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998 to 1100
https://www.ausmini.com/forums/viewtopic.php?f=5&t=84128		 Page 1 of 1
Author:  thehulk [ Wed Jan 08, 2014 5:51 pm ]
Post subject:  998 to 1100
Hey everyone!

So im looking into making the conversion from 998 to 1100.
And i was just wondering how easy it would be?
I currently have a 998 lying around in the backyard, would it be easy to get the parts to change it around since it is the same block, or should i just buy a 1100 and rebuild that?

Thanks boys!
Author:  Kennomini [ Wed Jan 08, 2014 6:29 pm ]
Post subject:  Re: 998 to 1100
It's only the crank you need, (if you buy new oversized 1100 pistons that is). The head can be modded as needed, the rods are the same/interchangeable and that's all you need to worry about.
It comes down to what you can come across at the time, it'll probably be easier to get a complete engine but if you come across a crack tested crank with good journals and if it's cheap enough then get it. Also if you buy a complete engine with head (& carby), gearbox etc well then you get extra spare parts.
Author:  simsy98 [ Thu Jan 09, 2014 4:19 pm ]
Post subject:  Re: 998 to 1100
I have an 1100 block, crank and head I think. Which I'm about to sell if you interested. Would need a rebuild as it's all seperate atm.

Sent from my HTC_PN071 using Tapatalk
Author:  thehulk [ Thu Jan 09, 2014 6:30 pm ]
Post subject:  Re: 998 to 1100
Thanks for that info!

Oooh! Really? How much are you asking? Hopefully not too much, im only a student! Hahaha
Author:  Irish Yobbo [ Thu Jan 30, 2014 7:48 am ]
Post subject:  Re: 998 to 1100
Yes, the block is the same, you will need a new crank, and no reason not to get new pistons (they're quite cheap). But you will also want the 1100 head which is far better than the 998 head and can be heavily modified - some say that a heavily modded 202 (1098cc) is as good or better than a modded 295 (998cc cooper).

The question is, can you get a 1098 head and crank cheaper than a used 1098 engine?
Author:  69k1100 [ Fri Jan 31, 2014 9:20 pm ]
Post subject:  Re: 998 to 1100
998 pistons are too tall. You will need new pistons, I too have a couple of cranks, they're not that uncommon but have wives tales of weakness attributed to them. If you have a good 998 then stick with that. The 1098 is a good upgrade over stock but of its performance you're chasing the 1275 is the one to watch. The rebuild costs between the various displacements are similar, it's the initial costs that get you. Don't be tempted to start a rebuild if you don't have the funds to see it through, better a complete good engine for less money.
Author:  thehulk [ Thu Feb 06, 2014 3:17 pm ]
Post subject:  Re: 998 to 1100
well ive now bought a 1100 block and crank, i recently had my current 998 head redone so ill use that one.
now i just have to call a few places to see how much the bottom half will cost.
if you do it you may as well do it right!
Author:  Irish Yobbo [ Thu Feb 06, 2014 3:27 pm ]
Post subject:  Re: 998 to 1100
If memory serves, the 998 heads have about 24cc chambers, and the 1098 heads have about 26cc. They're not a straight swap - if you use the 998 head, you may have too high a compression ratio (but since the c/r of minis is quite low, that might be what you want!). I'm not sure on the maths for the new compression ration you'll have, but I'm sure somebody will know.
Author:  Kennomini [ Thu Feb 06, 2014 6:14 pm ]
Post subject:  Re: 998 to 1100
thehulk wrote:
well ive now bought a 1100 block and crank, i recently had my current 998 head redone so ill use that one.
now i just have to call a few places to see how much the bottom half will cost.
if you do it you may as well do it right!

Are you going to over bore the engine 0.100thou over :P . And with the head the 998 can be made to be the same as a 1098 head but if you are going to go for a big overbore engine the 998 head will be what holds the engine back, don't forget the 5 port heads are restrictive by design so if you can upgrade the head to suit the engine best do it.
Author:  drmini in aust [ Thu Feb 06, 2014 6:30 pm ]
Post subject:  Re: 998 to 1100
You can open out a 998 head to the same as you can a 1098 one, but more Detroit Wonder Metal needs removal. A lot of work.
It'll go OK on the road with a 998 head though, will just be a bit breathless at top rpm.
Author:  timmy201 [ Fri Feb 07, 2014 1:08 pm ]
Post subject:  Re: 998 to 1100
Doesn't the 1100 have a much lower compression ratio than the 998? Something like 8.3:1? Bringing it up would be a good thing, but the reduced flow of the 998 head wouldn't help.

Good read:
http://www.minimania.com/ENGINE___1098_ ... ning__1128
Author:  drmini in aust [ Fri Feb 07, 2014 1:52 pm ]
Post subject:  Re: 998 to 1100
1100's C/R was 8.5:1, a 998 (except Cooper) was 8.3:1. Cooper was 9.0:1 I think.

A 1098 with a 998 head would probably be around 9.0:1. Personally I'd open the chambers out a bit before fitment.
Barney had a 1098 with a 998 head when bought, we drove it to Canberra and back and it went fine, no pinging etc.
Later I fitted a 1293A+, and sold the 1098 + rodchange box to an ausmini member.
Author:  Irish Yobbo [ Thu Feb 13, 2014 9:25 am ]
Post subject:  Re: 998 to 1100
It would probably be worthwhile using a 1098 head and just skimming it to up the compression. The 998 heads have slightly smaller valves - if you're going to the effort of swapping out the crank, a little headwork would be beneficial.
Author:  GR [ Sat Feb 15, 2014 6:27 pm ]
Post subject:  Re: 998 to 1100
Hi TheHulk
Ihave a set of +.060 pistons they are second hand but are in excellent condition and so are the rings they are yours for the asking just bore your block and away you go.
Graham Russell
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