Fiat 806: research and scratchbuilds

[CrazyCrank]

In my humble opinion, after studying all your posts, I think there is an issue in Drawing 2 !

 

Indeed: the engine is frankly left fitted...why not ? it"s not a problem.....BUT, if there is really such a large left offset for the engine, relatively to the symetrical axle of the chassis, THEN, the crank should be more off-center by the left than on the drawing.

Because the crank is always connected to the crankshaft, that is, if am not mistaken, systematically in the exact centre  between the two rows of cylinders. for a V-engine

So, on the drawing in the previous post f Roy, the crank should be on the top blue line

 

Sometimes, cranks are crazy 

[Roy vd M.]

34 minutes ago, CrazyCrank said:

Because the crank is always connected to the crankshaft, that is, if am not mistaken, systematically in the exact centre  between the two rows of cylinders. for a V-engine

 

That was my preassumption. But then I compared Drawing 2 to the engine drawing and I noticed two parallel 'circles'. See the green circle. Could it not be that in this car, as an experiment for example, the 'crankshaft' is not connected to the crank?

 

If that thought is incorrect, then I agree that the crank should be on the top blue line.

 

What does Italeri indicate (in their instructions) as link point of the crank to the engine?

 

Edit: see here:

 

 

It seems Italeri (and Protar?) also think the crank should be connected to the 'right hole'. 

 

This scan of the instructions also supports the idea that the kit was based on Drawing 1, by the way.

Edited November 12, 2016 by Roy vd M.

[Hannes]

Looking at the finished engine of my old protar, I can clearly see,,that the hole for the crank is more than 2mm left of the engine´s Center.  Hannes

[Roy vd M.]

Ok guys what do you think of this:

 

 

I drew some rudimental cilinders into the engine. In a V-engine, the crankshaft is always at the crosspoint of the cilinders, like this:

 

 

Based on the engine drawing, and assuming the cilinders are approximately as they are in the drawing, it is impossible that the 'crankshaft' is in the extension of the crank. Not only is the crank, as just mentioned by Hannes, slightly to the left, it's also much too low. 

 

So I guess that there was an internal chain between crank and 'crankshaft'. Alternatively, gear wheels could be in place. That we'll probably never know. 

 

I'm sure enjoying these explorations. We're learning a lot on a car that was scrapped so long ago, only on the basis of so few sources of information. And I'm sure there's a lot more valuable data hidden in these drawings and photographs!! 

Edited November 12, 2016 by Roy vd M.
Spelling

[CrazyCrank]

9 minutes ago, Roy vd M. said:

Ok guys what do you think of this:

 

 

I drew some rudimental cilinders into the engine. In a V-engine, the crankshaft is always at the crosspoint of the cilinders, like this:

 

 

Based on the engine drawing, and assuming the cilinders are approximately as they are in the drawing, it is impossible that the 'crankshaft' is in the extension of the crank. Not only is the crank, as just mentioned by Hannes, slightly to the left, it's also much too low. 

 

So I guess that there was an internal chain between crank and 'crankshaft'. Alternatively, gear wheels could be in place. That we'll probably never know. 

 

I'm sure enjoying these explorations. We're learning a lot on a car that was crapped so long ago, only on the basis of so few sources of information. And I'm sure there's a lot more valuable data hidden in these drawings and photographs!! 

 

You're right , Roy...So the engeeners had imagined a mechanism, whatover it could be made of, to drive the crankshaft by an off-centre crank !

This legendary car has probably some more surprises  in store for us !

 

[vontrips]

4 hours ago, NickD said:

VT - I was impressed by the match when I saw the earlier thread. I'm finding it much more difficult than that with the tools. Problem with cars is there are almost no straight lines, wheels move up and down and aren't necessarily parallel in any plane. The only saving grace is the plane of symmetry - which of course the 806 doesn't have - nightmare. Maybe I will just abandon the tech and reach for a phone!

 

Nick

LOL...That's me, I'll always find the easiest route I can with my limited resources. The lack of planes and datum lines is what's causing us problems. So far I can only use the chassis as my datum point. The Protar chassis is good (at least in side elevation). *Note Hannes; the shape and kick up looks OK, it's only the bend radius that is out by a small margin - just needs to be gentler eg. curve smoothed maybe 5mm out either side of bend.

 

The chassis ride height looks OK too. Not sure if the Italeri kit will sit the same with plastic leaf springs but this can always be massaged to suit. This is an old Protar kit with made up spring steel leaves. They could have settled over the years. Like I say, it's loose as a goose as far as data is concerned, but it's a good starting point!

