Rudi's 1430 supercharged classic mini - discussion

Here is the linky

Now this looks impressive, I know nothing like the calculations your doing and I love classic minis

Looks good mate, but with an added supercharger torque won't be much of an issue, I'd have gone for STD non stroked crank and a 73mm bore and looked at building it up to rev hard and handle high boost.

Those e45's can be modified nicely to be more efficient as well. If it's a blow through you should definitely consider fitting an in interccoler if possible, charger at the front is better than above the hot exhaust manifold.

Should be good fun though, get a salisbury LSD in there for real fun and arm excercises!

Cheers chappies.

The supercharger delivers torque low down, so to me it just doesnt make sense in fitting a more aggressive cam and push the power band higher up the rev range and make it narrower. Torque needs to exploit long gearing and loads of beans from idle. I'm using a modern profile cam with 270 degrees duration (@ 16 thou checking height), 0.065" lift on overlap and )0.315" of lift. Anything more and i'd be looking at 286 type profiles which are way too cammy and have sod all till over 3000 revs.

I did consider various options but engine longevity was also key and I wanted to maximise the torque and stick a longish final drive on it.

Part of the project was based on a challenge, people said it couldnt be done as I couldnt drop the compression low enough. I solved that problem

The E45 will be fine, it maxes out at 14,000 rpm and over 10ish psi the efficiency starts to drop off quite rapidly. It will be front mounted, above the manifold will be a plenum for the twin SUs. I have no concerns over heat tbh, but i may squeeze in a small IC.

I'm aiming for 130bhp and 130ish lbft of sausages. Of course I could make it more aggressive but it isnt solely a track toy so i'm aiming to maximise the 'area under the curve' and use it in town.

I'm tempted by a LSD, and am sure it will make driving round some bends 'interesting' !

Stay tuned for the next instalment

Yay! Someone who understands that it's not the height of the curve but how fat it is that defines the driveability of an engine once it's off the track!

Looking interesting, Rudi.

I'd raise the bar a little more, a good 1380 n/a can get to 130hp. Nothing worse than an awesome sounding engine spec and low hp from an owner erring on the safe side. The megajolt makes them less cammy mind. I'd go for an avonbar phase 2 cam.

+1

Great project thread, very thorough build. I'm going to enjoy reading this, keep it up

after working on minis for years Mr Vizard being a god in human form why have you gone to 1430 ... bore flex is a big problem and with forced induction ... why not 1299 or 1340
the best block you can get is a A+ block from a metro turbo better shells on the mains and more ridgid block
ultra lite flywheel and back plate are awsome ... makes the engine rev like a motorbike sc drop gears are good nice power transfer but it depends on the ratio you have ...
go for a dog box and a LSD with sc crown wheel and pinion ... they make a right noise ... but reliability is very good get rid of the duplex chain drive and go for a vernier belt drive a lot lighter than the chain and they dont stretch.you may want to look out for some austin maxi drive shafts they are thicker and you can have them machined to fit the outer cv joint

cheers guys

the road going highly cammed engine doesnt stand a chance. highly cammed engines have a narrower power band, require all driving to be within that range, require shifting to return the revs into the power band etc.

to get a rev hungry motor it isnt simply a longer duration cam, its different tolerances, which mean looser running and ultimately quicker wear. racers can afford to do it, they are rebuilt every few hundred miles. im hoping to design some longevity into it

higher revs means earlier failure which is fine if it is a track toy. anyone can build a screamer, but it simply means it will go bang quicker, and seal less a lot quicker.

i can achieve a higher average torque figure across the rev range, and plant it from just above idle. on the road mine will be quicker, much quicker

as for bore flex, im not concerned in the least, some of the turbo boys run 175+bhp 15+psi without problems on 73.5mm

vizards yellow bible may have been a good source in the 70's but things have moved on quite a bit since then. cam profiles have evolved significantly from the long duration, high lift on overlap to high lift fast opening and closing rates. they provide bags of torque, minimal scavenge effect and good emissions. on the downside wear is prevalent due to the aggressive opening & closing rates even without using heavy springs.

The A+ block is more rigid, ive over a dozen blocks including turbo blocks and i cant see any significant differences between the A+ blocks (with the exception of the mpi). One A+ casting is rumoured to be weaker but i havent seen any evidence of this.

Modern oils, pistons and ring packs and decent set of ARPs mitigate much of the old 'myths'. there is loads of meat around the cylinders, the biggest risk is breaching the oilway. if well built, correctly offset bored and with a decent engine builder (ie me ) it will be fine

In terms of gearing, it will be a standard helical box with sc drops, close ratio gears wont work with the design. Im running pre verto with an ultralite flywheel.

I expect it to go bang so i'll have a spare box to swap in at all times

I did go to a mini night at the Ace and some kid had a pickup mini running a T25 with a huge intercooler and NOS iirc he said it was 250, Can't remember what setup the NOS was mind as he used it on the drag strip.

Was it a pale pickup with blue cover? Ive seen one running 12's at the pod.

Yes!

personal experence SC gears and SC diff do make a difference...... i still question your bore choice.... but thats personal choice..... i realy do hope it all works out ok .... i will be watching this thread to see how things go
good luck with the project

It has been a while... update to my build thread here

Watching with interest, Rudi - many many years ago I had a mini which a previous owner had shoehorned something enormous into... took me ages to work out why spare parts never fitted!

(Re your compression: don't do what I did with an old Datsun A-series engine (Datsun licensed the A-series from Morris/Austin/Nuffield/whoever they were in the late forties) - ended up with a 1400 block and a 1200 head. Wouldn't start; stuck a second head gasket on to reduce the compression a bit. Went like stink after that - but only for twenty miles, at which point it expressed its disappointment at my engineering abilities by throwing two rods through the casing )

Ive not seen many old school transplants, they all seem to be Vauxhall or VTecs, or more recently rear mounted bike engines. Some micra transplants also, oh and different heads, ally 7 porters, and some twin cams variants.

Ive uploaded the baseline calculations on CR, showing all the necessary numbers. As it happens it doesnt look like i will need to play with much to get my optimum CR.

As this is a proper rebuild, I have the luxury of achieving the optimum spec by working on the head combustion chamber, deck height or even piston dish.

Ive seen a higher CR rattle badly when the boost was increase on the M45 supercharger so I'm aiming for 8.25:1 which should allow me some scope to 'play' without melting pistons trying.