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Discussion Starter · #1 ·
I have been reading up a bit on the Rover KV6, and it seems to have been common consensus in the past that max. engine displacement can be brought up to 2.7l as was implemented by KIA. I wasn’t able to find much explanation for that limit aside the fact that it was done by KIA.
Hypothetically speaking though, assuming a world where money grows on trees and reliability is of second concern, is the 2.7L ”limit” true? What are the technical reasons behind it? And if not, what would theoretically be possible?

I feel a bit like the KV6 is Rover’s middle child in the shadows of its young brother the K18, despite that guy making HGF messes In its youth. There seems to be not that much information out there and numbers of cars they are in are dropping fast.
 

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Discussion Starter · #3 ·
At the risk of sounding stupid, why can’t it be further stroked or put otherwise, what is limiting it to the spec stroke? I understand that it would be limited to the position of the crankshaft and con rod length, but could the latter not be replaced with shorter ones for example.
As regards bore, my thoughts were that if KIA managed to produce a “reliable” driver at 2.7, surely there must be (theoretical) room for a bit more, albeit at the cost of losing reliability. I understand the limits of bore a bit better since you are limited to the actual metal left between cylinders.
 

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Basically, the wider the bore and the longer the stroke increases displacement , so if the stroke goes fully up the bore to top dead centre and all the way to the bottom of the Liner/bore (bottom dead centre) . There is no way to increase displacement via stroke so the only way to achieve an increased displacement is to increase the diameter of the bore/liner and oversize the pistons , some engine makers don’t go all the way up the liner to lower the compression ratio of the engine (rover in the k16 turbo engine) so might be worth looking into wether the piston stroke of a kv6 goes all the way to the bottom of the liner & all the way to the top ,
 

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Discussion Starter · #6 ·
View attachment 139247 I’v

I’ve done some calculations and it looks like they could have increased the bore size by 3.2 mm per cylinder to achieve 2.7 L displacement
Thanks a lot for your explanations, makes it a bit clearer now. I’ve read that generally speaking increasing displacement by x% would increase torque and hp by the same x%, would you say that is true? Would translate to roughly 195 hp (assuming 180 as base), which is certainly not that much given the cost involved but still interesting to consider.
 

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A good way to increase horse power on a KV6 would be to turbo charge it , it uses the same pistons as the k16 so in theory a forged conrod and a lower compression piston (qed motorsport) would
Get you bags more power and torque than increasing the displacement slightly
 

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Discussion Starter · #8 ·
A good way to increase horse power on a KV6 would be to turbo charge it , it uses the same pistons as the k16 so in theory a forged conrod and a lower compression piston (qed motorsport) would
Get you bags more power and torque than increasing the displacement slightly
What about both lol
joking aside, I was under the impression that the engine room in the ZS is alread too cramped to put a turbo / super charger in? I remember that back in the day there was sprintex kit that was implemented a few times, bringing it above 200-220 if I recall correctly.

Reason why I am asking is that since V6 ZS’ have a tendency to snap their belts as the procedure is fairly expensive and thus often ignored, I was thinking to what extent such a car could be snapped up on the cheap and given engine needs a rebuild anyway, may as well get creative.

The idea would not necessarily be max. power since it is a FWD car, rather a good power to weight balance at around 5kg/hp -ish
 

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I think you could manage to get a turbo in there depends what you are looking for instant low end power I would be getting a supercharger , mid to high range power I would be going down the turbo route a interesting video for you below
 

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I have been reading up a bit on the Rover KV6, and it seems to have been common consensus in the past that max. engine displacement can be brought up to 2.7l as was implemented by KIA. I wasn’t able to find much explanation for that limit aside the fact that it was done by KIA.
I am not sure where you have got the information from regarding KIA making a 2.7 litre version of the Rover KV6? As far as I am aware (and as far as all the references to KIA and the KV6 that I can find suggest), the version used by KIA was identical to the early version of the KV6 as used in the Rover 825, with the exception of a different intake manifold (possibly because KIA had originally intended it to be fueled by compressed natural gas).

