COMPLETED!! supercharger project. progress so far...

[chickenjohn]

Does it actually make any difference as to what grade of oil you have in the SU dash pot as long as you have some oil rather than none at all?? I've experimented in the past with 3-in1, 20w50 and even EP90 and not experienced any real difference in a standard car acceleration. If you remove the air filter and look inside the carb at the piston while the engine is running, the piston hardly lifts at all, even when engine is revved. So is the precise grade of oil in the dashpot really going to make much difference???

[picky]

the type oil will make a difference, but on a standard engine there are still major inefficiencies in the engine eg small valve head, v restrictive exhaust) so the difference in power would be hardly noticeable.

Starter motor came today, I have fitted a BAK needle and official SU dashpot oil, tomorrow will attempt to start it and see if I can make any progress.

Picky

[bmcecosse]

Just 'revving' the engine uses very little air - and so the carb piston hardly rises. In service though - the piston should be set (with spring strength and weight) so that it just reaches full lift at highish revs with throttle wide open. If it opens before that - mixture control is lost, and if it doesn't ever reach the top then it's choking the possible air-flow into the engine !! The oil is just there to damp out fluctuations - and to make sure the engine doesn't 'gasp' when you suddenly open the throttle. Many find 3 in 1 to be better - especially if using a light flywheel and/or engine power improvements. Interestingly - the BMC Works Rally Minis had EP90 in the dashpots - to stop the pistons dancing up and down on rough roads which was upsetting the engine fuelling. There is also a possible adjustment on the 'free play' of the little piston on the shaft - again Works used different amounts of free play for different situations - but the logic of that is beyond me! It obviously allows the main piston an initial free movement - and then the little piston will hit it's stop - and begin to damp further motion with the oil. I guess they must have done trials to get the best settings - but as far as i know these have never been published.

[GAS]

Is the free play of the piston not SU's version of the accelerator pump.
Webbers squirt extra fuel when the pedal is pushed...
This free play richens the mix when you want to accelerate.

[picky]

got the new starter in today, engine turns over fast so no issues there but it fails to start. have tried needle and no dash oil, dash oil and no needle, and then no dash oil or needle (this worked before) but engine fails to start. getting a good spark (tested with colortune) but the spark plugs look completely dry when removed after trying to start the engine, I imagine they should be covered in fuel from trying to start it?



Picky

[Orkney]

Picky cant you beg borrow steal a known working carb and try that ? just for elimination of fuel or electrical problems? excuse the seemingly ignorant sounding advice but at least if you had a known working then migth help see whats wrong?

[picky]

got it started after taking the carb apart and back together again, idle at about 3000rpm though so must have a large air leak somewhere, still only starts without needle/dashpot oil.

Orkney I have had to make several modifications to the carb, which I am sure is the root of the problem. I have a hs4 carb that I can bolt on without the supercharger, and it runs ok with that so I can exclude fuel//electrical/timing problems as you have pointed out. Not an ignorant suggestion at all!

Picky

[Orkney]

Hmm...could it be as simple as the airscrew is putting pressure on the carb before correct mixture - so therefore the mixture isnt right.
I mean how do you regulate that?
Ive seen forced air on things before but not with SU's.
Suppose that goes to the beginning and people saying well shouldtn the charger be the other side of the carb - so your forcing a premix of air and fuel.
What your doing now is forcing the air onto a given mixture for normal air pressure - migth be that its good and burnable at the 3k revs and not below.
Dont think its a problem of if it will work just how to get it to do so.
Stick with it Picky - if anyone can make it work you can

[picky]

Ive done some more research on the metro turbo setup - that had a blow through hif44. My setup might be able to run ok, but only if there is very little boost, so I need to change a few things. The fuel pressure needs to be higher than the manifold pressure, and as the boost gets higher the fuel pressure has to increase at a greater rate. The metro turbo was equipped with such a device and an injection style fuel pump, that is going all the time and then an "overflow" pipe sends extra fuel back to the tank when the fuel pump is giving too much fuel (most of the time). This should be a big improvement, and is capable of supplying fuel at high boost. But the metro turbo still had the throttle in the carb, so my setup is still different, and will need alot more fiddling with.

