47 replies to this topic

[Bill USN-1]

i know megajolt isnt an option on this car because ur using efi but on the picasso mj site theres a lof of info about pickup wheels, where to get them and what can be modified to suite!!

also would a spi or twinpoint flywheel/pickup combo do the job?? after all rover put it in there for a reason!!

I did not find any specifics on the SPI/MPI flywheel. I assumed it was probably a 36 tooth wheel?

If so it will work for other systems but not the GM system i am using.
Mine is a 6 + 1.

Most of the aftermarket stuff is 36 tooth and a lot of them use the ford EDIS parts.
I'm sure most companies would cut a wheel for me.

They do list several options on that site. I looked when it was first posted.

Anyone have any links or pics of the SPI/MPI parts and specs?

My 96 MPI motor did not come with a flywheel or clutch (or head)but it does have the serpentine balancer on it.

[fikus01]

if you have a std flywheel could you use that as the timing wheel if drilled properly and balanced!! the spi tpi fly housing had a hole for a sensor!! or u cud drill ur own!! sorry if im seeming to complicate things on here but im learning more about this programmable electronic ignition lark as the days go on and want to be as ready as i can when i try it for myself!!

[Sprocket]

SPi

36 -2 one at TDC one at BDC

[Sprocket]

MPi

36 - 4 missing teeth at 30, 60, 210 and 250


The later SPi flywheels and the MPi flywheels are the same, the only difference is the reluctor, which is pressed steel and a tollerence fit in a groove of the flywheels.

These can be modified for other tooth patterns very easily.

Also worth pointing out, those who spend £300 on the Superchips icon could easily do much the same by moving the reluctor position, thus achieving the same for far less. And also be aware that the injection clutch diaphragm is specific to the injection flywheels, non injection diaphragms are in the region of 30 degrees out, but if you adjust the reluctor to suit it becomes not so much of a problem.

Edited by Mini Sprocket, 18 October 2006 - 08:32 PM.

[Bill USN-1]

SPi

36 -2 one at TDC one at BDC

Oh my...
That is very interesting Mini...
I have one of those fly wheels. 36-2
I thought I was missing something in the middle of it. I was try in to figure out how it mounted on the engine!!
Is there an online manual for the SPI or MPI motors?


Is the sensor on these a VR-variable reluctance sensor?


If so...fikus may be on to something...
Problem is I just ordered a complete new pre-verto clutch kit...so I need to make a decision fast before the order ships!!

I might be changing paddles in mid stream!! But maybe not...still need the clutch cover and arm..

Edited by Bill USN-1, 18 October 2006 - 09:20 PM.

[Sprocket]

The clutch diaghragm is missing on that fly wheel. The transfer case has a hole to mount the sensor under the starter, you can see it in the pic below.

The flywheel you have is the older type which has rivots holding the ring also. Makes it a bit more difficult to adjust its position. Dont forget what i said about the diaghragm and the timing errors though.

As far as Im aware, the sensor is a variable reluctor, I can check if its resistance tomorrow but i think its voltage. All this was discussed on MSEFI forum but it looks like some clever chap has binned it. As far as im concerned, if its good information, irrespective of it not being viewed often, it should be kept. Very anoyed about that to be honest.

As for tech info, you can buy the Rover Rave CD which was the dealer tech info refference, or you can buy the Technical literature from The British Motor Heritage http://www.heritage-...p/techpubs.html

Edited by Mini Sprocket, 18 October 2006 - 10:04 PM.

[Bill USN-1]

Thanks for the pics Mini they help a lot more then just talking about it!!


Did a little more parts cleaning and identifying.

Here is the stock throttle body- TB. and it's bore size.






And the 1 barrel GM TB.





And finally the 2 barrel TB






Now a couple interesting things i found...
The SPI injector measures the same resistance as the GM injector. 1.2 ohms.

The TPS- throttle position sensor from the GM TB bolts right on to the SPI TB!!




What that means is I could actually bolt the SPI on , swap out the TPS with the GM one and run the the system with my GM computer.

The only thing I lose by doing that is the IAC-idle air control on the GM TB.
But the idle can be adjusted manually like a carb.

One question I have is....
what is this thing in the bottom of the manifold?
It measures about 7ohms so I'm assuming it may be an electric heater....

[fikus01]

looks the same as spi on a rover k-series, i assumed it was a heater too!! only 1 rather large gauge wire feeding it that jsut seemed to give 12v or nothing!! spells out heater to me!!

im very interested in that tb design u have there!! eems like the missing rover link if u ask me!! the 1 thing they didnt do thay they should have to get the best out of the a-series!!

[Sprocket]

Why do you loose the IAC??

What is the IAC on the GM is it PWM, bipolar or unipolar stepper?

If its PWM then just mod the manifold to fit a PWM valve. If its a stepper, bipolar(4 wire) or unipolar (5 or 6 wire) you can use the SPi stepper.

The item in the bottom of the manifold is indeed a heater. Its used for cold start, youll get a flat spot in engine response if its not used and the engine is cold . As far as im aware it is powered all the time when the engine is running via a relay. Its a PTC elememnt so when the temp rises so does the resistance. Id be plumming in the water heating as well.

