Citroen C6 Tuning?

[Vallunstein297]

Hello everyone! Happy new year to everyone! With the new year, I have a new hope-indeed I want to buy a C6 some time this year. I have already decided that, I would prefer the V6 Petrol engine for a number of reasons. My question is- Even though the C6 is not made for sport by any chance, is it possible for this engine to produce more horsepower? And is the engine and transmission able to withstand horsepower increase?

[Jay-Bruce]

The Peugeot V6 Petrol engine doesn't have all that much tuning potential, which is strange as it's an over square engine, with shorter stroke than bore, so should be rev happy and make power. However, it doesn't seem to do all that well in the aftermarket, so you're probably looking at an additional ~20bhp with a map, maybe ~5bhp with a performance intake system "induction kit", another ~5bhp with a decat, which takes you to about ~240bhp, which is the starting point for the 3.0 V6 diesel.

[Vallunstein297]

The Peugeot V6 Petrol engine doesn't have all that much tuning potential, which is strange as it's an over square engine, with shorter stroke than bore, so should be rev happy and make power. However, it doesn't seem to do all that well in the aftermarket, so you're probably looking at an additional ~20bhp with a map, maybe ~5bhp with a performance intake system "induction kit", another ~5bhp with a decat, which takes you to about ~240bhp, which is the starting point for the 3.0 V6 diesel.

Interesting. Because i've seen the previous generation of ES9 to have some tuning potential. By all means, I'm not looking for any type of sport in the C6, I would just prefer it to be a tiny bit faster

[MattBLancs]

An Interesting review of the 2.7hdi and petrol v6 C6 models:



In summary: petrol sounds nice but lacks the mid range shove of the HDi.

The ES9J4S was shared with Renault who notably used in in the Clio V6. I think it made 255bhp in that application. Inlet manifold different not sure what other changes.

Think there was a guy seeking 600bhp from a twin turbocharged Peugeot V6, but not if much use to you as was to be mid mounted in his 406 Coupe.

I'm not sure more performance is something the C6 needs. Quite a few videos in the C6 on that Up N Down channel - worth a watch

[Vallunstein297]

An Interesting review of the 2.7hdi and petrol v6 C6 models:



In summary: petrol sounds nice but lacks the mid range shove of the HDi.

The ES9J4S was shared with Renault who notably used in in the Clio V6. I think it made 255bhp in that application. Inlet manifold different not sure what other changes.

Think there was a guy seeking 600bhp from a twin turbocharged Peugeot V6, but not if much use to you as was to be mid mounted in his 406 Coupe.

I'm not sure more performance is something the C6 needs. Quite a few videos in the C6 on that Up N Down channel - worth a watch

Thanks a bunch for the share! I've found this channel a while ago, and watched the comparasion two times already I agree, the C6 is a limo that is not made one bit for sport. But I would like it to have some good acceleration on the highways for example. The acceleration shown in the test is between 30-60mph, and it took a bit of time to reach that figure. I would imagine the time for going faster are even slower. The car weights quite a lot as well. That's why I'm asking if the V6 has any tuning potentials.

[MattBLancs]

I took the conclusion from that video to be that really it goes well enough - I'd imagine the later more powerful still 3.0 HDi as Jay mentioned, with 240bhp as standard (and presumably able to remap to give a touch more) would give that extra acceleration you seek.

Bear in mind that if course is giving the automatic gearbox even more to contend with if remapped. Up N Down has had issues / bought the C6 with issues and has improved but not eliminated them associated with that auto gearbox. In fact that is also worth considering on his review of the diesel, that it's not 100% as it should be.

Weight counts against it as a sports car, but does it no great harm as an "executive express" where it'll just excel at distance travel in comfort.

[Vallunstein297]

I took the conclusion from that video to be that really it goes well enough - I'd imagine the later more powerful still 3.0 HDi as Jay mentioned, with 240bhp as standard (and presumably able to remap to give a touch more) would give that extra acceleration you seek.

Bear in mind that if course is giving the automatic gearbox even more to contend with if remapped. Up N Down has had issues / bought the C6 with issues and has improved but not eliminated them associated with that auto gearbox. In fact that is also worth considering on his review of the diesel, that it's not 100% as it should be.

Weight counts against it as a sports car, but does it no great harm as an "executive express" where it'll just excel at distance travel in comfort.

Thing is, the C6 as it stand, is quite hard to maintain and reliability of the diesel engines is very questionable. And knowing the diesels, there would be problems with the EGR/ FAP filtre in the near future if I make any kinds of remaps or tunes. That's why I prefer the petrol V6. And the petrol v6 is far easier to maintain, and doesn't have the usual problems with FAP/EGR, because they don't exist there.

[Jay-Bruce]

The V6 petrol has a 0-60 time of 9.1s, the 2.7 diesel has a 0-60 time of 8.9s and the 3.0v6 diesel has a 0-60 time of 8.6s. So starting with either of the v6 diesels is a quicker vehicle, then a simple remap unlocks a lot of grunt for not a lot of coin, it's really the best "bang-for-buck" in tuning terms. Worth noting that the 2.7 diesel has a bit of turbo lag, which is absent in the 3.0 diesel, and in the 2.7 that lag is usually eradicated by the new map when the vehicle is remapped.

