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Posted: Fri Dec 16, 2005 9:49 am
by Mats
Never in a 75 block.

Posted: Sat Dec 17, 2005 12:46 am
by Maurizio
the 75 ts has no oil spray nozzles.

Posted: Sun Jan 15, 2006 1:26 am
by kterkkila
I've been thinking using aluminium in front flywheel, but after all decided to go with RST. Here's some pics:

Image

Image

The flywheel itself (with starter gear) weights 1.6 kilos and complete assy with original center triangle is 2.7 kg. Could make it still a bit lighter, there is lot of safety margin left..

What about crankshaft? Do you see any negative aspects in sharpening counterweights? How much metal could been taken away without disturbing durability? Taking them completely away may not be good idea, though..

Posted: Sun Jan 15, 2006 4:40 am
by TS_turbo
:shock: serios light flywheel is that i likie it ... what kind of steel is that?
SS or crome moly ? and what is overal thicknes of komplete wheel+cast triangle ... its must be the same as original cast wheel thicknes ... iam too curous about crank lightening ..there is alot of meat to remove, if i rememeber corect -1 kg of rotating mas(flywheel crank counterweights) is similar to -20 kg of dead weight in acceleration ...

Posted: Sun Jan 15, 2006 5:15 am
by Mats
Nice! :D

Looks like you made it out a sheet of steel? You can get a LOT more weight off if you could ditch the std cast iron centre. :)
The gain in rotational mass is HUGE! Very interesting.

Posted: Sun Jan 15, 2006 7:35 am
by kterkkila
Yes, it's made from stainless steel sheet. Not sure about the specific ASTM code. It was quite tough when turning in lathe, as SS's usually are.

Overall thickness is now 1.5mm more than in original flywheel, but that's near enough. Could compensate it by milling some material away, but guess won't bother..

The cast iron centre weights 1.1 kg. Could be lighter tough. Fortunately the mass is on small radius and won't do too much for inertia.

Posted: Sun Jan 15, 2006 11:36 am
by Mats
kterkkila wrote:Yes, it's made from stainless steel sheet. Not sure about the specific ASTM code. It was quite tough when turning in lathe, as SS's usually are.

Overall thickness is now 1.5mm more than in original flywheel, but that's near enough. Could compensate it by milling some material away, but guess won't bother..

The cast iron centre weights 1.1 kg. Could be lighter tough. Fortunately the mass is on small radius and won't do too much for inertia.
If you think stainless is tough, try titanium. :shock: :D
Are you going to fix the centre to the flywheel somehow? Might be a bit of a problem, balance wise, if you don't.

Posted: Sun Jan 15, 2006 11:44 am
by Maurizio
Nice done, I'm not that keen on the original cast iron.
You might consider doing the center also in ss.
And leave then material in the places you really need it the triangle between the thee bolts.

Saluti,
Maurizio

Posted: Sun Jan 15, 2006 12:34 pm
by kterkkila
I'm not going to fix parts together, but will mark them to keep them in same position after balancing.

I think I'm done with the front wheel for this time. May think SS center triangle later. Now must concentrate on other things, like rear flywheel. There's still some work to do ;)

Image

Should the crankshaft been knife edged like this Opel crank? Suggestions?

http://homepage.ntlworld.com/david.jack ... rt_eng.htm

Posted: Sun Jan 15, 2006 12:54 pm
by kterkkila
Great example.. That Opel engine was ruined soon due to broken crankshaft :shock:

http://homepage.ntlworld.com/david.jack ... _build.htm

Posted: Sun Jan 15, 2006 2:35 pm
by kterkkila
Have anybody been weighting 155's crank? Is there smaller counterweights than in 75's? Pics??

Posted: Sun Jan 15, 2006 2:53 pm
by Mats
kterkkila wrote:Great example.. That Opel engine was ruined soon due to broken crankshaft :shock:

http://homepage.ntlworld.com/david.jack ... _build.htm
Jumping to conclusions are we? :)
How do you know it wasn't from the fact that the block was bores alot and it cracked then snapped the crank? :wink:

Posted: Sun Jan 15, 2006 11:41 pm
by kterkkila
Mats wrote: Jumping to conclusions are we? :)
How do you know it wasn't from the fact that the block was bores alot and it cracked then snapped the crank? :wink:
Thats true, can't say which failure started the explosion. I guess the most serious mistake was to start hassling with Opels :lol:

Posted: Mon Jan 16, 2006 12:32 am
by MD
kterkkila

I like the way you're thinking and then having the balls to go out and just do it. Love it ! That's the good bit.

My conservative side suggests that you may develop your own broken crankshaft with such a light flywheel. The reason I say that is that "other" job of the flywheel is to absorb some of the vibrations and do some form of dampening itself . If there is not enough mass there, the crankshaft will have to do a lot more itself. The question is, can it take it?

I guess you'll just have to suck it and see .

I do agree with other comments that you may need to better integrate the two components and balance it as a unit before mounting onto the crank. I think it would be a safer and better option with better balancing outcomes.

Having said all that poobah, there is only one other thing to say, oh wow !

Keep us updated.

BTW. Opel, is that like a German Skoda ? :D

Posted: Mon Jan 16, 2006 4:57 am
by Mats
It's not like he is going to drive it 30 000Km a year with it... :)