Tuning turbo time!

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Tuning turbo time!

Done some piston work seeing as I have so many sets.

managed to machine out 6CC of metal dropping the C/R to 9:1


16valve engine combustion chamber dimensions i worked out for anyone thats interested

Standard compression 10.60:1... calculated at 10.5527:1 guess fiat rounded it off... close enough.
1242 16v standard.JPG

piston dish machined out to 20CC (20ml)
1242 16v low compression.JPG
 
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the piston tops are a tad over 6mm thick, and that is only about a 1cm square right in the center

I did some research and 5mm is safe on a piston. but that was on a much larger piston where the area under it is much bigger then 1cm so subject to more force. also the oil squirter keep it even safer.

I have machined 1.2mm from the top and made dish slightly wider with less of a taper.


ill get photos tomorrow after they are cleaned
 
Force is all relative. greater piston area = less force be square whatever. Sure compression has a lot to do with this as well. Still, I'm sure taking reasonable amount out will have no ill effects.

took me wrong :)
in engine with a CR of 9:1 will have the same pressure per area what ever size the engine.
flip one of our pistons over (or look at the photos i posted of the pistons) and you will see that you can only really see a small square of the piston crown between the metal around the gudgeon pin.
Only this area is 6mm. thick and the rest tapers up to 8/9mm onto the skirts.


My reason for say I should be ok machining more then recommended (i haven't)
is that it was for much bigger pistons where leverage forces (I think) would be more...
bit like braking a pencil... anyone can do it... but try braking a half in half :rolleyes:
 
yeh... whats the worse that can happen... blow a hole in the piston?...fragments band a couple of valves?... fragments go into the turbine causing mass destruction? lol

head... I am just going to smooth the transaction between valve seat and head there is a large step on each.
smooth a few lumps and bumps in the casting but thats about it.
with a turbo even if i got it perfect id only gain a little and id have more chance of fecking it up. (plus im to lazy to mess about with 16ports!)
 
right, not much to say as ive been working on my mates 16valve conversion, but I lobbed off the end of a 16valve manifold and found it to be impossible to use for a cheap turbo manifold (was going to weld a turbo flange onto it just to test the engine before building a proper tube manifold)

looks like ill be building a jig to make a real manifold. might as well make a few...
 
Apropos power, probably not a lot, directly. Apropos when the power comes in, a great deal. You can usefully use a smaller i/d pipe than the original, smoother, larger radii on the curves, equal lengths (or volumes -- easier to check) to spool up a larger turbine(or turbo) more quickly.

These things are usually made up of 30-40 schedule mild steel gas/steam pipe. Bloody thick and pretty much indestructable. That way you also avoid the horrors of dis-welding.
 
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