Turbo Crank ID?

[stage169]

What is an easy way to know if the crank is a turbo or NA crank?

I've read the NA crank is rolled filled at edge of the main journals and not the rod journals. The crank I have both look the same. From some of the pictures on the net this radius must be hard to see?

Thanks, Brian

 

[m233roller]

Brian,
I guess it depends on the pic. ALL turbo cranks have rolled fillets on both the rods and mains.

 

[stage169]

I realize it is probably simple enough to tell for somebody who has seen both but I haven't. This 109 engine came out of an 86 Bonneville made in Mexico I think. I guess it should not be a turbo crank but if you don't mind this evening I'll try and get a good pic of it and see what you think. This is about the best picture I've seen on the net. Brian

 

[A2000RICH]

What is an easy way to know if the crank is a turbo or NA crank?

I've read the NA crank is rolled filled at edge of the main journals and not the rod journals. The crank I have both look the same. From some of the pictures on the net this radius must be hard to see?

Thanks, Brian

sometimes its hard to see in a pic but if you have it in your hands its extremely easy------sometimes there will be a dark circle at the edges of the crank journal where the rod bearing doesn't touch that sometimes looks like a groove in a picture--------but the groove is about .030 deep and you can easily see it and feel it with your fingernail............RC

 

[stage169]

I ran my fingernail over a main and rod journal and did not feel a groove. It is not 90 degrees either. Probably not the turbo crank but I might get a better idea a friend has a 4.1 crank that he thinks is original so I can compare. Pic is not very good - Thanks for the help! Brian

 

[stage169]

Originally I put my finger on the journal and went to the edge and couldn't feel it on the main. Starting at the edge first I could definitely feel the groove on the main but not the rod journal. Now I know for sure! Brian