Picky

[Orkney]

Blimey Picky talk about pioneering away there
Right how about this for a suggestion (only suggesting because i'm not doing it )
Take the charger off - get it running on a turbo setup - then apply the charger to that - it has been done, think i read the merits of doing so in the only if your stark raving mad chapter of the Viz tuning the A series - it 'Might' alleviate the fuel problem if the turbo set up regulates it? and that should be a VERY BIG question mark BTW
if after all that youve still got too much fuel then nitrous the beggar

[bmcecosse]

GAS - the slowly dampened piston is the 'fuel boost' on acceleration - the pioston is held down below the ideal position so forcing the air to rush through the small gap and sook up more fuel! the little 'free play' on the little piston is to allow the piston to jump up a little - and so let SOME air into the engine - or it would be bvery sluggish to accelarate at all. Mucho fiddling with this - and the carb spring and the oil in damper (I'm told red tin 3in 1 is 10W and blue tin -never seen one - is 20W) eventually sets it up to suit the engine - for example there's no point having say a light flywheel on the engine and then holding it back with thick oil in the damper etc etc.
Picky - i really do think you are re-inventing the wheel - yes the fuel pressure must be higher or none will come out. Best in my view to exactly copy the Mutro Turbo example - I imagine MG/Rover spent about £1,000,000 getting it sorted out - and it did work! OR - go with the method used by all others doing this conversion on (mostly + GAS) Mini engines - and suck through the carb. It works.

[Orkney]

Picky - i really do think you are re-inventing the wheel

course he is - but we were all young once
I reckon he's at the on principle it isn't going to beat me stage about now - I'd have been on sledgehammer stage long ago

[picky]

Orkney I think you are exaggerating the progress I have made, it may be unusual to fit a supercharger to a morris minor but it is certainly not "pioneering". 3 bearing carb'd 8 valve engines are no longer considered pioneering these days!

on principle it isn't going to beat me stage

I like that though! spot on

bmc I have various pipes from different points of the system leading to to and from the carb that I have experimented with and was hoping would work at low boost, but have come to the conclusion that the "rising rate" fuel regulator from the metro setup and high pressure fuel pump are a must.

Picky

[bmcecosse]

Oh the high fuel pressure is essential - otherwise the scharger will just blow it out the overflow - if there is one ? To be honest - your idea will work a whole lot better if go to a form of fuel injection rather than trying to use a carb.

[picky]

I will eventually go megasquirt injection, but this would bring on a whole new era of troubleshooting! I should be on the road if I can get the fuel pressure in the carb correct...

Picky

[Orkney]

Orkney I think you are exaggerating the progress I have made

nah - just admire the spirit and patience to be honest - hence i meant you are pioneering with your project - when BMC said about reinventing the wheel I can see where thats coming from too to an extent - well if it were me older me now that is i'd stand back, look think and probably conclude no way thats going to cost too much and get the same performance from putting in a pre made sporty lump or cram a V8 in e.g.
Ive a craving to have a trav with lotus cortina running gear, silly work - but the parts are very close and i can just imagine teh result - it may get done it may not, but if i had the time and resources there would be no question.
Working on the scabby trav & renewables are the only 2 things that have never got me mad in terms of overcoming difficulties as work progresses, what your doing is regardless of the cost a challenge that no doubt you'll win. And when you do you'll be all the better for it - and have a great car to drive as well as know if somethings wrong and how to fix it.

[bmcecosse]

Picky - it's going to drive you mad, and it won't be ready for Term Time. Why not just stick the carb on the front of the blower - and get the car running for now ! You can try all this again next hols - but in the meantime you are getting no fun/pleasure from all your hard work. With the blower sucking through the carb it will work - there will still be plenty of challenges to keep you busy (ask GAS !) - but at leat you will have the use of the car.
All this stuff has got me thinking about putting one of these blowers on my TR7......... Whole lot easier than doing a 'Sprint' conversion - or fitting a V8 as seems to be the way !

[picky]

That would be alot of hassle bmc, but I have a hs4 carb that I can bolt on in the usual place and disconnect the supercharger - making it a normally aspirated engine if I need to drive the car anywhere - will take 10 minutes to do. Ive got till 29 september....

Picky

[GAS]

I am 2 years down the line with my traveller.It's just coming good now but i have very little confidence in it on long trips.....

But it is bloody good fun,so that makes it worth it.

Keep at it Picky,you'll get there.....

[picky]

:D:D:D:D