Edited November 12, 2016 by vontrips

[vontrips]

49 minutes ago, CrazyCrank said:

 

You're right , Roy...So the engeeners had imagined a mechanism, whatover it could be made of, to drive the crankshaft by an off-centre crank !

This legendary car has probably some more surprises  in store for us !

 

I wondered about this when I saw Roy's post earlier. Now I think I have it, though I'm no expert on old race engines. Looking at the supercharger housing design on the front of the engine it was most probably a 'Rootes' type supercharger. This is basically two meshing cylinder screws that would be gear driven in opposite directions from the end of the crank. Look them up - they are wonderful pieces of engineering. Designed to intermesh tightly enough to create airtight pressure to compress air at thousands of rpm, yet never contact enough for wear! The supercharger would be in the way of crank access so the starter crank would have to drive the crank through a supercharger shaft...taa daa! Italeri have the hole for the starter crank in the position shown on the end housing on Roy's drawing. 

 

Must be bed time. Just thought this through again and realised they could not have been geared straight off the crank as they would be both be rotating in the same direction! Must have had some funky inter gear in there too...zzzzzz

Edited November 12, 2016 by vontrips

[Roy vd M.]

17 minutes ago, vontrips said:

I wondered about this when I saw Roy's post earlier. Now I think I have it, though I'm no expert on old race engines. Looking at the supercharger housing design on the front of the engine it was most probably a 'Rootes' type supercharger. This is basically two meshing cylinder screws that would be gear driven in opposite directions from the end of the crank. Look them up - they are wonderful pieces of engineering. Designed to intermesh tightly enough to create airtight pressure to compress air at thousands of rpm, yet never contact enough for wear! The supercharger would be in the way of crank access so the starter crank would have to drive the crank through a supercharger shaft...taa daa! Italeri have the hole for the starter crank in the position shown on the end housing on Roy's drawing.

 

This makes perfect sense. I was wondering what the second circle beside the 'crank circle' was for, but looking at the drawing here, this could be it. Turn the drawing 90 degrees and it looks like our 806's two neighboring circles! Fiat's engineers would have been keen to position the crank as low as they reasonably could, thus allowing for as much radiator surface as possible and at the same time minimizing torque and car shuffling / shaking when cranking up the engine. One of two rotary vane rods were used. Great thinking VonTrips!

 

 

 

(Courtesy Wikipedia Commons)

[Hannes]

For historical Information I just want to add, that These Roots - compressors with their two 8- shaped Rotors are no real compressors at all,because they don´t comrime the air,they just fasten the airflow.  Hannes

[Hannes]

Sorry,wrong expression,What I wanted to say is, that  the airflow gets faster,so the engine must make  more rpm to take Advantage  from more air coming in,contary to a super-charged engine of today.If the air gets comprimed,there will be more Oxygen molecules in the same volume and ,that means more power.

In our case the roots -compressor Forces the engine to run faster.  Hannes

[Hannes]

Not comprimed,Compressed. My English must get better... Hannes

[CrazyCrank]

Hi fellows

 

While my brass parts were beeing nickel plated, I've made  a Google research for the diagram of a Roots Blower (supercharger), because the idea that the starting crank can drive the crankshaft from/through the supercharger, via a mechanism to be identified, does not satisfy me, until I've discovered this mechanism !

 

Here is what I've found

 

 

Could you study this diagram and explain me your theory ?

I'm going to do so, and we  shall compare our opinions...right ?

 

Not to be unpleasant, but I do like to understand how things work, and I wouldn't accept we were wrong 

[Hannes]

What I can also see, is the fact, that the roots commpressor on drawing 2 Shows other  dimensions than as shown in the engine´s drawings.(and model)Maybe a improved Version.

You may remember,That I shortened my Radiator case below it´s Fixing Points.I´m almost convinced, that the hole for the crank lies in the middle of the compressor case,because it makes no sense,that the crank should go through a moving part.It would be much easyer,to alter the holes in the Radiator and the grill. Many greetings!  Hannes

[Hannes]

Dear crazy crank There´s a pin in the middle of our model´s roots compressor (not shown on your Explosion drawings) That´s the place, wher in my believe the hole for the crank should be situated.It´s simply integrated in the compressor case.

We cannot be sure,if the improved compressor as shown on drawing 2 already was used for the Monza race or the older Version. I hope,we will find out.

