PROBE FORGED PISTON SOLID MODELS AND SPECS! LOOK!

[starscream5000]

Doward I believe Ian is making a fair comment here, as well as starscream5000 earlier on refering to the extra light weight issue. This really is something that needs looking into. We are all excited, sure (me too honestly, this seems to be a trully 7m purpose made piston) but let's not get carried away and miss/skip the basic stuff.

Yes, I am very curious as to where the extra mass is being taken off, there is clearly more material up top on the Probes due to the new design, and if the skirts are anything like the stock lengths, then they are most definitely longer than JE's skirts, so where's the lighter weight guestimate coming into play from? Are they making the piston itself thinner for weight savings? I'd personally like to have a slightly thicker, beefier piston, something closer to 305-310 without wrist pins...

 

[MA70Snowman]

damn why can't the GB end on the 15th, everyone knows payday for us govt employed is on the 1st (BILLS) and the 15th (spending money) ouch this is going to hurt. but i'm on the train

::CHOO CHOO::

 

[starscream5000]

Not 100% sure on the weights but I think it's without pins, I've e-mailed JE for confirmation.

Eagerly awaiting for this information.

If it turns out that the JE's are that light WITH wrist pins already (doubt it though) then I can breath a little easier, but, if it's the opposite, then we are going to have to tell probe to make these pistons thicker as there's no way I'm running a thin, light ass piston on my daily driven 450-500 supra. If I wanted that, then I'd bought a set of JE's. This is something that we most definitely will have to have cleared up or I will have to back out of this group buy because I don't want to risk my multi-thousand dollar engine on a set of thin pistons, and I'm sure no one else does either. Let's take our time with this and make sure everything's right the first time .

I'd hate to be the guinee (I know I spelled it wrong) pig on a set of crap pistons...

 

[Sar-Supra]

Well, as far as I can remember we were talking about streetable pistons. Weight is an issue and I just dont want to risk having a meltdown with my engine... :3d_frown:

Let´s wait and see... Don´t get me wrong but if they are even lighter than JEs I´m sorry but have to say goodbye. It would be a shame, however.

 

[IJ.]

No word back from JE yet I'll give my machine shop a ring and see if they have my piston weights on file (they should).

As for "50 posts" I raised a valid concern and it needs to be sorted BEFORE they cut the first set as they'll use XX blank that will have xx interior dimension to make the piston so XxX bore size will have xXx thick skirts.

The "design" looks to have longer skirts so if the finished weight is lighter than a JE it has to mean either the crowns are thinner or the skirts are thinner either is unacceptable for a DD high hp 7M.....

As stated eariler I'm not trying to rain on the parade here just to try and make sure you all don't end up with light weight racing parts unsuitable for street motors (JE's are right on the limit and due to their ring sets aren't a DD piston)

I have NO dog in this fight as I don't SELL parts and I'm not involved in the commercial side of things at all, look at me as a free consultant but if those involved have a problem with this let me know by PM and I'll happily leave you to it.

 

[starscream5000]

Well nothing's set in stone yet, as this is only a poll so far, but when the first prototype comes out well know for sure on the weight, and want lots of pics inside and out . I'm sure John will have the same concerns as us as we've voiced them pretty well here.

 

[Doward]

Guys guys guys! I'll be running a PTE67 myself - believe me, I've got a VERY vested interest in ensuring that the pistons are strong enough to handle EVERYTHING and then some of what I've got planned!



Ok, just got off a three way phone conversation with Shawn and Eric. We thickened up a couple of spots - now @ ~300 grams per piston (will update the specs to reflect that) and these are the THINNEST spots of the piston:

0.230" thickness of the crown under the 20cc dish
2.232" total skirt length
0.143" skirt thickness

Shawn actually laughed when I asked if he would run these in a 600rwhp 3.0L I6. No problems!

Hell, when he was going over the blueprints, he was telling me he could actually LIGHTEN THEM EVEN MORE for an all out race application!

 

[IJ.]

300+ makes me much more comfortable Dow!

Can Shawn measure the Crown under the valve pockets?

 

[IJ.]

