8 replies to this topic

[nmt_oli]

Right, i have aquired a free 1098, that hopefully has a fairly solid bottom end. I would prefer to usethis in my fun small block build to my 998, as you can get a significant amount more torque due to the extra stroke.

I know the bores are the same, and stroke is different, but can you use 998 pistons in a 1098?

im looking at these: http://www.minispare....aspx?pid=38611

[fikus01]

i believe thre are differences in piston height but wont swear to it! i know the 1098 ones are dished. if u can get both sets apart and see i think that would be your best bet!

[cap'n crunch]

http://www.theminifo...x...&hl=stroked

the search is your friend

if i remember rightly it was mentioned that you would have to 1098 pistons.... i think

Edited by cap'n crunch, 01 April 2007 - 11:56 AM.

[Dan]

Yes you need 1098 pistons to make a 1098. The piston crown height is lower to accomodate the extra stroke without having to make a whole new con-rod. 998 pistons will stick out of the top of the block at TDC.

[nmt_oli]

Ok thanks for that, should have searched, bad Oli!

in that linked thread, the person was talking about converting his 998 to 1098. this sounds interesting, as if my 998 is an A-plus block, i could theoretically use that, bore it out, find correct pistons, and fit the 1098 crank.

This could be a cracker of an engine me thinks.

[cap'n crunch]

Ok thanks for that, should have searched, bad Oli!

in that linked thread, the person was talking about converting his 998 to 1098. this sounds interesting, as if my 998 is an A-plus block, i could theoretically use that, bore it out, find correct pistons, and fit the 1098 crank.

This could be a cracker of an engine me thinks.

Yep thats what i am hoping to do, small bore all the way!!!

[nmt_oli]

Im having trouble finding over-size pistons for 1098 though, mini spares have LOADS for a 998, +20, +40, +60 and even +80 thou, and some of those in high perfromance versions. Can't see any 1098 pistons though

[fishy]

Im having trouble finding over-size pistons for 1098 though, mini spares have LOADS for a 998, +20, +40, +60 and even +80 thou, and some of those in high perfromance versions. Can't see any 1098 pistons though

Some years ago, I was asked to build an engine for a friend that he had bought from the least reputable of early mini parts suppliers, who is thankfully not as prominent as they used to be.

The engine was a kit of parts supposedly produced by Downton Engineering as a 1088cc conversion. What was actually supplied was a modified 295 head, a 1098 crank, 544 cam, some A+ 998 flat top pistons, and some A+ rods.

The 998 pistons had been machined down to deck height , and having paid a lot of money for what was essentially a bag of scrap, we thought we'd try it and see what happened. This we did, built it with the 544 cam, and the thing was pretty impressive, giving a good 5 years reliable service before being sold on.

Pistons can be a real problem for these engines, I don't recommend going the above route unless the engine is purely a bit of fun to build, and try. The top ring is very close to the piston crown, but I can assure you it can work and can work reliably, only thing I can't remember is which pistons were used.

I know this probably goes against good sense and common wisdom, but its your money, and your bit of fun, so I'll leave it up to you.

[nmt_oli]

very interesting, thanks for that. will def look into machineing 998 pistons.