3.8 Or 4.1 NA High Compression Pistons


Active Member
Feb 22, 2003
Looking for new high compression pistons for an NA application for use in production 4.1 engine or 3.8 with stock length rods and crank. The higher the compression the better. Will consider sizes from stock bore to .060 over.
DSS piston sells a small dish piston "off the shelf". I run a set in my 109. 10.5:1
NA build, I'd suggest cast pistons for a 1985 Buick 3.0 v6
NA build, I'd suggest cast pistons for a 1985 Buick 3.0 v6
I am looking for a race piston. I should have been more specific and said forged pistons. Those 3.0 pistons are cast aluminum and don't have any valve reliefs. Those would be a great piston for a 3.8 in a street car with a small cam. I tried a set of those in a 109 block. The deck clearance was about .060. I may still use them if I have to. CR was well over 11:1.
Try Racetec for custom slugs.
I had Earl Brown help setup and order a set for my own 10:1 4.1L
I may have the pistons your looking for. They would be for the 3.8. . I would need to dig them out and measure them for you. They are forged trw from early 80,s. Let me know if your still looking. Thanks Zach
Okay so I have a set of Bms cosworth pistons part number pa0849/2 .20 over flat top pistons with pins, no rings. Compression height aprox 1.45" diameter is approx 3.815" . I also have a set of pistons that I believe are trw, but also stamped JE inside, they are 3.974 approx, and compression height is 1.825, .This set is cut for valves and extremely hefty. No pins or rings for this set. I will take $350 for the cosworth set plus shipping, and $300 for the trw set plus shipping. If you have more question or need pics please shoot me a text or give me call. 928 951 0200. Thanks Zach
Found a NOS set of 3.8 .020 over BMS/TRW pistons. Still looking for something similar for a standard or .020 over bore 4.1.