TRW L2388 Pistons

I was looking through the engine rebuild receipts that came with my car trying to get a little insight on how the engine was rebuilt. One of the receipts indicates TRW L2388 pistons were used but it doesn't say what compression ratio they are. Does anyone here know what the CR is for those pistons?

Those are low comp pistons, 72 and later style, you're under 9 to 1 unless the block or heads have been cut. They work great in a 400 block for a small cammed street car as they have almost the same comp height as the 68-9 383 pistons.

Those are the lowest compression height forged 440 pistons TRW sold.

With 88-90cc open chamber heads and .040 gaskets it could easily be under 8:1.

The c/h spec I found is 1.926, which would put it down the hole .150 +/-....... Which is 36.5cc. @ +.030 over.

With an 84cc head, .040 gasket, +.030 over bore and an uncut block, it's 7.95:1.

Basically, it's a forged replacement piston for something like a 76-78 motor.

Depending on what the goals for the car/motor are....... It might be worthwhile to swap them out now.
Or..... Add some boost maybe.

Swap to some 75cc E street heads, .027 gaskets gets it up to 8.65.
Mill the heads to 70cc gets you to 8.98.

Not to hijack,but what would the comp ratio be with L2266 TRW pistons with everthing else the same as the OP's build?

The difference is roughly one point of compression.

With everything else exactly the same, the 7.95 combo goes to 8.9 with the 2266's.

The c/h height is .065" taller.

Thanks.

The engine is a 67 440 with the 915 heads. I'm not an engine builder so I don't know all of what is involved but if I wanted to up the compression to the factory spec would all I have to do is change the pistons or are there other things that would have to be done? Also, forgot to mention, the 2388's are .040 over according to the receipt.

In theory, the 2266 is the "correct" piston for a 67.

To replace the pistons pretty much requires the whole motor be torn down.
At that point, there are "better"(more modern design) pistons that could be used.

The problem with the 2266's is they are down the hole .086" on an uncut block, so you don't get any quench benefits of the closed chamber heads.

The two big questions you'd prefer to know the answers to before tearing anything apart, which may or may not be provided in your paperwork are; what is the chamber volume on your heads now....... And if the block has been decked, how much was taken off(or what is the deck height dimension)?

Knowing the answer to those questions would enable you to make a better decision on exactly which pistons would make the most sense.

Are your 915 heads hand stamped H.P. on the passenger side front and driver side rear?
The reason I'm asking is all the 1967 440 motors came with 915 heads, only the HP motors had the bigger 1.74 diameter exhaust valves

The problem is, Chrysler advertised compression was usually a full point higher than as-built compression. Maybe some engine combinations were closer, but there are a lot of 440s running around with compression in the low 7s.

Since I have all the money in the world (yours) I would disassemble the entire engine and measure everything. Then I'd buy a new set of aftermarket connecting rods. They are usually 6.760 rather than 6.768, the blueprint dimension. Measure the head cc and the block deck height. Then you can decide what compression height piston to buy, to get to zero deck.

With zero deck, compressed gasket thickness, valve pocket volume and head chamber volume you can figure out what your compression ratio is. It'll probably be too high for pump gas. Then you figure out how many ccs of dish to cut in the piston top.

With oversize, compression height, dish volume in hand, you go to piston manufacturer and get a custom set made.

Now you're getting somewhere.

Back in the day custom piston manufacturers were few and far between. So most of the time you were left trying to jerryrig a shelf stock forged piston into a space where it didn't belong, like using a Ford 460 piston in a 400 Mopar block. Or you were stuck with whatever TRW or Sealed Power made for your engine. It doesn't make sense to do this any more.

R.