Oh and if you wish to shorten the name it Sprocket or Sprox for short

Edited by Mini Sprocket, 19 October 2006 - 10:47 PM.

[fikus01]

looking at the size and shape of the carb wouldnt it be easier to try mounting it to one of the downdraft webber manifolds?? or even the tpi one?? i know that rover put a lot of development into the tpi manifold to increase the torque etc!! (only for it to be ruined my a tall diff)

[Sprocket]

The increase in torque on the MPi allowed Rover to fit the 2.7 diff without affecting the overall performance compared to the 3.1 diff in its predecessor. What it did do is reduce driveby noise ( that was also the main reason for front mount rad) and increase MPG, also giving a far more comfortable drive on the motorway. Without the 2.7 diff, chances are the Mini would have ceased production in 1997. The MPi was a whole package just to stretch production to 2001. Any one thing if it was not done it ouldnt have passed the regulations and cesation would have been 1997.

So, granted a 2.7 diff is not a performance item, but thats not what it was fitted for. It certainly didnt reduce its performance.

The MPi does not have a heater because its port injection, nor is it water heated. It is still a single trottle manifold and would still require modifying.

Ill be very honest and say that i wouldnt bother with the twin throttle unless you are intending to run an engine with mahoossive power. Im running a modified 44mm throttle body with a larger 611cc injector on my 80bhp 1399cc with uber potential still to come. Bigger injectors suffer at idle and when one is required, its better to fit two smaller ones. Standard power levels its not remotely required.

[Bill USN-1]

If its a stepper, bipolar(4 wire) or unipolar (5 or 6 wire) you can use the SPi stepper.

The GM is a 4 wire stepper.
So once I find the wiring diagram and possibly the pinout for the SPI ECM, it should be a simple change over. As big as that thing is, I seriously thought about cutting it off to clean up the looks some!!

Oh and if you wish to shorten the name it Sprocket or Sprox for short

Sprox it is...I used to watch the Jetsons cartoon growing up, IIRC the dog was named sprocket, so it would feel wierd calling you by a dogs name......

looking at the size and shape of the carb wouldnt it be easier to try mounting it to one of the downdraft webber manifolds?? or even the tpi one??

I didn't want to wait too long to get the project started, I would have liked the weber manifold but I think it would have cost me a little more then the 15-20 euro I paid for this complete setup.
I have heard the weber is about as easy to find as hens teeth There was one on ebay for about 250 euro!! But if anyone runs across one for cheap...let me know. Weber or MPI.

My plan is to use the manifold as is and simply make seperate 1/4" adapter plates for each TB. Then I can tune with one, swap and tune the next, to see if there is much difference.
I still need to take the bore measurements and figure out the area for each.


Sprox...did you say the regulator is set to ~15psi on the SPI?


edit:....

area of bores.

SPI- 1.610=2.035
GM 1- 1.680=2.216
GM 2- 1.375=1.484 X2=2.968

Edited by Bill USN-1, 20 October 2006 - 05:58 AM.

[Sprocket]

yes, fuel pressure is 15 psi or 1 bar in the metric world.


Right then, if the GM stepper is indeed four wire, you need to carry out a slight mod to the SPi stepper.

Remove the motor from its housing. There is a small PCB that os soldered to the motor terminals, six in all. The middle two are soldered together with one wire. This is the center tapping for the winding of a Unipolar motor. You need to make sure that this is removed and that means making sure that there is no connection between the windings also. You now have a bipolar motor. Alternatively you can retro fit a bipolar motor quite easily into the housing, if you find the right one.

Bipolar motors are some what smaller than the Unipolar motors for the same holding torque, so, the only problem i see with modding the original unipolar to bipolar is the amount of current it will draw. Will the ECU be up to it. Like I said its not difficult to retrofit for a genuine bipolar motor

http://www.allegromi...irpax/smh29.pdf

http://www.solarboti...h_steppers.html

http://www.doc.ic.ac...stepper/others/


And yes i am nick named after a dog, but its more to do with the dog from fraggle rock. In the uk the Captain of the light house was Rikki Foulton, a Scottish actor and comedien. I being Scottish gott branded Sprocket because of the way the Captain pronounced it. Its stuck ever since.

[Sprocket]

Oh and another thing

The throttle size on the SPi was the same across ths Rover SPi range. It served the 1.1k8, 1.1k16, 1.4k8 and the 1.4k16(which is rare as hens teeth) The injector was the same for the 1.1k8, bigger on the 1.1k16/ 1.4k8 and bigger still on the 1.4k16.

The throttle of 1.615 or 41mm will satisfy up to 84hp as standard.

[fikus01]

oh me dear god!! i just gave away a a spi 1.4 k16 tb a ew weeks ago!! he didnt even want the tb, jsut the heater plate off the manifold i jsut cudnt be bothered to seperate it!! i think im just guna go give him a call!!!! (runs to pone very fast!!) :S:S:S