19 replies to this topic

[sambarnes]

What is the the first stage of tuning on an mpi. Obviously exhaust is in there but what else is there thats simple and relativly cheap to do?

[mykweb]

depends how much you want to spend

Alloy Throttle Body - possible 5-6 BHP gain £145
K&N or Pipercross Induction Kit - possible 2-4 BHP gain £35-£70
Decat Pipe - possible 2-3 BHP if that £20
Decent Spark Plugs and HT Leads - possible 2 BHP gain £40 upwards
Stainless Backbox RC40 or such like - possible 2-3 BHP £100 upwards
Highlift Rockers - possible 2-3 BHP maybe more £150 upwards
Uprated Cam shaft but means engine out £160 upwards for the cam plus labour or DIY

Real BHP gains are in Replacement Head, stage 2 3 or 4 fast road head.

Remember what ever you do to the MPi you are limited by the gash ROVER ECU which I beleive never makes it over 99 BHP. The John Cooper Works kit for the MPi was claimed at 90BHP but I have never seen one that actually makes that figure.

If you seriously want to tune the MPi , get a new RCu but they are around £500 upwards but you also need a rolling road and a guy who knows what they are doing.

If anything Spend your pennies on supension. Negie Camber, Uprated Dampers, Red Dot Donuts, uprated tie bars, polly bushes, solid mounts etc....

Mike

[theoldmini]

what power differences will a head make
and what would you put with it

thanks

[mykweb]

what power differences will a head make
and what would you put with it

thanks

What power gains. well stage 3 kits usually consist of

RC40 stainless Backbox and some people swap the Cast iron Manifold for a LCB, but the Mini has an LCB as standard.
K&N or Pipercross Induction kit with pipes OR a replacement K&N element for the airbox
1.5 Roller Tip Rockers.
Performance Spark Plugs and HT leads
Stage 3 head fully polished, ported and gas flowed, 35mm inlet valves and increased compression ratio.
Power Boost Valve for the Fuel pressure. This is adjustable.
Gaskets for the head and rockers

Cost = £899 - £1100 depending upon where you buy it and what you already have

The kits are sold by Minisport, mini spares and other suppliers. They all claim 90BHP but I have yet to see one make exactly 90BHP, Closest I have seen was 86 and that was on a freshly built engine running 100 octane fuel.

I am saving for my Avonbar stage 3 head, they are around £590 ish and fitting it myself. The only parts I am missing from the list are the Head and the Fuel pressure valve.

Mike

[theoldmini]

So if I put a head and 1.5 ratio rockers I will notice a big improvement then. I have the rc40 and a k & n already fitted . What difference does the boost valve make as I thought the ecu would sort the extra fuelling. thanks

[Cooper1999]

One mod which did make a difference was this:
http://forum.minicoo...read.php?t=9730
I'd advise against the 52mm throttle body, unless yours is cracked, or you're going to a different ECU in the future.

As for the difference a head will make, here's one I prepared earlier:
http://forum.minicoo...read.php?t=9731
Fitting 1.5 roller rockers can muck up the emissions with the standard ECU so I didn't bother with them.

Horses for courses!

[miniman retford]

One mod which did make a difference was this:
http://forum.minicoo...read.php?t=9730


Horses for courses!

It's a lot easier just to remove the stop as i did, only one screw ! & yes i think it did improve performance !

[Cooper1999]

Provided you don't go over-centre! Anybody want to develop a barrel throttle body?

[mykweb]

One mod which did make a difference was this:
http://forum.minicoo...read.php?t=9730
I'd advise against the 52mm throttle body, unless yours is cracked, or you're going to a different ECU in the future.

As for the difference a head will make, here's one I prepared earlier:
http://forum.minicoo...read.php?t=9731
Fitting 1.5 roller rockers can muck up the emissions with the standard ECU so I didn't bother with them.

Horses for courses!

Yes cutting the bump stop off the standard throttle body works but you still have the odly shaped butterfly which messes up the air flow, and before you say it NO you cant grind it flat... ROVER thought of that one.

The alloy throttle body goes well on a car. Even with a zaust and air filter it will improve the engine's breathing and make acceleration a lot smoother and the throttle will respond with a slight blip. The alloy construction allows the butterfly to open and close fully and smoothly.

As for the rockers. I have them on a standard Rover head and standard MEMS. I also have a Swifttune SW5i cam, but come emmisions time.... sails throu first time.



THEOLDMINI - if you put on a head and 1.5 rockers yes you will notice a difference, but only for a while then you will get used to it. lol Its not going to be a massive difference, like getting in a mini and then getting in a db9...

