K series superlight or 1.6 Sigma roadsport
Discussion
Hi all, I'm looking to purchase my first Caterham and want to spend around 20-25K. I've been down to my local dealer and seen a k series superlight for under 20k, it does seem though to have had a lot of work done to it (spec below) :
1.6 Caterham Superlight No.128
Rebuilt and uprated engine (2007) Producing In The Region Of 200bhp
Performance Cylinder Head
Emerald K3 ECU
Jenvey Throttle Bodies
Uprated Heavy Duty Clutch
Lightened Flywheel
Limited Slip Differential
De Dion Rear Axle
6 Speed Manual Transmission
Porsche Riviera Blue Paint
Lowered Drivers Floor
Carbon Fibre Front Wings
R500 6″ Front & 8″ Rear Wheels
Wide Track Suspension
Adjustable Platform Dampers
Track Day Roll Bar
After having heard numerous people complain about the k series reliability issues, how reliable is the above car going to be? Is 200 BHP even possible or are they over estimating ?
My other option would be to buy a 1.6 Sigma roadsport and then get a few upgrades done when I have some more free cash.
I'm mainly looking to use the car on the road with a few track days thrown in and want something reliable.
Any advice would be appreciated.
Thanks
1.6 Caterham Superlight No.128
Rebuilt and uprated engine (2007) Producing In The Region Of 200bhp
Performance Cylinder Head
Emerald K3 ECU
Jenvey Throttle Bodies
Uprated Heavy Duty Clutch
Lightened Flywheel
Limited Slip Differential
De Dion Rear Axle
6 Speed Manual Transmission
Porsche Riviera Blue Paint
Lowered Drivers Floor
Carbon Fibre Front Wings
R500 6″ Front & 8″ Rear Wheels
Wide Track Suspension
Adjustable Platform Dampers
Track Day Roll Bar
After having heard numerous people complain about the k series reliability issues, how reliable is the above car going to be? Is 200 BHP even possible or are they over estimating ?
My other option would be to buy a 1.6 Sigma roadsport and then get a few upgrades done when I have some more free cash.
I'm mainly looking to use the car on the road with a few track days thrown in and want something reliable.
Any advice would be appreciated.
Thanks
Hi Yoyoman,
I’m pretty new to Caterham ownership myself but went through the same dilemma as you very recently. My intention was to spend about £20-23k on a nice low mileage car to keep for ever. What did I end up doing? Spending nearly £28k (£3k of that because of needing an SV with lowered floors) on a year old one!
My concern with more affordable cars was not just the mileage but the physical age too.
The superlight you are looking at seems nice but it’s 20 years old.
I do have one mate who had two superlight R’s (197 bhp K series)over a twenty year period and goodness knows he trashed them on the road and track but he did have to do three (if I remember correctly) head gasket replacements during that time. I think it was something to do with the cylinder liners not being installed at the correct depth in the bore which seems to be critical.
If you don’t mind having that done every so often then go for it.
My concern would be the highly tuned nature of the car, I believe (from this and other forums) that the K series is arguably the very best loved engine for the Caterham as long as it is kept relatively standard tune.
I’m sure it sounds a bit dull but I decided to buy the latest generation 1.6 sigma in 135 bhp form, it’s almost as light and revvy as the K series, upgradable simply at Caterham themselves to 152hp and above all else, still in production.
Hopefully you’ll get many more more experienced replies than mine before you make your decision but that’s my tuppence worth. Have fun in your quest!
I’m pretty new to Caterham ownership myself but went through the same dilemma as you very recently. My intention was to spend about £20-23k on a nice low mileage car to keep for ever. What did I end up doing? Spending nearly £28k (£3k of that because of needing an SV with lowered floors) on a year old one!
My concern with more affordable cars was not just the mileage but the physical age too.
The superlight you are looking at seems nice but it’s 20 years old.
I do have one mate who had two superlight R’s (197 bhp K series)over a twenty year period and goodness knows he trashed them on the road and track but he did have to do three (if I remember correctly) head gasket replacements during that time. I think it was something to do with the cylinder liners not being installed at the correct depth in the bore which seems to be critical.
If you don’t mind having that done every so often then go for it.
My concern would be the highly tuned nature of the car, I believe (from this and other forums) that the K series is arguably the very best loved engine for the Caterham as long as it is kept relatively standard tune.
I’m sure it sounds a bit dull but I decided to buy the latest generation 1.6 sigma in 135 bhp form, it’s almost as light and revvy as the K series, upgradable simply at Caterham themselves to 152hp and above all else, still in production.
