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Mpi Rally Car Carb Conversion


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#1 James Harris

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Posted 05 February 2017 - 12:04 PM

I did my 1st tarmac rally last weekend with my mpi mini, we didn't do to bad getting 4th in class but had lots of problems with the car going in and out of limp mode and not enough revs or power so I have decided to bin the injection and go down the carb route.
The engine is going to have a full rebuild which will include
Re bore to 1380
Balanced crank
Centre main strap
Stage 4 mpi head which I have
Pre verto clutch competition
Ultra light flywheel
Duplex lightened timing gear
Webber 45
Omex ignition

I want to try and keep the mpi clocks working in the dash oil light, temp gauge and rev counter etc. I'm just taking out the engine loom is there anything I will need to keep from the loom to keep everything working on the dash and can I still keep the bits of the loom for starter motor and alternator or do they all need the ecu?
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Edited by James Harris, 05 February 2017 - 12:17 PM.


#2 minidaves

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Posted 05 February 2017 - 01:45 PM

just need to hard wire all the bits in the rev counter runs on wasted spark so you ecu will need to do the same


Edited by minidaves, 05 February 2017 - 01:46 PM.


#3 craig 1010cc

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Posted 06 February 2017 - 09:19 AM

If you're going to go down this route, have you checked that you are going to be able to get it mot'd?

Wiring wise, I'd rip out the MPI loom and fit one from a late 80's Mayfair as this will have the feeds for oil, water temp, ignition, main beam and indicators. I haven't tried a MPI clock set in an earlier mini, but I think they'll work fine.

#4 DomCr250

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Posted 06 February 2017 - 01:52 PM

I think if it's an earlier non cat engine then they should MOT it OK and apply the normal pre-cat rules...  you'd need a tester who has a good understanding I'd suspect.



#5 Cooperman

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Posted 06 February 2017 - 02:34 PM

It is not wise to go to 1380 for a rally car.

Rallying means quicker engine wear and when a further re-bore is needed it will mean a high cost for sleeving or a new block.

Best to go to the next size up and after it is at 1330 cc, sleeve it back using standard sleeves to 1275 cc. 

You will gain very little going to 1380.

 

The only problem with rallying a classic Mini, as I found out when I built an Endurance Sped 1990 Cooper is that the build cost is as high or higher than doing a modern car, but it is very hard to be competitive. Although you may start off not seeking a high finishing position, once the 'bug' gets you then you will want to win your class. I sold that Mini and bought a Rover 214 Si Twin-Cam which was far more competitive and much cheaper prepare and to run on events.

 

For historic rallying it is a different matter as a Mini can still be on the pace if well driven and well prepared.



#6 Sprocket

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Posted 06 February 2017 - 06:15 PM

I think if it's an earlier non cat engine then they should MOT it OK and apply the normal pre-cat rules...  you'd need a tester who has a good understanding I'd suspect.

 

If they test it on the VIN of the car, it will fail, if they test it on the engine number, it will fail. the limits on the MPi were set wider than the norm so it would pass, but take the cat off or put a carb on it, and you'll need a friendly MOT tester that's got a bit of brains about him (quietly walks backwards with the sniffer :whistling:)



#7 Allrounder

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Posted 06 February 2017 - 08:19 PM

Have you looked at the specialist components mpi replacement kit if the regs will let you use it, by the time you've got the carb/manifold/complete ignition system etc you won't be fair off the cost. If it's tarmac single venue events your mainly doing then I would of thought a nice torquey engine is what you want coupled with the right gear ratios.

#8 James Harris

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Posted 09 February 2017 - 07:56 PM

Iv got a friendly mot tester, as it goes he's also building the engine. 😉 He's built quite a few 1380 mini rally engines and are all still going strong. Iv also got a spare block. The car will be running a 45 webber iv seen the specialist components kit but just fancy a carb. As to it being competitive I know a mini is going to be hard to be a class winner but I'm a trier and want to prove a point. We did post 1 stage time 2nd in class by only 4 secs but then the car played up big time. It's running a straight cut box with straight cut drops x pin diff on 4.1.1 ratios
Going to have a good look at the loom this weekend and take the engine out ready for a major rebuild!

Edited by James Harris, 09 February 2017 - 08:01 PM.





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