10 replies to this topic

[ryomini]

Hello

hoping to pick up a little more info on the possiblities of tuning the spi mini (keeping the injection and standard ecu for now)

I see some suppliers offer a lightened steel flywheel but this requires changing numerous other parts in order to be adapted – and costly

 

How about a lighter clutch pressure plate (compared with the standard set up), would that help me 'spin her up' a little faster

Obviously balancing the whole clutch mechanism will make things smoother.

 

Has anyone made any interesting performance gains on the Spi clutch assembly that I should know about before reassembly (ie for now it seems I have to stay with the original clutch (as I'm keeping the injection) but may be able to upgrade the clutch plate – please correct me if that is wrong)

 

(other upgrades would be the usual oversize pistons, tuned head, valves, timing chain etc)

seems that the spi mini flywheel and clutch assembly isn't easily modified

 

[jaydee]

A common mod is to move the reluctor ring to gain one or two degrees extra advance

Anyhow this could make an interesting read:

http://www.calverst....Fi flywheel.htm

[nicklouse]

less rotating mass will allow things to accelerate faster and that is it.

 

there is some good reading on this in Vizards big book. including some math to work it out.

Edited by nicklouse, 19 November 2015 - 02:32 PM.

[Steve220]

I'd rather get the crank knife edged than lighten the flywheel.

[brivinci]

Is this to be the first mod you are doing to the car? Less mass is good but also has its downsides. Momentum becomes less. They sell lightened flywheels for the SPi. I've never driven a car with one fitted but would be interested in seeing how much improvement there is.

[ryomini]

@nicklouse Yes, and you have racing experience so you know very well how the difference feels.  I believe that the Spi mini flywheel is not good for lightening so what can be done (and the steel lightened flywheels available demand changing other parts too) with the original one is my curret problem

 

is it worth modding the crank as @Steve suggests ?  I don't see many other members modding the crank appart the usual polishing, grinding, checking etc

 

@brivinci this is the first mini I have ever taken apart - I am hoping to modify the motor for fun road use, I have a thread 'Project W' I hope to flow the head, clean it all up, balance all parts statically and dynamically, add straight cut gears and a cross pinned diff, after that I'm not so sure what else,

[Blatherskite]

We had a near 20bhp increase on the SPi by:
Polish & port
1.5:1 rockers
Maniflow LCB exhaust at 1 3/4"

The selection was called Stage 3 tune by Minisport. With some nice tyres at 12" and 1.5 degree negative camber, really made a noticeable difference to the car.

[Guess-Works.com]

If you want to change the flywheel, I would advise the following...

 

http://www.med-engin...ultra-light-st2

[ryomini]

@jaydee that article made a lot of things clear

a steel lightened flywheel will save you 2kgs (4lbs) and cost around 500usd then you will need a rally clutch for around 200usd for the timing to work (original clutch is not compatible with the upgrade flywheel for timing issues)

are these 2kgs worth a 700 usd investment (and that's before shipping)

 

@Blatherskit that is really good to hear as I am getting ready to port the head, do the valves and I am going for 1.4 rollers if I can find them as I have read many threads saying the 1.5's cause quite a few problems,  I'll stick with my very neat little pipe for now but may upgrade to the lcb later on  - I'd be more than happy with a 20bhp increase along with some weight saving that should be going on too

 

@gearbox - WOW *-* exactly what I am looking for, looks fantastic.  If they can post to Japan for a reasonable amount I will be saving up for one of those.  Thanks for the tip :)

[Guess-Works.com]

@gearbox - WOW *-* exactly what I am looking for, looks fantastic.  If they can post to Japan for a reasonable amount I will be saving up for one of those.  Thanks for the tip :)

 

If they wont, I will...

[ryomini]

@guessworks thanks for the offer

will let you know when I am ready for that part - maybe next autumn ?