Hopefully you’ll get many more more experienced replies than mine before you make your decision but that’s my tuppence worth. Have fun in your quest!
Edited by Spency747 on Saturday 14th March 11:52
K series liners arent always the best, and waterpumps leak very slowly contributing to HG failure.
There is a thread on herer with a chap building a k series turbo in which he details all the weak points and how to address them.
If you want to build it before you drive it a K series is a good way to go, if you just want to fit the engine and drive it then a sigma is probably going to give you less headaches re reliability.
personal preference rules the day, but a well sorted K series is a joyful thing to thrash about in.
There is a thread on herer with a chap building a k series turbo in which he details all the weak points and how to address them.
If you want to build it before you drive it a K series is a good way to go, if you just want to fit the engine and drive it then a sigma is probably going to give you less headaches re reliability.
personal preference rules the day, but a well sorted K series is a joyful thing to thrash about in.
I love the k-series, but being out of caterhams for a (long) while, I've not driven a Sigma to compare.
Regarding the spec of that k-series, there is no way on earth that a 1.6k produces 200 bhp. It'd have to be a very serious motor indeed and you'd not want it I suspect. Far too highly strung. It could be an 1.8 which would make more sense.
The rest of the spec looks good. There was a delightful balance of the original 1600 superlight especially on ACB10s. That might be lost with the 8" wheels on the back. Depends on the actual power of the motor.
You'd need to buy on condition and if the motor has been rebuilt then the provenance of the engine builder. There is always a chance of HG failure, it's just one of those things. People say warm them up properly and change the oil frequently and you'll be fine. That's tosh. Obviously if you don't do that you are not helping yourself, but it's not really the cause. A properly rebuilt one could well be ok. I've had 4 HGs go between my caterhams and my rover 25.
I'd be happy to go again with a k, but would be very interested in knowing it was rebuilt by a proper person in a proper way (Dave Andrews for example).
Bert
Regarding the spec of that k-series, there is no way on earth that a 1.6k produces 200 bhp. It'd have to be a very serious motor indeed and you'd not want it I suspect. Far too highly strung. It could be an 1.8 which would make more sense.
The rest of the spec looks good. There was a delightful balance of the original 1600 superlight especially on ACB10s. That might be lost with the 8" wheels on the back. Depends on the actual power of the motor.
You'd need to buy on condition and if the motor has been rebuilt then the provenance of the engine builder. There is always a chance of HG failure, it's just one of those things. People say warm them up properly and change the oil frequently and you'll be fine. That's tosh. Obviously if you don't do that you are not helping yourself, but it's not really the cause. A properly rebuilt one could well be ok. I've had 4 HGs go between my caterhams and my rover 25.
I'd be happy to go again with a k, but would be very interested in knowing it was rebuilt by a proper person in a proper way (Dave Andrews for example).
Bert
I had an original superlight from new (car no 3 which was their NEC showcar) and it was a superb handling car and the ACB 10’s are fab apart from the tramlining (but not a big deal for me)
I kind of regret selling that car but that is because I still think of it the sense of what it was at the time and being original. Therefore when looking at the spec of the superlight you are considering it’s not an original spec car in lots of ways so you need to decide if you are comfortable with that.
Going back to my original superlight, whilst it was really quick in the sense that the lack of weight combined with the grip generated by the ACB 10’s made it fab, it did lack a bit of outright grunt.
Ultimately I sold the car to go Karting and returned to Caterham 16 years later with a two year old sigma supersport, whilst this was not quite as good as the superlight because it had a 5 speed box and less carbon items, the engine has a bit more torque than the k series and works really well. IMO the lower powered cars work better with the 6 speed box, but don’t be put off by the sigma because it’s a cracking motor but try and get one with a 6 speed box
The other option is try and get your hands on a Superlight twenty which are based on the original superlight albeit with a sigma engine, 6 speed and lots of carbon and represent good value in CATERHAM terms.
A friend of mine has one and loves it.
I kind of regret selling that car but that is because I still think of it the sense of what it was at the time and being original. Therefore when looking at the spec of the superlight you are considering it’s not an original spec car in lots of ways so you need to decide if you are comfortable with that.
Going back to my original superlight, whilst it was really quick in the sense that the lack of weight combined with the grip generated by the ACB 10’s made it fab, it did lack a bit of outright grunt.