Are you perhaps getting confused by the events following KIA going bust and being taken over by Hyundai? - production of the KV6 was ended and from then on, the petrol versions of the Sedona were fitted with an Hyundai 2.7 litre engine.

The KV6 was effectively a joint venture development between Rover and KIA, although KIA only joined the development project in 1994 after design work had started. From what I can gather, KIA paid £10 million into the joint project, which they understood as being half the development cost (in fact, that was pretty much the entire cost, so Rover got the engine designed near enough for free).

I don't think that the KIA version differed from the Rover version apart from the inlet maniold and a few modifications made to some components to alleviate the need for special tools for disassembly/maintenance as (at the time) there was a much less specialised service and repair set-up in the far east.

Rover subsequently reworked a significant proportion of the engine internals for the later version used in the 75/ZT and 45/ZS, so these later engines are not quite the same as the ones used in the Rover 825 and KIA Sedona anyway, and a lot more reliable - the Rover version gained a poor reputation in the 825, and by all reports, the KIA version was even worse for blown head gaskets. These problems were largely put to bed with the redesigned version that Rover used latterly, and your suggestion about cam belts snapping is entirely due to owners not carrying out maintenance and replacing the belts when due, and certainly not down to any unreliability issue with the engine itself.
 

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Discussion Starter · #11 ·
I am not sure where you have got the information from regarding KIA making a 2.7 litre version of the Rover KV6? As far as I am aware (and as far as all the references to KIA and the KV6 that I can find suggest), the version used by KIA was identical to the early version of the KV6 as used in the Rover 825, with the exception of a different intake manifold (possibly because KIA had originally intended it to be fueled by compressed natural gas).

Are you perhaps getting confused by the events following KIA going bust and being taken over by Hyundai? - production of the KV6 was ended and from then on, the petrol versions of the Sedona were fitted with an Hyundai 2.7 litre engine.

The KV6 was effectively a joint venture development between Rover and KIA, although KIA only joined the development project in 1994 after design work had started. From what I can gather, KIA paid £10 million into the joint project, which they understood as being half the development cost (in fact, that was pretty much the entire cost, so Rover got the engine designed near enough for free).

I don't think that the KIA version differed from the Rover version apart from the inlet maniold and a few modifications made to some components to alleviate the need for special tools for disassembly/maintenance as (at the time) there was a much less specialised service and repair set-up in the far east.

Rover subsequently reworked a significant proportion of the engine internals for the later version used in the 75/ZT and 45/ZS, so these later engines are not quite the same as the ones used in the Rover 825 and KIA Sedona anyway, and a lot more reliable - the Rover version gained a poor reputation in the 825, and by all reports, the KIA version was even worse for blown head gaskets. These problems were largely put to bed with the redesigned version that Rover used latterly, and your suggestion about cam belts snapping is entirely due to owners not carrying out maintenance and replacing the belts when due, and certainly not down to any unreliability issue with the engine itself.
I actually thought to have read it somewhere, perhaps it was mentioned in a forum but I did indeed never really find the evidence for it, so I am more than ready to believe you since I have been carrying that uncertainty around with me for quite awhile. As always, thank you for a more detailed view on things. I have heard that the early KV6s were essentially hand-built and not super reliable.

I was also not at all blaming the KV6 for snapped belts, just picking up what seems to be a not so uncommon observation. Awhile ago I was close to buying such an example, unfortunately I didn't really have the space for it. I thought how better to learn tinkering on a KV6 than to start with a dead one and perhaps save it.
I have been driving my MK2 180 as a daily for a couple of years now and I can't say a negative thing about the engine. It is very smooth and the sound is just gorgeous. Quite a change from my banging and rough ZR and although I appreciate my ZR greatly as well as the K18 I have developed a soft spot for the ZS180 and the KV6, which is why I am trying to learn more about it. Unfortunately mine is also due a belt change and based on the quotes I received, I can understand why some people on a budget just risk not doing it.
 

