supercharger or turbocharger ?

[grumpydad]

Hi
as above this is to go on a standard 1275
we can get hold of a Shorrock supercharger
now I think this was a standard bolt on mod in the mid 1960
or do we get hold of a turbo of a mini

a bit more about the car
it is my daughters for every day use she is 22
but the problem is she is now into classic car rallying
she has just done Le Jog meant to be one of the hardest events in Europe
we managed to come 30th out of 65 starters
she has entered a sereys of events over this year
9 weekend events over 12 months
run buy the historic rally car register
and she calls me a sloth when the triumph TR4 or earl porch overtake us
on the transit sections
so all help most welcome
the only problem is the car is a A35

thanks

[MarkyB]

A35s went very well in pre'57 racing, think of it as underdeveloped Mini!
Plenty of space above the engine as I recall, it's like looking at an A series in a well compared to a Minor

[ASL642]

Having had an A35 that's a perfect description of the engine bay! The Minor engine bay's a dream to work in compared with the Austin, but as said there's plenty of room on top of the engine.

[MarkyB]

Are there different classes in classic car rallying?
Between stages isn't what rallying is about surely?
Insurance for a 22 year old driving something like a supercharged or turboed A35 is likely to make you a much grumpier dad!

[grumpydad]

yes there are different classes
with different orgnisers
age and that about it the cut of date seams to be about 1965
and the A35 is 1958
so you could roll up in some thing made in 1964
with say 3 lts and we would compete against us

Insurance well yes but it makes me less grumpy
than having to pick her up of the street in a drunken stupor

[MarkyB]

It's about power to weight ratio not just cubic inches.
A 3 litre car of that era will weigh well over a ton, hardly nimble.
What engine does it have now and what has been done to it?

[bmcecosse]

I'm sure you have asked this question before - maybe even more than once? The answer remains the same - avoid the turbo - you want push all through the rev range - so go for a supercharger.... But the engine will need to be specially built for it - you don't just bolt it on any engine and hope for the best.....

[grumpydad]

MarkyB
how can I answer that on a public forum
I might be accused of cheating
lets just say a standard 12xx cc with a 1 3/4 carb

bmcecoss
sorry I have not
but I understand that in the late 1950 and early 1960
that a Shorrock supercharger was a standard bolt on mod
and the claims were 50% plus increase in horse power
I saw a old add for one that was for a Morris Minor

now the Shorrock supercharger was probable low pressure
but how much was low pressure

[Suzukimorris]

Go eaton BMW mini supercharger, currently doing that myself.

[bmcecosse]

Yes - supercharger is (and was) the way. But you need to drop the compression ratio first. And provided the rules allow it of course.

[grumpydad]

suzukimorris
were are you is it worth having a meet up ?
If not please tell me more

bmcecosse
why do you need to drop the compression ratio
when you fitted a Shorrock kit there is no mention of this
in any of the documentation I can find

[bmcecosse]

Because - back in the day, engines had low compression ratios anyway (7 to 8 ) - and there was 5 star fuel available to use when the scharger was fitted - and it was a low pressure blow anyway. Nowadays - we don't have 5 star, and the engine will already have a high ( 9 to 10 ) comp ratio. So it would immediately detonate - and the pistons will last 15 minutes if lucky...

[Fingolfin]

Roy means "7 to 8" not "7 to ", just for clarity's sake.

[bmcecosse]

Silly smilies.....

[gilburton]

I'm only going from memory but I stuck a shorrocks kit on my mini in the late sixties and it was the easiest tuning mod.
The only slight downside was the torque. The supercharger used to knock on the bulkhead on acceleration lol
I think mine was the c75b?? I think the oil feed was total loss so you had to check your engine oil regularly!!
There were kits for spridgets so I don't see the need for lower compression it was literally a bolt on job.
Possibly they altered the pulley ratios depending on car??
More info here
http://www.shorrocksuperchargers.co.uk/