Down on power, please help

[HGCramer21]

Hi, I'm racing my Caterham 1.6 K-series at the moment and when put on the dyno back to back with some of the other guys it seems to be around 8hp down which is a noticeable amount when you're racing a 120hp car.

On the dyno the second part of the torque curve looks pretty dull, as though something is restricting the power from around 5,000 RPM +.

It had a full engine rebuild last year and until recently was one of the most powerful on the gris. I've also changed the exhaust and checked the manifold. It was on a hub dyno so nothing to do with tracking. Fuel / air in take and ratio is ideal. Cam timing is correct. Had the top end checked and nothing wrong with valves, or piston rings. Put new plugs in.

I'm now largely out of ideas, my next suggestion might be to look at the transmission but seems unlikely that this would cause a problem. ANyone have any suggestions, I'd greatly appreciate them!
Cheers
Harry

[HustleRussell]

Gareth Cordey's old car? I was thinking about buying that, it would've been the wrong time for me though.

Have any other supergrads been on the same dyno? I've seen several at Surrey Rolling Road but that's a chassis dyno. Never seen one hub dyno'd. So what's your point of reference with respect to how much power you're expecting?

[DVandrews]

It's not unusual for the pistons to suffer with fractures to the ring lands, give the engine a compression and/or leakdown test to establish that all is well mechanically.

Oily

[HGCramer21]

Yes indeed, how did you know? I know the car has the potential because it went so well last year and at the beginning of this year. It may well be up for sale again so feel free to drop me a line if you're ever interested. Want to get the power issue sorted first though of course!

Andy Mac had it on a rolling road up against another super and it was 8hp down on that. I've also had it hub dyno'd at Blink Motorsport near me and the torque curve is identical. I'm baffled!

[HGCramer21]

Thanks Oily, I've done a compression test and all is fine, hopefully doing a leak test on Monday see if that reveals anything. The pistons and rings were checked a few weeks ago and no probs though.

[HustleRussell]

Have you topped your oil up?

[HGCramer21]

Yep.

[HustleRussell]

How high? My classic used to be dog slow if I filled the oil to 'MAX' due to crank windage. I'm sure I've heard similar is applicable to K-series (although Oily is here to set me straight if I'm wrong)

[CharlesElliott]

Yes, same on a K series.

[HGCramer21]

Interesting. I don't have it at max but have it about half way between the mark on the dip stick. Maybe I could afford to lose a bit more.

[CharlesElliott]

Should be OK then. Obviously the risk starts to increase the less oil that's in it.

[cseven]

You could try giving Paul Freeman a call, his contact details can be found on the grads site. Sounds like you haven't got much to go on but he might be able to give you some more things to try/eliminate?

Steve