mk1-forum.net

Hi

I have decided to use a 1098 engine in my 1970 mini clubman. Is there anyone in here who has experience with imp pistons in a 1098 unit ?, or have suggestion how to make a nice quick 1098 unit for road use.

Best Regards Kristian

A good article here:

http://www.minimania.com/web/SCatagory/ ... ticleV.cfm

Don't be tempted to overbore WAY Oversize. Using Imp pistons in Minis was an OK idea when they were cheap & plentiful & you could put up with massive oil consumption but nowadays it's not such a good idea.

The bore walls are so thin by the time you have bored them out that lost of oil gets past & makes for a smoky mess.

Best to stick to the sort of spec in the minimania article, this will make for a reliable, powerful, smoke free engine you can be proud of.

Brings back memories of my first mini years ago. 1098 with a 20thou bore, lightly modded 12g295 head, twin su's on a worked manifold, light clutch and flywheel, lcb. It went very well, or at least it seemed to back then. Would show 1275GT's a clean pair of heels. It ran out of steam quite quickly though, not sure of the diff in it.

Graham Russell has his own design 1098 oversize pistons for sale. Call him in Australia, make sure you check the time is correct and let it ring for a long time because he is probably on one of the machines or the dyno.

Russell Engineering
113 North Rocks Rd
North Rocks 2151
Australia
+61 2 9630 2195

best of luck
michael

I'm using MiniSpares +80 1098 pistons in the Frogeye, you need to slim down the dizzy drive to clear the skirt. Not run it in fully yet but with a standard 295 head, twin inch and quarters and the MS Evolution cam it pulls really well! Next on the shopping list is a modified head once its run in, nothing too fancy.

I'm also planning a similar 1098 spec engine for the Inno MK1 and will be using the Evolution cam again, its a cracking road cam!

AndyB72 wrote:I'm using MiniSpares +80 1098 pistons in the Frogeye

Didn't know they made them that big!

But wouldn't it be better to bore out a 998 to the maximum size to get a 1152, due to the throw of the crank you should be able to rev it easier and more

I think you can even get +120 ones, or have a been dreaming again.

The longer stroke of the 1098 engine gives a very useful increase in torque for a road car.

Hi

Thanks for all the answers. I will not go for imp pistons, instead I will use some 0.80 minispares flat top pistons as Andy suggest.
I already have a 12g295 with larger valves, and I will give it a lightened flywheel and backplate.

Which clutch do i need, would a standard do, or would i need a orange ?

Andy is it this cam you use http://www.minispares.com/Product.aspx? ... 279&title=

My idea was to use a kent 266

Best Regards Kristian

Not sure of availability now but the sprite 1098 had higher compression pistons , what about 997 cooper cam with 12G295 head

The ado16 MG1100 and MG/AH Spridget 1098 used the Downton 998 Cooper head, and a good choice it was for a longstroke 998 engine. A 997 Cooper cam is perfect for a 1098 engine.

Only rebore a 1098 as less as possible, as Mark has said, the oil consumption isn't very good as 1098cc, let alone anything more wider.

the oil consumption is down to the flex of the crank. Fit a mainstrap to prevent it.

Hi Kristian that's the one, I think MiniSpares North have one or two in stock. I was thinking about the 266 too but the Evo cam is cheaper, I'm from Yorkshire. Also I thought the 266 might move the power band a touch too far up the rev range for what I wanted, I don't really want to rev it too hard and cause reliability problems. It's well worth getting everything balanced too while its all in bits.

masnarda wrote:the oil consumption is down to the flex of the crank. Fit a mainstrap to prevent it.

After tearing down several engines fitted with main straps I've lost total belief in them. I just cannot understand what they achieve.

I understand more and more engine builders are moving away from them - I doubt I will use one on my next build.

Without subscribing to the Calver love/hate debates that usually crop up when he is mentioned, I believe this short article he wrote is enlightening:
http://www.calverst.com/articles/Engine ... issues.htm

Vegard wrote:

masnarda wrote:the oil consumption is down to the flex of the crank. Fit a mainstrap to prevent it.

After tearing down several engines fitted with main straps I've lost total belief in them. I just cannot understand what they achieve.

Could very well just be the flex by the crank between each main bearing is the problem, even if the main bearing caps were made of granite. And the thinner the bore walls get, the more it will flex.

A decent set of top quality oil scrapper rings might be a good suggestion, if they are available these days. I once years ago (about 30!) fitted an unusual set that was chromed and had a funny looking spring in between a pair of scrapers that came in three bits, if I remember right. Worked quite well. Consumption was about a pint of oil every thousand miles under hard use, rather than the usual near half-gallon.

These are them, I think, Cords. No idea if they still produce A-series rings any more, http://www.cordsduaflex.com/history.html