Beardmore Bros Minor Supercharger Conversion

When building the car I always knew that I would need / want more power. After driving the car I know the chassis will take a lot more. I have also always wanted a supercharged engine so it makes sense to fit a supercharger to my latest Minor. I did consider turbo charging and it would probably be an easier project, but 3 aspects put me off. 1) Heat. Turbos give off lots of heat and with my engine being buried without a lot of airflow around it I am worried parts may melt! 2) I like a responsive engine and even though turbo lag can be reduced the engine will never be as responsive as a mechanical supercharger. 3) I like torque especially at low revs. A supercharger excels in this aspect.

This latest section of the site will cover the process I follow when under taking a new project. I will start at the very beginning of how I think things through, what I want, what I need, how I find out information, make decisions, design parts and purchasing. Then the actual fun part of the build and driving.

As always, my number one priority is reliability. I obviously want as much power as I can but I want a reliable engine that will last at least 20,000 miles (32,000 Km) and run on commonly available pump fuel. My first thoughts are that the octane rating of the fuel and detonation (knocking or pinking) will be the limiting factor, not the strength of the Fiat engine I will be using. I would hope that 350bhp to 400bhp is possible, which should make the car pretty quick and shred the rear tyres!!!

The number two priority will be weight distribution. The supercharger will not be mounted on top of the engine!

I know the basics of supercharging, they are a crank driven air pump, the more air that you can get in the cylinder, the more fuel that you can put in so the more power you get. There are several types of supercharger. They can be simply split into 2 kinds. The ones that are like a turbo but instead of the exhaust gas driving the compressor the engine drives it. These have similar characteristics to a turbo, they tend to give more boost at higher revs. The other type compress a certain amount of air per blower revolution. These generally give good boost at low revs. So guess which type I intend to go for? This information is my current understanding and will probably change as I do research.

The first thing I did was write down a list of everything I could think of that would apply to fitting a blower. I think this is called "Brain Storming" in industry but it is something I have always done.

Supercharger
What make?
Size? Small one spun faster or a large one slower?
Power comsumption.....size of drive system (belt, gearbox, drive shaft)
Position.....Can it be upside down, vertical, crank driven?
Distance from blower to engine.....does this really matter?
Intercooler....Air to air, air to water, makes, position, size?
How much boost can I run?

Engine
Forged pistons...what make, will Integrale ones do? Find the ones with the smallest piston to bore clearance.
Are big end bearings available for the Fiat? Will ones from any other car fit?
Will I need new conrods? Will ones from another car fit?
What is the best cylinder head to use? Integrale, Thema or Tipo, turbo or non turbo head.
Do I need new camshafts? Will my existing ones do?
Look at the spec of Integrale engines that give 350 to 400bhp.
Do I need to move my water outlet from the front of the head to the rear?
What clutch will cope with the torque I plan? Will it fit my flywheel or will I need a new one?
Will I need bigger head bolts or studs?
Will the block require wire rings?
What head gasket to use?
Do I have all the other gaskets required in stock?
How do I get the drive to the blower? With a belt or drive shaft off the crank? Will these work with the dry sump pump?
How do I get the compressed air into the engine? Use the throttle bodies or a single body?
Design of the airbox? This has to fit in around my steering column or can I move the column?
Can I bolt an air box directly to the inlet manifold and fit the injectors into the manifold?
What grade of ally is the inlet manifold? Can I weld to this?
What angle do the injectors go at? Do they point at the valve? How will the fuel rail attach?
Would it be easier to use an Integrale inlet manifold with mountings for the injectors and fuel rail?
Will the existing injectors be big enough?
Will the fuel pump and fuel line cope?
What about the exhaust system? Will the 2 1/2" system flow enough? What silencers will I need?
What about my radiator? will an aluminium be better?
If I use an air to water intercooler I have to plumb another water radiator. What do I use?
Will my existing engine management system be up for the job or will I need another system? If so which one?

Running Gear
Will the Fiat gearbox cope?
What other gearboxes are available? Will they fit, what ratios are available? What ratios do I need?
Can I get straight cut gears?
I will have to use the 7 1/2" diff and this does not have a LSD. What LSD should I use?
What other tyres are available, especially soft sticky ones?

Tools and Equipment
Do I have the equipment to do the job?
Do I need a mill? Is this a good excuse to buy one?
If I do not get a mill and if I need any machining who will do it?
Who do I get to do my engine machining?

Research
These days the research is so much easier with the internet. Manufacturers have catalogues and technical specifications to download. There are forums or message boards where you ask for advice from some very knowledgeable people who have probably done everything before. However you have to know how to find the information and being able to use search engines efficiently is quite a skill.

