2.4 piston/rod combos

[Force Fed Mopar]

Planning on putting a 2.4 into my Daytona, so I'm looking at all the different piston/rod combos. The combos being:

Stock 2.4 Stratus rods/pistons
SRT-4 rod/pistons
T2 rods/2.5 TBI pistons
T2 rods/2.5 turbo pistons
T2 rods/ SRT-4 pistons
T2 rods/ stock Stratus pistons

And before you jump all over it, yes I realize the stock NA pistons are weaker, and forged turbo is stronger than cast turbo, yada yada. What I am looking for is comparison info, ie pin heights, weights, ring land dimensions, crown thickness, top ring land to crown heght, etc etc. I am probably going to start out with the stock Stratus stuff and see how far it goes, just cause I'm curious like that

I am also very curious about the pros/cons of the stock-style domed (ski-ramp) pistons, vs the dished 2.5 turbo pistons, vs the flat-top pistons that are available from the aftermarket. I am under the impression that the domes quench better, which is better for quelling detonation? If so, why the flat-tops? And what happens when you go dished 2.5 piston?

I know that the 2.5 piston radically drops the compression, but I have numbers that range from 6.8 to 7.2:1.

[cdavis]

The stock stratus stuff is 9.4 :1 compression. That's way too much, unless you're just going to run 5 psi boost. Lol. I know unaclocker did his and iirc the rods gave out at fairly low boost. Maybe 8-10 psi. I would just go with the srt stuff. It's fairly cheap and can handle a lot of power. I've heard 400whp. I'm in the middle of a 2.4 swap for my shadow and that's the route I'm going until I can build a better short block.

[Force Fed Mopar]

Yeah I would run low boost on stock Stratus parts. Like, direct line from intake to wga lol.

[Aries_Turbo]

I am also very curious about the pros/cons of the stock-style domed (ski-ramp) pistons, vs the dished 2.5 turbo pistons, vs the flat-top pistons that are available from the aftermarket. I am under the impression that the domes quench better, which is better for quelling detonation? If so, why the flat-tops? And what happens when you go dished 2.5 piston?

the srt ski ramp pistons do provide good combustion chamber quench characteristics so you can run alot more ignition advance.

even though the 2.5L dish creates a much lower compression ratio, it has less quench. you can probably run more ignition advance on the SRT stuff than the 2.5L dish.

the flat tops.... i hear that some dont like the unequal weight of the dome and feel that it makes the pistons rock back and forth and over time, with real high power, will deform the piston skirt.

i bet in a 400hp or less application, the piston would be fine for a long time but maybe if you are going for 800hp or something crazy like that, a flat top would be better.

i myself would want one of two things:

1. the stock SRT piston... cause they are cheap and easy to replace if broken provided you dont mess up the bore or head.

2. a dished piston thats cut to match the shape of the combustion chamber and the edge of the piston real close to the head at TDC for good quench.

Brian

[BadAssPerformance]

You forgot all the many aftermarket combos, such as the one I'm running... FM's long GRP Rods / short JE pistons

j/k

Great idea to collect all the rod lengths, pin heights and deck heights for a KC artcile

[Force Fed Mopar]

that's the idea

[turbovanman²]

Rods are the same, we've covered this, lol, but SRT's have .866 piston pins so if you use SRT pistons with T2 rods, you'll need to find someone to put a custom bushing in.

STOCK n/a pistons and rods in a 2.5 sit around .014" in the hole in a 2.5 turbo engine, I'll know about 8.5:1 SRT JE pistons in a 2.5 soon so that should give you an idea of how 2.5 stuff will work in a 2.4.

[Force Fed Mopar]

Disassembled my Stratus shortblock today, not sure I want to try any boost on the n/a pistons now lol. Piston crown to top ring land width is only .120" I'll have more specs after I get them all cleaned up.

[Force Fed Mopar]

Took some measurements of the stock n/a 2.4 rods and pistons today.

[Force Fed Mopar]

Bump!

[ShadowFromHell]

Subbing, any new info?

[Force Fed Mopar]

Not really, although I have decided to go with SRT pistons instead of 2.5 pistons, general consensus being that the 7.2 compression is too low.

