engines

Post by **paul.kissick** » Sun Aug 19, 2007 12:28 pm

hey there could anybody give me advice on this subject, i have a 1098 and 948 engines. I read somwhere on here that you can put the crank of the 1098 into the 948 and you get 998?is this true, or is it far too much work. What con rods would i use and pistons.
Also the 948 block needs boring out how far could i take this out? Excuse my ignorance but the 997 and 998 are differant a series?

Post by **bmcecosse** » Sun Aug 19, 2007 4:55 pm

Slight confusion. In fact - you use the 948 crank in the 1098 block, and with 998 Mini pistons and conrods - voila, you now have a 998 engine ! The 1098 block is better because it has cam bearings already fitted - and indeed a better cam - well worth having.
So - you need - 1098 block with good bores, 948 crank with good bearings, and standard size 998 Mini pistons and matching con rods. In reality 998 Mini engines are virtually given away for nothing (everyone upgrading to 1275) - so if you check on ebay you could be lucky!

Post by **paul.kissick** » Sun Aug 19, 2007 6:36 pm

would this engine give me anymore benefits than the standard 1098?
thats if it was a half race engine?

Post by **bmcecosse** » Sun Aug 19, 2007 7:39 pm

Well - it will still be 100 cc short of the 1098, but it will REV more if that's what you want. So both engines will give much the same power - although the 998 version will have better ultimate power potential if you go all the way with it - v large valve (Cooper S) head and 649 cam - but you will be revving it to 7500/8000 and it probably won't last too long! My own 1098 engine is a great unit - with 12G940 head and big carb it pulls like a train and seems to be unburstable! I've been trying to burst it - so I can have an excuse to fit my 1275 engine - and still it keeps hammering on, excellent oil pressure and not burning oil!! And quite frankly - it's plenty powerful enough for sane road use on standard wheels and tyres - which I discovered several times yesterday (in heavy rain) are v much the limiting factor for cornering and braking.!
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Post by **paul.kissick** » Sun Aug 19, 2007 8:24 pm

is there any way of making the bottom end stronger?
I think i was told about a crankshaft stabiliser or something, if there is such a thing where could i get one? Thanks so far for the help.

Post by **bmcecosse** » Sun Aug 19, 2007 10:15 pm

Yes - with either engine you MUST use a crankshaft damper - from a Mini engine. And of course duplex timing gears and chain are worthwhile. If it's a v powerful engine - you can make a 'strap' for the centre main bearing - and it's a good idea to lighten the flywheel which aids acceleration in the lower gears, but also raises the critical vibration period of the crank making it less likely to break. Oil cooler is also a v good idea!

Post by **picky** » Sun Aug 19, 2007 10:18 pm

you can have the crankshaft hardened, either turftrided or nitrited. This makes the outer surface tougher, so that the bearing surfaces last longer.

Much easier and very beneficial is a "centre main bearing cap" very cheap from mini tuning places, and can be fitted without removing the engine. it basically bolts ontop of the main bearing and gives it a bit more strength.

also try and get hold of a later type crankshaft pulley, which has a damper built in, this stops harmful vibrations going through the crank.

You can also have a crankshaft made from billet steel, but they cost well over £1,000 and are only really needed in a full race engine. But you wont manage to break one of those!

Hope that helps!

Picky