As I mentioned earlier, the two impellers,connected by some gears with the crankshaft(or in your example with the gearbox) don´t compress the air,they just Speed up the air flow and therefore the Expression compressor is wrong!  Many greetings to belle France!  Hannes

[vontrips]

25 minutes ago, CrazyCrank said:

Hi fellows

 

While my brass parts were beeing nickel plated, I've made  a Google research for the diagram of a Roots Blower (supercharger), because the idea that the starting crank can drive the crankshaft from/through the supercharger, via a mechanism to be identified, does not satisfy me, until I've discovered this mechanism !

 

Here is what I've found

 

 

Could you study this diagram and explain me your theory ?

I'm going to do so, and we  shall compare our opinions...right ?

 

Not to be unpleasant, but I do like to understand how things work, and I wouldn't accept we were wrong 

Nice find CC! Any description as to who made it? 

 

Note, the lower drive shaft is longer and passes out through the bearing cap. The bearing cap has a hole in it for the crank lever. The fact that there's also a 'woodruff key' to help crank lever engagement is all the info I need! 10/10

[CrazyCrank]

9 minutes ago, vontrips said:

Nice find CC! Any description as to who made it? 

 

Note, the lower drive shaft is longer and passes out through the bearing cap. The bearing cap has a hole in it for the crank lever. The fact that there's also a 'woodruff key' to help crank lever engagement is all the info I need! 10/10

 

Hi Vontrips, I think your explanation rather credible, however:

- 1/ it's curious that the crank come through a moving part in the blower..what happens to the crank when the engine start, moving at high speed all the mechanical part of this supercharger

- 2/ How is connected the blower with the crankshaft ?

 

There are here several unknowns !

 

[Roy vd M.]

Thanks for the explanation Hannes and thanks for the drawing CrazyCrank.

 

1 hour ago, CrazyCrank said:

Could you study this diagram and explain me your theory ?

 

First let's conclude that we'll never know what this compressor really looked like internally. It's a race car so it could look very different from your drawing. I think the drive shaft as seen in your diagram could have extended a bit further, a gear wheel on its end. That gear wheel could be connected to what we call 'crankshaft' nowadays. The most important reason to not extend the 'crankshaft' to couple the crank is that the radiator would be in the way. 

 

Quote

it makes no sense,that the crank should go through a moving part.

 

Hannes, my theory is not that the crank went through a moving part... my theory is that the crank was CONNECTED to the moving part (= the drive shaft for the compressor).

 

Quote

Note, the lower drive shaft is longer and passes out through the bearing cap. The bearing cap has a hole in it for the crank lever. The fact that there's also a 'woodruff key' to help crank lever engagement is all the info I need! 10/10 

 

Well spotted! It supports the above theory.

 

Another subject... you have probably noticed that according to Drawing 2 the left engine head didn't fit within the regular body curves:

 

 

This is what the left bonnet looked like in detail:

 

 

 

 

 

 

It looks like Protar's interpretation of a similar conical raising like the one on the right side (to be seen in Photos 1, 2 and 3 here), is correct. It seems to me that Fiat put a symmetrical one on the right side of the bonnet only for symmetry / similar airflow purposes. Unless I'm wrong there was no technical need for it. 

 

To see how the shadows were cast, let's look at the position of the starting grid in Google Map. It's the same as current Monza circuit. Does anybody know what hour the 1927 Milano (Monza) race started? Anyway I think it's something like this:

 

 

whereby the red arrow represents the sunbeams as estimated.

 

Now take a look at the photos. Doesn't it seem to you that the white '15' numbers were NOT painted on? The white seems to cover the louvre holes, so to me it looks as if it's not paint but cloth or something. It can be seen in two separate photos so I don't think it was 'photoshopped' at the time.

 

Different subject: I'm not giving up on trying to establish the 'truth' in Photo 5:

 

 

For starters I found photos of the stands taken from around that time. I intend to use them for checking (as far as possible) photo 5's measurements.

 

 

 

Edited November 12, 2016 by Roy vd M.

[CrazyCrank]

well considered Roy, for the shape of the bonnet ! Congrats !

 

[Hannes]

Maybe we could get more Information by La Stampa, a very welln known newspaper from Torino that´s always been connected with the Agnelli Family..It still exists and maybe in their archieves some new informations can be found. We could Appeal to the italian national pride.  Hannes

[CrazyCrank]

1 hour ago, vontrips said:

Nice find CC! Any description as to who made it? 

