Citroen XM Forum

A few years ago Chris uploaded the XM production figures http://www.club-xm.co.uk/forum/viewtopic.php?f=2&t=7833 and there were apparently a few PRV 24V auto sold.

re E10, you can't really get any performance improvement from the fuel, as they start with a low octane base and add 10% methanol to get the rating up to the stated 95 RON (or whatever the rating is).

I didn't read anywhere that E10 fuel would actually provide more performance (or economy) - quite the reverse, in fact.

E10 is no different to standard 95ron unleaded but E85 is the holy grail, 30% more e85 is required to match the power of standard petrol but that is the benefit, cooler intake temps due to more fuel injected and more heat removed during vaporisation and and 105 octane rating makes it very knock resistant meaning you can run more timing advance and high combustion chamber pressures meaning more power, safely.

Dean wrote: ↑

Tue Mar 10, 2020 7:03 pm

E10 is no different to standard 95ron unleaded...

I thought that our current unleaded was E5 (max of 5% ethanol), Dean.

Indeed but I meant proper old school unleaded. I must admit I’ve not noticed any difference running E5 and although it does emulsify something awful if left out in the air I have no problem starting the car after 2 or 3 months. I will give the new E10 a try but I’m sure it will be fine, I am running injectors that are about 50cc larger than stock.

I run the Ford AA on it with no additives and that’s happy enough, the tank evaporated dry each winter given it’s a vented tank but I chuck some more in come spring and refit the battery and she fires up and runs just fine so I have no trouble there either.

D

So. What stops a hp18 going forward that gradually lost forward drive with a slipping clutch syndrome to no drive..? The valve block was all good from what I could see.. I swapped it out in the end. At 267k it had earnt its living.

Did it stop going backwards too? I would imagine a seal gone in the fed drive clutch pack if the oil pump was outputting good pressure and there were no valve block issues.

That's a pretty dramatic topic swerve, even for us, guys!

It is the clutches that wear out on a HP 4-18.
More torque will exacerbate that.
SAAB possibly increased the fluid change cycle, but probably just let gearboxes fail, with the owner picking up the cost for a rebuild.
If increasing the applied torque, it would be wise to add more cooling capacity.

I think a twin turbo installation might be easier to do....just add a pair of Xm tct turbos onto the end of the manifolds and fabricate new exhaust downpipes.
With an increase of fuel pressure, your fuel system may well have enough capacity without further modification, given those injectors you sourced.

xantia_v6 wrote: ↑

Tue Mar 10, 2020 6:26 pm

A few years ago Chris uploaded the XM production figures http://www.club-xm.co.uk/forum/viewtopic.php?f=2&t=7833 and there were apparently a few PRV 24V auto sold.

I thank that is an error. Note the year is 1996, so more likely the very first Es9J engines, also note some are attributed to being estates...which the V6-24 was never sold as.
The V6-24 was designed as the performance flagship model, the inclusion of an auto box would have made it slower than the V6-12v in manual form.