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Sigma 125bhp to 152 upgrade?


Andy135

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I've searched on here and a more general google search but can't find a definitive answer. Investigating the feasibility of turning an Academy car into a 310R and I'm presuming that it's possible to upgrade an entry-level Sigma TiVCT 125bhp engine to 310 specification (152bhp). Can any owners confirm this?

Caterham and Premier don't appear to offer anything from 125-135bhp, only from 270 to 310 spec, according to respective websites. I'm pretty sure it's technically possible but I'm curious that there doesn't seem to be anything on the internet offering/confirming the same. Of course, it could just be me not looking in the right places... thoughts?

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possible to upgrade an entry-level Sigma TiVCT 125bhp engine to 310 specification (152bhp). Can any owners confirm this?

Yes, I did this.  Wasn't cheap though as I paid for Caterham Gatwick to do it as part of a service and MoT.  Maybe £1500?

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Thanks Mrp, I did look there and I'm sorry to say I still can't see where the TiVCT upgrades from 125 to 152bhp are called out. I can see the fixed cam upgrades from 125 to 140, then the VVC (TiCVT) upgrade from 135 to 152, but that's all.

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Hi Andy - this was what I was hoping to hear. All the literature on the Caterham Parts site seems to be focussed on the 270 to 310 upgrade, but makes no mention of starting with the 125bhp engine. Thanks for sharing your real-world experience.

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The 125 to 135 upgrade is just a remap. The 135 to 152 is more involved, and involves a cam change and normally a lighter flywheel I believe, as well as another remap.

So basically a 125 to 152 change is exactly the same as the 135 to 152 change, since you get a remap automatically with the latter.

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Just to confirm, my car was a 2016 Academy car that I bought in Jan 2019.  125hp to 150hp upgrade involved new cams (they gave me back the old ones) and a remap.  Not noticed much difference on the road, but big improvement on the track..

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Hi Andy.

The other guys above are right! The TiVCT engines are mechanically identical up to 310 spec and can run 3 maps without mechanical mods. 125, 135 (AKA 270 map) and 140bhp. You just need a specialist with the right laptop to talk to the standard caterham ECU.

Mine left the factory as a 125, but was mapped to 140BHP by GP Sevens when I bought it. I'm just about to go to full 310 spec. This, as others have said involves cams, oil catch can, air filter, and a few other odds and sods, and another new map to 152 to make use of the new cam profile.

So GP Sevens are about to fit the full 152bhp/310 conversion for me, so this...

https://caterhamparts.co.uk/other/6493-engine-upgrade-kit-for-sigma-ta-to-152bhp-310.html

I'm also fitting a light weight flywheel at the same time which markedly improves throttle response and makes it "feel" more powerful (it doesn't add BHP!) This isn't part of the standard 310 spec, but is a factory option. Premier Power offer an even lighter one... which is better, but more expensive.

https://caterhamparts.co.uk/other/5335-flywheel-lightweight-for-sigma-variable-cam-engine.html?search_query=fly+wheel+sigma&results=310

I'm also probably going to add a cat bypass pipe (easy to put the cat back on for MOTs) for a tiny bit more low end puff, but mainly for more pops and bangs 

https://caterhamparts.co.uk/collectors-catalysts/3664-cat-bypass-pipe-4-1-sigma-side-exit-rhd-uk.html

Thats, the 310 bit of your question. The R bit would be adding LSD, rear ARBs, adjustable suspension collars etc if you don't already have them. Then you'd be full 310R...

Hope that helps.

Kris

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