41 replies to this topic

[jimjammie]

I understand that the SPI Mini isn't particularly easy to tune. Especially as regards the emissions for the MOT.

Does anyone have any advice on the best way forward.............looking for about 100BHP at the flywheel and who best to go to for tuning or who buy from.

[Sam Walters]

its been done by a fella called Sprocket, i dont think its been easy though, to be honest it would be easier to build a 1380 with a sw5 cam and a fully worked head to get your 100bhp running on a hif44, perfectly drivable and a shed load of torque.

[mini_turbo_pete]

If you can find a nice early Rover 820 in a scrap yard they an a SPi system on them they had a much bigger throttle body but in my opinion i would dump the injection system.

You get about an 8hp gain by not using the injection and putting an 1 3/4 on it.

Edited by mini_turbo_pete, 29 February 2008 - 11:01 PM.

[timbo]

everyone will tell you to go carb. But there isn't much difference in modifying either. If you want a nice drivable but quite rapid spi then you can't go far wrong with the following-

stage 3/4 head
1:5:1 ratio rockers
full exhaust maybe maniflow or rc40, you can either keep the cat or go straight through although you may have a bit of trouble with not having a cat come MOT time. I think there is a sports cat for sale by one of the suppliers however.
air filter pipercross or K&N.

This will give you a noticable increase in power and can all be returned to standard should you want to. Then depending on how deep your pocket goes then you could do-

all of the above plus
full engine rebuild
stage 4/5 head
lightened internal
more suitable cam
larger bore throttle body
new custom ecu or megasquirt
straight cut gearbox

which would give you a fast engine, which if it just isn't fast enough for you could always be supercharged.

[Sprocket]

100 bhp at the flywheel is indeed possible, and very driveble. The SW5 is not the cam to achieve it either. You will need to go to 1380cc at least to get it. Use the Kent 274 or the 274SP cam and then anything goes as regard tuning as you would any engine, whether carb or not.

Lightweight flywheels can be used but will need a crankshaft trigger installed on the pulley and set up correctly. The ECU will have to be replaced with another along with the injector.

A Large bore LCB would be required, but the standard size LCB would suffice if thats all you can afford.

Everything that can be optimised should be, by similar methods as per Visards books.

If its done correctly you will get in the region of 100bhp and 100lbft torque, pull from 1500rpm all the way up to 6800rpm where the ECU cuts out, it will come on the cam and feel very strong from around 3000rpm

Build this on an engine from a carb car and keep the engine number and pin it back on the block when the machining has been done so you can prove its identity and get round any emissions issues, not that there would be, if you build it right. The cat can be retained, but at this level of tune, would be loosing you some power, but not so much you would generaly notice while driving.

100bhp 100lbft is a lot in a Mini and a whole lot of fun

[jimjammie]

Thanks Sprocket et al.

Looks like 100BHP at the flywheel might be a bit difficult to obtain That's not really a problem but I would certainly like more power & as much torque as possible.

This is the present state of "tune"
Group N spec with a new Rover 1275 single point injection engine
MBE engine management system
Swift tune SW5i cam
Mini spares Hi lift roller rockers

I'd like to keep the injection and the same engine [COSTS!!] but could be persuaded to go carb or throttle bodies depending on cost and the ability to pass the emissions on the MOT. Big valve head? But from whom? Cam if I'm not going 1380?

Sprocket though seems to be advising a complete engine change.........Build this on an engine from a carb car and keep the engine number Is that right Sprocket in that you are advising me to ditch what I have and start afresh. Sounds a bit drastic & somewhat expensive but no doubt you can comment further on this. I'd especially be interested on the expected costs of going down that road.

What thinkest the panel? I'd also be very interested to get advice on who to do the work. Drop me a PM if you don't want such comments on the forum.

Ta

[timbo]

Are you saying that your engine is currently a Group N spec engine? I would have thought that you should already be making 100bhp.

[jimjammie]

No sorry. Although it says Group N spec it actually isn't. It's a standard engine with the "bits" detailed.

I would have doubted anyway that Group N would produce 100BHP at the flywheel.

