15 replies to this topic

[Twitch211092]

Hey everyone,
Sorry if this is in the wrong spot. New to the engine upgrading side of things.
 

So I've just bought a 1999 JDM rover Mini cooper with air-conditioning but both my wife and I find it quite lacking in power. I used to have a 73 Leyland mini with some work done and I remember that was heaps of fun so I'm trying to get back there. 

 

 

I don't want it mental fast that would be pushing the engines design limits but would just like to give it the power it needs to overtake easily up a hill. 

 

I'm having to shift down to 3rd up a hill and mash the throttle with 2 people in the car to hold my speed. 

 

I was thinking about cams, rockers, head, studs, springs etc etc. Do you guys think I need to upgrade the fuel pump?

 

I've done some research so far and this is what I've come up with though it's not finished.  (approx. $ in AUD)

 

What do you guys think, would this be ok, have I missed something or picked too much?

 

1. MED ST3 CAMSHAFT KIT (HT fast road Cam)- 1.5 ROCKERS MED $1,050.00
2. Stage 3 1.3i Mini MPi Cylinder Head OZ mini sport $1,994.00 as MED don't have stock of a JDM mini head.
3. Final Drive Kit - Standard Full Helical - 3.105:1 OZ mini sport $333.00
4. ARP HEAD STUD FIXING KITS MED $260.00
5. Uprated Head Gasket Set - Mini 1275cc - Copper OZ mini sport $112.23
6. MED ALLOY ROCKER COVER KIT MED $160.00
7. ANGLED FEELER GAUGES MED $22.00
8. Flywheel Puller Tool - Heavy Duty OZ mini sport $59.00
9. A 3.1 final drive TBC
10. A MED HEAVY DUTY X-PIN DIFFERENTIAL MED $460

     

Cheers,

 

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[Spider]

Can I suggest including your location in your profile, it'll help with replies.

 

Just change the final drive ratio. The late Minis have a tall or crazy tall final drive that IMO, just strangles them. I've found with most road engines something around 16 mph / 20 kph per 1000 engines revs is the sweet spot.

[Twitch211092]

Thanks for that. Yeah I'll update my location now. Yeah thinking going for a 3.1 as it will have abit of highway work but also zippy winding and country roads planned

[nicklouse]

As it is an MPI you will get little from those mods.

 

have a read of the MPI section.

 

final drive change yes and as you are in there the Xpin change.

[Spider]

 Yeah thinking going for a 3.1 as it will have abit of highway work but also zippy winding and country roads planned

 

From experience, I feel even a 3.1 is still too tall.
 

[Lplus]

 

 Yeah thinking going for a 3.1 as it will have abit of highway work but also zippy winding and country roads planned

 

From experience, I feel even a 3.1 is still too tall.
 

 

I use 3.2 in a lightly modded 1275 and a lightly modded 1098 estate and wouldn't go any lower numerically.

[Twitch211092]

Thanks everyone,
I didn't know there was an MPI section so I'll have a read through it. 

[coopertaz]

agree bin the ludicrously tall drive on the later cars, for FD love the 3.44 wouldn't be too low running 13" rims. don't forget will also need to change speedo drives whatever FD you choose.

[Twitch211092]

oh so true! thanks @coopertaz
do you know if there is a guide out there for final drive to speed drive changes. I'm thinking 3.2 as I have lots of highways around me to get to anywhere but alot of hills as well. what do you think?

[timmy850]

I have a 3.44 diff in mine. 100kph is about 3800rpm and 110kph is about 4100rpm. A mini engine will happily rev all day on the highway at that rpm

 

There's some ratio calculators below which lets you check RPM and speed with various combinations of wheel size and diff ratio. 

http://www.guess-wor...ech/ratioKM.htm

https://www.classicm...chnical/gearing

 

There are also many mini specialists in Australia, some who sell parts and some who modify minis

Readspeed

Graham Russell

Link Automotive

Mini Classic

Karcraft

Minisport Adelaide

 

From the UK my preference is minispares

Minisport OZ is an offshoot from Minisport UK

[Pete649]

Here is a page from one of the original manuals which gives some final drive speeds.

 

 

 

 

 

[Spider]

Here is a page from one of the original manuals which gives some final drive speeds.

 

 

That's handy for sure but also high-lights why I prefer to express a suggested final drive ratio as a certain speed per 1000 engine rpm. The chart in the older manuals is based on 10" wheels, which have a rolling diameter of roughly between 19 and 19.5". It looks like Twitch has 12's, these have a rolling diameter of from about 20 to 21.5". It makes quite a difference.

Here's a page from a Special Tuning Manual, that has a formula and a tyre chart, though most (all ?) of these would now be well and truly NLA now days, but does illustrate the differences;-

 

 

 

 

[Midas Mk1]

My MPi was originally 2.7 13’s, on 3.2 10’s now, with 97bhp I wouldn’t even think of higher gearing, my 1380 has a 3.4, swapped it from a 3.1 last year, brought it alive.

[Twitch211092]

Thanks Midas, I was thinking 3.2 but did your 3.4 really make all that much difference? Maybe I should go 3.3 or 3.4. Just didn't want it working too hard on the highway but right now its so sluggish... It's kinda sad haha

[coopertaz]

on 3.44 still ok on highway have other car running it on 12's and can go along quite happily at 70mph just over 3500 revs. would expect very slighly less on your 13's. i used the guess works calculator for the drives and is 5% high when compared to sat nav. also used calculator for other mini with 10's and a taller diff with same result, so a vote from me for this calculator