Fiat Engine Conversion.

[biggelmo]

Ok,it's time for something different.....
I love driving my Mini, I love its handling, I love its brakes and I quite like the the engine (now it's runing sweet).
BUT......
A little bit more power would be nice.
The ability to run on unleaded fuel is a bonus.
And 5 gears would be lovely.

One thing that has showed itself time and again is that cruising at 65mph at 3800rpm on a motorway is not fun, I know that I can change the diff ratio from its current 3.4:1 to something like a 3.1:1or 2.9:1 but 5 gears is what im after and A series 5 speed conversions are'nt cheap.

So....

After looking into other popular engine conversions (Micra,Swift & Vauxhall) I settled on a very different Fiat 1242cc 16v engine and 6 speed box from a Mk2 Punto Sporting which ticked all the boxes and had an extra 6th gear.
Then I started researching on various Fiat/Punto forums and it turns out that for naturally aspirated performance tuning the 16v is not to be touched due to it having hydraulic cam followers that severely limit cam choise......pooh,now what...
After more forum trawling I now know that the best e ngine to go for is a Punto Mk1 75 8valve engine.
The Punto 75 is 10 bhp down on a 16v but has a one off big valve/big port 8 valve head with higher compression and a one off cam known in Puntoland as an 866 cam,this has timing and lift measurents which are close to "fast road" figures.
As for the gearbox I will use a Mk2 Punto 5 speed box which has a 3.4:1 diff and an overdriven 5th gear,it also has cable gear change and a hyraulic clutch which should make thing easier.

Some will remember that I brought a front bulkhead section with a front subframe from Dean,well this will be used to allow me to fabricate a front subframe and hopefully sort out all the install problems so that I can then drop the Fiat engine/box/subframe into my Mini with no hassle........famous last words.

The subfame is nearly finished (you know I dont hang around) and ive got loads more to tell you and photos to post but its time for bed
WATCH THIS SPACE.

[paul1275s]

'The Italian Job'?
Sounds interesting, looking forward to the piccies!

[biggelmo]

OK,as promised here are the photos of the subframe build.


First off I made a support frame out of some thick steel plate and box section that locates on the tie bar mounts and rear body mounts,i also added an extra temporary support under the subframe towers.


Locating the front tie bar mounts will mean that I can chop out the side rail and still have an accurate position for the tie bar mounts.


The subframe will mainly be built from folded 3mm steel plate which is what the original subframe is made from.
I got the metal folded to my measurements by Alan Stone at SLS Fabrications in Hailsham.


This is the design I will be copying, I found this on an Irish rally foum site.
I like the simplicity of it when compared to the box section efforts.


A friend of a friend gave me a knackered 5 speed Fiat gearbox,here it is sitting in an uncut subframe.


Here's the subframe with the sides and front chopped off.


Fiat gearbox in the hole.




After a few hours of cutting,grinding and welding I had this.


Hers the Fiat box back in but not quite in the correct place.
You can also see the masking tape stuck to the subframe on which ive marked the centre lines and the inner wing position.


Heres the other side.


Getting there....


I then added a temporary box brace to stop the side bending in when I removed the front rail.


New extended 40mm box added.
Hopefully this should sit inside the "bump" in the front panel behind the bumper.


To get the Fiat box across into the right place I had to chop more out of the side.


And then make an extension.


Thats a better fit,




Plenty of room.




Then I had to slightly modify the subframe to allow the box to move back.


Driveshaft hanging in position.

This is as far as ive got so far, ive now got a Punto 75 engine waiting to be bolted to the gearbox and then hung in position on a borrowed engine crane that ive picked up today.

[biggelmo]

More on the engine.... I was a bit brief yesterday.

Im using a Fiat Punto 75bhp1242 "FIRE" (Fully Integrated Robotised Engine) from a 1997 Punto.
As I said earlier these are the tuning engine of choice for our Fiat friends owing to them having a one model fitment cylider head with bigger straighter ports,bigger valves,higher compression ratio and a super dooper camshaft (866).The P75 also had multi-point fuel injection and a fairly decent exhaust manifold and when all these improvements were put together the P75 made 15bhp more than its lower spec brother the Punto 60........dont you just love Fiats model numbers.

For my conversion I'll be dumping the the injection system and the ecu/electronic ignition and simplyfying things by fitting bike carbs and a points distributor from an 80's Fiat Uno which is a simple fit as the P75 cam still has the distributor drive groove in its end.
A decent 4-2-1 stainless exhaust manifold is available and when coupled with the bike carbs and a skimmed and flowed cylinder head (more on this later...) Im hoping to get the power up a little to somewhere around 85-90bhp, this figure is easily reached by the Fiat crowd but they stick to the multi point injection and fit a bigger single throttle body.
An 85-90bhp 5 speed Mini will be quick enough for me and with the bike carbs should havea nice induction burble.
One thing that does need attention is that the standard P75 FIRE engine is not very well balanced, also the flywheels are ripe for lightening which will improve engine pick up so ive already taken the flywheel to an engineering chum to be lightened.
Once everything is balanced and the lightened flywheel fitted then the engine will safely withstand 8000rpm.

Back to the cylinder head.....
The bigger/straighter ports in the P75 head do not need much in the way porting.......just a "heavy" de-coke and valve guide boss removal is enough according to Fiat tuning gurus ,so iv now got a spare cylinder head to play with.....

[biggelmo]

Standard inlet port.


Slightly modded port.


866 cam


Complete head.


P75 engine

[MiniGT5]

Years ago someone told me that a punto head would fit an a-series with a bit of work as the bores all line up on both

Can you confirm this with your new head?

Good luck with the conversion

N.

