CT to xud11 conversion

Unread post by **Dommo** » 27 Feb 2010, 10:06

James, regarding the Saab engine my point was more that the Saab engine is similar economy, however has a decent kick up the arse to it thanks to its low rpm torque, and a healthy 205 hp at full chat, which can be remapped to 250hp quite easily.

davetherave wrote:If you are looking into veg oil Dommo, perhaps consider installing a twin tank system? Thats what i want to do to the prestige!!
It will allow alot easier start up in the cold, and cause the pump less wear i believe!

I have an in-line fuel heater that I hope to fit as close to the fuel pump as possible, which should help cold starts (hopefully

)

Gareth, you say I'm wrong, but then list numerous reasons why the engine is bad

XantiaMan wrote:Its lack of fuel economy is down to the compression ratio, its old school 8 valve cylinder head, and the weight does play a part. Activas are getting on for 1450kg, thats still heavy by modern standards, and a 1/4 of a ton IS a lot of weight, its more than another engine and gearbox combined!

The Saab engine is much more efficient and modern, because it has a 16 valve head and higher compression ratio. The latter makes a huge difference to the off boost economy. The XU10 engine is almost an antique in comparison.

What about this makes it good? (And I dont mean to sound like a tosser, but it's true, in my opinion) You have to bear in mind, I'm saying all this because at OEM spec it has poor fuel economy, and is slow, 150hp from a 2 litre turbo is NOT good, no matter what anyone tells me.

XantiaMan · Unread post by **XantiaMan** » 27 Feb 2010, 11:17

I'm simply giving the reasons why its not what your were expecting or hoping. It was an engine designed for the XM, with an Auto box strapped on. Meant to give smooth, torquey performance.

In standard form, not ideally suited to an Activa if you want lots of bhp. This can be changed in steps of course. They were too conservative with the timing and compression ratio, this made it a quiet engine but poor mpg.

Unread post by **CitroJim** » 27 Feb 2010, 19:08

Dom,

I can't help thinking you've got the Activa all wrong. It was never designed or marketed as a sports car; Citroen had never done them so were not about to do so with the Activa.

The Activa was conceived and marketed as a true luxury GT (Grand Tourer) intended to take its occupants from point A to point B smoothly and quickly in a refined way. This it does very well and the CT engine was a good match, being designed, as Xantiaman says, for the luxury end of the XM and to be hooked up to an autobox. The engine was never tuned for absolute power; it was tuned for constant, high torque to give a relaxed cruise and a lazy, laid-back character. A high-revving, rorty thing would have been out of place.

The demograph of typical Activa owners were those who did not give two hoots about 0-60 times, power or any of the other facets of concern to a sports car owner. The car was targeted at those more interested in the refinement and how well it could cope with a fast cross-country jaunt. In short it was designed as a gentleman's GT and never to appeal to the more racier types. Exactly the same market segment the SM, CX Turbo and the various incarnations of the BX GTi were aimed at.

This explains why the car is visually so under-stated and looks like any other Xantia.

In Citroen's book, if you wanted something a bit racier, go to the other side of PSA and get a Pug.

That said, it was a shame they did not do a Xantia GTi with the Activa bits and a well-tuned 16 valve engine. It would have gone down a storm but then again, it would have been out of character with the rest of the Xantia range.

But take the Activa for what it is and you find it fits its intended role and audience very well indeed.

You know the 406 Coupe was originally going to be the Citroen Activa? Now that would have been something to behold.

I still reckon you have a problem with yours. Lack of boost most likely.

Unread post by **Dommo** » 27 Feb 2010, 19:54

No I understand that it's not supposed to be a sports car, which is totally fine by me, it's just that I feel Citroen decided that because it's a 'Gentlemens GT' sort of car that they could make the engine uneconomical and no-one would care. That's my only gripe with it. If it were a powerful and relaxed/gentlemens GT sort of engine however, the poor economy is to be expected.

Unread post by **CitroJim** » 27 Feb 2010, 20:00

Dommo wrote: If it were a powerful and relaxed/gentlemens GT sort of engine however, the poor economy is to be expected.

The V6 delivers that and in Activa guise would be great

In fact, the V6 is a tad more economical than the CT engine....

Having said that though, the V6 is not as refined as the CT in my opinion. I have to have Radio 4 up a few notches louder in the V6 than I do in the Activa

Citroenmad · Unread post by **Citroenmad** » 27 Feb 2010, 23:34

Bearing in mind that the CT was not designed for the Activa, it was first in Xms way before Activas, so Citroen obviously threw them in as they already had the engine. So i dont think its a case of no-one would care about it not being great one fuel. Its a real shame that we didnt get the diesels and V6 over here.

