I've had to find another set of pistons for my 428 (detonation caused broken skirts). I found some forged TRW L2245F .030 pistons and just wonder how they compare to Badger P174 .030 pistons. Can I use the forged TRWs without any problems? I know it always helps to have an engine balanced, but this engine hasn't shown a signs of a vibration with the Badger pistons.

These pistons are shown as replacements for a 428, but balance issues, valve clearances, or which rods to use and such seem to be covered anywhere. If someone is using these pistons or has experience with them I would appreciate some help.

Thanks in Advance.

 

Almost all after market pistons are of like weight for replacing stock pistons. The only time I ever saw a difference was a set of racing pistons without wrist pin holes, so you could bore your own and control deck height. When you bored the hole at different heights the weight would be different due to the amount of materials removed. But there was a great big warning on the boxes to that effect.

 

Thats what I thought about the weight, but wanted to get a confirmation from someone. Having never used forged pistons before I just don't know what to look out for.

I didn't state in my original post that these pistons were used in another engine before. The person that was using them decided to go with another style forged piston for a compression ratio change. They look ok to me, I just see small areas that look a bit polished and some very thin scratches on the sides from being used, so I don't see a problem using them. The rings are still on them and they look to be fine. I will not reuse the rings for obvious reasons.

 

Purely, I think you might want to weigh the old pistons and the new ones on a gram scale. The TRWs, like the 2245s you are thinking of useing, frequently seem to be on the heavy side. If you have the engine apart anyway, have your machinist spin the crank with weight of the new piston clamped on- he can tell you if balancing is needed then. The 2245s are the lower compression of the two forgings that TRW/SpeedPro sells- 2303 being the other. What heads are you using ? What fuel ? I'm presuming that we don't want the same detonation issues as before ? DF

 

Yup, weigh the old ones, keep track of which cylinder they came out of, and trim the TRW's until they weigh the same. Weigh all the TRW's first and match them up to the old ones as close as possible, in case you have one TRW that is lighter than your heaviest "old' piston and you get the last TRW and it's lighter than the last "old" piston

When my machinist balanced my 390, he commented that aftermarket pistons (especially forged ones that are going to be used for hi-po) usually contain some extra material around the wrist-pin area so that you have something to remove when balancing... I think you're probably going to be pretty darn close but matching the weights is certainly recommended

 

I'll take the pistons to the machine shop and have them weighed. Hopefully they aren't that much heavier than the cast badgers. How much difference can there be in one set compared to another before it it too much? I can't find specs on these forged pistons like compression height and pin height. Any ideas?

The heads are D2TE-AA. There is a 006 stamped into the under side of the heads that I am assuming is the thousandths removed from them by a machine shop.

After taking the engine apart I found no sign of damage to the number 7 piston or cylinder. I thought it had a hole burned through it, but so far I don't see any damge to it. Probably a crack between the ring lands. I did however find broken off skirts in the oil pan from number 2,3 and 4 pistons. The skirts broke off only from the top sides of those pistons.

Anyway, most of the reason the detonation happened is because the engine had a vacuum leak when the climate control split in half while driving. I had driven it on a long trip that day too, so after getting off of the highway I noticed the engine had a miss in it. I was using 89 octane gas which is not what I normally use, so that added to the problem. No doubt that I do not want anymore detonation problems.

Later I ran a compression test and the number 7 reading was close to 60 psi compared to the other cylinders of around 150 +. So, for some reason the pistons that have broken skirts have no compression problems. It just seems a bit strange to me to see that much damage on those pistons and no loss of compression.

 

Thanks guys! I appreciate the help. I'll post what the machine shop finds later.

 

Detonation didn't cause those cracked/missing skirts. That's Ford's pistons. Same thing happened with many stock cast pistons, seen em mainly in small blocks, and a few in FE's. Detonation will break the ring lands and damage the piston tops, also breaks the rings. As for replacing cast with forged without balancing, I've done it on a 390 and had no problems.

 

The damage is not limited to the skirts. There is some damage to number 7 which isn't obvious except in lower compression readings. The ring lands or rings are damaged on this piston for sure.

I have been looking the forged pistons over and noticed that the skirts are appear to be a bit shorter than the cast piston skirts. Is this normal or would someone have machined them off the achieve a lighter weight or balance? The area underneath where the wrist pin boss is looks heavily machined as well. Being that these pistons were used in a 428 already for a short time, they were probably lightened to balance that engine.

Just curious but how much heavier are L2245F .030 over pistons than plain cast badger .030 over pistons that are supposed to weigh same as stock pistons?

 

Should be the same weight if they are truely replacements. Replacement pistons (forged or cast) that are standard, +.015, +.030 or +.060 pistons should all weight the same if the engine is to come out balanced with the original crank and rods.

 

Many forged pistons have shorter skirts, this equates to less drag. Nobody removes the skirts to balance a piston. If they were balanced, the metal removed is usually done with a drill press, and this metal will have been removed from the bottom of the pin bosses, in short there will be drill holes there.

 

Ok, so no machining of skirts, just shorter for less drag. I can understand that since most anyone is looking for increased performance when they use forged pistons.
The weight issue is getting clearer, but I wish there was a specification list somewhere on what this type of piston generally weighs in comparison to stock cast pistons and which ones are supposed to work without any special machine work for balance. Looks like I am just going to have to weigh them and go from there.
The other issue I still can't find any specs on is the piston to wall clearance requirement. No listing anywhere for this either. I have checked many websites with TRW, Sealed Power and Speed Pro information with no luck. Any suggestions?

 

Any competant auto machinist will know what the piston to wall clearance should be. The newer forged pistons are designed to run tighter clearances than the old ones. I built a 331 stroker recently but don't recall what the P to W clearance was. As for the balance issue, like I said before I ran a set of TRW forged replacements in a 390 without rebalancing it and had no problems. Matter of fact, I used the same set in three 390's without problems. I had problems with the first motor they were in, not piston related. The second was run about 30K miles before being pulled for a 427. The third ws slapped together to go into a 70 F100. I put many thousands of miles on it til I sold it. Unless you're going to really push the rpm limits, I wouldn't worry about it.

 

Yeah, I can just get the machinist to give me the clearances. I weighed one of the forged and one of the cast pistons with an electronic scale just for fun. The forged piston weighed 31.4 ounces and the cast pistons weighed 32 ounces. If these are unmachined, modified or lightened forged pistons then they don't follow the forged pistons weigh more than cast pistons rule. Maybe the standard 4.13 pistons weigh 31.4 oz or close instead of the 32 oz the .030 oversize pistons weigh. Can anyone varify this? I know this is ounces and not grams. What I am asking is whether or not an oversize piston will actually weigh more than a standard piston? Or did they somehow maintain a standard piston weight even in oversize pistons?
I am probably just going to use these pistons without balancing. I am not going to rev this engine that high, so high rpm vibrations don't even come into this really.

 

I converted your onces to grams, which is what measurement an engine is balanced with. The forged are 17 grams less than the cast. ( 907.2 for the cast vs 890.2 for the forged) Forged pistons are denser than cast, therefore a forged unit would weigh more than an exact same dimensioned cast unit would, but you say the forged ones you have, have shorter skirts, thus the reason they're slighly lighter. Some material may have been removed from them if they were in a balanced motor before. In balancing an engine you want the components to be as light as possible to start with, before balancing, to keep the rotating mass down and to make it easier to balance the crank without adding metal.