Sorry John and Paul. I promised you guys pics months ago to show the difference between the old TRW and newer Sealed Power/Speed Pro pistons. I was posting one of my sets on EPrey and remembered it...........

Forgive me, Medication made me an idiot the last few months......   

Anyway, these are the pics. The original TRW L2443N's for the 460 are on the left, the gook made Speed Pro's are on the right. Same part numbers......... 

Tell me which YOU would use?

 



Ray

just to add my 2 cents the speed pro pistons have a cleaner looking cast however the top where the spark and combustion is suppose to start has really sharp edges, thats NOT ok. detonation will occur there.

Since they're forged, "casting" is kindof a relative term there, but yeah, it IS a whole lot prettier......until the first spark hits it.......after which who cares?

The point when we were talking about it quite awhile ago was how much stronger the originals were, let alone material they were made from and the obvious difference in the skirt length limiting piston slap. GC was having a 460 built....yada, yada, yada.....and this piston part number came up. I know a few others on the boards here have some experience with this piston as well.

But notice the external boss differences where the wrist pin is (extra thick on the original ones, inside and out), and where/how  the weight balance machining is done on the underside of the two, PLUS the really surprising differences in the ring land thickness. 

A couple other things hard to see in the pics is just how thick those wrist pin bosses are on the originals compared to the "overseas" ones (You can kindof get the idea in the first pic) and the tops are thicker, heavier also allowing machining to whatever chamber volume/compression ratio you want.

What alarms me, and Paul has mentioned this may times, is that these are all the same part number. The Sealed Power/Speed Pro one I ordered as a "replacement". I really didn't need one, I just wanted to see what Lakesonly was talking about. Now I know.

The point being, probably OK with either in a performance build unless splitting hairs or pushing the edge. The PROBLEM is when you go to rebuild, re-ring, whatever, and need just 1 or two replacements.................and these carry the same part number, no revision number, Etc. and I'm quite sure this happens with probably every aftermarket manufacturer.

Ray   

The above picture shows the first design by TRW and goes back to the 1980s, and it shows the latest design as offered by SpeedPro.  I'm pretty sure there are two revisions between the first and last versions shown above (a total of four L2443 designs).  Changes include shortenting the skirt, changing the pin clip groove design (and clip type), changing the valve pocket, relocating the ring pack, etc. Some of these changes took place after a discussion with the product line manager at SpeedPro.

Both of the pistons pictured above have features that I personally don't care for. If it were me and I had a choice only between the two pistons shown above, I'd opt for the early TRW design even though it has the long skirts.  But the L2443 that I really like is one that was offered by Federal Mogul/SpeedPro between the two above examples. The one I like had its skirt shortened, still had the square-cut clip grooves, was American-made through-and-through, etc.

Those "long skirt"  versions I had are sold now, but we will simply agree to disagree on the benefits/shortcomings of those, OK Paul??? 

Ray

I don't understand; where are we in disagreement?

LO

I just still like the idea of the longer skirts and a little more mass that the older ones have, personally.

Technologically speaking, today, this doesn't hold water I'm sure, but back in the day, the longer the skirt, the less piston slap and rattling you had to listen to when using forged pistons.

Ah. I did say that I prefer the oldest version over the newest version.  But yes, I do have a preference for the version(s) that were between the two versions pictured above.

In regards to the long tang at the end of the skirts in the original TRW's: These TRW L2443NF pistons weigh about 900 grams with pin, and the pin is down at 1.76", and they have a solid dome on the top. This makes the L2443 very top heavy and so the L2443NF piston rocks over hard in a loose bore when chaging direction at TDC....kinda like snapping a whip. And so when the bore is loose enough and the piston rocks over, that tang at the end of the skirt in the original TRWs can break off.  Having pointed this out, I should also make very clear that it is generally uncommon for this to happen except for the highest horsepower engines which run relatively loose piston-to-bore clearances.

In regards to the newer pistons "rattling" more, I don't think that's the case since the newer design has a different cam grind to the piston (I am not talking about camshafts, I am talking about cam-ground piston machining). In other words, along with the revision of the skirt comes a revision of the cam grind on the piston.  Otherwise things would rattle like hell when cold, such as if you cut the tangs of the original TRW which had a cam grind based around that long skirt.

P.S.: Hey Ray, please snap another photo of the two different pistons, another side-by-side profile shot, but with the pistons rotated 180* so that the new picture shows the difference in how far the valve relief depths penetrate down toward the ring land of its respective piston. The original TRW's valve pocket is really deep and dangerously close to the top ring while the later one is less so.

LO