I think a Activa 2.1td would be a nice combination. I cant quite imagine that a 2.1TD would perform like a CT even when tuned, but it should provide good levels of torque and economy. I remember our Activa performing very well, i got wheel spin in 3rd going up hill. I remember it as being a very quick car, 150 bhp in a light car (by todays standards) it should be fairly lively. my mistake.

Jim, could the differences in refinement be slightly due to gearing, or are they similar, ratio wise?

XantiaMan · Unread post by **XantiaMan** » 28 Feb 2010, 07:45

Activa's and Xantias in general are very heavy even by modern standards. There is only 50kg difference between an Activa and my ST and the Exclusive weighs even more.

Citroenmad · Unread post by **Citroenmad** » 28 Feb 2010, 10:37

Sorry, Gareth, i take that back. I assumed that it would be fairly light weight, checking around on parkers (though not always to be believed) shows its not far from modern rivals. Not a huge difference between that and a C5.

Unread post by **Dommo** » 20 Mar 2010, 12:48

Just having more brain farts on the topic..

I understand that the hydractive system switches to hard mode if the accelerator is flat out for more than a second or so? Where does it take the feed for this from? The throttle body, or the pedal, or the engine ECU? If it's the pedal then that's fine but if it's anywhere else I've no idea how to transfer that to the diesel??

Did the 2.1 with a Bosch pump ever come on a hydractive car? If not, that could one of the reasons they swapped to the EPIC pump?

Cheers.

addo · Unread post by **addo** » 20 Mar 2010, 13:39

I reckon it's from the control pot on the pedal.

DickieG · Unread post by **DickieG** » 20 Mar 2010, 13:49

Dommo wrote:Just having more brain farts on the topic..

I understand that the hydractive system switches to hard mode if the accelerator is flat out for more than a second or so? Where does it take the feed for this from? The throttle body, or the pedal, or the engine ECU? If it's the pedal then that's fine but if it's anywhere else I've no idea how to transfer that to the diesel??

The Hydractive system is totally independent of the engine, the switch to firm mode via the accelerator is done by the red pot located above the accelerator pedal, it works by detecting the speed of movement of the accelerator, both up and down. The pedal doesn't have to move very far at all to switch over to firm mode.

Dommo wrote:Did the 2.1 with a Bosch pump ever come on a hydractive car? If not, that could one of the reasons they swapped to the EPIC pump?

Cheers.

Bearing in mind the above the engine is irrelevant when it comes to the Hydractive ECU, it is programmed either XM or Xantia and not engine specific.

Unread post by **Dommo** » 20 Mar 2010, 18:43

addo wrote:I reckon it's from the control pot on the pedal.

DickieG wrote:
Dommo wrote:Just having more brain farts on the topic..

I understand that the hydractive system switches to hard mode if the accelerator is flat out for more than a second or so? Where does it take the feed for this from? The throttle body, or the pedal, or the engine ECU? If it's the pedal then that's fine but if it's anywhere else I've no idea how to transfer that to the diesel??
The Hydractive system is totally independent of the engine, the switch to firm mode via the accelerator is done by the red pot located above the accelerator pedal, it works by detecting the speed of movement of the accelerator, both up and down. The pedal doesn't have to move very far at all to switch over to firm mode.

Dommo wrote:Did the 2.1 with a Bosch pump ever come on a hydractive car? If not, that could one of the reasons they swapped to the EPIC pump?

Cheers.
Bearing in mind the above the engine is irrelevant when it comes to the Hydractive ECU, it is programmed either XM or Xantia and not engine specific.

Brilliant, cheers fellas, I'm just trying to make sure there's nothing stupid like that that I've missed as I really don't want to get half way into the conversion and realise things like that hydractive won't work 100%.

Just need to find out whether the wiring loom for the RPM sensor is the same, and whether I can just literally plug in the 2.1TD clocks and everything will work. Do 2.1 clocks normally have an oil temperature guage?

Cheers again, Dom.

Unread post by **CitroJim** » 20 Mar 2010, 19:44

Dommo wrote:Do 2.1 clocks normally have an oil temperature guage?

Only the VSX/Exclusive Dom.

No worries as you can carefully transfer the oil gauge between the instrument packs.

addo · Unread post by **addo** » 20 Mar 2010, 22:14

I would really love the auto gear indicator LEDs to be integrated with an oil temp gauge. It'd probably be a massive fiddle, though.

Unread post by **Dommo** » 21 Mar 2010, 01:38

addo wrote:I would really love the auto gear indicator LEDs to be integrated with an oil temp gauge. It'd probably be a massive fiddle, though.

Having never been in an auto Xantia I've no idea what this means??