62 replies to this topic

[George929]

as the title says really how much does your average over bore ive got a 1275 im building and i want to go bigger was thinking 1330. and would just like to know how much really :)

[mike.]

Just go for 1293, theres very little benefit in those few extra cc's, and if you just bore it to 1293 you've got more life left in the block if you or a future owner wants to rebore it again.

[George929]

sorry but i asked for the cost thanks for the suggestion though :)

Edited by George929, 17 January 2012 - 01:08 AM.

[lrostoke]

think we paid about £100 for the boring, biggest cost is the pistons and rings. You'd have to check somewhere like minispares for prices

[Bungle]

where are you, someone should be able to suggest someone to ask in your area

[racingbob]

as far as performance concerned i believe its 2 bhp per 20 thou

thats the reason i took my race car to 1380cc years ago

if it was me i would take it to 1330cc

[Frisco]

Depends on the condition of the bores really. If there is damage or heavy wear you may have to go bigger.
Take it to a machine shop and get them to measure it

[samsfern]

They have to "cut" twice to get 1330, so it'll be a bit more expensive than 1293 or 1310. Pistons will be pretty much the same price though.

[danie garry]

i was pricing around over here and was getting a price of about 50 euro, 40 odd pound so it seems cheaper here!

[George929]

im in around the Middlesbrough area. the bores are good its only done 44 thousand miles. i was just talking to ian at green and white minis and he was saying 1380 is best but 1330 is still pretty good. and safer for more miles. i was thinking of 1380 but im not keen on the whole offset bores malarkey.and the pistons are quite abit more expensive. im wanting NA with about 110bhp.

[Cooperman]

If you go to 1380 you may well not be able to bore further if ever this becomes necessary. Once offset bored the block cannot be sleeved back to 1275 and a further larger bore can break through into the water jacket on some blocks, or become too thin. They are never going to cast any more blocks, so a 1380 represents one more block lost to rebuilding in the future.
At 1330 you can always sleeve back to 1275 and, effectively, start again. To get a few bhp gain between 1330 and 1380 requires the biggest valves possible and can give some gasket unreliability.
But, of course, it's your engine and your choice in the end.

[Carlos W]

Is the block on standard bore?

If it is and you're going to 1380 and having yours offset bored do you fancy swapping with my +0.030 overbored block?

[George929]

Is the block on standard bore?

If it is and you're going to 1380 and having yours offset bored do you fancy swapping with my +0.030 overbored block?

nope sorry ive found a right gem of an engine so its all mine haha sorry

[Frisco]

If your boring it to 1380 it doesn't really matter what its current condition is

[Carlos W]

If your boring it to 1380 it doesn't really matter what its current condition is

Agree!