I've had both v6 diesels, a 2.7 in a 407 coupe, and a 3.0 in a mk.III c5 tourer (X7) the 3.0 feels a lot livelier, especially down low in the bottom of the rev count. The 3.0 also has better tuning potential than the v6, offering bigger gains for a remap

However, you've stated you want a petrol rather than a diesel, so this link might be of interest to you: but this link viewtopic.php?t=54468 is a thread that goes into a bit more detail. Matt's comment that the "Renault V6" is actually the PSA/Peugeot/Citroen V6, with a better inlet manifold that unlocks 255bhp vs Carlsson's 235bhp, is interesting, possibly the most interesting thing you'll find as it suggests renault clio v6 parts could be sourced as hop-ups for your C6? So maybe you need to look more into what the Renault community do for tuning options?

I had a quick look into Renault stuff for you, and found the following comment "engine was detuned for longevity - even the MK2 was at 275 before they dropped 20 bhp for warrantly cost reasons" in this thread https://cliosport.net/threads/best-webs ... ing.53041/ - so even in de-tuned state, it's still making 20% more power than the Citroen variant, ergo those are some Gucci AF manifolds they are using to make it breathe so well. So maybe Renault manifolds, decat, remap, could be a 250-300bhp car? I'm guessing the mid engined sports-car Clio V6 would have a shorter and less restrictive exhaust system than a front engined Citroen C6 limo, hence saying your tuning potential would be Renault Clio V6 starting point and a little bit, rather than much more.

You might make more power by sportifying the exhaust system, increasing tubing diameter a size or so, and removing one or two boxes, but going down that route would introduce more exhaust noise, and potentially be at odds with the character of the car. It wouldn't make much sense to buy a citroen limo with a soothing floaty magic carpet ride that is engineered to make long journeys soothing, and fit a boy racer almost straight-through exhaust system that gives you a headache in 50kms. But done right, you could end up with something fairly unique, with a lovely v6 growl on heavy throttle applications, but serenely quiet on light throttle crusing.

I really wish you the best of luck with this, and look forward to seeing your progress, either grafting Renault bits onto a C6 petrol engine, or upping the ante with the diesel tuning. Such enthusiast threads are always a joy to read and are refreshing change from the usual car forum threads about diagnosing and solving faults on mundane vehicles.

[MattBLancs]

The C6 is a complex car, definitely. I don't think avoiding the diesel necessarily changes that significantly.

The V6 diesel has some instances of snapping crankshaft, but otherwise seems to be fairly reliable. There's a great number of Land Rover Discoveries that this engine has the bad luck to be installed within (2.6 tonnes to shove about) and they aren't all failing so don't think that engine has to be avoided at all costs. Particulate filters are getting hard to avoid really but should not write off the car if need attention.

As discussed, there's no simple power addition option for the petrol V6 (whereas the diesel is a simple remap, turns up fueling and boost pressure, significant increases quickly generated) anything that gives the petrol a significant increase (e.g. turbocharger) is a big job and not likely to be the benefit of engine, or gearbox, reliability/longevity. (And for balance a remapped diesel isn't helping the auto box either)

But I think you need to try a C6 and then decide if it is "too slow"


Some excellent points and first hand experience of the HDi engines from Jay - typed whilst I am typing!

I'll try and dig on the Coupe forum later, am sure someone bought a Clio V6 inlet to try and fit it to their 406 Coupe

Worth bearing in mind the Clio V6, mid mounted, doesn't have any height restrictions, do may well be that inlet would not fit under the bonnet!

[MattBLancs]

Such enthusiast threads are always a joy to read and are refreshing change from the usual car forum threads about diagnosing and solving faults on mundane vehicles.

Just to add, wholeheartedly agree, not trying to talk down your ideas for a faster C6, just adding my thoughts

[Hell Razor5543]

I believe the V6 3.0l diesel C5 was the fastest production car Citroen produced, running at 149MPH. The V6 diesel 3.0l C6 was the fastest of this range achieving 146MPH.

[Vallunstein297]

People,thank You very much for the comments on the topic! Really, as Jay mentioned, both the diesel and the petrol seem to have very similliar times from 0-60. I should also mention that, I really love the diesels in general, but I would marginally prefer the petrol variant in the C6. I believe a petrol engine suits better every luxury car. Another reason for this choice is, I do live in a big city, and driving a diesel in the cities is still possible, but with the new regulations, the diesels might end up in the garages or outside of the major cities. And third, but certainly last reason, with the current prices of the petrol/diesel, It is far more affordable to drive a petrol right now. In addition, it is very popular here to have LPG with some vehicles. Certainly, I know for a fact that if I decide to do it, the 3.0 Petrol has no problems with having LPG.
Thanks again for the responses from everybody!

[Jay-Bruce]

It was a fun thread, and happy to have helped, you'll need to update this thread with pictures of the C6 when you get it

[Vallunstein297]

It was a fun thread, and happy to have helped, you'll need to update this thread with pictures of the C6 when you get it

Sure thing But I suspect its not going to be happening earlier than late 2023 or even mid 2024 Unless I win the lottery and can afford to buy and maintain a C6.. for a few months

[cit-rotti]

A poor man prays to God for many weeks that he will win the lottery because he needs the money so badly.

After long weeks of waiting and praying, an angel appears and speaks to him.

God has heard you for a long time - but you also have to hand in the lottery ticket.