Ultimately I sold the car to go Karting and returned to Caterham 16 years later with a two year old sigma supersport, whilst this was not quite as good as the superlight because it had a 5 speed box and less carbon items, the engine has a bit more torque than the k series and works really well. IMO the lower powered cars work better with the 6 speed box, but don’t be put off by the sigma because it’s a cracking motor but try and get one with a 6 speed box
The other option is try and get your hands on a Superlight twenty which are based on the original superlight albeit with a sigma engine, 6 speed and lots of carbon and represent good value in CATERHAM terms.
A friend of mine has one and loves it.
The Orig Fergie said:
I kind of regret selling that car but that is because I still think of it the sense of what it was at the time and being original. Therefore when looking at the spec of the superlight you are considering it’s not an original spec car in lots of ways so you need to decide if you are comfortable with that.
That's a very good point. Whilst there is a huge urge to upgrade, in many cases the standard cars work really well as a balanced package. That's not to say they always got it right, but they certainly did with the original superlight. So with a modded car, you have to be sure that the package works well for what you want. I personally quite like the lower powered caterhams with not too much grip. Others like the super-ballistic duranail cars. Each to their own.To the OP, you need to drive and see what works for you!
Bert
BertBert said:
I love the k-series, but being out of caterhams for a (long) while, I've not driven a Sigma to compare.
Regarding the spec of that k-series, there is no way on earth that a 1.6k produces 200 bhp. It'd have to be a very serious motor indeed and you'd not want it I suspect. Far too highly strung. It could be an 1.8 which would make more sense.
The rest of the spec looks good. There was a delightful balance of the original 1600 superlight especially on ACB10s. That might be lost with the 8" wheels on the back. Depends on the actual power of the motor.
You'd need to buy on condition and if the motor has been rebuilt then the provenance of the engine builder. There is always a chance of HG failure, it's just one of those things. People say warm them up properly and change the oil frequently and you'll be fine. That's tosh. Obviously if you don't do that you are not helping yourself, but it's not really the cause. A properly rebuilt one could well be ok. I've had 4 HGs go between my caterhams and my rover 25.
I'd be happy to go again with a k, but would be very interested in knowing it was rebuilt by a proper person in a proper way (Dave Andrews for example).
Bert
With respect, I have built over 50 1600K series engines that have produced over 200HP, the most powerful was 232BHP. That said an engine of that output will need to be built sympathetically and with knowledge of the inherent weaknesses of the K series, if these are addressed correctly then there is no reason that an engine of that spec. should not be reliable.Regarding the spec of that k-series, there is no way on earth that a 1.6k produces 200 bhp. It'd have to be a very serious motor indeed and you'd not want it I suspect. Far too highly strung. It could be an 1.8 which would make more sense.
The rest of the spec looks good. There was a delightful balance of the original 1600 superlight especially on ACB10s. That might be lost with the 8" wheels on the back. Depends on the actual power of the motor.
You'd need to buy on condition and if the motor has been rebuilt then the provenance of the engine builder. There is always a chance of HG failure, it's just one of those things. People say warm them up properly and change the oil frequently and you'll be fine. That's tosh. Obviously if you don't do that you are not helping yourself, but it's not really the cause. A properly rebuilt one could well be ok. I've had 4 HGs go between my caterhams and my rover 25.
I'd be happy to go again with a k, but would be very interested in knowing it was rebuilt by a proper person in a proper way (Dave Andrews for example).
Bert
If the reason(s) for head gasket failure are properly understood and corrected then there is no reason why the head gasket should fail. Proper preparation and assembly is key.
As suggested I would research the provenance of the engine, it is one of mine and you know who commissioned the upgrade I may be able to furnish you with further details.
Dave
DVandrews said:
With respect, I have built over 50 1600K series engines that have produced over 200HP, the most powerful was 232BHP.
Dave
In which case I stand corrected Dave
In the general case, and regarding this car, I would be very careful about claims of high horsepower and take them with a pinch of salt. However if it checks out as being done properly by a proper person, that's a different matter.
Out of interest, what has to be done to get 232bhp from a 1600k? Carmichael went to some lengths to get his monster 1800 strong enough.
Bert
The spec was..
bottom end - steel rods, Omega pistons, ductile liners, lightweight flywheel.
Head— VVC with 32.5/28.5 valves, same spec as I did for Peter, 2180/1444 cams (hotter than Peters),, Jenvey 45mm DTH TBs, unequal length trumpets, 4-2-1 long manifold, Emerald ECU.
Similar specs gave 264 on an 1800 and 286 on a 1900.
Dave
bottom end - steel rods, Omega pistons, ductile liners, lightweight flywheel.
Head— VVC with 32.5/28.5 valves, same spec as I did for Peter, 2180/1444 cams (hotter than Peters),, Jenvey 45mm DTH TBs, unequal length trumpets, 4-2-1 long manifold, Emerald ECU.
