CNC lightened crossflow pistons

[B.Leonard]

I now have the ability to lighten crossflow pistons in an automated fashion. Special thanks to Chris Lake and Al Stoker for advice in the preliminary design stages to determine minimum thicknesses.

A stock Wiseco runs about 750g and I can get them down to a durable 550g or an ultra light version of 505g. My 2.6 XP will have 550g pistons with 312g rods for excellent throttle response and durability over 7k rpm. I can also taper grind the inside of piston pins to loose an additional 20g of reciprocating weight.

I am also working on producing custom OMC looper pistons in the diameter and pin location of your choice. This will enable running a 3.0 style rod in a 3.3 style bore or any other combinations.

Anyone interested in a set of these send me an email at bllkml@yahoo.com I can do crossflow pistons now, looper pistons to come soon :)

-BL

[B.Leonard]

505g would look similar to this. This was one of several prototypes;

http://bleonard1.tripod.com/Webpics/sterling/WisecoCutaway1.JPG

-BL

[H2Onut]

wow thats a BIG PICTURE


So when can we expect Mercury pistons and rods ?

You da man BL !

[B.Leonard]

http://bleonard1.tripod.com/Webpics/sterling/WisecoCutaway3.JPG

-BL

[B.Leonard]

http://bleonard1.tripod.com/Webpics/sterling/WisecoCutaway4.JPG

-BL

[B.Leonard]

This is what I am running in my lake/race 2.6 XP.

http://bleonard1.tripod.com/Webpics/sterling/ProMarine2.JPG

-BL

[Bill Rogers]

Wow, that's awesome BL. I spent a lot of time messing around with crossflows - always hated the heavy pistons. I remember measuring a set of "RS" pistons that weighed around 650g, and that was with the huge half-moon scallop on the intake side. I never would have guessed that a reliable 550 was even possible! I believe you *are* da man!

You're giving me second thoughts about selling my 2.6! :D

[B.Leonard]

They should really help bring the old flow into the 21st century :D

Best thing about it is it only takes an hour per piston. Clamp the piston into the machine and let her rip. You can go across the street and get a burger :D Even the grind marks are identical from piston to piston so quality/consistency is nearly perfect.

The blemishes on the inside of the Pro Marine are from previous "hand" grinding/lightening. The Wiseco was untouched (stock) so it was a good prototype to cut in half for viewing.


-BL

[84exciter]

how u gonna put um back together?????:D

[Instigator]

All I can say is holy crap!!
Freagin awesome Bruce!!
I knew you were up to something;)
Are you starting with Wiseco's??

[B.Leonard]

I'm running the Pro Marine psitons simply because that is what was in my 2.6 when I bought it and they had very low hours on them.

I wouldn't hesitate to run the Wisecos now that they can be made so light although the Pro Marine pistons have a scalloped bin boss (just above the pin in the pictures above) which is lighter. They could also run with 1-2 thou less clearance.

For over 7500rpm the forged Wiseco is probably the best choice, after the 200+gram diet of course :D

-BL

[Dr Thunder]

how much $ per piston ?

[Hooty]

That's REAL impressive! Did you write the program? Doesn't really matter, somebody did a slam-bang job.

c/6

Hooty

[BarryStrawn]

BL - When do you plan to start testing these puppies?

[B.Leonard]

Yes.

The pistons were modeled/digitized using Ashlar-Vellum CAD software and then machined to spec produced by the software on a CNC machine.

Myself and 2 other engineers (Rob Fryvogel of www.carbinite.com and Ray Vinson from Vinson Machine) worked in conjunction with advice from Chris Lake and Al Stoker on minimum thicknesses and balance/harmonic bobb weight issues.

We're looking into purchasing forged billet slugs raw from a popular piston manufacturer and producing whole custom pistons for the OMC looper to our spec.

There always seemed to be a need for serious pistons in this area and we're going to meet that need.

We figured we would start with lightening crossflow pistons since they were SO overweight to start.


-BL

[MattGreen]

Bruce:
Kudos would be an understatement ! You've hit on a small, untapped market, if you can afford the time and money to do this, go for it ! A set of 3.3 pistons with the proper pin height would fit really well in my V4...........(or Chris'..............) Keep us updated.

Thanks
Matt :D :D

[B.Leonard]

I should be able to have my motor together by the end of June with the 550g pistons and 80g pins.

I believe Rob King is going to try a set of the ultralights.

