k1200rs 1380 engine build
Turbo Mini Forums

Yeah to be honest I have only ever seen pistons balanced to ensure that the weights match. If the cut-outs are identical and the original piston weights were close then it should be ok.

If something is worth doing, it's worth doing half of.

I had to notch the skirt of my pistons to clear the oil jets

I'm not clear on the function of these oil jets that are so popular. Is it to attempt to reduce the piston crown temp without changing combustion temp directly or some belt and braces exercise for lubrication?

For cooling under the crown. I'm having them for the small amount that they cost (in relation to new pistons and a rebore)

Don't you need a huge oil pump to maintain pressure with 4 jets pissing oil at pistons or do the normal uprated turbo pumps suffice?

btw. Hope I didn't need them, find out on the RR i suppose.

Has anyone used ceramic crown coatings on here? If so how did it go?

I wouldnt bother trying to balance the pistons side to side. Balance the weights as best you can though.

Back in the day before modern technologies made manufacturing more consistent, Manufacturers used to blance the pistons by using different weight gudgeon pins. I know this to be true since my NOS Cooper S PEP pistons were all out of balance. After selective asembly, all pistons weighed the same.

The BMW oil jets that I'm using have a 3 bar valve in them, so do nothing until about 45psi.

No point putting a massive oil pump in the extra pressure it generates just gets dumped away at the relief valve...

Anyway, there are topics about that if you have a search....

Well really disappointing progress, rods and pistons balanced and put on, just waiting for the cranks, flywheel and pully to be balanced, gearbox stripped and rebuilt, then I am hoping to do a dummy build.

A little work done yesterday all came back from balancing, so have been able to do a dummy build,


Then needs a skim and should be ready to build up I hope.

Edited by philc on 5th Nov, 2011.

Looking good !

Has the head been ported ?

"So wat we gonna do tonight Brain?"
"Same thing we do evernight Pinky!"
"Try to take over the world!"

Progress is slow, I have done several dummy builds, put in the oil jets, winage tray is in and have now build up the bottom end. I need to sort the gap out on the cam buckets, then the head can go on.
I really need to start on the car itself, just means spending more money but all good.

Whats taking care of the fueling if you don't mind me asking?

I'm at the planning stage for mine.

some progress, engine painted 'red' and end plate and seals on.

Edited by philc on 27th Jul, 2012.

i see ypu had the end of the head welded what was the reason for this ???

thanks dan

Edited by minidan on 17th Aug, 2012.

Dry deck by the looks of it.

ahh right

I will be looking at VEM's ecu when I have some cash along with the standard throttle boddies.

no welding, all the oil and water ways have been threaded and plugs, then skimmed

where does the oil feed for the head come from ?

made a start on the body work, removed the rear bins and back seat.
Previously had a weber box, took this out and put another plate in, with the intention of putting the bulk head back to as normal as I can.

Edited by philc on 1st Sep, 2012.

rather you than me...

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

looking good ,wiring is a ball ache but youl get there

give em hell

I couldn't remember if I torqued up the caps and mains, so spilt to check, thankfully I did, but I would have rather checked now rather than when it is fully build and in to run. anyway took some photos