Technical Differences between SPi and MPi engines?

[JDMT]

Apart from the obvious injection system and I believe the exhaust manifold is different, what is the difference?

My real question is can I use just the block and head from an MPi to put into my SPi with all the SPi bits on it? I don't want power steering.

If I use the MPi system would I have to change ECU and have new keys made with the MPi code?

I've just bought an MPi for the tyres and seats and a few other little bits but my engine is old now and I'm thinking I can use the MPi engine from the newer car for now until I get round to doing a 1242 swap.

Any input would be appreciated, thanks .

 

[JDMT]

Ok so I've been reading loads of different threads and I understand a bit better but I'm actually a bit more confused.

I assumed the MPi system would be better but it doesn't seem so.

If I used my Spi head on the mpi block I would need to use the crank pulley from the spi engine and the alternator/crank pulley from the spi also?

Then I could use the same ecu (spi) and just change literally the block?

My big ends are on the way after an oil pressure issue incase you're wondering and I have a full mpi car spare.

 

[Jajr2009]

Difference spi and mpi being p60 and p75
P75 has higher compressio
P75 has 866 cam, later p60 has 866 cam too 1996>
P75 has 4 injectors and probably a different ecu map.

You could use the full p75 engine there is a way to cut the spi wire at injector and make the 4 injectors work. Been covered here on the forum. I have not done that yet.

Or use the p75 block with crank and pulleys
P75 headgasket, p75 belt, p75 866 cam and camgear along with your 1108 head, you can even use the bottom of the p75 throttlebody and machine or dremel it to fit the 1108 top and u will have a 38 mm spi throttle body.

Kinda like what i'm doing right now but with p60 176.b4.000 engine

 

[JDMT]

I'm even more confused now because I thought the P75 was a 1242 engine? I have 2 seicentos, both 1108cc, one spi with knackered block which I'm keeping and one mpi I'm taking parts from.

So you're saying I can use mpi block and spi head with mpi cam/pulley? Would the timing be compatible with the spi ecu? I've read here the pulleys are 3 degrees different, or it may have been the crank only, I can't remember.

And use the bottom of the mpi throttle body? This is interesting.... I'm not too bothered about a full mpi conversion, but I fancied a bigger TB.

I have searched around the forum but there is so much varying info and I can't seem to find anything on this specific combo.

Also do you know if there are differences or advantages to either gearbox?

Thanks for the reply.

 

[Jajr2009]

I must of misread I tought u had a 1242 mpi block from a p75. My apologies. Imo I think the block from the 1108 are both the same. Maybe someone on here can confirm.

If you have to remove gearbox engine and to install a 1108 back. Why not get a 1242 block?

What of the spi of yours is damaged? Headgasket? Rings? Helps me get an idea of what the problem is.

 

[JDMT]

The problem with my current spi engine is the big end shell bearings. I had an oil pressure issue which was resolved quite quickly but the bottom end has developed a knock. It's still running and seems ok when it gets warmed up but I'm not happy to just leave it.

The reason I'm not doing the 1242 conversion right now is just a case of money. I managed to get the mpi car cheap for tyres and parts, it runs but has had a rear shunt. So it would just be a temporary fix so I can keep using my car until I have enough to splash out on everything I'll need for the 1242 job. I've just bought bottom arms, track rod ends and poly bushes and this mpi came up in the same week and I've skinted myself getting it all!

On the plus side though the running gear will be ready for the transplant when the time comes as I've already installed new dampers and 40mm springs.

And the reason I want to use my spi head is that I've had it skimmed in the last year when I did the head gasket, and I'm happy to keep the spi system for simplicity.

I have no ABS and no power steering either and I'm happy with that!

 

[Paul106xsi]

I've never done it myself but my understanding is that the mpi bottom end is a straight swap for the spi bottom end. I believe the crank pulley only needs changing for the 1.2 conversion, hopefully someone who's done this before will be able to confirm.

You could use the whole of the mpi engine but it then needs looms replacing etc etc to match the different ecu so would be a load more hassle.

 

[JDMT]

Well that's good news, should be a straight forward job then.

 

[JDMT]

Started stripping the mpi engine down today, emptied the water and it was horrible brown, then emptied the oil and there was quite a bit of water in there. Not the end of the world.

First thing I noticed is the cam pulley seems to be different and the timing belt is slightly bigger than on the spi. So I'm not sure which combination of belt and pulleys I can use to keep my spi head. Someone must know, please help!

 

[cc1]

You must use the complete spi pulley system with spi alternator.

 

[JDMT]

Thanks mate, are the cams different? Is there any way I could use the mpi alternator as I noticed it is slightly different with a bracket on the back and the one off the mpi is younger and looks a lot cleaner than mine!

 

[cc1]

With reference to the alternators, as long as the pulley lines up and uses the same belt. You can change the pulley if needed. The electrical connections should be the same.
The mpi cam is a 4x4 and is designed for lower rev range performance.

 

[JDMT]

I think I would prefer the lower rev range performance, would it just work without any problems/modifications to the timing from the ecu?