That is correct. Eg a 286 is just ok for road use in a 1275 or bigger, but put it in an 850 and it's only good for racing, maybe.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I'm a bit worried that if I spend money on my 1098 to reach my goal output in both torque and HP that I'll fall short.

Don't worry about the numbers too much, they are just numbers after all. Your requirement was a lively and fun to drive car - remember this above all else!

If you spent money just making the 998 like new again, you will be amazed with how much better it drives. By making a new modified 1098 and dropping it into a car that had an old 998 in you will be beside yourself with how much better it drives.

I once upgraded from an old worn out 850 to a reconditioned, but stock, 998. The car was transformed into a rocketship.

cheers
michael

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the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

I don't think you'll have any issues getting the numbers you want with the set up you've mentioned. By the time you add those parts, increase the compression ratio and include a modern cam and spend some time getting it all built properly it'll go pretty well.

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Would there be much difference in output of the engine between a compression ratio of 9.5:1 compared to 10.5:1?

Many years back my mates had 1100 Clubmans The only mods were extractors Twin 1.5 Su No head mods and a waggot was it 238 cam?? similar to 544 .One went like stink and the other was not the same.
Cam timing rocker ratios I don't know but others may have more on this and yes they can go great.
We were kids and it was all hit and miss .Things are more refined now.

Some difference, yes, but again, it is all about the package. There is not much point going for 10.5:1 compression without cam and head mods to suit. You could make things worse if you do certain things without the others - like the valve springs and cam combination. You might get 10% difference in numbers at the top end, maybe 5% torque difference, but what does that mean when driving it? Unless you are trying to knock tenths off a qualifying time at the track, there is not much point.

Design the whole package around what you are trying to achieve, but don't worry too much about the numbers up front i.e. don't say "i want 70hp atw", say "a lively and fun to drive car - and reliable based on a 1098 engine". That is what i did with my engine build, and quite honestly i was surprised by the numbers on the engine dyno, but far more importantly i am absolutely stoked with the way it drives.

Having said all that, IMHO, 10.5:1 with appropriate cam, head etc would make a very good 1098 road car if you are prepared to stump for 98 octane fuel all the time.

cheers
michael

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the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

Thanks MiniMick. With the mini being a weekender in search of fun roads, I think that a compression ratio of 10:1 would be a good target. Around here there is 100 octane fuel as well.

Won't need 100 with 10:1. Might even get away with 95.

Be careful with the 100 octane fuel, it often has high ethanol content (15%) which might not be compatible with all of the fuel system components. 95 and 98 are usually pure ULP. 91 has up to 10% ethanol, so the same caution with fuel system components is wise.

If all of your fuel system components are ethanol compatible, you can run e85 (i.e. 85% ethanol) and 14:1 compression like all of the racaers do!

cheers
michael

_________________
the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

That is really high compression. Does anyone know if the HS2 rebuild kits are ethanol compatible?

Get on the phone to Midel on 1300 350 351 or http://www.sumidel.com/

Maelgwn

P.S.No affiliation, just bought stacks of stuff from them when I had Jags

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Maelgwn No Mini Yet

Thanks for that Maelgwn.

Can anyone help me with a question that I have? I have read that an A series engine looses around the 15hp mark through the drive train from flywheel to wheels, but would the torque losses be about the same?

Hi NOT850, we just completed a 1098 +100 Russell eng Pistons with a std 295 head with 60 off it, small bore race valves inlet 1.260 ex 1.070 supplied by Russell eng, nice seats and short trun modified and the Russell eng 266ss cam, Wornaford long manifold 45mm weber 34mm chokes medium bore long centre branch extractors.
The result was peak hp of 101.6 @6500 and 90 ft p peak and 85 ft p @3500
When I get a chance I'll put a dyno sheet up

those are excellent figures Matt R , congratulations on a good build, that cam has an excellent torque band.

NOT 850, the HP loss figures and the torque figures are not linear - and not quite so predictable. As power increases heat losses etc seem to increase quickly. For example a 145 HP at the wheels race mini might be 100-106? hp at the wheels, whereas an 850 putting out 30 HP at the fly might only lose 15 percent. The torque again is more dependent on the cam , with some cams holding torque over the drop off ( where revs increase but torque doesn't) better than others.

i haven't read all this thread , but give consideration to the rev drop between gears and the final drive you use. .... keep that engine on cam in the gear changes