9 replies to this topic

[KermitStu]

i have been searching through the forum and there is tones of info on modifying a carb engine but what can be done with the mpi. maybe we can get a list going of mods that are able to be done ?

so if people say what they have done ? and how? that would be great. we can a get a one stop shop thread for modifying an mpi

[Cooper-202S]

You could make the following changes to an Mpi however I cannot vouch for how effective they may or may not be.
Effect Cost
New air filter K&N or similar - Improved performance and HP -Inexpensive
New High quality plugs and leads - Generaly improved performance -Inexpensive-
New exhaust Manifold med/lrg bore - Improved performance and HP - Moderate
Med/lrg bore exhaust & silencer - Improved performance and HP - Moderate
Roller rockers -Less mechanical resistance - Moderate
Roller rockers with 1.5 or 1.7 lift -As above with better gas flow - Moderate
Uprated performance clutch - Improves power delivery - Moderate
Port existing head with race valves - As above - Dependent on spec
New Cylinder head, stage 2 upto Stage 4 fast road - More Horse power - Depends on the head
Lighten and balance Con rods - Improved acceleration -Moderate - Expensive
Wedge and rebalance crank - Improved acceleration -Moderate - Expensive
Lightened flywheel - Improved acceleration -Moderate - Expensive
Skim head or block for increased commpression -Possibly more HP & torque - Moderate - Expensive
Larger throttle body 52mm - More HP - Expensive
Open out inlet manifold - More HP - Expensive - requires specialist
Regrind Crank upto 84mm stroke - More torque & HP - Expensive
(New con rods and pistons required)
Billet crank 84mm+ stroke - More torque & HP - Very Expensive
(New con rods and pistons required
Replace ECU with fully mappable unit - All of the above - Very Expensive

This is by no means an exhaustive list please feel free to add.

[elvisthepizzaman]

Thats a good list of mods. Its basicly everything you can do with a carb setup with the difference being the computer controlled fueling. I want to mention that if you do these mods then the engine will be more powerful but the gearbox will still be the weakest part. The large 13" wheels attached to the 2.76 differential puts a tremendous amount of stress on the gearbox already. Going all out on the engine and ignoring the gearbox will be a recipe for disaster. Plan on adding a set of straight cut gears to the list. You might even think about going to a set of lightweight 12" wheels before doing the mods as this will bring back some of the acceleration lost to the heavy 13s. Swapping out to a 2.95 will also bring back the acceleration but will cost you at the top end.

I would add to the list of having the pistons/rods/crank/flywheel be balanced together as a whole assembly in addition to each component being lightened and balanced individually beforehand. It reduces overall vibrations. The hard part will be finding someone with the equipment to do this.

[KermitStu]

thats great any one know of any more mods available ?

[CooperTrooper]

thats great any one know of any more mods available ?

superchip

[mini.rich]

thats great any one know of any more mods available ?

Hi, i'm looking into it at the moment, because i have the engine out and in pieces;- due to the oil pump knackering up and dropping a valve stem.
There really is only so much you can do before the ECU starts to take a dislike to it.
I had a stage 3 head with LCB manifold and RC40 system which was ok, but like all i crave more power
I'm planning on:
-Boring out not exactly sure what but maybe 73.5 as i will get the most out of it.
-Posibbly stroking the crank.
-Having it all balanced and lightened.
-Fitting an SW5 cam; there is not a lot of choice when it comes to cams because of omissions test at MOT.
-Refitting my stage 3 head, or possible fitting a stage 4.
-Duplex venier timing set up
-Megasquirt ECU
-Weber 40mm(twin choke) injection setup (with a maniflow manifold i just happen to have )
-Straight cut gearbox and drop, which i alsohappen to have.
-3.1 diff is most likely aswell.

I'm not sure on the flywheel front atm, gotta look into it. But thats the asic spec i'm gong for. I'm running 12's by the way.

Richard

[KermitStu]

sounds good let us know how it goes. what do you have? / started with a 1.3 mpi?

"Weber 40mm(twin choke) injection setup" how and where can you get that from?

Edited by KermitStu, 30 July 2008 - 07:41 PM.

[KermitStu]

what about these power boost valves i have been hearing about do they guve more power or are they they to smooth ou tthe accelaeration dose anyone have one fitted?

[Sprocket]

Power boost valves enable you run all the fancy bits listed above without running the engine lean.

They do nothing on a standard to mild tune engine, contrary to the name, they do not boost the power

[mini.rich]

sounds good let us know how it goes. what do you have? / started with a 1.3 mpi?

"Weber 40mm(twin choke) injection setup" how and where can you get that from?

Originally when i bought it, it was a standard MPi, i put a stage one kit on, and then added a stage 3 head. To be honest i didnt think there was a massive increase in power/acceleration compared to standard, most likely due to the tall FD. Unfortunatley i never rolling roaded it, so dont know the actually know the power increases.

Its not actually a weber, its a Jenvey 40mm twin choke pair of throttle body's, they have the same mounting flanges as a weber. I'll get some pics up tomorrow.

Hopefully it won't take to long to build, i've put my other rebuild on hold to do this. As i miss driving a mini so much, i'm fed up of the escort.