5 replies to this topic

[mambaman]

I think most are aware that SPi's are ecu (fueling/ignition) limited to the amount of power they can give and most top out around 85bhp.

I know you can get enlargened TB's which are opened up to 1.75", but do they give anymore power over the 80-85? or are they required to get to the dizzying heights of 85bhp?

Does anyone have any ideas as to what can be done to increase the potential? Im looking at non-drastic options which dont involve ripping out stuff.

Comments are welcome, but can we avoid the carb debate as im looking at keep the injection

[Bungle]

try a pm to mini sprocket if he does not see this

he likes playing with injection minis

[Sprocket]

Well

Its not realy the throttle body that causes the problems but the injector.

The injector is only good for 87bhp at %85 (%80 being the accepted normal maximum in the automotive industry). Anything over and above this then you are running the danger of the injector hitting %100 (on and open constantly) this results in no more fuel reaching the engine, which can cause the engine to run lean when on load ( foot to the floor) maybe resulting in engine damage.

So, And it has yet to be proven, fit a bigger injector and it should improve things. Be warned though as idle may well suffer as the injector is now so big that it now has to try and supply as little fuel as it can by slowing down the duty cycle, in doing this the system looses its controlability. Its kind of hit and miss.

I have successfuly run a standard SPi with the bigger injector from an 8valve Metro 1.4 K but it may not pass emissions, i never had it tested.

The 1.1K series is the same injector as the Mini and good for 87 bhp. The 1.4K series 8valve injector should be good for 103 bhp and the 1.4K series 16valve injector should be good for 116 bhp. All these figures are at the %85 duty which should be considered the limit.

Going back to the throttle body, i would say its only worth the bother of modding one to 44mm if you are expecting max power or Like me, have gon BIG on CCs. As far as I am aware, you cannot buy a larger throttle body for the SPi, you have to make one and its far from easy, trust me.

Setting all this up NEEDS the use of a Service tool like the Crypton ACT and a trip to the roller to ensure you are not going to melt any pistons.

Also not that tuning the SPi engine to these levels requiring the use of a bigger injector may well need different ignition timing curves that are unchangeble on the standard ECU, but then its only like using the standard distributer on the same engine with a carb, so you are never going to get the full benefit any way.

Hope this helps

[mambaman]

After seeing you white mini project on TM i was hoping you would find this thread

44mm TB's were available from W&P, afaik they are just bored out Std TB's with bigger butterfly's? But i havent looked into it at all.

Interesting to find out the info on the injectior, has anyone actually tried it with the replacement injector you mentioned? Im half tempted to try it now as his car is still working. It'll be 1380 if i can get this working properly, if not it'll be 1293.

What are you doing for a TB? I presume a more conventional throttle pot and some work to put all the sensors on?

What are your thoughts on the kent MD274 vs sw5i?

[Sprocket]

my vote is the Kent 274SP, it was specificaly designed for the SPi. I was looking at it too, other people in the know have said that is the cam to have for the SPi.

My throttle body is a bored out standard one with a HIF44 throttle disc, but like I said, its not easy.

As for the injectors, you can use similar bosch items from many other manufacturers, but they dont realy get much bigger than the 1.4kseries 16valve SPi injector due to the problems at idle. Find them at your local scrappy, Rover 100 1.4, Rover 214, like I said if you can find a 16valver 1.4 SPi grab it because there aint many. No need to remove the injector from the housing as the housing exactly the same.

The Bosch part number for the injector you should look for are - Mini and 1.1K8 - 0280150682, 1.1K16 and 1.4K8 - 0280150683, and unconfirmed, the 1.4K16 - 0280150657

[mambaman]

cheers for the info, i might give it a bash just to looksee. Any chance of anything seriously going fubar?