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the engine is based on the Honda v6, as Honda owned rover at the time. The 827 was a single cam per bank, and the 800 2.5 KV6 was a derivative, with an the extra cam per bank (which is why the second cam is driven from the back of the head). You may be able to use an 827 bottom end with 2.5 KV6 heads, but that really is a pointless exercise, as it is cheaper to buy a zt260, or a 330 bmw, which have engines far more reliable than the KV6.
 

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Discussion Starter · #13 ·
Did Honda actually own Rover? I thought they did a technical cooperation which ended when BMW acquired them?
To be honest, the discussion is obviously not really about reason or logic. Clearly there are “better” or faster or more reliable alternatives out there, but that is not really the point.
I do of course like the ZT260, its crazy story and hopefully it will one day round off my Zed collection, but to me the ZS180 represents a more interesting concept with its overall low weight, in part also linked to the fairly light V6. And since I have been experiencing the V6 for a couple of years now, I can’t really say anything negative about it, quite the contrary.

Within the MGR Z range it is (to me) probably the best suited for a sportier project car, not based on max. Power but a proper thought-through weight/power balance, which is why I am intellectually curious to learn a bit more about it since it seems to me that it has been a bit forgotten compared to the K18.
 

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Discussion Starter · #14 ·
I think you could manage to get a turbo in there depends what you are looking for instant low end power I would be getting a supercharger , mid to high range power I would be going down the turbo route a interesting video for you below
That certainly sounds and looks juicy. Thanks for your opinion on that, I will try to dig a bit deeper on the supercharger topic. Realistically speaking though, how complex is it to fit a supercharger with no market-ready kit (as was the case with the sprintex for example awhile ago)?
 

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Anything can be done with the drive and enthusiasm to do it , I’m currently taking a rover k series 1.8 turbo engine from a rover 75 and mating it to a dq250 dual clutch transmission from a vw golf R and putting it into a mg zr it’s all about knowing what you need before starting the project , I’m using most of my parts from the newer mg6 platform, with supercharging a kv6 I would be using all the standard internal components and using thicker custom made head gaskets to lower compression and using a supercharger from say a old Mini Cooper (eaton m25) or the twincharged VW 1.4 tsi and just piggy backing it off say the alternator with some custom made bracketry then using something like water methanol injection as fueling so no need for expensive ecu’s etc it can be done in the cheap with the use of eBay etc
 

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the engine is based on the Honda v6, as Honda owned rover at the time. The 827 was a single cam per bank, and the 800 2.5 KV6 was a derivative, with an the extra cam per bank (which is why the second cam is driven from the back of the head). You may be able to use an 827 bottom end with 2.5 KV6 heads,...............
The KV6 is a Rover K series family design, and has nothing whatsoever to do with Honda. You can try fitting KV6 cylinder heads on a Honda bottom end if you wish, but you will find they don't fit. The engines are not the same at all.

Honda and Rover had a licensing partnership from 1979, which grew into a formal joint development partnership in 1981. This agreement was terminated by Honda in 1994 when Rover Group was sold. Rover was owned at the time by British Aerospace, although the partnership with Honda had led to an agreement for Rover to take a 20% share in Honda, and Honda to take a 20% share in Rover. Honda never owned Rover, and when BAe had offered to sell them the whole company in the early 1990s, Honda offered to increase their shareholding, but not to take full ownership, which wasn't accepted by BAe, and Rover was subsequently sold to BMW. This was the point (and the reason) that Honda terminated the partnership agreement, and eventually sold their 20% stake in Rover to BMW.

The KV6 was developed after this, due to Honda firstly substantially increasing the price of the engines supplied to Rover, and then announcing that they would stop manufacturing it altogether in 1995 - thus the reason why the KV6 was developed. Honda had no part in its development, and neither was any Honda IP used.

Did Honda actually own Rover? I thought they did a technical cooperation which ended when BMW acquired them?
That is pretty much it in a nutshell - Honda only ever owned 20% of Rover as part of the reciprocal ownership agreement that came about whilst the technical partnership was at its zenith.
 

