More build questions.
Turbo Mini Forums

Since I have only experience with old stuff. Can I fit a pre-verto clutch into an A+ housing? (would rather use big idler bearing)

As I will be using an MG standard leaded 12G940 which I am planning to modify myself. I will keep the valve sizes the same. As I am looking at running the MG cam with 1.5 rockers, the idea is to maximise power below about 6500. (as much as I can get). So, I plan to open the inlet ports out considerably, removing the bosses. Obviously the exhaust heating was a problem on the original turbo and so I am going to hesitate here. As I don't need the pulsing, I can afford to get better flow by opening out the exhaust ports and keeping the valves the same. I assume the heating of exhaust valves (necessitating sodium cooled...) was due to the resistance of the turbo. As I shouldn't have this effect, I assume that I can open the ports out more and remove more of the boss. I am considering wasting the backs of the valves and stems a small amount. Making them more "penny on a stick". (This probably isn't a good idea, I'm just interested in whether it is do-able or not).

So cutting through the crap, can I remove quite a bit of the exhaust port boss?

I am going to be (reluctantly) running the best cast turbo pistons I can find so I imagine I will be removing quite a bit of material from the combustion chamber.

Do you guys match the top of the piston to the block and also (as closely as possible) match the combustion chamber to the shape of the piston dish. Turbodave keeps going on about "squish" and I can find no reference anywhere (apart from 2 stroke books) on how this is important in a turbo engine. I would have thought that it would make the engine detonate more.....enlighten please....

Apart from the cogs, what do you do to your gearboxes and why? (oil fed nose bearing, competition layshaft)

Finally, considering I want this to be as reliable as possible and it isn't going to be a massive mileage car, is castor oil a good idea?

Since I will be starting from scratch, I figure I can run whatever oil I want. Does castor oil and engine build lubricant form gums?

(big load of questions there, I do sort of know what I'm up to theory wise, just need to get approval before I do something stupid).......s

Bugger off, I'm getting there.

" is castor oil a good idea? "
someone had to do it .lol.

Everyone knows that instructions only have to be read if the thing doesn't work....

Fookin howay man! The film strength is unbeatable, leek!

Oil development has evolved to be acceptable for lubrication and unfussy about changes. Mothers Pug has done 180000 miles and the drain plug has never been off. She just throws more in when the light comes on. I am aware that some performance oils just have stuff added to them for when the film fails.

Since we are uncompromising performance enthusiasts, what is the best shit to use?

S

Bugger off, I'm getting there.

i am under the impression castor oil makes a form of acid which attacks the lead indium type of bearings ? any one ?
what amount of power are you looking for ?
dont waist the back of the valves unless they are (a) stainless (b)you have done it before and they survived !
oil i use is valvoline turbo 15w 40

If my memory serves me right, castor oils chief constituent is a bigish hydrocarbon chain with an acid bit at one end and an alcohol bit at the other. Which basically adds up to a built in stickyness and viscosity for a smaller molecule. This is where its great film strength comes in, by hydrogen bonding (which is why water is a liquid and not a gas)------(In a molecule containing both hydrogen and oxygen, the oxygen bits will be attracted to the hydrogen bits and vice versa, hence mutual stickyness and kick ass film strengths!). Even your best synthetic stuff doesn't have this.

Indium is soluble in acids, it says in my book. That would follow for the lead/indium bearings. Assuming the acid is the right sort of stuff (strong, small molecules in water?) Although castor oil is technically an organic acid, it happens to also be an oil which means that the stuff is pretty water repellant. I would hazard a guess that indium was soluble in "proper" acids as it would form a salt which would then dissolve. The likelyhood of this happening in an engine I would think minimal. But, anything's possible, you would best find out experimentally.

So, if indium dissolves in acids, I would expect that everyones oil, unless you changed it yesterday contains a larger or smaller amount of water dissolved in the "detergent" or as an emulsion. This would probably contain a whole cocktail of acids derived from the combustion products and blow by. That would probably shag bearings more than the castor oil.

Interesting point though. s

Bugger off, I'm getting there.

The head first.

I have done all my heads plus a couple to my mates. All have been non turbo heads for turbocharger use.

I cut most of the guide bosses away, intakes are basically all gone, some is left in the exhaust port. I use bronze guides and Rimflo valves. The exhausts are with std diameter stem, not 8 mm like turbo valves.

As for cutting the stem, I´d probably leave them alone.

Yes, you can fit old style clutch into any housing.

My gearbox is all helical, used to run comp diff pin and now a Minispares twin pin setup. Pre A+ gears and drops. Idle gear bearings are the smaller ones. No oil feed anywhere.

Castor oil ????????? Use good quality synthetic oil, I use 10W60 Castrol TWS.

Hedgemonkey (stu?)
Why are you askign about castor oil... I get the impression you only asked it to let everyone know how much you know...

Apologies if speaking out of tone, but that's the way it comes across

Sorry Dave, I have a habit of coming across that way. My logic was that as mid range torque goes up (in multiples) so do the pressures experienced by the oil. Gearboxes allready give it a hard time unblown. I just wondered whether castor was a sensible choice whilst everything is clean........If nothing wears appreciably, it must be still ok.

Thanks Jukka, that sounds like what I was planning to do. I will have a look at rimflow valves, but I don't know whether they are overkill for a engine with no pre-turbo behaviour. I just liked the idea of wasting the backs a bit and making the ports have huge flows.

Stuart, Power wise, I am (as everyone) looking for the most possible. I am going to set myself a target compression ratio of 8:1. With minimum overlap and MG cam, 1.5 rockers as well as an unrestrictive head, running a pulley which I would have calculated would have given me an effective compression ratio of 11:1. I expect that I should be in the 100 at the wheels territory. (hopefully). As I have to build down to a price, I will just do the best I can to that spec, saving enough for a rolling road session.

First things first, I have to get the engine actually in one lump before anything gets bolted to it.

Coming across as a bigheaded tosser is just typical me. I'm pretty modest really

Bugger off, I'm getting there.

Well, I had the Rimflo intakes already in the head that I used, and chose the same for exhaust because they are a little bulkier than a normal competition valve. The idea head being more tolerant to heat.

castor oil
all i know is that f1 engines dont use it ,if its so good why don't they ,and then i got a lecture !
main point was that there is no oil which can withstand certains areas in an engine
any one tried olive(maybe added chillies and garlic) or sunflower ?
on the subject of valves , the 32 mm standard stem race valves from minispares is too thin on the head thickeness and can 'tulip' as jukka mentions ,the rimflow exhaust is the one to use if going standard stem route

Thanks for the info about the valves.

Still not sure about the oil though. I suppose it is a matter of religion and taste

Bugger off, I'm getting there.