Similar specs gave 264 on an 1800 and 286 on a 1900.
Dave
Edited by DVandrews on Monday 16th March 11:00
I love my K-Series. The noise and the way it zings round to the 7,500rpm red line gives it a character that just isn’t there with the sigma engines cars (haven’t tried the duratec). As a race car the engine has been super reliable and only ever rebuilt to re-shim the valves (trying to squeeze a few extra horse power out).
I’m selling now (*cough* see classifieds *cough*) only because the regulations have changed and the sigma has an advantage (cams can be timed on the sigma but not the k-series). If everything was equal I’d chose the k-series every time.
I’m selling now (*cough* see classifieds *cough*) only because the regulations have changed and the sigma has an advantage (cams can be timed on the sigma but not the k-series). If everything was equal I’d chose the k-series every time.
- please note, as per government advice, I did cough into a tissue and threw it in the bin.
Vimes said:
I love my K-Series. The noise and the way it zings round to the 7,500rpm red line gives it a character that just isn’t there with the sigma engines cars (haven’t tried the duratec). As a race car the engine has been super reliable and only ever rebuilt to re-shim the valves (trying to squeeze a few extra horse power out).
I’m selling now (*cough* see classifieds *cough*) only because the regulations have changed and the sigma has an advantage (cams can be timed on the sigma but not the k-series). If everything was equal I’d chose the k-series every time.
Just race the K series in CSCC Mag 7s! ;-)I’m selling now (*cough* see classifieds *cough*) only because the regulations have changed and the sigma has an advantage (cams can be timed on the sigma but not the k-series). If everything was equal I’d chose the k-series every time.
- please note, as per government advice, I did cough into a tissue and threw it in the bin.
From a different perspective, I built a Sigma 125 Roadsport S3 in 2011, I do the odd trackday, but just for fun and I wouldn't describe myself as a particularly fast driver. The standard sigma engine is brilliant for B road use, there is a good spread of torque and it is easily quick enough up to 80 to be great fun. The tuned versions will be much quicker on track at the top end, but I haven't upgraded as the chance to wring the engine out to even 6500rpm on the road isn't that common in the South East. With modest 185 Rain Expert tyres it makes a very well balance fun Seven that isn't constantly trying to bite you if the weather turns bad 
Thank you all for your feedback.
I think I will probably go with a sigma engine.
Whilst a k series is tempting, I haven’t got the knowledge to change head gaskets and don’t want the worry of one going on me. Or maybe I should hang on a few months to increase my budget and get into a Duratec 🤤
I think I will probably go with a sigma engine.
Whilst a k series is tempting, I haven’t got the knowledge to change head gaskets and don’t want the worry of one going on me. Or maybe I should hang on a few months to increase my budget and get into a Duratec 🤤
Glug69 said:
Vimes said:
I love my K-Series. The noise and the way it zings round to the 7,500rpm red line gives it a character that just isn’t there with the sigma engines cars
The Sigma 150 revs to 7500rpm and the sound from the throttle bodies is fantastic??Yoyoman said:
Thank you all for your feedback.
I think I will probably go with a sigma engine.
Whilst a k series is tempting, I haven’t got the knowledge to change head gaskets and don’t want the worry of one going on me. Or maybe I should hang on a few months to increase my budget and get into a Duratec ??
Why would you need to know how to change the head gasket on the k-series in order to own one? it's not a job you'll be doing every weekend... I think I will probably go with a sigma engine.
Whilst a k series is tempting, I haven’t got the knowledge to change head gaskets and don’t want the worry of one going on me. Or maybe I should hang on a few months to increase my budget and get into a Duratec ??
The Ford engines are brawny but as Vimes says, I'd take a k-series. There's a big difference in the power delivery and noise which just makes the k-series a perfect match for the Caterham.
HustleRussell said:
Glug69 said:
Vimes said:
I love my K-Series. The noise and the way it zings round to the 7,500rpm red line gives it a character that just isn’t there with the sigma engines cars
The Sigma 150 revs to 7500rpm and the sound from the throttle bodies is fantastic??That's your opinion, however I don't agree😁 I've never seen a K series owner any happier with there car than I am with mine, but I have heard nearly every one of them worrying about the head gasket, pretty sure a sigma powered car is more reliable and doesn't need to be treated with kid gloves like the K does.
Why would you need to know how to change the head gasket on the k-series in order to own one? it's not a job you'll be doing every weekend...
Probably because they have a reputation for head gasket failures if you don't spend 15 minutes warming them up😉
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