Nigel Adams Posted November 16, 2022 Share Posted November 16, 2022 I have a 2013 Series 3 Roadsport 125 which I bought a year ago, mainly for road use although I did break my track day virginity at Snetterton last Spring. I have decided to upgrade the Sigma 1.6L engine to the 310R spec with new cam shafts, remap and lightened flywheel plus other tweaks to get to 152BHP. The goal is to get the most welly/fun from the car that the engine allows. Caterham dealer Krazy Horse are doing this - I bought the car from them and they were excellent (Ian Beddis is great BTW). At the moment I have decided not to go for the Limited Slip Diff as I'm not sure about it reading other posts on here and thought I'd see what I feel about the changes as can always add later. Also, it has 185/60/R14 alloys which I'm very happy with but the Avon tyres I have are no longer in production. The 310 runs on Orcus 6x15" with the Avon ZT7 195/50/R15 tyres (I believe) so I may get a set of those too, but again will wait to see how it runs first. I'm guessing the wider tyres and more track focussed tyre will improve grip still further with greater bhp though no issues at the current power output. Any views from members would be helpful. Link to comment Share on other sites More sharing options...
Tom_Arundel Posted November 16, 2022 Share Posted November 16, 2022 Going by the date, isn`t yours a fixed cam engine? It is probably not necessary to go wider on tyres, I`m considering going narrower on the front next time! Has it got adjustable suspension spring platforms? Supersport had different valve springs, retainers, belt tensioner bits, oil catch tank, battery position, air intake etc.. Caterham will reflash the ECU for you. It`s worth getting the head ported (8-10 bhp) (or DIY!) I`ve got a spare pair of non-variable cams......where are you? Link to comment Share on other sites More sharing options...
Nigel Adams Posted November 16, 2022 Author Share Posted November 16, 2022 It's a standard Roadsport 125 with Sigma 1.6L engine so suspension not adjustable. The upgrade basically makes the engine the same as the 310R as I understand it - all the bits on the Caterham Parts website. Thanks for thoughts on tyres. Thinking I will stick for now and see how it goes as not really an issue. I'm in Hertford. Link to comment Share on other sites More sharing options...
StevehS3 Posted November 16, 2022 Share Posted November 16, 2022 Unless you particularly like the style/size of another wheel, personally I would get some R888R tyres for your 14" wheels, fit an adjustable platform kit to the dampers and get it properly setup by a professional. Link to comment Share on other sites More sharing options...
Nigel Adams Posted November 16, 2022 Author Share Posted November 16, 2022 Thanks Steve, I hadn't thought of that. A good solution and will save me a heap of money too. The Avon tyres I have are probably getting to the end of their lives anyway and they don't do them anymore. Link to comment Share on other sites More sharing options...
simon_h Posted November 16, 2022 Share Posted November 16, 2022 Depends if your engine is a VVT one or not as to whether they can make it the same as a 310. If its fixed cam you can get to supersport spec with cams and the other required parts and then multi throttles get it towards 150 but it wont be 310 spec. Link to comment Share on other sites More sharing options...
ptr_drvr Posted November 16, 2022 Share Posted November 16, 2022 Remember, lots of power on narrow, not-super-sticky rubber will produce more fun than the inverse.Depends on if you're planning to use the car all winter, and/or if you're going to be doing lots of trackdays. Then changing the wheels & tyres accordingly would make sense. Link to comment Share on other sites More sharing options...
Nigel Adams Posted November 16, 2022 Author Share Posted November 16, 2022 Thanks Simon, it is definitely the 310 upgrade they are going for with new camshaft, race plugs, air filter plus the lighter flywheel.. Link to comment Share on other sites More sharing options...
Nigel Adams Posted November 16, 2022 Author Share Posted November 16, 2022 Thanks Pete, good points. I think I'm going to see how it handles with the extra power and go from there. Link to comment Share on other sites More sharing options...