Ok jusy got off the phone with my shop and the JE weights are without pins (thought it was but wanted to double check so the information was accurate)

 

[Doward]

Stock piston, for comparison:

Skirt thickness - 0.102"
Skirt length - 2.792" from the top of the piston crown - 2.002" from the oil ring (need to find out where the standard of measurement is, LOL)
Thickness under the crown - .322" thick

Yes, the Probes are thinner under the dish, but if you look at the design of it -

The red line is the weakest point in the piston of a STOCK completely round piston crown.

The black lines are the weakest point in the PROBE piston - do you see how the extra meat of the crown strengthens the area directly in the middle? Further, the squish from the head/piston crown is going to force the air/fuel mixture into a more hyperbolic shape, given the flame front the ability to quickly increase pressure, and then hold the pressure longer (as the flame front burns through the twin thicker mixtures on both sides of the combustion chamber - so you are going to have the highest points of pressure at those black lines.

See the blue line? That's the piston pin location. Guess what - directly under the black lines, you still have the extra meat from the pin bosses!

This is a prime example of engineering at work guys These pistons are strong where they need to be, and thinner where the material is not needed.

As for the thinner area directly in the middle - this also doesn't include the fact that the forging is just flat out stronger than the cast I'd like to find out the thickness under the dish of some other aftermarket 7M pistons

 

[Doward]

No, we could make them thicker - but why would you want to make them thicker? The stress points of the dish, are going to be thicker than the wrist pin itself - (.866") so the total amount of material will be over 1" thick. Do you really think more meat than that is necessary?

Probe Industries starting making forged pistons in 1987. They have 20 years of experience doing this - I think they know what they are doing, lol

 

[Doward]

Oh Ian, I forgot to mention - the valve reliefs are higher than the base of the dish itself (at least from the pics)

 

[Doward]

ROFL! Just got off the phone with Aaron, who has a set of the Ross forged pistons for the 7M there at his shop.

The Ross pistons are .260" thick in the center. A difference of .03"

LMAO, and the Ross are generally accepted as the 'strongest' and 'best able to withstand a beating' of the 7M pistons, are they not?

These Probe pistons are an amazing buy!

 

[bigaaron]

I just measured a Ross piston at the shop, it's only .260" thick in the center. The skirt is .2" thick! The Ross piston feels unusually heavy to me :dunno:

 

[Doward]

And Doward gets the jump!

 

[TobyCat]

Once I figure out shipping to Cold Canadia payment will be sent. Thanks again Doward and Aaron, this is amazing.

 

[Doward]

Shoot Aaron an email (aaron@driftmotion.com) or a PM (bigaaron) to find out the price of shipping

 

[IJ.]

I'm not overly concerned about the Crowns.......

Ross are heavy due to the skirts and beefy thrust surfaces, the JE's are much thinner by comparison and you quoted that the Probes would be thinner/lighter again.

I'm pretty well over this I tried to help but you're going to do what you're going to do good luck I hope it all goes well.

 

[bigaaron]

I'm not overly concerned about the Crowns.......

Ross are heavy due to the skirts and beefy thrust surfaces, the JE's are much thinner by comparison and you quoted that the Probes would be thinner/lighter again.

I'm pretty well over this I tried to help but you're going to do what you're going to do good luck I hope it all goes well.

Your input is greatly appreciated IJ, and it will have some effect on the final design from what I hear.

 

[Doward]

Not at all, Ian! I appreciate the input from EVERYONE in this thread!

The JE's are much thinner than the Ross pistons, that is true.

The stock skirts are only ~0.1" thick. The Probe skirts are right now ~0.143" thick. That is 43% thicker than stock!

From what Aaron was telling me, the Ross skirts in places are almost 1/4" thick. That seems a wee bit overkill, in my opinion. Maybe if you are pushing 1000+ hp, then you could use it!

Today, I'm going to try to find out what Wiseco and JE can tell me about their crown thickness, and skirt thickness, for their 7M piston.

We've got two weeks before we place this order, so 'fine tuning' of the piston can still occur - I'm in constant communication with Eric and Shawn over there @ Probe!

Remember as well, that we added 6 grams of weight back into the crown - the pistons are now ~300 grams, and no longer lighter than the JE pistons!