Hi guys and gals,

Can anyone tell me what the approx percentage of drive train loss is normal in a mini?

also, i notice now after i had my car dynoed today that the torque output is much higher than other mini engined dyno sheets i have seen.

is 194 ft/lb of torque right? or is that a misprint?

if my engine is making 53HP at the wheels, around what would that be at the flywheel?

cheers

jason

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'66 BRG Morris Mini Deluxe 60HP ATW

10% of your oil every 2000 kilometres is a normal loss.

About 20% losses through the drive train, but there can be other variables like tyres, tyre pressure and even how it has been strapped down.

The 194 ft/lbs torque would have to be incorrect. I'd expect to see between 60 and 90 ft/lbs from an engine like yours.

The 53 HP quoted has that been corrected?

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it says on the dyno sheet "not corrected"

what exactly does that mean?

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'66 BRG Morris Mini Deluxe 60HP ATW

It means the torque is measured at the wheels. That's why it is so high.
divide it by the [diff ratio x the gear ratio used] and you will be somewhere near it, but low due to drivetrain losses.
These losses are not all in the gearbox, a major one is the tyres. Sticky fat ones give lower dyno readings than hard old skinny ones do.

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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.

ok, well thats got me buggered i have no idea what diff ratio i have or what ratio the 3rd gear i have is

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'66 BRG Morris Mini Deluxe 60HP ATW

.....And there is also Air Pressure, Altitude, Humidity and Temperature corrections that should be applied, although on the Temp, you really need the Air Temp of that going in to your Carb, rather than just the Air Temp of the day. You can look these up for yourself and note them on the back of your sheet.

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sounds like a lot of trouble for not much gain considering i am not after the absolute maximum power from this engine

just wanted an explanation, and thanks for your feedback guys i now understand what "corrected" power is.

not really any point in working out the percentage of drivetrain loss if the figures are not corrected anyhow is there

horsepower at the wheels was 53 and i suppose that was an ok result considering its my first ever mini engine build

the aim was to make sure the engine mixtures were ok and there was no danger of it having some catastophic internal disaster due to a lean mixture or something similar. mixtures were great right through the rev range so i am happy with that for now.

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'66 BRG Morris Mini Deluxe 60HP ATW

Your main reasons for having the Dyno Tune are sound, but it can be useful to have reliable and repeatable Engine Output figures for a later time when you go tinkering..........

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If you like a "Rule of thumb" for drive train losses in a mini,,, then expect to see that wonderful "reported" std Cooper "S" engine HP out-put to be 74hp (cough) at the engine,,, dribble away to only about 44hp at the wheels

& a nice 1100 from 50hp back down to 30hp

-----------------------------ish---------------------------------

so take "almost" 20-30hp losses depending-------------------------ish------------

(with std helical gears & std-ish tyres pumped to 30lbs on an average-ish day, down a hill with a back-wind ---------------ish-------------------

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

30hp loss is about right. Mine on engine dyno (much more accurate) had 120bhp, on the rolling road dyno it had about 84hp (but was running very rich, i suspect it's now closer to 90hp)

But as GT mowog suggests, you go back in winter and magically will have more hp......

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Lillee - 1969 Morris Mini K

oh just pump up the old hard skinny conventionals

run it up at night time

cool the fuel tank down with some ice wrapped towels

wheel align dead straight with good hard tie bar bushes

spray mist of ice cold water across the carb inlet

don`t strap the car down very tight

lightweight motor oil in the wheel bearings instead of grease

etc etc etc

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Nah you had ~74HP then mate, I have the records...
Mine made 86.6 on the same day, I have the trophy.

Dynos vary heaps, they are only good for tuning, and comparisons on the day. Even then they vary a lot.
I saw a 140HP (on engine dyno) 1152 turbo get 125 ATW, a 140HP stroker 1400 get barely 100. Same days, same dynos.
Hint- the turbos ran in 4th gear, not 3rd.

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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.

Forget about the figures, just use it like you intended, to get it tuned.

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1964 998cc Cooper
1971 Mini K x 2
1972 Clubman GT

84, 74, what's the difference. 120 flywheel hp happy?

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Lillee - 1969 Morris Mini K