Phil Six 7 Posted November 16, 2022 Share Posted November 16, 2022 Hi Nigel,Good luck with the upgrade, I'm sure you will enjoy it. I see you are in Hertford, I'm not far in Bishops Stortford and bought my car from Ian at Krazy Horse too. As you say, really excellent service and very helpful, hopefully a good place for the club to meet next year. Link to comment Share on other sites More sharing options...
K7 VCT Posted November 16, 2022 Share Posted November 16, 2022 The 310 upgrade is only for the Ti-vct engines from late 2013 onwards. Easy way to tell is are there wires going to solenoids on the corners of the camcover ?If not you can't have the 310 152bhp upgrade. It will be a 140 bhp supersport one. Link to comment Share on other sites More sharing options...
Tom_Arundel Posted November 16, 2022 Share Posted November 16, 2022 As a matter of interest....For road use my `140` fixed cam (146bhp) goes better on the Ford plastic manifold. I have throttle bodies for track use, they add about 7bhp (153bhp) right at the top (7K+) but knock a hole (-11%) in the torque curve just where you need it(4k-5k) for road use. I did my own `head job` which took it up to 135bhp on standard cams, then air box, ECU and SS cams did the rest.......Head job is best first step on engine.Adjustable spring platforms improve the handling. Link to comment Share on other sites More sharing options...
Tom_Arundel Posted November 16, 2022 Share Posted November 16, 2022 As a matter of interest....For road use my `140` fixed cam (146bhp) goes better on the Ford plastic manifold. I have throttle bodies for track use, they add about 7bhp (153bhp) right at the top (7K+) but knock a hole (-11%) in the torque curve just where you need it(4k-5k) for road use. I did my own `head job` which took it up to 135bhp on standard cams, then air box, ECU and SS cams did the rest.......Head job is best first step on engine.Adjustable spring platforms to improve the handling. Link to comment Share on other sites More sharing options...
7_Malc Posted November 16, 2022 Share Posted November 16, 2022 The 14" wheels you have are a great choice for the road, and will be good on track too.13", without adjustable suspension would lower your ride height by around 10mm, while the 15" wheels need shallower profile tyres which lack the compliance that helps the seven ride so well on the 'average' British B road. Stick with the 14s for now, and get a set of Toyo R888Rs. You can add a second set of wheels and tyres later if you want to try some alternatives. Link to comment Share on other sites More sharing options...
Nigel Adams Posted November 17, 2022 Author Share Posted November 17, 2022 Good point K7 VCT, yor are correct. My engine is the version that can be upgraded to 310 spec. Link to comment Share on other sites More sharing options...
Nigel Adams Posted November 17, 2022 Author Share Posted November 17, 2022 Thanks Malc, good advice which I will follow. Link to comment Share on other sites More sharing options...
Nigel Adams Posted November 17, 2022 Author Share Posted November 17, 2022 Thanks for the info Tom! Link to comment Share on other sites More sharing options...
ptr_drvr Posted November 17, 2022 Share Posted November 17, 2022 Make sure you come back and let us all know how you get on (please )! And what the car is like with the power increase! Link to comment Share on other sites More sharing options...
DanRo Posted November 17, 2022 Share Posted November 17, 2022 Hi NigelMine is a K series so can't help with engine info but on the tyre side, earlier this year I went from 140 to 190bhp. I decided to keep the 185/60/13s all round to see how I would get on, as I loved the balance with that set up. Having spent all summer driving it like that, I have no plans to go for wider tyres. Having to be more considered with my right foot has made driving more interesting. I haven't had any traction issues, although I have been careful on greasy roads. Good luck with the mods. Sounds very exciting. Link to comment Share on other sites More sharing options...
Nigel Adams Posted November 17, 2022 Author Share Posted November 17, 2022 Thanks Dan, sound advice. Looks like I'll stick with the tyres and see how it goes! Link to comment Share on other sites More sharing options...
Nigel Adams Posted November 17, 2022 Author Share Posted November 17, 2022 I will do! Link to comment Share on other sites More sharing options...
Nigel Adams Posted November 18, 2022 Author Share Posted November 18, 2022 Thanks Dan, good advice - plus I have had no issues with the wheels/tyres so far. Link to comment Share on other sites More sharing options...
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