[Sprocket]

I only suggested to use a carb block for making it easier when it comes to emissions testing. There is no real need to use another block. I was thinking how I do things, sorry. I have an engine in the car, I build another engine and swap it out. If all you have is one engine, then use that. There is no major differencies in blocks between Carb and SPi. It was purely something that was intended to help with the ever problematic emissions test.

Group N is Showroom spec, therefore minimal modifications are allowed. I think you can carry out minor mods to the engine to increase its power by 10% from standard to counter the added weight of the safety equipment that was mandatory, IE Safety cage and fire extinguishers. So its a pretty standard engine, 1293 would be alowed as its a standard size rebore and still falls within the 1300cc class.

If you have the MBE programable ECU that Minisport marketed for the SPi, then you are free with tuning on this, if i remeber corrctly the MBE ECU is an Alpha N controller and doesnt use the MAP senosr, so you can use any cam you wish.

100bhp is not difficult to achieve, it will cost though, but that would be the case anyway. I wish more people would build an engine properly rather than just sticking the biggest cam they can get in there to get the results. the trick is to get the results with less. Then there is the old saying, 'no replacement for displacement' 1380 is the way to go.

You will be hard pushed to get 100bhp with an SW5 however you go about it. The SW5i is for the MPi, if do not have an MPi block, then there is no need to use one of those, there is no difference in profiles.

I have lined some one else up with a spec list to build a 100bhp SPi engine using the SPi injection manifold, injector and A standard ECU. It should in theory pass emissions as the standard engine would. The problem is the Cat, to satisfactoraly pass the emissions correctly, you need a cat, the standard Mini cat is very good, but will be costing you BHP, maybe 5% around 100bhp. You can get aftermarket cats that flow better, or you could just remove it and see how you get on with the emissions test. I achived 100bhp with the cat, so reconed that there was more there without it.

Powerfull engines are never cheap!!

Sorry for the confusion

[jimjammie]

Thanks Sprocket. No problems. I just picked you up wrong.

I'd be very interested in your spec list to build a 100BHP SPI engine & a rough idea of the costs.

Losing the odd 5BHP isn't really a problem. As long as the engine is reliable & and has good torque. In fact the 100BHP is just a figure to aim for. It doesn't have to be the magical ton.

Someone suggested that Omex might be a good bet as regards fitting a different programmable ECU. They're also apparently good for throttle bodies. I've no idea if that's right or not & I'm just basically trying to feel my way back into a little light competition.

[Sprocket]

100lbft torque is gearbox breaking amounts. Depends when you say 'reliable' as to what it actualy means. Any powerful A series engine is generaly reliable, but the time between overhaul periods is usualy shorter. Reving the nuts off it doesnt do 'reliability', in the normal sense, any good. Thats why i recomended the Kent 274 cam, more so the scatter pattern version.

Problem with programable ECUs is the fact that you will never ever get it tuned to the same degree as a standard production ECU, it will also not be as reliable as the standard production ECU. If you stick with the standard SPi injection manifold set up, you can still use standard production ECUs, not nescisaraly from a Mini If you want to fit a wilder cam than the 274 then you do need to consider the programable ECU for more than one reason, but then its starting to become more like race engines.

I'll PM you a spec list and you can look at it from there, but you need to 'blueprint' everything to get it to work, unlike the majority, who just bolt stuff together and wonder why they dont get the results, this goes for carbs as well.

[timbo]

Sprocket could you PM me the spec list aswell please mate.

cheers, timbo

[ICAM]

Sprocket could you PM me the spec list aswell please mate.

cheers, timbo

Me too

[John H]

Sprocket could you PM me the spec list aswell please mate.

cheers, timbo

Me too

me three if thats ok. my spi is starting to be broken and needs some engine attention

[jimjammie]

So Sprocket, depending on price, [Look forward to receiving your spec] it looks like you're really saying that I'd be better binning the SPI & buying say the MED Type R at £2,750 inc gearbox. Mind you that doesn't include any of the ancilliaries such as carbs, distributor, alternator, manifold etc etc. It's also an extra £350 for S.C. close ratio gears.

Thoughts anyone?