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 Post subject: 998 to 1098.... How Too?
PostPosted: Sat Jun 24, 2006 11:39 pm 
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As the topic states.... exactly what needs to be "swapped" to convert a 998 into a 1098...
and what are the consequences as far as reliability and life span???

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PostPosted: Sat Jun 24, 2006 11:58 pm 
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just the head i beleive... but i know nothing...


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PostPosted: Sun Jun 25, 2006 12:01 am 
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666 is absolutely right... on his second point... ;)

you need the crank, rods and pistons..

you can change the head if you like, but it isn't necesary...

i the work is done properly with the right parts, then the reliability should be the same..

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PostPosted: Sun Jun 25, 2006 12:04 am 
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cush wrote:
you need the crank, rods and pistons..

is it as "simple" and pulling the engine a part and swapping these over then putting it back together and tuning it?
or are there other smaller changes needing to be done?

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PostPosted: Sun Jun 25, 2006 8:04 am 
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Rods are exactly the same, for both 998 and 1098.
1098 crank is longer stroke, and the piston pin to crown height is shorter to compensate.
If you are reconditioning the motor and want to go to 1098, you need to buy oversize 1098 pistons, and get a 1098 crank- which will probably need regrinding like the $30 one I just bought. 8)

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PostPosted: Sun Jun 25, 2006 10:45 am 
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Thanks Doc :-) thats what i wanted to know.
When mini's came with 1098's from the factory, was the 1098 block different from the 998 block they used in later years? or were the 1098 made in this same way?

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PostPosted: Sun Jun 25, 2006 11:19 am 
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1100cc ones did.. :)


and the K

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PostPosted: Sun Jun 25, 2006 12:09 pm 
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Just to balance the thread
If you convert to a 1098, the motor will not rev as hard but you have heaps more toque. That is it will pull a lot harder without the need to change down. My mini, when it was a 1098, would pull away in top gear very smoothly from as low as 30 km which is great if you get baulked etc in traffic.

But if you pull down a 998 motor to convert it to a 1098, dont expect just to swap the bits and have it going. Without any machineing being done, you are up for a cost in excess of $300 - machining will add quite a few dollars to that sum.

Is it a good conversion ???? Both the 998 and the 1098 have their good points and their weaknesses. Neither motor, without quite some modifications, is going to turn you mini into a bullet.


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PostPosted: Sun Jun 25, 2006 4:12 pm 
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Thorlek wrote:
Thanks Doc :-) thats what i wanted to know.
When mini's came with 1098's from the factory, was the 1098 block different from the 998 block they used in later years? or were the 1098 made in this same way?

Only difference between a 998 A series and 1098 A series BLOCK here in Oz was the engine number. They were otherwise identical.
The factory fitted either 998 crank & pistons, or 1098 crank and pistons.
Both sizes were built here at the same time by BMC, in the mid-late 60s.
They kept making the 1098 into the 70s for the Clubby.

re the HP- the 998 was 40HP @5250 rpm, the 1098 was 50 @ 5100 rpm (according to my book).
998 had 52 lb/ft torque @2700 rpm, 1098 had 60lb/ft @2500.

So, I've heard all this stuff about 998s being better revvers, but in stock form, there just ain't much rpm difference. :lol:

1098s did get a better flowing head (12G202) than non-Cooper 998s, if converting a 998 to a 1098 it's worth finding one. Cam too...
And, if you use the HS4 carb and manifold off the 998 Clubby, that's worth a couple of HP over the stock 1098 one (which had an HS2).

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