Blacken Posted December 7, 2009 Share Posted December 7, 2009 I'm considering boosting my Roadsport 125 Sigma up to the full 150 via the conversion offered by Caterham. I would be getting the factory to perform the job but I was wondering if anyone out there has already had this performance mod done? How did it affect the character of your car and what are the pros and cons? My Roadsport is pretty standard i.e. 5 speed, ZV3s etc. I use it for touring and the odd blat (aren't they all?). I would appreciate any guidance. Link to comment Share on other sites More sharing options...
TobyCoulson Posted December 7, 2009 Share Posted December 7, 2009 It might be worth spending the money on CR500's and an LSD and then see if you want a power upgrade. C7JUG Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted December 8, 2009 Share Posted December 8, 2009 Definitely change the tyres before going any further Link to comment Share on other sites More sharing options...
mattobrien Posted December 8, 2009 Share Posted December 8, 2009 I changed from ZV3's to Yoko AO48's (they don't do CR500's in 14 inch wheels) - it was one of the best upgrades I had - the other thing worth doing (if you haven't done already) is to get the car flat floored and the suspension set up properly. Again this transformed the handling of my car. Link to comment Share on other sites More sharing options...
Pete-B Posted December 8, 2009 Share Posted December 8, 2009 Blacken, I had the conversion carried out after talking to James at Dartford. My car was the first one to be done, the update wasn't offered at that time and I suggested to James that if they did mine and used it as a guinea pig to get their pricing right it could then, perhaps, be offered to anyone else. But to answer your question I'm absolutely thrilled with mine, the extra BHP make a huge difference I always thought the 125 was a bit underwhelming. When I first had it done there were problems with the 150 with uneven running etc which I'm sure you must have read about, or could do, if you look through the archives, but that as now been sorted and she runs as sweet as a nut. I don't know what the present cost is and I'm sure there are people out there who would be cheaper but you have to weigh that against your book being stamped as a official Caterham update which would make a difference if you come to sell and also the CC guarantee. But if your'e happy with the price I would say go ahead I'm sure you won't regret it. Peter Link to comment Share on other sites More sharing options...
mecacy Posted December 8, 2009 Share Posted December 8, 2009 HI, i would have a word with DVA Dave Andrews,he would be the best chap to advise,his knowledge is free, and is non commital. phone 01908322652 Link to comment Share on other sites More sharing options...
Martin J Posted December 8, 2009 Share Posted December 8, 2009 Speaking from experience (ooops ) ditch the tyres in favour of some stickier rubber such as Yoko AO21's *thumbup* Have a look at the minister engines website as they do (or did) a 160hp upgrade for the 125 sigma that is probably better sorted than the caterham one & may even be cheaper as well Link to comment Share on other sites More sharing options...
Martin J Posted December 8, 2009 Share Posted December 8, 2009 160 hp sigma oooo 🥰 I could be tempted myself! Link to comment Share on other sites More sharing options...
TheManAlive Posted December 8, 2009 Share Posted December 8, 2009 Any ideas of the price to upgrade to the 160? Also, any recommendation on where to pick up tyres at a good price? What should I be paying for yoko a048s? Link to comment Share on other sites More sharing options...
jchasey Posted December 8, 2009 Share Posted December 8, 2009 I had the '160' Minister upgrade to my 125 but it only produced 130hp (by their measurements) and they have been unable to come up with a solution to hit the promised performance. It did improve things from the starting point (circa 100-109hp for Sigma 125s out of the box, again by their measurements) but a ways from where I'd like it to be! John Link to comment Share on other sites More sharing options...
