Probe Forged Pistons: You want 'em? GB!

[IJ.]

Majority of the guys interested in these will be on the stock ECU so will never see 7000+......

As I said you need to come to terms with who you're building these for and not get bogged down with race crap John.

Say after me "It's NOT a race car"

Race parts just don't have the longevity for a DD unless people are willing to freshen up a motor every 10>20K miles.

 

[Halsupramk3]

8.4:1 or 8.5:1 cr should be fine. a 1.2 or so hg would make the cr higher if you want it and thicker gasket would lower it down.

i would think getting rings that are common either after market or oem size would make it easier to acquire in the future.

 

[jdub]

I agree with IJ John...we have plenty of options for race type pistons. A forged, lighter weight stock style is something you don't see.

 

[Cya]

those were my thoughts, you said yourself it you want a full race build go JE. If you were to need to replace pistons (other than just being old) you would be buiding for 500+hp. If you spent the money to go JE you would be building for more than 800hp with aftermarket rods, to my understanding these were to be the 500-800hp range seeing as how the stock rods have been proven to 750 (with treating and ARP rod bolts for relibility). Or do I have something mixed up, since we were talking about pushing around 650 for a DD.

 

[Doward]

There are really only 2 'mainstream' forging alloys used. 4032 and 2618. 4032 is lighter, but won't withstand detonation as well as 2618. Also, 2618 expands a little more than 4032, requiring a slightly looser clearance between the piston and bore.

Let me find out what options we have for rings. If it's going to be a PITA, we'll stick with stock ring sizes.

I would like to have anti-detonation rings put in the top ring land, though - I don't think any current piston for the 7M has that feature (and it could be nice to have, since the Lex/550s is the most common upgrade there is)

Don't worry, Ian - you're slowly beating it out of me

 

[IJ.]

::dead horse:: ::fundy::

 

[VanSupra]

Stock compression ratio pistons built exactly to CP's specs. I feel this will cover the entire spectrum for everyone here's builds from moderate to extreme.

1) Doward
2) S turbo 87
3) zachm611
4) TobyCat
5) mark3monster
6)MassSupra89
7)Born2drv
8)90T04
9)woodytsi
10)bmoss85
11)LilMissMkIII - pending shipping price to Aus
12)screaminglemon
13)bustedknuckle
14)starscream5000
15)knight202
16)Supraguy@aol
17)VanSupra (2) sets

 

[tig321]

Let me find out what options we have for rings. If it's going to be a PITA, we'll stick with stock ring sizes.

I see probe is currently listing 1.2x.1.2x2.8
Just what are the stock ring sizes? I can't seem to find it anywhere, 1.7-8?

I would like to have anti-detonation rings put in the top ring land, though - I don't think any current piston for the 7M has that feature (and it could be nice to have, since the Lex/550s is the most common upgrade there is)

These anti-detonation features you speak of sound intriguing.

From Probes website

Probe Forged ...Pistons also feature the latest design innovations in ring land technology. The top ring land features radial anti-detonation grooves. These grooves knock the peaks off shock waves within the cylinder, reducing the propensity to detonate. The second ring land features our pressure equalization channel, which is a shaped channel that works by equalizing the pressure seen between the top and second ring with the pressure in the combustion chamber. This feature enhances ring seal, improving power, engine life and fuel economy.

I'm keeping a close eye on this. I'm looking for an engine this month that will go in my DD. Hopefully I can find one and asses its condition before the group buy begins.

 

[Doward]

Stock ring sizes by all accounts that I've found, are 1.5/1.5/4.0

Uh... let me just go measure them, lol.

Yes, they are 1.5/1.5/4.0

BTW - Probe's already told me that *none* of the specifications are locked in yet - we can alter them any way we see fit. I'd like to go with a slightly thinner ring - but nothing like the 1.0/1.2/2.8s of the rest of the aftermarket pistons (except the Ross pistons - they are stock sized rings, IIRC)

*edit* Ross pistons are 1.5/1.5/3.0 with a 19.3cc dish.

 

[IJ.]

Ross rings are a good compromise.

 

[Doward]

I'll find out tomorrow what we can do for rings

 

[IJ.]

And remember you want a medium hardness ring for our motors, also if you feel detonation may be an issue on this type of build steer clear of Moly filled rings.

The Engineer should be able to point you in the right direction.

 

[Doward]

Do we have any hardness info out there on our block?

 

[MassSupra89]

Yup, It's all in IJ's head. He really needs to team up with Jeff Lange and write us the MKIII bible.

 

[knight202]

Doward, can you also find out, if say some of us want a second set, or fubar a current set, what the wait time and such will be on a new set thanks

Chris,

 

[IJ.]

Do we have any hardness info out there on our block?

Sorry this is only based on my experience I haven't tested the hardness but after prepping many different brand Iron blocks you get a feel for how hard/soft the material used is and the 7M is some of the hardest I've ever machined. (guess that makes me an internet genius again......)

 

[Doward]

Don't worry Ian, with the average intelligence shown on the internet, it's not hard to get classified as a 'genius'

 

[Doward]

If anyone's got anything else they want me to discuss with the engineer, let me know. I'll be calling around noon-1pm, EST (which is like 8-9am PST )

 

[MA70Snowman]

hey doward slot me in for a set of those pistons will you. been following this thread and really am liking what i'm seeing. so yeah.. sign me up.

 

[Doward]

np - you're like number 25 or 26 so far

Eric was out today :3d_frown: - calling back again tomorrow!