Even with the ultralights, if the pistons are kept under melting temp we don't foresee any problems due to the uniformity the CAD/CNC process allows us. There is no way you could get that by doing them by hand.

The only problem we're not sure of with the ultralight version is bobb weight/balance harmonic issues since I don't believe anyone has ever run a crossflow with that light of a piston.

There are many theories on the effects bobb weight has on balance and harmonics so we just need to try it and find out.

The 550g lake version has been run by several people without any balance issues.

-BL

[Robbie B]

Geeezzz BL.... what a breakthrough.
Light weight flow pistons who other than you would of thought of such a thing.
Real impressive work, congratulations on a fantastic effort.
I thiught my pistons were light at 600 gms.
Got a question though, how did you get that big ugly belt sander that your so good with in to those little pistons.........LOL!!!!
:D :D
Got any idea on $$$$ yet??:eek:

Robbie

[Bill Rogers]

Bruce, what's with the blue color? You haven't left them alone with Agent M have you?;)

[B.Leonard]

Robbie, oh man that's funny! :D I was going to post "Look what I did with my cordless drill and a 1/2" drill bit!" LOL!!

The light just hit that cutaway different in that picture where they look blue. It's the same piston.

$40.00 for a crossflow piston, $45 for a looper, $15 to taper cut the inside of the pin down to 80g. Buyer pays shipping.

We're modeling a looper piston right now so they will be available soon.

The first whole piston planned is the 3.3 piston that can use the long rod as Matt mentioned above.

-BL

[Dave S]

Looks like a big BIG merc KG7 slug :D

[B.Leonard]

Do to popular demand Merc pistons soon to come! :rolleyes:

I'm looking for someone to volunteer a few pistons (used) to model and cut up so we can get setup to do Merc stuff also.

-BL

[H2Onut]

YOU ROCK YOU ROCK,,

When can I come over and spy them, I mean SEE them !!!


Hows the Boyzzzzzz

U MUST STAY!!!!:(

[ShorePounder]

Bruce, see your other post regarding Merc pistons. I got one for a 2.4 that's good enough for your intended use, but not good enough to return to service.

[Dave S]

There's got to be TONs of burnt ,broken ,cracked, and unpined Merc slug's :D

[Gerben]

Damn!

Is this the same guy from a while ago:
Hi I have a bathtub with a Johnnie on the back, it runs 36mph..???

Looks great!
Gerben

[JcGibbs]

Bruce,

I'm the guy lightening your pistons. I thought I'd shoot ya' a pic or two of the 3.5 Wiseco piston I just programmed and machined this morning....huge difference in wieght!!

Jc Gibbs, Vinson Machine

[JcGibbs]

another view.......

[B.Leonard]

Those pistons look familar! Before that is :D Keep that machine plugged in, there are several sets headed your way.

-BL

[novalves]

Vellum is CAD only.

How are you programing the tool path?
Programing on the controll?
Toolpathing an exported DXF in another program?

[Forkin' Crazy]

What about the scallops? Looks great!

With the scallops it would be even lighter?;)

[Carbinite]

What do you think? .25 dome thinkness should be pretty uniform.

[Carbinite]

I assume you mean the underside of the pin boss?
We left about .020 on the boss for balancing puposes.

[Forkin' Crazy]

No, the scallop in the skirt on the intake side. I think it is 1" radius....I don't think I have any pics, but will look. The scallops with the coinciding cut in the block came on XP and GT motors and make a short cut for the intake charge.

[B.Leonard]

Both areas would allow for more weight loss. The Pro Marine and the factory pistons are already scalloped under the pin boss.

How 'bout it Paul? Wanna try it? :D

-BL

[Forkin' Crazy]

Why HELL YEA! I gotta fix my boat situation first (gotta get another). So that will put a damper on if for a while....:(

[Carbinite]

Oh. You mean the XP scallop. Was that only on XPs? Yes, it is a 1 inch radius. The 3.5 pistons that we are currently playing with don't have that scallop.
The computer model shown on my last post is supposed to weigh 508 grams. I 'm thinking it will probably come in at about 520 grams.

[Forkin' Crazy]

I just didn't see any scallops in any of the pics. Mine are already cut. Is that 550 g on the forged or cast pistons?

Would it be better to have them cryroed first?

[Carbinite]

I think that it would be good to have them cryroed I don't know if it matters if you do it before or after machining. BL had some pictures of his XP pistons that we machined and it show the scallop. I was thinking on removing some skirt from the sides below the pin boss like an automotive piston. At this stage I think that it might really weaken the piston and cause one or both sides of the skirt to collapse. 520 is light enough for for my comfort zone at this stage of testing.

