6 Dom. Same as found in the De Lorean and Renault Alpine amongst others. A very different animal to the PR ES9J4 V6.

PRV stood for Peugeot Renault Volvo. Because the ES9 was never used in the Volvo it is just a PR. You can see PRV6 embossed on most of the engine castings...

Koukku · Unread post by **Koukku** » 01 Apr 2010, 13:12

On page 13 of this presentation there's a good pic of the manifold showing the two chambers:
http://www.scribd.com/doc/2148413/X1X2- ... esentation

Unread post by **CitroJim** » 01 Apr 2010, 13:17

Excellent Stuff Koukku

Many thanks indeed for that! It all makes sense now...

Koukku · Unread post by **Koukku** » 01 Apr 2010, 13:19

CitroJim wrote:Oh for TopGear to be like that again It's actually rather sad to see how it's degenerated over the years. Clarkson has a lot to answer for and to think some would like to see him as Prime Minister

I often think it would be better if James May was the sole presenter and Clarkson and Hammond were relegated to a spot on CBBC (The BBC Children's channel). Top Pedal Car perhaps...

It's quite amazing how the show changed to Lamborghinis and the like right after Clarkson took over. But I do find the show entertaining, not very informative though... James May as a sole presenter, and Clarkson & Hammond as comic side kicks, now that would be something!

citrov6 · Unread post by **citrov6** » 01 Apr 2010, 14:31

don't worry my memory is starting to kick in in bits now, its more annoying that it takes so long . but there are three important bits that i remember so far, weight distribution, weight transfer and torsional moments, torsional moments cause wheel lift, then loss of adhession on the other tyre makes the car slide on the road until the other side comes down. anyway i never studied that in great detail and i will leave it there before i get a head ache

Xaccers · Unread post by **Xaccers** » 01 Apr 2010, 14:52

I'm sure I read that with the hydraulic suspension as the outside strut is compressed under turning forces, the inside strut is extended in compensation increasing road grip compared with a sprung car.
Is that correct?

Basically taking the front suspension of a hydraulic citroen, push down on one side and the other extends as fluid is expelled from one strut into the other.