K series change-up light

[Parbo]

Cn anybody tell me at what revs the change-up light on my 1996 K series 1.6 (135 bhp) should come on? Mine doesn't appear to be working (either that or I am not giving it enough welly! )

Thanks

[Wrightpayne]

If its a supersport 7600rpm

[Parbo]

Thank you kind sir.

[Toby S]

It's 7,400 or 7,500 I think on my 1993 1400 supersport, as the rev limiter kicks in at 7,600 or 7,650. May be different on on the 1600. Only gives you a second or so to put the gear change in before hitting the limiter though

Originally put on as the VDO rev counter ran out at 7,000 (well mine does) and if you were running a 5 speed Ford type 9 box, you needed the extra revs between 2nd and 3rd (the main gear to rev the nuts off it, sometimes 3rd to 4th) to keep it in the power band on the up change,

I had to change mine a year or so ago as it stopped working (rev limiter hit with no light coming on before hand which is a bit of a give away sign) - Caterham had them in stock and for once I don't recall they were that expensive complete with new loom - £20 ish.

[Parbo]

Thanks Toby.

[Wrightpayne]

Toby is right - I knew 7600 was in there somewhere.

I’ve actually removed mine and fitted DRE shift lights which are programmable and just 3 wires to connect at back of tacho.

Ian

[CageyH]

7600 rpm on standard pistons is pushing your luck.

I also have a DRE light and have lowered my rev limit.

[Parbo]

Thanks Cagey, will bear that in mind.

[Wrightpayne]

I understand the piston problems mainly affected the race series and subsequently allowing the use of forged pistons.

For road use with an occasional foray to the dizzy heights of 7600 I think you will be fine (mine is 21 years old and still going strong)

That said, my DRE lights are programmed with a lower max. There are 5 LEDs on the DRE and you set revs in three stages for the first two, second two then larger 5th LED so you can see the limit approaching. A nifty bit of kit for not a lot of dosh and much better packaged than the Caterham ACES system

[Toby S]

7,600 rpm set up too high ?

My 1992 1400 supersport is on standard factory setup as far as I know from an ECU set up point of view (few other tweaks elsewhere around the head, throttle body - 52mm and crank -polished all doen by previous owner) - Single change up light and standard Rover ECU which I guess probably will be an ECU2 given the year, and therefore I guess mine is as close to factory setup you get - Looking at the original handbook (an A5 Green little ring binder file book) max power (130bhp) is quoted at 7,400, hence it would make sense for change up light comes on then, with an additional 200 rpm's before you get to rev limiter to give you a chance to shift.

I would assume Caterham knew (big assumption I know) what they were doing and the engine capability when they progammed it for the quoted perfromance and set up when they first produced and sold it - mine never seems to struggle getting there (especially in second) and the engine doesn't sound overaly strained - its done 35,000 miles so is well run in. Valve guides on the other hand ...hmmm... it does like to drink a bit (a bit like me). 

For a 1400 with peak torque quoted at 5,000 rpm and max power at 7,400 rpm - keeping the revs between these ranges gives a very spirited performance, sound and indeed smell and with a 5 speed type 9 box they need to be revved through the gears to achieve this - under 5,000 revs I admit its a bit limp (OK for a Sunday drive out with the mother-in-law) 

 

[CageyH]

If you won’t take my word for it....

http://www.s262612653.websitehome.co.uk/kengine/kpistons.htm

[Toby S]

1600 engine with loads more power and revs though

Perhaps a 1400 which is a smaller bore (smaller diameter pistons, thicker sleeves although same stroke) may be a bit less fragile - also less extreme levels of power - I can't recall seeing any major blow up problems being reported (other than head gasket - but no doubt I will now) and I'm not sure whether there are any alternative forged pistons available in the size. I don't think an ECU2 is reprogrammable is it - Less use of the right foot may be the only solution but that's really not in my nature.

 

 

[CageyH]

The OP has a 1600.

[Wrightpayne]

Article talks about higher power engines being a problem and a more sensible limit of 7200 on a stock engine. Failures in racing were prolonged high revs rather than occasional peaks you hit on the road.

In the great scheme of things not a major expense if you bust a piston.

I have a 911 and either bore score or IMS bearing failure is a five figure rebuild :-0

 

[Toby S]

Sorry - forgot that - Only the 1400 is in my manual I'm afraid (it pre dates the 1600 k coming out !)

Gives all the torque and peak power of all the cars available at that time, 1600 GT, Sprint, 1700 Supersprint,  Cosworth BDR (1600 and 1700), and Vauxhall 16v (a time when you could have 3-4 different manufacturers engines) - makes quite interesting reading

[CageyH]

Generally speaking the stock pistons is good for around 160BHP and 7200 maximum RPM, even at this level some will fail, a better prospect is the Trophy 160 piston from late 160VVC engines which has wider ring lands and smaller piston pockets, this seems capable of handling 180-190BHP and 7800RPM.