Sealed Power and TRW performance programs were not merged until the middle 1990s as the two aftermarket operations were acquired by Federal-Mogul. I am rather familiar with that since I was one of the guys that did it. I did one TRW branded catalog, and then a TRW/Speed-Pro catalog, then finally a Speed-Pro only catalog over a few year period.
The TRW forged pistons always have the "F" after the base part number. Prior to the 90s, Speed-Pro/Sealed Power purchased forged pistons from TRW and reboxed them using their own part numbers. That's why the parts seem identical but the stamped numbers are different.
On older stuff that smooth interior surface with no sharp edges is normally a good giveaway that you are looking at a forged piston. Cast pistons most often have a bunch of hash marks and criss cross patterns on flat surfaces - which are used to help the filling characteristics of the mold they are made with.
Thanks Barry for your help. Below is the answer that I received from Sealed Power (Federal Mogul). Your info confirms the info that they provided.
One other question that I have, and I did pass this on to them, regards the suffix on the TRW number that I have. The
L2291 number that I have does not have the F suffix but instead has an A. Do you know what the difference, if any, is?
Another question that I had for them regards the depth of the eyebrows differing from one piston to another. The parting line that runs across the center of the dome between the eyebrows is flush with the piston top on some of the pistons and recessed .010" to .020" on others which I assume also makes the eyebrows deeper as well. It was probably a quality control issue from '78 but not sure. Have you run across that?
Lastly do you know anything about the forged number 2143-97 that is inside of the dome of all my eight pistons regardless of the part number? Apparently there is an actual L2143F part number that is also a 390 piston with a small dish. Wondering if 2143-97 was a basic forging that was used for more than one piston?
Below is the answer from FM on the identity of the pistons.
Phil the L2291F is a TRW forged piston & the 2217P is a Sealed Power forged piston made by TRW, both pistons are the same, here is the specification that I found. The L2291F is still in production, but cannot mix old pistons with newer (2002 + up) designed pistons.
Compression Height_______________________1.776"
Dome Volume______________________________-10.0cc
Deck Height w/stock block________________0.014" (below deck)
Skirt to Cylinder Wall Clearence_________0.002"-0.003" (automotive application)
From Federal-Mogul Motorparts Garage Gurus Product Support Team
Please Call The Federal-Mogul Motorparts Garage Gurus Techline @ 800-325-8886.
Sender's Name: Phil Clowes
Sender's Subject: vintage pistons
Sender's Message: I have a set of pistons for a 390 Ford, with a standard 4.050 bore, that I am trying to find more info on. These pistons were purchased around 1978. At that time I had requested forged TRW pistons. Seven are stamped on the top 2217P STD and the eighth is stamped L2291A STD. All have a forged in place number inside that reads 2143-97. My research shows that both of these numbers ( 2217P and L2291A) were, at one time associated with TRW.
Are these pistons indeed a TRW item or Sealed Power item?
Are they forged ( they are smooth inside with no parting lines)?
Are the two parts numbers equal?
Do you have or know where I can find more specs on them such as compression height, dome volume (eyebrows), deck height, area above the top ring and the recommended skirt to bore clearance.
Any help will be appreciated.
Thank You
PhilBarry thanks for you input. By the way, great book that you wrote. I picked it up a few weeks ago. Because of it I'm sure I'll have at least 17 more questions for you.
Phil