question on the 109 factory block

[ericttype]

I was wondering on the 86-87 gn 109 block, it has a turbo crank and 2 dot rods, what type of piston did they use from gm cast ? thanks Ron

 

[bison]

I was wondering on the 86-87 gn 109 block, it has a turbo crank and 2 dot rods, what type of piston did they use from gm cast ? thanks Ron

They used a eutecic cast piston. A very good design

 

[Blazer406]

GM also cast in some steel inserts near the wrist pin area that you can visually see from the underside of the piston.....kinda serves like rebar would in concrete.......so this also adds to the strength.....

There is a board member here in the 600-700 HP that is still running stock pistons....... he recently (and finally) broke one......but heck.... they were never designed for that power level...... they are real impressive IMHO....

 

[pacecarta]

stock 109 turbo pistons were buick hepolites with the steel reinforcement
http://www.gnttype.org/techarea/pictureguides/pistonguide/38turbopiston.html

hypereutectic cast pistons to go with the cast rods and the cast crank

and yeah they're junk :biggrin:, only about 600 mid 10 passes and i split #3 , http://www.turbobuick.com/forums/at...high-mileage-stock-bottom-end-piston-3top.jpg
recently a few of us pushing them over the 600hp level on pump gas and alky had a few similar failures with the pistons but thats where the extent of the damage stopped,,, just replace with another cheap stock junk piston