K series engine rebuild - advise on spec please

[Smithy77]

So not long ago I bought my "dream" Caterham - a mint 2002 Superlight with a 230bhp K-series lump, complete with 6 speed/3.92 LSD, full cage, Quantums etc etc. I bought it knowing it needed a remap, so after a month of farting around adding serial connectors to the MBE and not really driving it, I eventually got it remapped at Track and Road. A healthy 230bhp@8000rpm was the result. I got a mere 24hours of mind blowing enjoyment out of it before the bottom end let go.   Oil starvation was the cause (long story).

To cut to the chase, the engine is currently in bits in the hands of Tom New. Pistons, rods and crank damaged beyond repair. Thankfully, the head has escaped unscathed. I'm posting to canvass opinion on what spec I should rebuild the engine to.

The engine when I bought it was a Caterham supplied Minster R400 spec K-series with Caterham dry sump belltank system, but it underwent a rebuild and upgrade by DVA in Feb 2015 which included the following:

Full engine balance; 32.5 inlet valves with full big valve porting to head; 1444 cams; VDSK springs; steel caps; original pistons retained with modification for valve clearance; head fettled for cam and follower clearance; piper verniers; TBs port match to head; Turbo 11.5mm oil scavenge pump.

So other then being balanced the bottom end is standard R400 spec. Can anyone confirm what this is exactly over and above a standard 1.8 K-series? Just out of curiosity.

So, what spec should I rebuild the engine to? I'm not wanting anymore power, so any upgrades would purely be for longevity as this car will be a keeper for many years. I'll be meeting Tom tonight to discuss, but he immediately suggested steel rods and new valve springs (the latter I am a little unsure of the necessity as since the DVA work it hasn't been on track and only covered a 1000 or so miles). Let me know your thoughts!

Cheers

[oilyhands]

The springs will be fine. A new stock crank is up to the job and will not be fatigued. Steel rods are a no brainer as stock rods will need to be bought and bushed and it isn't that much more expensive to buy steel rods. Omega pistons with anti scuff coating and larger pockets are ideal together with Westwood liners.

The R400 has a stock K crank and selected single tang rods, it has Omega pistons which have interference fit small ends in the rods, the big end bearings are Mahle Motorsport (VP2) steel and bronze backed lead indium.

What happened to the old engine?

Oily

[Smithy77]

Thanks for the info Dave. Do you suggest getting the whole lot fully balance again too? What is involved?

The cause was a lack of oil. Only 2L was drained, this is despite me regularly checking the level using the standard Caterham dry sump method (while running AND straight after switch off) and all the time looking like the oil was plentiful. I even had fellow club members check the oil with me and we all agreed it looked fine. Doing some reading on the subject it would appear the Caterham method is far from accurate or reliable.... seems I learnt the hard way 

[oilyhands]

The Caterham tank is too small IMO, but that is b@st@rd luck, sorry to hear it.

If the flywheel, clutch and pulleys are already balanced and you use a new factory crank then the balance will be pretty good as the factory balance of the crank is good. A rebalance is ideal.

If you have any difficulty sourcing the parts I keep everything here including a number of new cranks.

Oily

[Smithy77]

Standard oil capacity is 4.5L from memory isn't it? To be giving false (good) readings with a 2.5L discrepancy is very worrying. Once I get to know the engine with correct oil levels, all will be good I'd like to think....

[Smithy77]

 

If the flywheel, clutch and pulleys are already balanced and you use a new factory crank then the balance will be pretty good as the factory balance of the crank is good. A rebalance is ideal.

Regards the rebalance, so that's the crank, along with the rods and pistons presumably? Are you able to confirm the extent of balancing work whilst in your hands Dave? Did you balance the flywheel, clutch and pulleys?

[oilyhands]

All the rotating parts will have been balanced together dynamically, the rod and piston assemblies would have been scale balanced.

Oily

[LesG]

I've just built up a lovely 1.8 K to replace my previous 1.6, and it is a cracking engine! The increase in torque feels amazing out on the road, and I'm looking forward to my first hillclimb with it next Saturday.

With regards to the checking oil level, I run the CC dry sump system aswell, and have only ever used the 'top the oil up until it dumps the excess into the catch tank' method. All the other advice did little other than confuse me, so I figured wasting a bit of oil was better than er, running it dry (sorry to hear that by the way).

[Smithy77]

I also tried the "overfill" method too, as I noticed the catch tank was dry. I topped up twice with about 0.25L at a time and after the 2nd little top up, I started getting oil in the catch tank, so thought I was covered with that method too. I wouldn't rely solely on that method....

[mcerbm]

Maybe a mechanical oil pressure gauge would also be a good upgrade to give you reliable and accurate oil pressure readings. Oil pressure warning light / buzzer could also be useful?

I have had mine for a few years now and it's very reassuring. 

[ECR]

Don't forget to check the condition of your scavenge pump during the rebuild.

See here : https://www.lotus7.club/forum/techtalk/dry-sump-scavenge-pumps

Good luck !

[Smithy77]

I have a mechanical OPG fitted, and a low pressure warning light is on my winter job list.

I did read that thread about scavenge pump failure, which inevitably heightened my paranoia somewhat! The pump was given the all clear during the rebuild so I wont worry about that for now. I think I'll be sending it off for a refurb next winter though.