[ShelGame]

Planning on putting a 2.4 into my Daytona, so I'm looking at all the different piston/rod combos. The combos being:

Stock 2.4 Stratus rods/pistons
SRT-4 rod/pistons
T2 rods/2.5 TBI pistons
T2 rods/2.5 turbo pistons
T2 rods/ SRT-4 pistons
T2 rods/ stock Stratus pistons

And before you jump all over it, yes I realize the stock NA pistons are weaker, and forged turbo is stronger than cast turbo, yada yada. What I am looking for is comparison info, ie pin heights, weights, ring land dimensions, crown thickness, top ring land to crown heght, etc etc. I am probably going to start out with the stock Stratus stuff and see how far it goes, just cause I'm curious like that

I am also very curious about the pros/cons of the stock-style domed (ski-ramp) pistons, vs the dished 2.5 turbo pistons, vs the flat-top pistons that are available from the aftermarket. I am under the impression that the domes quench better, which is better for quelling detonation? If so, why the flat-tops? And what happens when you go dished 2.5 piston?

I know that the 2.5 piston radically drops the compression, but I have numbers that range from 6.8 to 7.2:1.

I did a bunch of research back when I was going to put a 2.4 in a 2nd project Daytona (that I no longer have). Basically, the 2.5 T1 pistons and rods will work great, if you deck the block 0.06". From what I measured, that should be no problem for the block. But, if you don't deck it, the compression is wayyy too low. 6. something as you already mentioned.

pics:
http://www.turbo-mopar.com/forums/sh...l=1#post831503

[ShadowFromHell]

Interesting info Rob. But I have a feeling unless you have the 2.5 rods/pistons its gonna still be cheaper to buy the factory SRT stuff. Now, Can you use SRT pistons with T2 rods? Ive got a nice set of T2 rods, already ARP'ed and all checked out. I dont like the fact the SRT rods cant be fixed if you spin a bearing.

[Force Fed Mopar]

I have the rods and pistons, but don't want to have to cut the block .025-.060", as that will make cam timing and belt tensioning interesting to say the least. So I am trading my 2.5 pistons for some proper SRT pistons.

The SRT piston can be used with the T2 rods, as they are pretty much the same length (I think like .001-.002" different), but you will need to have custom pin bushings made, as the SRT pins are .866" and the 2.2/2.5 is .901". This is probably what I will do, as my machinist says it is probably a better option than trying to hone the aluminum piston out to the larger size. Unless I can get a good deal on some Eagle rods

---------- Post added at 08:41 PM ---------- Previous post was at 08:37 PM ----------

The stock stratus stuff is 9.4 :1 compression. That's way too much, unless you're just going to run 5 psi boost. Lol. I know unaclocker did his and iirc the rods gave out at fairly low boost. Maybe 8-10 psi. I would just go with the srt stuff. It's fairly cheap and can handle a lot of power. I've heard 400whp. I'm in the middle of a 2.4 swap for my shadow and that's the route I'm going until I can build a better short block.

I read his posts on Neons.org about it, and the rods broke when he overboosted to 18psi. They held up fine at 8-10psi.

[turbovanman²]

I have the rods and pistons, but don't want to have to cut the block .025-.060", as that will make cam timing and belt tensioning interesting to say the least. So I am trading my 2.5 pistons for some proper SRT pistons.

The SRT piston can be used with the T2 rods, as they are pretty much the same length (I think like .001-.002" different), but you will need to have custom pin bushings made, as the SRT pins are .866" and the 2.2/2.5 is .901". This is probably what I will do, as my machinist says it is probably a better option than trying to hone the aluminum piston out to the larger size. Unless I can get a good deal on some Eagle rods [COLOR="Silver"]

.

Go over to SRT forums, I picked up a set of Eagles to go with these pistons for $150, and they are MINT.

[Force Fed Mopar]

Go over to SRT forums, I picked up a set of Eagles to go with these pistons for $150, and they are MINT.

Yeah I am starting to peruse them, the Eagles are a lot lighter than the T2 rods. And wouldn't require custom bushings.

[ShadowFromHell]

Now I have a question, if 2.5 turbo pistons will "work" in a 2.4, would 2.4 pistons with T2 rods work in a 2.5 hybrid? Maybe with the top milled to alter the compression ratio?

[ShelGame]

Now I have a question, if 2.5 turbo pistons will "work" in a 2.4, would 2.4 pistons with T2 rods work in a 2.5 hybrid? Maybe with the top milled to alter the compression ratio?

They'll pop out the top of a common block. You'd have to cut down the pistons, or get 1.5mm shorter rods...

[turbovanman²]

They'll pop out the top of a common block. You'd have to cut down the pistons, or get 1.5mm shorter rods...

They actually sit in the hole, I tried it.