This is just me doing some dreaming about my ideal engine .

Im just after some ideas on how the "brains" on here would do it.

I realize that it is the total engine package, not just the fancy parts that you buy. So this is what id like....

- I would like it to be: N/A , twinky and emphasis on response and revs. I do want it to be reliable, and be able to handle track abuse. I dont care about numbers , i just want it to be fun and it to scream .

I had an Evo IX for a few years so i know how awesome boost is, and I know that i would have more usable power with a turbo and lots of torque would make it quicker in the real world. But i really prefer revvy responsive N/A engines.

Is my dream possible/practical with an Aseries, or am i just better off doing an modern engine swap. ?

What engine specs would be required?

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Tim
Dusk Blue
1964 850

hee hee,,, we are currently building 4x N/A twinkys

i`ll shed some more light on them as we go along,,, all the info & pics we take with this lot should help you

stay tuned

Oh !!! & no,,, you`re not dreaming,,, they`re a pretty wonderful little thing actually.

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

im keen to see more.... what a teaser..

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Tim
Dusk Blue
1964 850

I think the idea is a very good one.

When there is a car with a twinky available I'd recommend it be taken to a place with a hub dyno. There is a hub dyno at a tuning/modifying shop very near my place and it will soon be relocated to Virginia in a very modern shop. I spoke to the owner/manager last weekend and he said he's not a carby man, strictly EFI. (so my Dellorto 40 is something he doesn't want to touch )

The benefit of the hub dyno is that they are immune from the tyre pressure and strap-down differences that badly affect the more common rolling road dynos. You can realistically do a tune and then come back a year later and expect comparable numbers. Car to car comparisons are possible too. No good for a "shootout" at a car show as the set-up time is too long.

Matt, any of your twinky customers planning on running EFI and looking to get a dyno tune?

M

I'm currently collecting all the parts I need to build my twinky donk.
It will be;
N/A single throttle body, 1360, A+ block, lightened and balanced crank, pre vetro orange dot clutch, 4.15kg light weight steel flywheel, Quafie LSD, EFI (still deciding on ECU), haven't decided on gear box yet (probably just run with the std rover cooper ratios I'm currently running in the car but I might swap back to a remote change shifter instead of the rod set up to help hold the engine still), it's an 8 valve head and I think that's about it. I think I'll get it tuned for mid range torque I don't want a 8000rpm screamer for a daily driver.
Should be coming out of the car in a few weeks and the build will begin.

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Respect mine and I'll respect yours.

Cool,
So what would be the best engine size if you want it to rev??
Or does the size not make a great deal of difference, just how it is prepared?

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Tim
Dusk Blue
1964 850

I have spent some early days looking into twin cam conversion and one day would like to build a nice little revvy motor with a sweet 8 port cross flow note to it, but need a car finished first So I follow these kinds of threads with interest.

This might be considered a dumb question for some, but for some time I have been wondering what is "twinky"?

twin cammy
t winky
twin cam you
twin k1100

Hope the answer is not blindingly obvious

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1968 Morris Mini Deluxe - members gallery
1970 Morris Cooper S - members gallery
Mini's I grew up with
Slot car couch

Mmmmm Twinky

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Tim
Dusk Blue
1964 850

I think it's just an easy slang style word instead of saying "BMW K100 twincam" you just simply say "twinky". But it dosn't actually come from any real word combo.
Well that's my best guess.

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Respect mine and I'll respect yours.

Just to touch on the single throttle body option mentioned above, is that for space? As I'd say there's a fair power gain to be had from quad throttle bodies on an n/a motor. Correct me if I'm Wrong on the Beemer heads but on other engines that's the case

From my understanding an engine that revs happily is usually over square

The next paragraph assumes the displacement is held constant.

The larger bore to stroke ratio means the piston has less distance to travel and therefore has a lower piston speed.

Force is mass x acceleration so a smaller bore to stroke ratio exerts more force on the crank and big end, leaving it prone to shooting out the block at high revs.

English cars used to be taxed on their bore diameter, so reducing it reduced tax, this is why the aseries produces good torque at the expense of high revs.

The best aseries to use would be one that is well balanced and has the largest bore to stroke ratio, the 998 is good, 1100 is bad and someone enlighten me about the 1275.

Well the BMW motorbike dose have quad throttle bodies but they suck through 4 individual ram pipes but these are inside an air box that only has a 2 & 1/2 inch or 65mm opening and this opening sucks through another air box that contains the air filter and some sensors etc.
You can see the throttle bodies and ram pipe box in the top of this pic, (the ram pipe box is cut away to see what's inside and through that between cylinder 1 & 2 you can see the top edge of the hole that will suck from the filter air box).

In this pic from the other side of the BMW engine you can see the 2nd air box which also continues off through another pipe to the actually air inlet at the front of the engine/bike.

What I'm trying to point out is that with the stock system the bikes have their seems like a lot of possible air flow restriction. The bit I'm focusing on is the ram pipe box, it only has an opening of 2 1/2" that feeds the four individual ports so in my opinion it doesn't matter if it has the throttle body before the box or after it so long as it doesn't restrict the max flow by much more that the 2 & 1/2" opening.
Also if you look at the flow in this video http://www.youtube.com/watch?v=ueTNtwvczNY the throttle body/SU creates air turbulence which is bad so (again IMO) with the single throttle body feeding the ram pipes it will remove one more restriction that effects the smooth flow to feed our engine.

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Respect mine and I'll respect yours.

As far as I know and I don't lol a single throttle body will have a slight low pressure moment when you first open the throttle as it has to fill the airbox before it enters the engine, where as a throttle body setup will have a full airbox all the time amongst other things.. That video seems to show an inefficient airbox design the ram tube is almost touching the top so you'll never draw air well like that.

But at the end of the day, space is the killer.. So il shut up now