Sigma race cars advice
Discussion
I'm looking to buy my first Caterham for sprinting and occasional track day. Because of the class structure, I'm set on a 1.6 Sigma rather than a 2.0 Duratec. The cars I'm looking at are all race cars that can be returned to being road legal, as most of the Academy originating cars seem to be.
There seems to be a significant price difference between a 310R (152bhp - £18k) race car and a RoadSport/Sigmax (140bhp - £14k) and the difference would go some way towards starting down the PremierPower Engine upgrade path.
The Roadsport cars have the fixed cam Sigma engines whereas the 310R has the TI-VCT engine. Does it matter too much when tuned up? It appears that Premier Power recommend the Life ECU for the TI-VCT engine and that significantly increases the price of those upgrades. Ultimate, they all seem to get the same power so I'm thinking it doesn't really matter.
Your thoughts and advice gratefully received.
There seems to be a significant price difference between a 310R (152bhp - £18k) race car and a RoadSport/Sigmax (140bhp - £14k) and the difference would go some way towards starting down the PremierPower Engine upgrade path.
The Roadsport cars have the fixed cam Sigma engines whereas the 310R has the TI-VCT engine. Does it matter too much when tuned up? It appears that Premier Power recommend the Life ECU for the TI-VCT engine and that significantly increases the price of those upgrades. Ultimate, they all seem to get the same power so I'm thinking it doesn't really matter.
Your thoughts and advice gratefully received.
The 310R is the later car and a current model. You can still take it racing in the official Caterham Motorsport series. It has the Mazda gearbox and BMW diff.
The Sigmax is an old spec. It has the old Ford gearbox. Many were built with the old Ford Sierra diff too, the change to BMW diff occurred around 2012/13 iirc.
310r race against Sigmax in the Grads club and there isn’t a great deal to choose between them on pace. The Mazda gearbox does not provide a better shift or better reliability than the Ford one.
I don’t know much about tuning but the fixed cam engine as fitted to the Sigmax is a bit of a ‘Caterham engineering solution’ while the VCT is pretty much as it comes out of the crate. By this I mean, I’ve spent several days trying unsuccessfully to source a timing belt tensioner for a Sigmax, while I would guess with a VCT Ford could have one with you this afternoon.
Personally, in your shoes, I’d buy a good example of the early Sigmax Ford / Ford / Ford. They are cheap and plentiful. The Ford gearbox is ubiquitous. The Titan / Sierra diff is well understood and is a lighter and better installation than the BMW one. The chassis and suspension is the same as the current car in terms of performance (Subtle differences depending on gearbox / diff fitted).
The Sigmax is an old spec. It has the old Ford gearbox. Many were built with the old Ford Sierra diff too, the change to BMW diff occurred around 2012/13 iirc.
310r race against Sigmax in the Grads club and there isn’t a great deal to choose between them on pace. The Mazda gearbox does not provide a better shift or better reliability than the Ford one.
I don’t know much about tuning but the fixed cam engine as fitted to the Sigmax is a bit of a ‘Caterham engineering solution’ while the VCT is pretty much as it comes out of the crate. By this I mean, I’ve spent several days trying unsuccessfully to source a timing belt tensioner for a Sigmax, while I would guess with a VCT Ford could have one with you this afternoon.
Personally, in your shoes, I’d buy a good example of the early Sigmax Ford / Ford / Ford. They are cheap and plentiful. The Ford gearbox is ubiquitous. The Titan / Sierra diff is well understood and is a lighter and better installation than the BMW one. The chassis and suspension is the same as the current car in terms of performance (Subtle differences depending on gearbox / diff fitted).
HustleRussell said:
The 310R is the later car and a current model. You can still take it racing in the official Caterham Motorsport series. It has the Mazda gearbox and BMW diff.
The Sigmax is an old spec. It has the old Ford gearbox. Many were built with the old Ford Sierra diff too, the change to BMW diff occurred around 2012/13 iirc.