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Discussion Starter · #17 ·
Anything can be done with the drive and enthusiasm to do it , I’m currently taking a rover k series 1.8 turbo engine from a rover 75 and mating it to a dq250 dual clutch transmission from a vw golf R and putting it into a mg zr it’s all about knowing what you need before starting the project , I’m using most of my parts from the newer mg6 platform, with supercharging a kv6 I would be using all the standard internal components and using thicker custom made head gaskets to lower compression and using a supercharger from say a old Mini Cooper (eaton m25) or the twincharged VW 1.4 tsi and just piggy backing it off say the alternator with some custom made bracketry then using something like water methanol injection as fueling so no need for expensive ecu’s etc it can be done in the cheap with the use of eBay etc
Well it sounds fascinating, going to give it some research. Is it the eaton m25 or m45 supercharger, only found the m45 so far, which seems to have been included in the 1st gen BMW Mini Cooper. Is the m25 used in an older model?

On a related note, the cambelt is coming up for my ZS and I am a bit in a pickle as there are no specialised service providers whatsoever in my area / country. Chances are high they don’t have the special tools or may not even be aware of the fact it’s three belts. I seem to have read that doing the belt without the special tools could be done but at a risk (and is painful to do). Now I have found these on ebay at what seems a reasonable price based on what I have read about them. Now I would have 2 questions:
1) Can I trust these (quality wise) after all they are coming out of China
2) Assuming I can trust them, how hard would a DIY cam belt change be with the locking kit.

I want to avoid paying an excessive bill to someone who would ultimately not be doing it the way it should be done. Where I live (Luxembourg), such a bill would easily be in excess of 1000 pounds.
 

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Discussion Starter · #18 ·
The KV6 is a Rover K series family design, and has nothing whatsoever to do with Honda. You can try fitting KV6 cylinder heads on a Honda bottom end if you wish, but you will find they don't fit. The engines are not the same at all.

Honda and Rover had a licensing partnership from 1979, which grew into a formal joint development partnership in 1981. This agreement was terminated by Honda in 1994 when Rover Group was sold. Rover was owned at the time by British Aerospace, although the partnership with Honda had led to an agreement for Rover to take a 20% share in Honda, and Honda to take a 20% share in Rover. Honda never owned Rover, and when BAe had offered to sell them the whole company in the early 1990s, Honda offered to increase their shareholding, but not to take full ownership, which wasn't accepted by BAe, and Rover was subsequently sold to BMW. This was the point (and the reason) that Honda terminated the partnership agreement, and eventually sold their 20% stake in Rover to BMW.

The KV6 was developed after this, due to Honda firstly substantially increasing the price of the engines supplied to Rover, and then announcing that they would stop manufacturing it altogether in 1995 - thus the reason why the KV6 was developed. Honda had no part in its development, and neither was any Honda IP used.


That is pretty much it in a nutshell - Honda only ever owned 20% of Rover as part of the reciprocal ownership agreement that came about whilst the technical partnership was at its zenith.
That is what I thought as well.
Reverting back to the Kv6 cambelt topic, may I ask whether you have had any experience changing It? Reason I am asking is that I am unlikely to find a suitable garage where I live given that MGRs are all but gone here, so I figure they don‘t have the locking kit anyway nor will they be aware that it has 3 belts but the bill would undoubtedly be in excess of 1000 pounds for a job probably done in a risky fashion.
I foundthese online and wondered can a locking kit from china be trusted and how hard a change is with the right locking kit (assuming the engine is not lifted out).
 

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You might be able to rent the belt locking kit from someone on here Kv6 cam locking tool

If not, you could buy a new one off Ebay and sell it on here for the purchase price less what you saved on not renting one.
List it when you are finished and leave the advert open then the tool only moves on to the next user, this halves the risk
of transit damage.

There is probably more to it than that but the idea of a tool-pool for expensive but infrequent use tools has mileage.

I'm looking for a code reader for a KV6 ZS-180, that is what brought me back from the wilderness.
I need to find out what has upset the CEL and get it MOT'd, then maybe its Cam Belt time
 
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