12 replies to this topic

[danbmini]

hi all

iv got a spare engine in the garage at the moment, its a 1098cc. I was wondering whats the max you can bore a certain size out too or if they are all pretty much the same?
for example a common size upgrade is from 1275 to 1293, do excuse the lack of know how.


cheers dan.

[mini13]

hi all

iv got a spare engine in the garage at the moment, its a 1098cc. I was wondering whats the max you can bore a certain size out too or if they are all pretty much the same?
for example a common size upgrade is from 1275 to 1293, do excuse the lack of know how.


cheers dan.

it depends on how much meat there is in the block, for example a 1275 can be bored to 1400cc, and in some instances 1430ish depending on how good the block casting is.

iirc 1098's can be bored to 1215 using Imp pistons. not sure if thats the limit.

[danbmini]

hi all

iv got a spare engine in the garage at the moment, its a 1098cc. I was wondering whats the max you can bore a certain size out too or if they are all pretty much the same?
for example a common size upgrade is from 1275 to 1293, do excuse the lack of know how.


cheers dan.

it depends on how much meat there is in the block, for example a 1275 can be bored to 1400cc, and in some instances 1430ish depending on how good the block casting is.

iirc 1098's can be bored to 1215 using Imp pistons. not sure if thats the limit.

cheers, so its not really set in stone more depending on the block i have

[mini13]

a bit,

I think there were two types of 1098 block, one based on the 850 and a latter one based on the 998, I belive the 998 one can be bored further.

the limiting factor is more likly to be what pistons you can get hold of, for small bre's probably +20,+40 and +60 thou.

[HARBER07]

1430 is stroked? And a 1098 is a stroked 998.

[mini13]

1430 dosen't always have to be stroked,

an old mod used to be to bore to 74.somthing to take triumph 2.5 pistons giving just under 1430cc, not a very good mod as the pistons were a bit toffee.

I was just using it as an example.

similar thing with Imp pistons, except they are pretty strong.

All this is in vizards tuning BL's A series, and will be more accurate than my memory of the book.

[HARBER07]

Fair doos. Put a ? as I'm not in the know with big bores.

[Dan]

A small bore block is a small bore block.

There are two main block castings that you need to worry about, small bore and large bore. Small bore blocks are used to build 850, 998 and 1098 engines. The largest size they can be bored to realistically is equivalent to a 998 / 1098 (same bore in both engines as said above) +120 thou. Finding pistons for that size is tough. The largest size that pistons are currently commonly available for is +80 I believe.

[mike.]

I think +120 pistons are availible from austrailia at pretty reasonable prices. Can't remember the site for them but if your intrested PM mini boo, i'm pretty sure i've seen him talk about them before.

[HARBER07]

Australian Minisport rings a bell.

[Pooky]

So if my 998 is bored out +80 to 1062 would this mean that a 1098 bored out +80 would be 1162?

[cobblers]

So if my 998 is bored out +80 to 1062 would this mean that a 1098 bored out +80 would be 1162?

Almost, but not quite. the +80 refers to the diameter, so the overall increase depends on the current diameter and the stroke too.

[liirge]

I've got the +120 Thou pistons, they come from Minisport Australia.