1st October 2006

The internet was my first place to look for information and I started straight off with the exciting stuff.....the supercharger. I always use Google search engine and the first thing I put in was "Supercharger" This bought up various sites, describing supercharging and various manufacturers sites. The blower I was most familiar with is the Eaton. This is found on new Mini`s Jaguars and Landrovers. I expected to be using an Eaton but then I saw this site Wipple and the information was very interesting. They sell a twin screw positive displacement supercharger that is very efficient. The chart below illustrates.....

	Whipple Charger	Centrifugal	Turbo	Roots
Response	Awesome idle-to-redline rpm power. No lag.	Poor low-speed response, similar to "turbo lag."	Poor low-speed response. Turbo lag.	Good low to mid range power.
Driveability	Increased lugging ability in higher gears. Increased power throughout rpm range.	Must downshift to maintain boost level.	Must downshift to maintain boost level.	Increased lugging ability in higher gears.
Engine Torque Curve	Virtually flat curve; ideal characteristic.	Often worse than uncharged engine at low speeds.	Often worse than uncharged engine at low speeds.	Wide range; fall-off can occur at high speeds.
Heat Buildup	Low; intercoolers are usually not needed.	Low; intercoolers are usually not needed.	High; may need intercooler	High; limits boost available.
Noise	Very low noise levels.	Typically very noisy.	Very low noise levels.	Typically very noisy.
Adiabatic Efficiency	70-80%	60-78%	60-75% Peak	40-55%

Now every manufacturer claims their product offers the best supercharger solution, but the Wipple twin screw has the characteristics I am looking for. But more research is required to get independent opinions.

So the next search on Google is for "Wipple twin screw". This latest search comes up with a very interesting fact that the Wipple twin screw is actually based on a Swedish Lysholm blower. A lot of the sites are also saying the twin screw is a good blower, plus Mercedes and Mclaren use it on their cars as does the new Ford GT40.
So next into Google was Lysholm. This is a Swedish company and is where all the twin screw blowers originate from. This is good as Sweden is closer to the UK than the USA where Wipple are based. Lysholm do various compressors of different sizes and finishes. I need to find out which one I require.

Looking at the site I also see they do air to water intercoolers using Laminova cores. I have a Laminova oil to water heat exchanger on the Minor. The intercoolers are self contained units or the cores can be purchased to fit into a box of my own design. They have an online shop so I checked out the intercooler prices, around £1,000, thats a lot of money! However the cores are round £100 each. So it seems that I will have to make my own box for them to fit into.

Next I looked for Fiat engine tuning information. So I put "Fiat Twin Cam Tuning" into Google and Beardmorebros was the 3rd site listed! Guy Croft runs a business tuning the Fiat engine so I looked at his site http://www.guy-croft.com The site now has a forum which has lots of useful tuning information on it. A few hours was spent reading this and another forum is mentioned turbo124.com Now this is a real find! It is an Australian based site and these guys are seriously into modifying their Fiat engines, 16V conversions, turbos and superchargers. There is so much information here I have spent hours reading through it. I also came across a few references to Beardmorebros aswel!
The main things I have learnt so far from these 2 message boards is the following:
1) High quality Fiat big end (conrod) bearings are hard to get hold of. But a company in Israel called King can do them.
2) Small block Chevy big end bearings are the same size as Fiat and can be used.
3) Small block Chevy aftermarket conrods can also be used. These are strong and very cheap from the USA,
4) There is a big search for aftermarket rods from other cars especially longer rods that will fit.
5) 12mm ARP studs or head bolts are used in the Fiat for greater clamping force
6) 2 litre cranks are best left at stock journal size and not reground.

I now need to know the following:
1) Are King bearings any good and will they do for my application?
2) How much power and torque do I expect to make and will stock rods be OK or do I need aftermarket?
3) What are the size of these Chevy bearings and what needs to be done to fit them?
4) Can Chevy rods really be used and if so which ones?
5) What is the part number for these ARP head bolts or rods?

I could just ask on the forum but I like to know the facts and try to find my own info first. I have ordered a book on supercharging to help me learn.

Supercharged! Design, Testing and Installation of Supercharger Systems by Corky Bell

This should tell me a lot about blowers especially how to spec the correct size, fueling and what sort of power to expect.

To find out about the Chevy bearings, I first needed to know the spec of the Fiat bearings. So I search for engine bearings and find Kolbenschmidt I download their bearing catalogue and look up the specs of the Fiat big end bearing. While I was on I searched for other bearings with the same size and could only find other Fiat engines (Seat, Polski Fiat) So now I knew the Fiat bearing spec I could look for the Chevy one that is similar. I went to Summit racing as they are a company I know in the States and would list engine bearings. Looking on Summit gave me the names of some big American engine bearing manufacturers, Federal Mogul and Clevite. I went to their sites to look for catalogues to download. If the links are not obvious I find the site map a good way of finding what I need with the search function (Control F). Browsing I find that the Small Block Chevy 283 and 327 is the correct bearing. I go back to Google to try to find out more about small block Chevys. The small block chevy has 2 big end crank journal sizes, known as small journal and large journal! The small journal is the one for the Fiat and the main performance engine is the 327cu small block Chevy.