310r race against Sigmax in the Grads club and there isn’t a great deal to choose between them on pace. The Mazda gearbox does not provide a better shift or better reliability than the Ford one.
I don’t know much about tuning but the fixed cam engine as fitted to the Sigmax is a bit of a ‘Caterham engineering solution’ while the VCT is pretty much as it comes out of the crate. By this I mean, I’ve spent several days trying unsuccessfully to source a timing belt tensioner for a Sigmax, while I would guess with a VCT Ford could have one with you this afternoon.
Personally, in your shoes, I’d buy a good example of the early Sigmax Ford / Ford / Ford. They are cheap and plentiful. The Ford gearbox is ubiquitous. The Titan / Sierra diff is well understood and is a lighter and better installation than the BMW one. The chassis and suspension is the same as the current car in terms of performance (Subtle differences depending on gearbox / diff fitted).
This sounds like great advice, thank you. I hadn't even considered that they might use a different gearbox or diff so that's useful to know. Out of interest, why did they change to the Mazda/BMW combo? Availability of new parts, I would assume?The Sigmax is an old spec. It has the old Ford gearbox. Many were built with the old Ford Sierra diff too, the change to BMW diff occurred around 2012/13 iirc.
310r race against Sigmax in the Grads club and there isn’t a great deal to choose between them on pace. The Mazda gearbox does not provide a better shift or better reliability than the Ford one.
I don’t know much about tuning but the fixed cam engine as fitted to the Sigmax is a bit of a ‘Caterham engineering solution’ while the VCT is pretty much as it comes out of the crate. By this I mean, I’ve spent several days trying unsuccessfully to source a timing belt tensioner for a Sigmax, while I would guess with a VCT Ford could have one with you this afternoon.
Personally, in your shoes, I’d buy a good example of the early Sigmax Ford / Ford / Ford. They are cheap and plentiful. The Ford gearbox is ubiquitous. The Titan / Sierra diff is well understood and is a lighter and better installation than the BMW one. The chassis and suspension is the same as the current car in terms of performance (Subtle differences depending on gearbox / diff fitted).
I don't think sourcing parts for these units is a problem on an individual basis, however 'Type 9' gearboxes and Sierra differential units have been out of production for a long time. I imagine it was getting difficult to source scores of exchange gearbox and differential units every year at a reasonable price. Maybe it was getting tough to find internal parts to refurbish them too. Must've reached the tipping point where striking a deal with Mazda and BMW to supply new units was cheaper.
Matt W said:
That's true if you're comparing a Roadsport with a 310R. However, a Sigmax (also known as Supersport when Caterham ran a championship for the older spec cars) will have the LSD, wide track and uprated springs and dampers, just like the 310R.
That's exactly my understanding. From what I can tell, the differences are:Sigmax - 140bhp 'fixed cam' Sigma, Ford diff/gearbox
310R - 152bhp 'variable cam' Sigma, BMW diff, Mazda gearbox
I think the Sigmax variant suits my needs better as I have plans to upgrade with Premier Power engines.
Turn7 said:
From PP I don’t think there’s much choice .
My car has the Caterham 150 kit (cams and tb’s) which maybe a cheaper option.
I spent some time with Stuart at PP on Saturday at his new location near Leamington Spa. Worth speaking to him about what he can offer if considering an upgrade, many options not on his web site yet and not all about ultimate power.My car has the Caterham 150 kit (cams and tb’s) which maybe a cheaper option.
Instant Replay said:
Turn7 said:
From PP I don’t think there’s much choice .
My car has the Caterham 150 kit (cams and tb’s) which maybe a cheaper option.
I spent some time with Stuart at PP on Saturday at his new location near Leamington Spa. Worth speaking to him about what he can offer if considering an upgrade, many options not on his web site yet and not all about ultimate power.My car has the Caterham 150 kit (cams and tb’s) which maybe a cheaper option.
I am considering the lightweight flywheel option for a winter job......
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