1275 V 1071S ?

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richardACS
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1275 V 1071S ?

Post by richardACS »

Would be fascinated to hear from those who have owned both S engined Coopers. My own experience has been firstly with a 998 Cooper that had a nice smooth power output and then straight to a 1275 that I recall finding it quite coarse in comparison and not such a step up as I had thought it might be over the 998. Having later read that this was the norm have often wondered what the 1071 is like and can it be tuned to give 1275 levels of power and does it have a more smooth delivery?

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mk1
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Re: 1275 V 1071S ?

Post by mk1 »

I have had a few examples of both & much prefer the 1071. OK, there is not as much raw power as the 1275, but the delivery is smoother & far less rattly. A 1071 feels like it is a happy little engine where as a 1275 always feels to me like it is slightly annoyed with the world.

This is always transferred into the rest of the car, a 1071 powered Min is far smoother & quieter than one with the bigger engine.

It is hard to put these perceptions down in writing, but I hope you get my drift.
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big-un1967
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Re: 1275 V 1071S ?

Post by big-un1967 »

1275 is instant power, 1071 is a revyblittle chap.

When I was younger I used to do engine transplants for fun, and had no money!

I ran both 1071 and 1275 after running an Austin Experimental 998, which had been built as a test bed for more power. It certainly was what it said.

It revved all day, and gave equally as much if not more power than a standard 1275 unit. I still have it, and have never cracked it open to exactly why it was so bloody good.

Therefore a well built 998 can deliver. It’s normally from the top end, induction and exhaust. Hence Downton and others made a good living selling go faster bits

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Polarsilver
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Re: 1275 V 1071S ?

Post by Polarsilver »

I have three cars & they are all different experiences when driven .. the 997 is a lovely drive on back roads take your time but it will get a move on when needed .. the 1071 is the screamer but then SMMC were told to build it so it Revved .. the 1275Gt with1300gt engine is Wife favorite cos its comfortable. :roll:
I think you need to select & build your engine around whatever you want to do with It ?.. the cam choice is the starting point me-thinks.

InnoCooperExport
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Re: 1275 V 1071S ?

Post by InnoCooperExport »

mk1 wrote:
Tue Sep 22, 2020 8:13 am
I have had a few examples of both & much prefer the 1071. OK, there is not as much raw power as the 1275, but the delivery is smoother & far less rattly. A 1071 feels like it is a happy little engine where as a 1275 always feels to me like it is slightly annoyed with the world.

This is always transferred into the rest of the car, a 1071 powered Min is far smoother & quieter than one with the bigger engine.

It is hard to put these perceptions down in writing, but I hope you get my drift.
I suppose this could be because the 1071 is oversquare whereas the 1275 is quite a long stroke?

I think Polarsilver is on the money that cam-choice is also very important. When I started building my 1300 Export I was told by many people to use the 286 cam that cam with the car (brand new in a performance kit from Kent cams) as it would be a great cam for the car. I was sorely tempted because of all the talk of them being wonderful fast road cams, then I heard one run... I spoke to the owner who happened to be in the paddock next to mine at an event at Zandvoort, he told me "it's a nice cam, if you like shifting down". Needless to say I've stuck with the stock AEG531 "S" profile cam.
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Re: 1275 V 1071S ?

Post by nick@dunsdale »

Never driven a 1071 so couldnt comment on the driving experience

But have owned and driven various 1275's cam choice is important as mentioned but so is final drive equally as important

Driving a 1275 with a 3.44 or lower is night and day to driving one with 3.77 or higher, i found a midly modified 1275 with a 2.9 final drive very civilised to drive and still had acceleration when needed.

Also had a few 998 mini not cooper but in various states of tune and yes they are very nice to drive great for twisty B roads but do run out of steam on A class roads and dual carriageways
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richardACS
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Re: 1275 V 1071S ?

Post by richardACS »

Thank you each for the replies, the feedback seems to mirror my (unfounded) perception. I do like a revvy engine and one that is comfortable with itself as Mk 1 has mentioned. Perhaps it is the long stroke of the 1275 that is the basic reason but much appreciate all the views....

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Re: 1275 V 1071S ?

Post by SMOKE GREY »

I have owned or driven or rallied :D 997,998,970,1071 and 1275.

997. A good one is nice to drive, torquey for a small engine, and far better then most people will tend to tell you, though I bet a lot of these people probably haven't driven a good one. On saying that an average one is average! A friends father has a 997 with a Shorrock blower, super smooth and pulls like a train from 15mph to 100 mph all in top gear! My old car was Abingdon Group 2 spec, including H4 carbs and a 4.1 diff, set off like a scalded cat, pulled over 90 mph and I won rallies with it.

998. Sweet engine, seem to go for ever even if they are down on health. Need more revs then the 997, but with the right spec can get the results of a good standard 1070 performance wise. My car gave 73bhp on HS2 carbs and revved to 7k, again beating bigger engine cars, only really lost out on hills, and stop start, if you keep momentum up they are good fun.

970. A real marmite engine it seems. They will rev and rev and are super smooth. If you go for off road competition you can afford to run a wild cam and low gearing and use the revs but this makes for a horrible road engine. A friend off mine has a 970 road car with twin H4 carbs SW5 cam and a ported head with ports and valves not silly big. It is a really nice sweet engine, goes really well, he has some very nice cars, and has driven many interesting stuff, but is adamant the 970 is the best smile factor.

1070. Super engine, smooth,revvy and decent torque if sensible on cam choice. My car ran a 544, later a SW5 with forged 1.5 rockers and a 3.9 diff . Genuine 105 mph plus, and super sweet and quiet running. Paddy Hopkirk to this day says it's the best Cooper S engine, and he should know. His 33 EJB replica he owns, and his 6 EMO in which I have done lots of miles in, are very different cars, and interesting to drive back to back, EJB much sweeter and quieter and not much difference in outright performance.

1275. Always going to be the most powerful, excellent top gear acceleration, but can be a bit harsh and 'crashy' at times, though like anything, a good one is very impressive for an old three main bearing pushrod engine. All depends on what you want.

richardACS
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Re: 1275 V 1071S ?

Post by richardACS »

Smoke Grey - a nice resume of each engine! It can only be a hunch from not having driven a 1071, but a Downton treatment with the 1.1/2" carbs does hold a large attraction I have to say..

Lakeland997
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Re: 1275 V 1071S ?

Post by Lakeland997 »

Unfortunately, no one seems to make a 1071 stroke crankshaft any more.
The Minispares website says their forging can be machined to 970 1071 or 1275 stroke but only in batches of 10 and they don’t list any of the shorter strokes.
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