Herewith some photos of the T41 engines : The first is the photo of the prototype's, 41100, while still fitted with the original front wings.



Then 2 photos of 41111.





And finally, a photo of 41131.



Could those contributors of a more engineering/mechanical bent than myself please provide some analysis and/or observations. The engine currently in 41100 is No.2. Is this the same engine as in the (pre-crash) photograph? If not, any theories as to what happened to the original engine?

Any other comments on the Royale will be most welcome.

Thanks
Johan

PS. All the photographs are courtesy of The Bugatti Trust's website.

The top photo is the only one from the prototype Royale.

Taken from the photo's, there don't seem to be any differences on the engine. Can anybody confirm that the prototype had a higher volume than the production engines? Of course it may be that this difference can not be seen from the outside.

There is an obvious difference to the steering column though!

Having discovered the photo in the first place and buying it on Ebay, I can tell you that there are actually quite a few a differences in this engine compared to the production version.
In the cross section drawing that appeared in one of the Hugh Conway books it was shown with a spark plug on either side of the engine and this has often been argued that it was because the prototype had been built around a redundant type 34 block. This photo proves that it was not the case and externally the block itself is the same as the production unit.
There are however a number of differences in the alluminium components, the most important one is that the upper camshaft gear box at the front of the engine is of the same width as the cam boxes themselves. On the production versions, the cam box was the same width as the engine block and thus the narrower cam boxes stepped in slightly.
another obvious difference is that the crankcase is plain, without the Bugatti logo access plates on the side.
Other differences include the fuel pumps that are located in a different place, towards the firewall and the plated tube that covers the HT leads from distributor to spark plug is in two pieces whereas the production cars have a more elegant one piece component.
The carburettor is identical to all of the cars apart from 41100, which has a strange spring arrangment mounted on top of it.
In short, this photo tells me that although there are detail differences between this prototype engine and the subsequent production cars they all seem to be cosmetic ones.
I recently posted a reply proving that the wheelbase of the prototype was the same as the production car and it was an optical illusion that made it seem longer. The prototype initially had different wheels to the later cars, this was mainly because the diameter of the brake drums needed to be increased for obvious reasons.
In short, I can understand Ettore wishing to improve braking performance but would he have reduced the engine capacity by 15 % because he wanted to improve fuel consumption or slightly decrease engine performance? I think the engine was always 12763cc and never 14726cc.

Greg you are a genius! I am (still) busy with the Royale article, and I have come to exactly the same conclusion as you; the prototype engine was the same capacity as the rest. The only proof for the prototype's larger capacity is Bradley, and he could be a little economical with the truth. What do you think the chances are that the frame and engine currently in the Coupe Napoleon are the same components fitted pre-crash? My theory goes something like this : Ettore crashes Weyman Coupe - Factory repairs car after body is removed - Jean gets the nod for designing new coachwork - Ettore never drives again - 41100 is today essentially the same chassis as unveiled by Ettore in 1926. What do you think?

Regards
Johan

PS. You were absolutely on the money about the wheelbase. Question : If an author "borrows" ideas from other researchers yet acknowledge doing so in his article, is it still plagiarism?

From what I have read about Bugatti, everything that could possibly be reused was reused.
Looking at the other picture of the crashed weyman in the Raffaelli book the chassis took a hell of a bending and may have been uneconomic to repair. I feel sure that a lot of the car was reused though. sadly there is no way that I can think of to prove this. When I answered your question about the Royale Elephants on the Bugatti page I told you the story of the missing mascot from the Weyman..
Another strange thing about the engine photo of the prototype is that although 41150 seems to have the same radiator to the prototype, it has a unique cranked water outlet pipe on it that the prototype doesn't have for some reason.
I am still dubious about whether the prototype had a chassis number at all. There isnt one visible on the bulkhead in the photo.

It wouldn't surprise me if the prototype only got the number 41100 at a much later date, perhaps only when the Coupe Napoleon was completed. The factory was infuriatingly vague about identities for cars, at least until they were readied for delivery to the first paying customer. I believe 2 of the T59's carried T54 chassis numbers for a while and the King Leopold T59 has a 57 chassis number. As Jonathan Woods pointed out, 41150 may have been the second Royale, the prototype is 41100 (now) the Esders car 41111 then 41121, 41131 and the Kellner car (unsold) was 41141.

If Jonathan Woods is right about 41150 it would explain the similarity to the prototype's radiator, but the cranked water outlet pipe I was completely unaware of until you pointed it out. When I'm finished with the article I'm sending it to you for fact-checking. It is going to save me so much public humiliation.

Kind Regards
Johan