 

 

 

Excuse me, Vontrips, have not answered correctly to you

 

The diagram comes from this website: http://www.pdblowers.com/c48-rai-roots-blower-parts.php

 

[Totally Mad Olivier]

22 hours ago, vontrips said:

Steering wheel lower and more vertical (4mm body lowering will sort this-ish.

Agree with you John, the steering must be more vertical, which means that the steering column must be more horizontal and probably a bit shorter than it is (see my pic Posted Thursday at 08:28 AM on Gangshow).

. The 16th step was ever far from being easy, and the changes will impose me to come back on it if I want my steering wheel to be at the right place and the good angle.

22 hours ago, vontrips said:

Not convinced about the wider track from drawing 2. Not seen any evidence of width errors in my photos of the model,.

I bought you the proof that the tracks should be longer (6,5 mm approx on each side, rear and front) on PM, if we refer to drawing 2, but it is quite obvious too on photos 5, 6 and 7, no?

21 hours ago, Hannes said:

we can also see,that the Bonnets are not parallel with the engine .I measured 2mm  height difference.

I agree with you, Hannes. The 1st overlay John made with Rich's kit (missing on the new thread while it's a very important document) confirms that: the difference of height, important in front of the cockpit, goes decreasing more and more up to the grille.

 

19 hours ago, Roy vd M. said:

I was probably wrong about the slanted engine angle. Indeed the drawing of the engine turns out to be symmetrical

Yes, Roy, I think it was a wrong track. And the engine would not be easier to insert... I think the engine is fitted left side, as shown on drawing 2 and on your drawing with pink arrow.

 

19 hours ago, Roy vd M. said:

How do you know Drawing 2 doesn't represent the car on the photographs? It looks very close in several aspects, and much closer than drawing 1.

I am not sure Hannes is right on this assumption (maybe he is!) but it's true that I noticed a few differences between our car and this drawing: the steering wheel is very different, round and without the hub on which I spent so much time, the up of the grille's shape is different too and the rear seems (but this is to confirm) a bit longer, as Hannes says.

[CrazyCrank]

Another discovery !!!

 

The 406 engine that equiped the Fiat 806 Corsa wasn' t a V engine, but a U engine

 

I reproduce the text of the Wikipedia article about U engine:

 

"Starting in 1925, FIAT began preparing an engine and car for the new 1926 1.5 litre racing formula, adopted in both Europe and the USA.^[5] For the engine, designated the 'type 406', FIAT chose to mount two 750 cc six-cylinder banks side by side on a common aluminium crankcase, with their crankshafts geared to a common output shaft. A single Roots-type supercharger driven from the nose of the right-hand crankshaft delivered mixture to a pair of intake manifolds located between the cylinder blocks at 13 psi boost. The left-hand crankshaft drove the single water pump. A single shared centrally mounted camshaft, patented by Guido Fornaca,^[6] operated the induction valves which were on the inside of each cylinder bank; two camshafts mounted outboard drove the exhaust valves. Twin Bosch magnetos were driven from the tail of the central camshaft. The engine weighed 381 lbs, not excessive for the time. On test the unit delivered 187 bhp at 8,500 rpm at maximum boost "

 

So there were two  crankshafts in a unique crankcase on this engine, and by a set of gears, these two crankshafts came out on a common output shaft, probably situated at the lower part of the crankcase

This common shaft drove the engine flywheel at the back of the engine, and was probably connectable on the front of the car to the starting crank

The case in front of the engine is the supercharger, driven by right crankshaft

Above it, the water pump, driven by the left crankshaft

 

And at the upper middle of the supercharger, there is a hole where to put the crank ! IMHO

 

So, it seems that Hannes and I were right, not accepting the idea that the cranck cross through the moving parts of the supercharger !

 

I'll put a diagram later

 

CC

 

Edited November 12, 2016 by CrazyCrank

[Hannes]

Dear Olivier not only the car´s rear and the wind-shelter were improved regarding the aerodynamics,but also the grill and it´s case. So for me this confirms,that drawing 2 Shows a n improved Version of our car.

Regarding the great crankshaft,that could be turned by a small drive shaft of an impeller I am sceptical,because the materials of that time were not strong enough ,and the power that was needed to start the engine would have damaged this drive shaft imho.  Hannes

[CrazyCrank]

 

What do you think of that ?

 

[Hannes]

That´s exactly what I thought. Now the shortening of my Radiator grill and case makes more sense for me too. Greetings ! Hannes