After spinning a shell a Donington over three years ago, I have finally got my Mi engine back in and running. One of the reasons for the lengthy rebuild was that myself and Martin (crf450) have been having a look at the oil surge problem from a completely different angle and have built an engine which, so far, seems to have cured the Mi surge problems. I say "so far" as the car has yet to be put on track or tried with "sticky" tyres (888's etc....) but this was an engine that would surge on the road and, as already mentioned was killed by surge at Donington on road tyres. The main theory behind what we think causes surge is not that oil gets trapped in the head, but the fact that the Mi engine loses it's oil pressure far too quickly due to the piston located con rods. The 8v and the gti-6 engine both have crank located rods, meaning that pressure is held in the oil galleries far better than the Mi which basically has a massive oil leak from either side of the big ends, so when surge is encountered, the pressure just falls away instantly, as opposed to the 8v and 6 engine which hold onto their pressure for a few more vital seconds. The spec of the bottom end is as follows, Mi block and liners, 8v crank and rods, Mi pistons (these needed machining to give the clearance on the 8v rods) Modified main bolts with windage tray, Diesel oil pump (with the big gears) Oil pump cover, Baffled xu10 sump (plus the small oil pump baffle) The head is completely standard except for a PeterT inlet cam (plus chip)   On cold start up the oil pressure goes straight to the top of the gauge, but more importantly on hot idle the needle never drops below half way (this is even with oil temp on the third bar of the gauge) So far, on the road I haven't seen any oil surge at all, but I would like to try a proper pressure gauge on the engine rather than the notoriously unreliable Pug' gauge on a trackday just to be 100% certain that this has cured it.   With the PeterT inlet in the car feels really strong through the midrange with a mad rush at 5k to the limiter (Note to Peter... the limiter still cuts in at the std revs) it sounds awesome as well, with a steady, but lumpy tickover..   All the pictures are in here Mi conversion pictures   I would like to thank Martin for all the work that he has put into this engine (just look at the welding on the downpipe... work of art) and for the use of his garage and tools, plus putting up with all the mess I create when doing even the smallest job...! Thanks also to Clare for all the coffee and food that I have consumed.....   Cheers,   Nick