K series vs Sigma
Discussion
Yet another question, sorry.
I'm looking at buying a 1.6 roadsport but torn between the k series and the sigma, have driven both and the sigma feels a little more torquey but stretches the budget further.
For a mostly road car with a few track days and the odd hill climb and sprint which engine would I be better off with?
I'm looking at buying a 1.6 roadsport but torn between the k series and the sigma, have driven both and the sigma feels a little more torquey but stretches the budget further.
For a mostly road car with a few track days and the odd hill climb and sprint which engine would I be better off with?
Obviously a 120 k ex race would be cheaper than a 125 Sigma ex race Car, you can upgrade the 125 sigma to 145 Supersport spec for about 4k...a k series to 138 superlight spec would be a little cheaper but the 145 Supersport would be more capable!.... Stiffer chassis, more torque and a little more power, track spec dampers, Supersport is very stiff and very kart like.....if you can afford the Sigma go for it.....the k's are fine but I always found the coil packs breaking down were a pain, I had head gasket failures too... Not an peak of trouble with my Sigma Super sport in 3 years, very cheap to run!.
Edited by StEVEN7 on Sunday 2nd August 23:50
Obviously a 120 k ex race would be cheaper than a 125 Sigma ex race Car, you can upgrade the 125 sigma to 145 Supersport spec for about 4k...a k series to 138 superlight spec would be a little cheaper but the 145 Supersport would be more capable!.... Stiffer chassis, more torque and a little more power, track spec dampers, Supersport is very stiff and very kart like.....if you can afford the Sigma go for it.....the k's are fine but I always found the coil packs breaking down were a pain, I had head gasket failures too... Not an peak of trouble with my Sigma Super sport in 3 years, very cheap to run!.
Edited by StEVEN7 on Sunday 2nd August 23:51
I've just made the switch from a K -Series to a Sigma and, whilst the K was brilliant, I much prefer the way the Sigma drives.
It feels more sure footed (that could be its just better set up!) and the power feels much more linear.
I'm not sure how but the Sigma car feels more solid when you're driving it - I'm sure its not but that's the impression.
The hydraulic clutch is nice too!
It feels more sure footed (that could be its just better set up!) and the power feels much more linear.
I'm not sure how but the Sigma car feels more solid when you're driving it - I'm sure its not but that's the impression.
The hydraulic clutch is nice too!
I agree with what has been said above, but then I would as I have had a 125 sigma for 8 years. 
re the comment on the hydraulic clutch above, it is very light & smooth but a pain if it gives trouble compared to a cable opperated one as the slave cylinder is inside the bell housing.
re the comment on the hydraulic clutch above, it is very light & smooth but a pain if it gives trouble compared to a cable opperated one as the slave cylinder is inside the bell housing.
Edited by K800 RUM on Monday 3rd August 19:52
I've owned my 125 Sigma for the past 4 years and I have nothing but praise for it. My main use for the car is track days and it has been totally reliable and has never let me down.
I think its a great engine and combined with the 7 it manages to embarrass much more powerful and expensive machinery.
I think its a great engine and combined with the 7 it manages to embarrass much more powerful and expensive machinery.
I've had a Sigma 140 for 3 years and I love it.
It's just as fun on track as it is on the road and if you're driving it properly you'll find you're faster than nearly everything.
Servicing and running costs have been very reasonable. The only expense has been the cambelt change and fixing some cosmetic issues the previous owner didn't bother with!
It's just as fun on track as it is on the road and if you're driving it properly you'll find you're faster than nearly everything.
Servicing and running costs have been very reasonable. The only expense has been the cambelt change and fixing some cosmetic issues the previous owner didn't bother with!
I'm a K series (race car) owner, but would probably buy a Sigma if I could stretch to it. The Sigma will be metric whereas the K series - almost certainly - imperial. That's not a problem but it is nice to have the 'newer' one.
Having said that a 120bhp K series is slightly faster round a circuit than a 125bhp Sigma by 1-2 seconds/lap.
Having said that a 120bhp K series is slightly faster round a circuit than a 125bhp Sigma by 1-2 seconds/lap.
ghibbett said:
Hi Andy,
What is the cambelt change frequency?
As KRL said it's every 6 years. My car was 4 years old when I bought it so it was done along with the 2nd service and MOT.What is the cambelt change frequency?
Plans for this winter are an aeroscreen and getting it corner weighted.
In 140 tune it's an absolute joy to drive. Lots of top end but still plenty of grunt lower down when you aren't on it (or when the other half is driving!).
, still have 3 years on mine then 
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