Tell me about diy supercharging!!!

Hope you've got your 'flame retardant suit' at the ready.

'Cos if Dom sees this you'll know about it ;D

Ive been collaborating with Penski to sort out some kind of online diy turbo and supercharger information site.

Here are a few snippits on the supercharger side of things -

1.2 - Superchargers

1.2.1 - Centrifugal supercharger works in the same manner as a turbocharger providing boost by increasing the air velocity and converting this to boost by slowing the air in the housing. The drive is provided from the crankshaft using a belt, chain, or shaft drive. The belt and chain drives enable a higher gearing to be achieved, this is supplemented in the gearbox attached to the charger its self, the overall step is usually 10-15:1. This means that the impeller is spinning at 80000 - 120000 rpm at 8000rpm crank speed. Centrifugal superchargers are capable of similar boost to turbochagers and also have similar efficiency values of up to 80%.

1.2.2 - Roots supercharger uses a pair of identical rotors that can have two or three lobes, they are geared to run at identical speed and in close tolerance. They usually have a coating or sealing strip to provide a seal between the high pressure engine side and the low pressure ambient side, this can be supplemented with water or fuel injection. The air is carried on the outside void of the rotors between them and the housing flowing into the engine, as the lobe gets to the middle it matches the corresponding orifice on the other rotor closing the gap once occupied by air.
Due to pumping losses suffered from the lack of total seal and the design of the rotors, roots superchargers only manages around 65% efficiency, and the corresponding heat rise has to be tackled carefully to provide adequate power increases compared to boost.

1.2.3 - Lysholm screw superchargers have interlocking rotors similar to roots superchargers, the difference is that the rotors are not identical, they have a male and a female, the rotors also often travel at different speeds. Lysholm screw superchargers have no contacting parts and so the wear is very low, due to the lack of contact the seal can be maintained creating a higher efficiency and a higher boost capacity.


1.4 - Operation

1.4.1 - Centrifugal compression is not directly related to the engine speed, due to the way the air is compressed the boost will rise at a square of the shaft speed. This means is what causes the punch that turbocharger provide, at the turbine speed goes from 50,000 to 100,000 the boost will go from 4psi to 16psi, creating the kick in the backside they are so renowned for. This case is just as true for centrifugal superchargers, although this time the boost is directly related to the crankshaft speed.

1.4.2 - Positive displacement superchargers will provide consistent boost from a low rpm, this is because the quantity of air moved from the atmosphere into the engine is consistently more than the engine requires. The problem with this design is that it relies on the atmospheric pressure to fill the void between each set of lobes, as the RPM increases the time given to fill the void drops and so does the amount of air inhaled. This is where the drop in efficiency comes from with a roots supercharger compared to a centrifugal type.

Your injecton system is not calibrated to work with positive pressure, does it use a mass air flow system or a manifold air pressure system?

To get the setup working you can used the stock injection with a boost referenced fuel pressure regulator, this will increase the fuel pressure to the inejctors and so the flow as the boost rises. This will prevent a lean out but is very crude.

The next step would be an interceptor used in conjunction with larger injectors, this will allow the signal from the MAF sensor to be modified so as to provide the correct air fuel ratio.

What kind of ignition system does the FIRE engine use? I would recommend going for the meajolt distributorless system, as this will enable you to tune out detonation and retard the spark for boost.

I would recommend the use of an intercooler, any compression of air created heat, and the more heat, the higher chance of preignition.

What kind of car is it going into? I would make sure the brakes are up to the job of stopping a supercharged missile

J

i still fancy supercharging/turbo charging a fiesta 1100 lump with an R5 carb ;D

Excellent vid, I tried it ages ago with a Mini heater bodged into the intake of my 100E. It just made a lot of popping and bad running.

Kind of depends on what you do and how happy you are making stuff really ?

Have a look here for starters:

retrorides.proboards86.com/index.cgi?board=general&action=display&thread=1155401283

And decide whether you are capable of that amount of Fabrication if needed.

Heres another one with whats then required to fit that lot in the car:

retrorides.proboards86.com/index.cgi?board=general&action=display&thread=1160862566

Take a look at Blownimps "Imp S4" updates in readers rides as well

In theory, bolting a charger on an engine is simple, in reality it can be less so.

I design this stuff for a living which makes it easier but there is still a hell of a lot of work goes in to planning it even before you start....

What FiRE engine and in what Vehicle ?

Might be persuaded to make up a Charger installation kit if there was enough interest....
You, Ratlook, Hollywoods Panda, Nigels Fiat 500 etc ;D

Basically its a Pump which requires throttled air in, air out to some form of cooling, air out of cooler to inlet manifold, a bypass arrangement and some mountings that hold it rigidly in a position where you can get a belt run to it.

The injection side is a matter of remapping to suit the increased airflow in simple terms ;D

How easy it is really depends on how confident you are in the first place, if you are happy fitting different engines into cars that were never designed to take them and all the work that entails then its not too bad

If you cant weld, cant machine, couldnt swap an engine etc then its going to get expensive very quickly

If you want to do it then I can supply you with inlets and outlets for the mini Cooper S supercharger as well, which will make things a bit easier ;D

HTH
Dom

Once, when i had a beetle i put the tube's from the fan housing into the carb instead of the heaters
the result wasn't spectacular but it definately had more 'pep' after!
not a charger i know but cheap couple of BHP ;D

Thanks for the replies
It`s a 1242 8v fire converted to mpi and fitted to a C***uecento abarth,
Don`t flame me for it,I love them to bits(i`ve got 2 of the things).
(It`s like a mini but without the rust)

Blownimp Brakes are sorted,Punto turbo calipers and discs(20 grooved red dot)goodridge braided hoses

Cr500dom My mate works in a mini dealership so can get chargers cheap,But a custom built kit sounds good
Cheers
Adrian

Ratlookreliant One of my 1242`s had a power steering pump fitted to the block with an extra crank pulley for the steering drive belt,I was hoping to mount it there and use the spare pulley to run the charger,

cool, be weary that its bassically impossible (without risking killing the bloweR) to remove the pulley from an eaton m45, so its better to change the drive pulley to suit.

Dom, i would be very very interested in a kit, however, i have the 16v head with a 10.2:1 comp ratio + its been skimmed to check its true (so only a tad) and everyone else has a 8v version.

however, i would happily bin my head infavour of the 8v and a blower!!1

Nick

yea, that wasnt my concern - it was that the top of my engine is alot taller, and wider than the 8v's, meaning any kit dom made would probably not fit unless the blowers low down, but theres too much chassis down there.... but thats the eventual plan - blower, TBs... mmm


J, can r6 tbs be used like a down draught setup?

Nick