TheSamba.com :: View topic

Sat Mar 08, 2014 6:33 am

Anyone knows if the (original) Okrasa exhaust valves are the same items as stock 30/36 hp?

Sat Mar 08, 2014 12:04 pm

I believe the exhaust valves are the same, only the inlet valves are bigger (33mm)

Wed Mar 26, 2014 2:49 am

Yes the dimensions are the same, but what material did Okrasa use?

Looking at the italian IVAM exhaust valves for the 30/36 hp engine that is available today they have a Martensitic steel with C 0.45%, Cr 9%, Mn 0.5% and Si 2,9%. This is not a very good material for a high performance exhaust valve from what I can understand. Ok for a low performance 6.6:1 compression engine, but not for a high performer I would guess. In IVAMs vast catalogue I can find no other engine using an exhaust valve in this material (it's common for intake valves though).

Looking at the 34/40 hp engine IVAM uses an Austenitic steel with C 0.54%, Cr 21%, Mn 9%, Ni 4%, Si 0,2%, N 0,45. This seems to be the same material that Wolfsburg West is offering in their Okrasa-copy-kits. This is a better material more commonly used in exhaust valves.

So what did Okrasa use originally? Stock valves, or ones with a more high performance material? My Okrasa heads did not have the original valves, so I can't compare.