So the Fiat big end bearing is 19.5mm wide and fits a 53.9mm dia housing (conrod big end dia).
The small journal chevy bearing is 20.193mm wide and fits a 53.975mm dia housing.
I also found out that the Chevy conrod at the big end is thinner than the Fiat so there should be no problem in getting the wider Chevy bearing in the Fiat rod. So the Fiat rod will require opening out by 0.075mm and, 2 location slots machining and the holes for the oil supply checking and modifying if required. I also read that a chamfer may be required on one side of the Chevy bearing due to the fact that the Chevy is a V8 and you have 2 conrods on one journal so the only one side is against the fillet radius of the crank. However I am sure I have never seen a chamfer on stock Fiat bearings but as the Chevy one is wider this may be the reason one is required in the Fiat.

Chevy conrods have a few problems if you want them to fit them to the Fiat. The big end width of the rod is narrower so the rod can float on the big end crank journal, not good. The rod in the other direction across the bolts is too big to fit down a Fiat bore so the rods must be assembled from the bottom and the pistons fitted from above. Chevy rods are longer and have a bigger dia gudgeon pin so custom pistons would be required. The little end on the Fiat gets its oiling from squirter holes in the conrod big end, the Chevy rod will not have these. The later Fiat blocks such as the Croma had different oiling, not from the rod big ends so a Croma block would be required if non squirter rods were used.

All this is indicating to me that it would be easiest to use stock Fiat rods with Fiat bearings. Next would be stock Fiat rods with Chevy bearings, which would give a massive selection of bearing materials and qualities. If Fiat rods are not strong enough then after market Fiat rods with either Fiat or small block Chevy bearings.

I will have to research King bearings and see if the Fiat bearings are high quality.

My book on Supercharging has arrived so I am busy reading and learning. I have also been reading a lot about the T5 gearbox. This is available with 0.63, 0.68 and 0.72 5th gear ratio, so I can have performance in 1st to 4th and then really drop the revs for 5th gear cruising. Straight cut gears are also available and new gearboxes are cheap in the USA. They can be upgraded to take 600 bhp!! That will be more than my engine will produce. I just have to check that I can actually fit it to the Fiat engine and that it will fit into the chassis. My main worry is if it will stick below the chassis rails. Fortunately I have friends who have this box so I can measure.

All this research and choice of parts is easy. The main problem will be actually fitting the blower unit. My latest thoughts are for a front mount with a shaft drive off the crank into a simple gearbox to up the speed and change the direction of rotation. Having a shaft drive will mean the alignment of the blower will be less critical than if I have a belt driven set up. Plus having the supercharger at the front will mean the weight will be lower. The big problem is what to do with the dry sump oil tank. I can always get a custom made tank to fit in what space is left or put it in the boot. I really want to keep it under the bonnet to keep pipe runs short and leave boot space for camping gear and shopping etc!

I have been thinking about pistons. I do have the advantage that I can use Lancia Integrale pistons. They will be forged but according to David Vizard the way to choose forged pistons is to get the ones that specify the smallest bore to piston clearance. This means they expand the least which means less piston slap and better sealing. If you have forged pistons in the 84mm to 85mm bore range I would be interested in the recommended clearance.
I have been reading my new book on supercharging. The main thing I have learnt is that I should run a by pass valve and circuit. At part throttle the supercharger is pumping more air than the engine needs so a valve opens and lets the air recirculate back to the blowers inlet along a pipe. This reduces the power required to turn the supercharger and helps a lot with fuel comsumption.

This has nothing to do with supercharging but I came across this car build site and thought it was worth sharing. This guy is building a mid engined GT type car (think Ultima roadster but his own design) Have a look HERE at his GTT.

I have been looking at oil squirters. On a 131 / 132 engine the small ends are lubricated with small holes in the conrods at the big end. However if I use aftermarket conrods (Lancia Integrale) the chances are they will not have these oil holes. The Lancia Integrale lubricates the small end with an oil squirter (Part Number 7580672) that takes oil from the main oil gallery. With some machining work these can be fitted to the 131 / 132 block. The Fiat Tipo also has squirters (Part Number 7589255 ) that fit into the main bearing area.

I would guess these jets are fitted from the bearing side, otherwise the holes would be very difficult to machine. They will be a light press fit with some Loctite 638.

These oil jets will require a flat milling on the block then a hole drilling and reaming to take the squirter.

The oil squirter also performs another useful task and that is cooling the piston. Many other engines use oil squirters so it may be possible that one from another manufacturer will be better.

These Porsche ones seem smaller so would require a smaller hole drilling in the main bearing area. I will have to do more research.