[biggelmo]

Hi Niel, I have put a Mini 1275 head gasket and a Punto 1242 head gasket together and the bore centres are identical. :-D
Some of the push rod holes in the Mini gasket line up with the head stiud holes in the fiat head,the fiat head has an oil feed which doesn't line up with anything on the Mini block so that would need sorting.
Also im not sure where the cam belt would drive from as on the Fiat its driven from the OS end of the head which would be overs the clutch on a Mini, I suppose you could turn the Fiat head around and run it backwards the take the cam drive from the NS end from the crank nose.
The Fiat bore size is 70.5mm which is also very close to Mini size.

[MiniGT5]

Sounds about the same amount of work as required for a BMW K Head conversion then. Not that you will have that problem, with the whole engine swap

N.

[biggelmo]

Thanks to an easy job today I was able to get to the garage this afternoon and have had guite a productive time....


I borrowed this recipricating saw from work and its made the job a lot easier.


This ali lug is the crank sensor mount,as I'm converting back to distributor ignition it now surplus so I sawed it off.


All gone.

I then bolted the gearbox to the engine and couldnt help myself......i had to give it a try and see what it looked like. It was obvious that the plate section under the sump had to be trimmed to allow the engine to sit lower,then the support frame would have to come off as it to would be holding the engine up too high.
When I unbolted the supprt frame nothing "pinged" and the bolts were all a snug fit in it so the subframe has'nt twisted with all the welding.


I marked the section to be cut out to clear sump and set about sawing and chain drilling the curves.


I also had to cut the upper edge off to clear the. Oil pump.
I will have to weld in an angle section to give it a bit more strength.


The engine then sat down nice and squarely .


Then I tried my bonnet to see what clearances were like.......and its not too bad.


And this is the space for the Suzuki 600 Bandit carbs that I won last night on fleebay.

So I suppose it engine mounts next,ive got a plan in my head for them but at the moment I dont have the bits to make them.

[Stephen]

Looking good. I still think it's a lot of effort for little power though. Turbo it.

[monkeyjim]

Looking brilliant .
Wish I had time and space to get on with my MicraMini .

We have seen a lot of Punto's in over the years .
They do suffer from head gaskets and oil leaks and gearboxes , sure you would have found that out already , not knocking the project , just passing on what I know. Lovely revy engines and plenty around .

I fully agree with your reasoning behind not using a Aseries thats why I went down non Aseries myself.

When I originally bought my subframe from Allspeed to do the 1600 single cam vauxhall conversion Allspeeds owner told me that a 1.4 single cam vauxhall unit would run rings round a tuned A series . Should give you some idea of what to expect from yours . My Micra should have about 80hp so I am happy with that sort of performance.

Also on the Allspeed frame the front section of the frame that will sit behind the front valence across the car is a unboltable bar . I guess on the Vauxhall conversion there is a load of clearance required in front of the engine hence the wasted space in that area of the body is utilised . Fittting my Nissan engine in the Allspeed frame is aided by the clearance the front bar gives and helps with space at bulkhead to . Plus its a godsend when assembling/disassembling .

It must be so much easier with a bulkhead to mock it all up in ,than doing it my way using a mint shell . Not that my project was intended to be non A series in 06 when the shell was done.

[biggelmo]

Hi Jim, a chum of mine has been doing loads of Micra research flr his own conversion and has.found out that Nissan had to fit restrictions to the CG13 1275 engine as it made more power than they expected, if you removd the mesh from the throttle body top you gain an istant 3-5 bhp.
Nissan also resrticted it with a small throttle body snd inlet met manifold runners,throw them away and fitt 36 mm bike carbs and.it transforms the engine into something that can breath.

[biggelmo]

IsThis weekend has been spent making and fitting the engingine and gearbox mounts, a friend had so Mk1/2 Escort track control arm bushes sitting in a drawer which he had got from another chum whow used to use them as engine mounts in his 2litre Spedeworth hotrod to support a 2litre Pinto engine so they should be fine with a flyweight Fiat engine.


First off I cut a piece of the 3mm folded section then removed the tin end cover from the gearbox and layed it on and marked the 8 bolt holes and the inner hole.


Then I had the labourious task of chain drilling the centre hole....68 holes drilled twice (pilot & main) and the finished off shaping the hole with a die grinder.


Then I cut and welded a pair of strengthening gussets.


This is where it fits sandwiched between the box and end cover.


Next I cut a section of mountain bike fork steerer tube and welded in position and when it had all cooled down pushed a TCA bush into it.


These were then cut,drilled and welded into position.


For the first engine mount I used som 3mm folded angle and drilled it to suit 3 exsisting bolts on the block.


This is the basic idea ive got.


Again I used a section of fork steerer and welded into place, then I postioned the mount againdt the tower and drilled 3 holes to bolt the mount to the tower, I know it looks a bit "arse about face" with the captive bolts on the front but space is tight when tne doughnut is fitted in the tower so ill use mushroom headed allen bolts for the main build.


Finally iremoved all the old fixings into the block and fitted new bolts,i also cut and welded a stregthening gusset.


All done.


All nice and level too.


The front engine mount will go somewhere here.


Now I can start to think about where theses babies go..........BROOOOOMAAAAAH!!!!....... sorry.


This is the shape of the inlet manifold flange that I will be attempting next,if anyone knows someone in the Eastbourne area who is handy with a freehand plasma cutter then speak up other wise its chain drill time again......cant wait.

[monkeyjim]

Dont worry , throttle body gauze is long gone . ;D

Dave

[paul1275s]

Try Metalform, Courtlands Road Industrial Estate. They do laser/water jet cutting. Great job so far, enjoying this one, I am always contemplating which non A series to put into my GT shell, it's good to see something a bit different.. My choice would be a 205GTI 1.9 lump, but I think they are too tall, I want in excess of 120Bhp if I have to make all that effort!!