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Increasing BHP


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#1 kev

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Posted 05 November 2004 - 08:02 PM

I have brought a mini sprite 1275 cc, M Reg 1994 / 1995, 40,000 on the clock.

I want to increase the BHP, I have made some enquiries but have been left confused.

Some have told me to fit a stage 1 kit, plus change the carb, to an MG Metro carb
some have said change the head as well to an MG Metro head as well as the stage 1 kit, another has told me to buy a 90bhp MPI tuning kit for around £900.00.

I understand if I just fit a stage 1 kit, plus carb this is "bolt on" stuff, but if I buy the tuning kit what else would I have to change to marry up the gearbox and the diff ?

This is my first project, for next years "Italian Job" and am aware I will make mistakes along the way, my knowledge of working on cars is limited, Precision Engineering is my living (cnc milling)

What would your advice be ? open to all suggestions.

Many Thanks

#2 Madmax

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Posted 05 November 2004 - 08:42 PM

i would personally go for the MPi tuning kit, it consists of a cylinder head i think, along with LCB and filter...im sure theres more to it than that. but from what ive heard its an excellent match for a bit more power in a 1275 MPi. If by 'marry up' you mean adapt to fit, you will not need to make any modifications, unless you want a nice cruising RPM. Which will involve changing the final drive ratio on your differential. Considering your doing the italian job run, this is something i would definately consider doing. Final drives are around the 1-200 pound mark for a good one. Im getting a 3.44 final drive for mine, which means 60mph is a non-ear deafening 3500rpm.

good luck

james

#3 TimS

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Posted 06 November 2004 - 01:28 PM

if its already injection then i would leave it on and would not go for a carb set up. By the soudns of it you have Multi point injection. mini sport do the 90bhp kit which it £895 but you willy get around a 45% increase in power which is incredible. it consists of stg 3 cylinder head, new spak plugs, 1.5/1 roller rockers, exhaust manifold and exhaust and air filter and is surposed to give quieter cruising speeds acording to the advert, but im not sre how they work that one out! though you canm only do this with MPi not Spi so u need to find out which one you have

#4 Dan

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Posted 06 November 2004 - 11:42 PM

A 1994/5 Mini sprite is going to have the SPi engine fitted. You can't fit a carb (well you can if you like but you'll never get it through the emissions test for your car) and you can't fit the MPi kit. Unless you buy a new ECU to replace the one you have you will be keeping the Rover fuel and ignition maps. Now these are OK, they are just designed for economy and smooth running over pure power. The SPi ECU cannot be remapped, but you could try to find out if the ECU from a Cooper engine of the same age can be fitted and will give you any increase in performance. There shouldn't be any coding issues as this engine is fairly old but ask a specialist to confirm that before buying one. You can of course fit a different cam, improved head, flow the inlet manifold (the SPi one a fairly poor as standard), change the rockers, general tuning really. Also on this motor you can play with the sensor ring on the flywheel to trick it into giving you more spark advance. It will re-adjust itself after you reset the ECU to cope with any modifications you make to it, and will release more power. It's just that you are stuck with the injection points and durations and the ignition timings laid down by Rover. You can however fit different injectors and a higher pressure fuel regulator so that it will inject more fuel within the given duration.
There is a lot of scope for improvement, check the writings of Keith Calver at the Minispares website for advice and ask around the various Mini tuning specialists to find out what they offer the SPi owner.




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