Race Engine Forum UK

I don't know the material but if steel obviously a lot stronger in bending (under clutch load) than cast iron thus a thickness across the weakest & most highly stressed region of c 10mm would be less of a worry.

However - as a rule - when designing anything highly stressed like a FW it is vital to create adequate radii in regions like those I have marked red (below).

I think you are 'on the right lines' using cad for the design but there is no engineering excuse for not doing specifying your own radii - the smaller the radius the greater the stress concentration that develops. Your final product looks as if it has very modest radii - the kind you get when a good machinist has no drawing 'callout' to put in anything other than that (usually referred to as 'break all sharp edges').

You may be perfectly happy with your setup and that is your right. However I consider it important to remark on these things for the benefit of all.

G

The radii are there, they do not show in the drawing but are visible in the pictures.
Always hard to guess from a photo, but I'd say they are somewhere around R3-5. "You mileage may vary" of course.

Nice to see a drawing here.

regards
Tom

just small update...

I´ve chcecked the crankshaft from my old 8v engine and it seemed quite well - so I decide to use it (I have spare 5 crankshafts from various engine in various condition..).
Machine shop and race-engine builder in my neighborhood carefully measured and checked for straightenes and the conclusion is : no need for regrind of main journals, and 1st regring of con rod pins due to ovality of pins...

New wide pulley was modified from bravo 100TD engine (simply accomodat e22mm belt from tipo/bravo TD, but 24-25mm belt from 1st gen of Ducato is also possible to fit.)

block: lovered by 3mm , fully cleaned, removed balance shafts, plugged unnecesarry oil ways...

now I´m waiting for pistons (originaly tipo 107kW)- machined acc. to my specs... by this friday they should be done...

To allow significantly higher lift of cams around TDC, increase of CR to calculated 11:1 and considerably lighter in comparison to STD pistons - (430g measured vs. 375g calculated - after mashining them 3mm down and creation of dome, the weight was 382g..))

The reason why I am mashining the piston is simpe - comparison of 102kW vs 107kW and 16v Turbo piston, where the original minimal thickness is around 7mm...at the bottom of the bowl and mine maschined pistond will have same 7mm thick (standart 107kW has 10mm and for example tipo 1.8 16v has 11mm! thick)..

It will be road going engine with fast/ultimate road specs. Im not planing racing use (in comparison with my coupe...) so Im not worry about the live expectancy of this engine.. its quite my own development of some parts and Im trying to put together the best from factory and modyfi it to better spec..

I forgot to take some fotos of piston.. they have to be now deburred and weight matched..

but the work on my tipo has wery little progress because of Im also working on Skoda felicia kit car (currently suffered front-end damage during the race) and VW GII rallye replica (new engine & gearbox build..)..but these cars are suitable for another forum sections and their own threads... unfortunately I haven got a lot of time to present them...these cars were fullz built fromscrath - everything is my friend and mine work... from sandblasting the carbody - welding in the roll cage- painting, suspension mods.. to engine and gerbox mod and assy...

Hi Honza.
I have one question about the Felicia. What kind of carburators did you install on it? And is it the standart 1.3 engine?

Hi

Its whole engine from Fabia 1.4 MPi (pushrod engine), - stiffer block in comparison to 1.3 in felicia, crank with 78mm stroke and bore 75,5mm like 1.3. Bottom end standart, but blueprinted and lightened. Camshafts 296/296 and 7,5mm lift..

Head is 1.3 MPi 50kW felicia, highly modified,carburetors Webers 40 or 45 acc. to what kind of race is planned... 40 are more torqier with better pedal feedback, but less power and lower redline - used for race on snow... estimated bhp with this spec. are about 125bhp

45 are used for road, circuit, rallye races... estimated power ver 140bhp.. estimation based on comparison with similar car

some new progress with tipo:
-Wiseco S566 pins
-ARP rod bolts
-OMP seats

arrived

-shotpeened rods

today I wake up very early and worked on engine for my tipo..
first few numbers:

piston weights: 375 to 376g
piston pin weight: 90g
rods -656x3+1x658g

piston to bore clearance 1,2,4 cyl 0,1mm; cyl. no. 3 0,08mm (factory values are 0,04-0,06; 0,1 is probably goog for intended use of engine)
piston rings eng gap matched to 0,30 top ring; 0,35 second... so in the lower range of factory specs. for that engine.

It looks like you did not use ARP connecting rod bolts on your engine build as you planned, what made you change your mind ?
Tom