Forensics - stock 250 with boost.

powerband

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Finally disassembled the original tired 250 in the 74 Maverick that received my first attempt at forced induction (Turbocharging) . Buick derived draw-through turbo with simple J-pipe enabled spooled up T3 to get 15-20psi at the intake log with turbo-specific Q'jet (850?) wide open' blub-blub... .
... the fun didn't last long and suddenly got a lot of blowby , leaky head gasket , less power - so pulled the engine. Head , Bearings, Cam looked OK , except slight scratch down rear wall of Cyl #6. I though it broke a piston ring but after removing piston, it was the OEM piston ring's land's that broke away from piston. Block is good for an overbore but it is a lesson in limits ...





Basically used the original engine for figuring 74's engine bay dimension options for forced induction projects. The Buick draw-thru works well enough but is too big for the 250 in the Maverick, may try a shorter 200 but for now working on 250 forced induction blow-thru carbed' setup with supercharger forced induction.





have fun
 
Any updates?

Isn't a broken piston land an indication of too little ring gap, where the rings don't have enough room to expand, drag on the cylinder walls, and pop the land off the top of the piston? If so, sounds like all you'd need to do is open up the gap on your 200's rings, at least until you found the next limit.

:beer:
 
jamyers":37hdr2em said:
Any updates?

Isn't a broken piston land an indication of too little ring gap, where the rings don't have enough room to expand, drag on the cylinder walls, and pop the land off the top of the piston? If so, sounds like all you'd need to do is open up the gap on your 200's rings, at least until you found the next limit.

:beer:


I believe this is exactly what I was told when I watched a episode of enginmasters on youtube, they were talking about nitrous not forced induction but I bet it is the same issue.
 
Elwood":2rajjg40 said:
jamyers":2rajjg40 said:
Any updates?

Isn't a broken piston land an indication of too little ring gap, where the rings don't have enough room to expand, drag on the cylinder walls, and pop the land off the top of the piston? If so, sounds like all you'd need to do is open up the gap on your 200's rings, at least until you found the next limit.

:beer:


I believe this is exactly what I was told when I watched a episode of enginmasters on youtube, they were talking about nitrous not forced induction but I bet it is the same issue.

If the ends of the ring are shiny ,they were most likely butting.
 
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