Anyway why bang on about BHP... its tourqe that really counts

Mike

[Cooper1999]

Mike, I have to agree - the MPi does seem a little fickle with regards to emissions, some being affected more than others. My take on it was a good proportion failed at MoT time, and as the car is my daily driver I didn't want to have to *lady garden* on 'adjusting' the mixture, only to have to adjust it back afterwards. The main reason for fitting the roller rockers was to try and reduce any side loading on the valve stem (however small it would be!) and I was told by a number of people that you only really get the benefit of the 1.5's at higher (4500 - 5000 plus) revs. Again as it's a daily driver the truth is I'm not often up there, so to speak! It's bloody good fun when you do stretch it's legs though.
I did notice a lighter throttle pedal after fitting the alloy throttle body - thought it might have something to do with my rerouting the throttle cable for a more natural position. It could be the original one flexing I suppose. The reason I suggested not fitting one is because of the results on the rolling road (Slark's @ Salisbury). There was no difference when a restrictor was put on to simulate the original diameter plastic body. Both the alloy body and the roller rockers could be dispensed with (saving me money) and I'd still have got the same performance really!
I ended up with 74bhp, about what the early Cooper S used to have - I can only imagine how much fun they must be with their shorter final drives (which I'm not going to change to because, yes, it's my daily driver (and gets used on the motorways)).
Can I ask why you've got a cam fitted but no head? My next job is to build a bottom end and I'll be looking to maybe do a cam swap. Would I need another ecu to make the most of it though?
Questions, questions...

Edited by Cooper1999, 15 September 2009 - 07:57 PM.

[mykweb]

yeah sure, the reason why I got the cam and not the head was I did not have the £590 for the Avonbar head that I am after. LOL

I stripped my MPi back and rebuilt it from the ground up, and got my mini mechanic to rebuild my engine as it had a cracked gearbox casing, the front mount had sheared in the casing, there was scoring on the inner walls of the pistons and the engine had done 110,000 miles.

So figured when the engine is out get the issues fixed. I thought as well why not get the bottom end built the way I want to, saves taking it out twice to do the same job. So I got a SW5i cam fitted and duplex timing gear and lightend pullies, uprated clucth and got the block bored out to 1293.

I am nearly saved up for the new head and it will be a case of bolt it on and rolling road it to get the ECU to learn the new settings.

The engine as it is runs like a dream. I have a great rev range, however motorway driving can be noisy.

Technically you would need a programmable ECU to make the most of any Mods you do to the MPi engine. Remember that the main point of the ECU on the MPi was for emmsions. It will always give the best settings to make the engine run the best and to make the most of the fuel. What ever engine mods you do the ECU's programmed settings will still think everything is how it came out the factory and will still try work on economy.

The programmable ECU's start around £450 and go up from there. Emerald looks a good one, and might be the route I go for, but you do need a rolling road and a boffin with a laptop to fully setup the mappping for best results. The one I am loking at has 3 settings, one for full out power, one for daily driving, and one for MOT. This switch is hidden under the dash and you can change it back to the minimum settings for MOT time.

Other routes people have went to for MPi tuning is to scrap the MPi block and fit a carb engine. The same ammount of tuning spec will cost at least half the price, and you can do a lot more with carbs. But for relability and efficiancy the MPi is great.

Mike

[Cooper1999]

Yeah, makes sense doing the bottom end while its out (not fancy trying to do your own head?).
I have to agree with you on the cost/ease of tuning the carb engine over the injection, but I'm keen to stick with the MPi set up - I'm slowly gathering bits together for a Mini Marcos and would like an injection set up on that.
I didn't know that Emerald had the ability to switch. I was looking at Canems myself.

[mykweb]

maybe its not the emerald that is switchable. I have been looking at that bloody many they all apear as ECU's in my brain

Hmmm, I could proberly get my head ported and polished and the new inlet valves done locally for a fraction of the cost. I have yet to talk to the tuning comany in my local area who are carb mini daft

Mike

[Cooper1999]

Go on Mike - do it yourself! It's not that hard to make a decent improvement over the standard flow. All I did was buy a copy of Vizard's book and a Dremel! There's no difference in the head of the carb car and the injection ones (in terms of flow). There's a good feeling of satisfaction goes with it too.
If I can get my hands on a knackered old block I'd have a crack at making my own flowbench, but they're bloody hard to get hold of!
So much for simple tuning, eh sambarnes!!!

[Sprocket]

There is only really one option open for the MPI where programable ECU's are concerned and that is Megasquirt with the latest siamese coding. The only other possable option is CANEMS, oh and perhaps Polestar, but Megasquirt is closer to the mark on price