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#1 Cameron2310

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Posted 09 May 2018 - 12:13 AM

Hey, looking into buying a 1275cc as my first proper car to do up over the next year or two but would like to ask about some possible issues before I invest in one.

 

Due to the heads only being 2 valve per cylinder and with reduced air flow, are there any reasonably cheap ways to switch the heads out for a better flowing 4 valve per cylinder head? I heard somewhere that you could put 4 valve BMW heads on a regular block with some tweaking, but not sure how feasible that is without sending it off somewhere.

 

Another factor is the tranny. The MG Metro that was designed to replace the mini, that only had 94 HP with a turbo, had to have reduced boost in lower gears due to the tranny not being able to stand up to the forces so I can only assume that the earlier mini would have an even weaker transmition? I've also read a few people having trouble with 2nd and 3rd gear wearing out quite fast. Would I be looking at replacing the entire thing if I wanted to go to about 120whp? It would probably cost more than the car if so :(

 

Alongside the tranny is the flywheel. I don't know much about fly wheels other than that they store energy and really wouldn't like that to disintegrate if I upgrade the engine.

 

Thanks for any info, all is appreciated :)



#2 mini_in_progress

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Posted 09 May 2018 - 08:49 AM

Get good breakdown cover and you will be fine.

 

In all seriousness tho, it was revolutionary tecnology60 years ago when designed, i love the mini. But if you want power and reliability errrrrrrm maybe not for you

 

 

Yes you can put the bmw k1200 bike head on but you will need the block having some work done to accept, and also the management would need to be aftermarket.

 

There are larger heads availible as direct fit that are 8port billit alloy that will set you back a few quid like this one...https://www.minispar...px|Back to shop



#3 nicklouse

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Posted 09 May 2018 - 09:37 AM

never presume anything. the Mini and Metro gearboxes are the same with minor differences.

 

yes the head can be change. yes the flywheel can be changed. it all comes down to money.

 

BMW head and engine kits are available starting at a few thousand and up.

 

you don't need stupid power in a Mini to have fun.



#4 Ethel

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Posted 09 May 2018 - 11:02 AM

16 valves aren't twice as good as 8 valves - that probably sounds condescending, but there's a valid point to make. Power is related to the volume of air the engine consumes in a specific time, so it can burn the equivalent volume of fuel. If you have a 1275cc engine geared at, say, 3000rpm to do 60mph that has a more concrete limit on the amount of air it can consume than the number of valves. The A series has relatively good low to mid range torque because it breathes well enough at those rpm. The only way to get more power from better breathing is to increase the rpm relative to road speed and have a bottom end that can take it.

 

You touched on what may be a better solution when you mentioned the Metro Turbo. Forced induction gets more air in without increasing engine revs.

The manufacturer's idea of what makes a reliable transmission for offering a warranty to the heavy footed and mechanically unsympathetic general public and what can be achieved with thought and care aren't the same - Metro Challenge racers were running at least 140bhp.

 

The worn out 2nd and 3rd synchros are down to having to cope with the added work of slowing & speeding up the transfer gears. How you change gear makes a big difference to how quickly they wear out.

 

If you're a new driver look at insurance before you think about tuning any car and if you're thinking of buying a Mini be sure you have the money to get it in good order generally before spending to make it faster. 



#5 Retroman

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Posted 09 May 2018 - 02:22 PM

Its amazing what can be done to a Mini on a conservative budget,

 

especially if you are willing to do some yourself.

 

All the engine gearbox and carbs can be changed to upgrade for more go

 

You also might consider better brakes and suspension for more stop and better handling

 

With all that done to whatever degree you can have some serious fun

 

A lot depends on what you want from it, the only limit is your imagination and budget.

 

 



#6 timmy850

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Posted 10 May 2018 - 02:51 AM

5 port heads can still make great power, the historic racing guys make heaps of power and you can make huge power with a 5 port turbo.

 

There are plenty of options out there:

Turbo

Supercharger

7 port

8 port

BMW K head

KAD 16V head

 

The head really needs to get picked to match your total engine spec. If you put a fancy head on a tired old block and factory cam you'll get really poor results. 

 

Again with the gearbox there are plenty of options to upgrade it and make it stronger.

 

Is there any particular reason for your 120whp target? Mine probably only makes 20whp but it's still an absolute ball to drive... 



#7 grizzler73

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Posted 10 May 2018 - 08:30 AM

My first car was a 1976 Mini 1000, standard everything and the best fun! It had a Van rear subframe as my Dad had a a crashed one in his yard and let me have the subframe to pass the MOT, it went sideways everywhere... You don't need loads of horses to have a smile on your face in a Mini. If you want performance by a modern car.

The comments about insurance are valid, also you can sink thousands into a modified car and it would still not be as fast as a modern hot hatch.



#8 Icey

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Posted 10 May 2018 - 09:26 AM

Hey, looking into buying a 1275cc as my first proper car to do up over the next year or two but would like to ask about some possible issues before I invest in one.

 

 

Get the car first, then start thinking about a plan as you'll likely have many other things to think about before you get to how many valves the head has.

 

As others have said, there are so many options with the A-Series which you pick comes down to what you want to use the car for.

 

For example, if you're just going to be using it on the road then you really don't need to look at the complex builds just a worked head and mild cam will give you a fun, reliable car.



#9 Ethel

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Posted 10 May 2018 - 10:24 AM

Have to agree with Grizzler,

 

It's the handling that makes the Mini an exceptional car and that's really hard to improve over how Issigonis intended it. The lack of power will teach you to anticipate and read the road ahead, making you a better driver. Replace any tired rubber (suspension cones especially) and care of any worn and slack components to experience fully how great the design is before trying to improve it.






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