[novalves]

Scallop height refers to the valley that is created between toolpaths when parts are profiled using a bull or ball nose endmill.

They become larger when the tool has a smaller radius.
They also become larger as the distance between the toolpath increaces.

They also increase surface area and the related heat transfer.

[aircraftman]

Im a little concerned about the balancing issues this may cause. has anyone had any intelligent thoughts on harmonic issues this may cause? just want some reassurance on this.

isnt the crank balanced with the weight of the pistons and rods taken into consideration?

Guys my pistons arent going to be there until next week now cuz of some money issues. but they will be there!!! sorry for the delay.

[aircraftman]

I found a very thourough explination. look!!!!!!!!!!!

http://www.victorylibrary.com/mopar/crank-bal-c.htm

aLL YOU HAVE TO DO IS WEIGH THE ORIGIONAL PISTON / rod pin etc assy. with the origional crank.
next weigh the new pistons / rods pin etc, and basically subtract the weight difference from the counterweight of the same crank.

the bob weight and harmonic issues will change slightly but without having the time and equip to measure the balance running with accelerometers,

your closer to stock balance tolerances than youd be without doing the balancing.

[B.Leonard]

People have already run them at 550g with no problems.

We have been looking into it quite extensively I can assure you. There are many different views on what balancing is and how to do it and if it is needed at all.

I'm going to have my 2.6XP put on the balance machine to see what's up and I will keep you informed. Honestly, I don't think it could get worse than stock though :rolleyes: I think the wheels on my trailer are balanced better than the crank in this old flow :D

-BL

[Carbinite]

I think it strong enough?

[Dr Thunder]

I know of a guru who has run OMC pistons at 490 { they are lighter than wiseco to start with } and has had no problems. My question is are you a wiseco dealer so that I could just by pistons from you already lightened?

[B.Leonard]

Not a problem. What size/weight are you looking for? I'll e-mail you a price.

What specific year/size motor is this guru running? What kind of use and what rpm?

-BL

[Talon2.5]

BL i have a 2.5 top guided piston that i can send if ya want it

cool stuff!! looking good!! :cool:

[B.Leonard]

Bringing the 235 into the 21st century :D

Taper ground wrist pins, were 106g now 83g! Stock id in the middle for strength, tapers out to .068.

-BL

[Dr Thunder]

87 150 xp 3.5 bore .020 over lookin for the 505g version hopefully around 6500-6700 r's with the outboard jet.

[Mark75H]

How are you grinding out those wrist pins? I thought they were as hard as rocks?

[B.Leonard]

Hard but not that hard. Standard carbide bit.

The taper also moves the center of gravity towards the middle of the piston reducing stress on the rod even more.

-BL

[Forkin' Crazy]

How many CC's will that add in crankcase displacement.

Seems wasteful to cut the block at the bypass covers and front of the front half when gaining so much on the pistions.



:confused:

[B.Leonard]

In my opinion from talking to many people about this, tightening up crankcase volume only improves low end responsiveness and cyl scavaging. It does nothing for high rpm power and can actually slow the motor down if too tight in those upper rpm ranges. In a crossflow I doubt the there is much flow behind the piston at all at high rpm.

How many CCs are we taking out? I don't know exactly, I estimate 50-70cc. We can find out exactly since we know we're removing 200g in weight.

As far as it being counter productive to cutting the covers, intake etc... Yes you will have to find more area to reduce to make up for it. That it not a problem though. There are several areas to do that around the reed cages if you insist on getting it back. The advantage of durability by far less stress on the con rod far out weighs the volume issue if you ask me.

We'll know for sure soon. I should have mine running in a couple weeks. The crank is being balanced right now but everything else is ready. My estimates say it is going to be an absolute torque monster (stock GT/XP port timing) and VERY responsive (lightened parts and crankcase stuffed to the max). I don't expect more than 7200rpm given the stock intake.

Bigger intake is the next phase :D

-BL

[Forkin' Crazy]

I can relate to what you are saying.

Would it be easier to measure the cc's buy submerging a before and an after piston into a graduated flask with a liquid in it?

Working on a pretty big project, Bruce, but when I get through, I am definitly gonna do it!

[Mark75H]

Since I have been involved with a similar project dropping the compression ratio on an old inline 6 by carefully measuring the metal removed from the piston crown, the specific gravity of aluminum is 2.7...........therefore 200g=74cc.