Camshaft & Stage Two Head
Posted 30 August 2015 - 05:42 AM
Spitz, how do you find the driveablility of the 1098 with the 3.1 gears? I'm looking at 10" wheels and not sure how well it would drive around town with the 3.1 gears.
It is a perfect match I find.
It is still very quick off the line, and I can easily sustain 120kph on a long trip ( think thats about 73mph in the old measure )
I'm running 12" tyres, but as pointed out….near zero difference from 10" due to the overall height of the tyre
Uncle Cooperman, Voted Mr TMF 2011
Posted 30 August 2015 - 08:24 AM
Cooperman I am contemplating running 12" wheels but I've heard a few people say that it ruins the ride quality of the mini. The only Mini I've driven was the one I owned when I lived in the UK which was a Mini City E on 12" wheels with a stage 1 kit from minisport. I don't know any different. However with the poor quality roads around here the higher profile tyres would be a better option.
12" wheels are OK as you run with either a 145/70 or 165/60 profile tyre and there is still a decent depth of sidewall to help with the suspension. The Mini suspension was designed to have a short travel and for the tyres to do a fair bit of suspension work, especially on their original 145/80 x 10 tyres.
The problem comes with the 13" very wide wheels where the sidewalls are only a 50% profile and the width of the tyre is too great on a light car to allow the ideal tyre contact load/sq.in onto the road surface. This is especially a problem in the wet as the contact pressure is necessary to squeeze the water from under the tyre and prevent aqua-planning.
I recently drove an MPI on 145/70 x 12 tyres in the wet and it drove beautifully with very predictable handling and good road-holding.
Formally Known as NOT850
Posted 30 August 2015 - 09:50 AM
My main thought is because my mini currently has the twin leading shoes drums and I have a Metro turbo set up that I initially bought for the mini but then came across a set of ROH contessa 10x5" wheels for the car instead. From memory the ride quality wasn't that bad with my city E with the 12" wheels. I like the look of the Australian Mini Cooper S wheel arches on the mini and the 12" wheels would look good with these arches.
Uncle Cooperman, Voted Mr TMF 2011
Posted 30 August 2015 - 10:16 AM
My main thought is because my mini currently has the twin leading shoes drums and I have a Metro turbo set up that I initially bought for the mini but then came across a set of ROH contessa 10x5" wheels for the car instead. From memory the ride quality wasn't that bad with my city E with the 12" wheels. I like the look of the Australian Mini Cooper S wheel arches on the mini and the 12" wheels would look good with these arches.
You don't buy a Mini for the ride quality 
. Personally I don't really like wheel arch extensions and believe that classic minis, especially early ones, look much better without extensions and with the original 10" x 3.5" wheels.
Formally Known as NOT850
Posted 30 August 2015 - 10:21 AM
After seeing the pictures of Timmy850 red mini I am starting to think the same as you Cooperman. I think the metro turbo set up with not see my mini at all. I don't think the mini rides that bad. Definitely not like a modern car but as you said you don't have a mini for that reason.
Formally Known as NOT850
Posted 03 September 2015 - 12:01 PM
.080" off a 295 head will give around 24-25cc from memory.
Assuming flat topped pistons, a nominal deck height of .005", and 24.5cc in the head, your CR will be around 11.2 - so you may find that you need more capacity in the head than you already have...
The 12G295 is ideal on a 1098 (and compromised on a 998) as standard.
The +.100" engine I have on the bench at the moment had to have the standard 28.3cc head enlarged to 29cc to get the CR down to 10.3, so measure the chamber size and the deck height before doing anything else.
Numbers wise, the +.060" 1098 I threw together with an MG Metro cam chucked out 63 brake and 66 torques, so you will be in the same ballpark with your build.
Vipernoir, if running flat tpo pistons would raise the compression ration too much would I be able to then have the block decked enough to get the compression ratio up a bit more to make it closer to the 10:1 that I am looking for?
One Carb Or Two?
Posted 03 September 2015 - 10:15 PM
No.
If you have too much compression with flat top pistons (probable), then your two options are dishing the pistons (making sure you still know which is the front) or enlarging the combustion chamber.
Decking the block will only raise it higher.
Do a dry build and measure everything.
Passed Test
Posted 04 September 2015 - 02:50 PM
Buy this months practical classics magazine - full article on compression ratios
Formally Known as NOT850
Posted 05 September 2015 - 12:09 PM
According to my CR calculator:
Bore 1098 (oversize +040 to 1131cc): 65.588mm
Stroke 1098: 83.73mm
Head capacity (estimate): 27cc
With flat top pistons you're looking at around 10.3:1 (allowing for the gasket volume etc). You'd have to measure the volume of your actual head. Standard they are 28.4cc
That's using flat top 1098 pistons in the smallest overbore (+040).
http://russellengine.../mini-products/
Have you read the new 1098 build by GR too? it's got some updated tech since the old build.
http://www.ausmini.c...php?f=2&t=87949
http://russellengine...ct-68mm-part-1/
Timmy, where did you get the compression ration calculator from?
Formally Known as NOT850
Posted 05 September 2015 - 03:50 PM
Please excuse my ignorance, but I have used a compression ratio calculator and inserted the details for the 1098 with a 40thou overbore and the cc of the shaved 295 head which came out to a compression ratio of 10.3:1. However, when I change this information to a 60thou overbore the compression ratio increases to 10.4:1. Shouldn't the ratio decrease and not increase?
Up Into Fourth
Posted 05 September 2015 - 06:28 PM
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