Martin J Posted December 8, 2009 Share Posted December 8, 2009 That's interesting, but perhaps yours was just a "sick engine"? Blimey, 100to 109 hp isn't much more than the Ford 1.6 CVH was producing best part of 20 yrs ago Link to comment Share on other sites More sharing options...
jchasey Posted December 8, 2009 Share Posted December 8, 2009 The upper end of 100-109 was what 'normal' 125s were making. (Mine was towards the lower end ☹️ 102 to be specific) Measurements differ on different dyno-kit of course, but these were all numbers that Minister was measuring on their own kit. Link to comment Share on other sites More sharing options...
Martin J Posted December 8, 2009 Share Posted December 8, 2009 Running up on a dyno was that as measured at the rear wheels, what does that make the true power at the input to the gearbox ? Or does the rolling road allow for losses through the transmission? Link to comment Share on other sites More sharing options...
jchasey Posted December 8, 2009 Share Posted December 8, 2009 That's the wheel power figure. (Just checked annotation on output graph from the printout) For comparison they said that K-series 1.6 engines (our of the box) were about 115 I believe. John Link to comment Share on other sites More sharing options...
Martin J Posted December 8, 2009 Share Posted December 8, 2009 I've heard that people that race 7'sin the academy etc say that the stock sigma doesn't have the top end of the k series. I really like my 125 & think that it's a rugged & torquey engine. I don't plan to waste money upgrading the car or engine but in the (very) long term would like to upgrade to 175 duratec 7 🥰 Link to comment Share on other sites More sharing options...
TobyCoulson Posted December 8, 2009 Share Posted December 8, 2009 Martin can that easily be done or is it a very involved procedure? Link to comment Share on other sites More sharing options...
mic Posted December 8, 2009 Share Posted December 8, 2009 Its straight foward upgrade but probably expensive. Bellhousing and gear box input shaft will need changing also. Link to comment Share on other sites More sharing options...
Blacken Posted December 8, 2009 Author Share Posted December 8, 2009 Hi Guys, I do appreciate all the input. I spoke to Dom @ Caterham about the upgrade and he said that if I wanted more of a linear improvement ( i.e. for overtaking)then the power kit was the way forward. If I wanted to improve the cornering and general handling he recommended the move to 15" wheels with CR500 tyres plus the wider front track suspension upgrade. I gather with the CR500s, they do need warming up to get the best out of them gripwise. I took part in the "7 Wonders of Wales" blat in August and at times my car seemed to struggle to keep up with other Sevens particularly on the radical overtaking front. Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted December 8, 2009 Share Posted December 8, 2009 For more mid range torque, look at a 4-2-1 exhaust system too Link to comment Share on other sites More sharing options...
Blacken Posted December 9, 2009 Author Share Posted December 9, 2009 It's all beginning to look very expensive! Link to comment Share on other sites More sharing options...
TobyCoulson Posted December 9, 2009 Share Posted December 9, 2009 It comes down to that old scenario. How fast can I go? How much do you want to spend? I think the CR500 upgrade is a must before you do anything else though. Link to comment Share on other sites More sharing options...
Blacken Posted December 9, 2009 Author Share Posted December 9, 2009 Given that I don't do track days and I'm now on a 6K limited mileage, what is the durability of the CR500s compared with the current ZV3 tyres? I am still using the original set (18 months use) and they are in fine fettle - current mileage 6700 approx. 🤔 Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted December 9, 2009 Share Posted December 9, 2009 The ZV3 will last for ever, but not grip very well on such a light car ... especially in the wet, so life of the tyres or car may be suddenly shortened ! CR500 wear well if not used on track. We get around 8k rear and 15k front on a lardy SV with 160 bhp and spirited driving !! Link to comment Share on other sites More sharing options...
Blacken Posted December 9, 2009 Author Share Posted December 9, 2009 Thanks for the info Ian - much appreciated! Link to comment Share on other sites More sharing options...
Fishy Dave Posted December 9, 2009 Share Posted December 9, 2009 Your car doesn't seem short of power on the straights John. . You didn't tell me you had the 160 upgrade Dave David Smitheram, Wiltshire (South) AR, 07718 368173. 1400 supersport race car Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now