Hypereutectic vs. forged pistons

sixstanger00 · Mar 16, 2013

g36 monkey said:
Biggest off the shelf one from comp is 218/226 and .500 lift. That's what I have. I'd be worried about driveability much bigger than that, but you can give it a try! I'm interested to see.

I've watched a vid on YT where a guy had the SSM cam, I just can't find it now! :angry4:

sixstanger00 · Mar 17, 2013

Here's a vid of a V6 with the SSM cam:

http://www.youtube.com/watch?v=dL3ulMQlX9k

sixstanger00 · Mar 24, 2013

Still doing a little shopping.

I found a forum where I guy had a pic-by-pic build of his 4.3 stroker:
http://www.moddedmustangs.com/forums/v6-mustangs/256810-assembling-h-c-i-4-3-v6-2.html

There's a pic of the pistons he used, and I googled the part no.

They're standard 4.2 F-150 pistons, machined for a .050" overbore.

I've found a set of pistons that I think will work for my stroker on Summit Racing:
http://www.summitracing.com/parts/slp-h850cp1-00mm/overview/make/ford

And here's the "long rods" that SSM uses:
http://www.summitracing.com/parts/sca-66125/overview/

Does anyone think this wouldn't work?
The bore of the pistons here is 3.850", which is actually .010" smaller than I originally planned for, but for $134 set of pistons, I'm prepared to sacrifice that .010"

This would make the overbore .040"

The other concern is of course valve clearance. The long rods are 6.125" in length, and thus are a little longer than the factory 4.2 rods.

Hoseitdown · Mar 24, 2013

How can one machine a standard piston for an overbore?

sixstanger00 · Mar 25, 2013

Hoseitdown said:
How can one machine a standard piston for an overbore?

Some places that sell pistons have options for an overbore.

For example, if you're purchasing replacement pistons for a 4.2 V6 that's rebored and rehoned, you would need oversized pistons. That's actually why they have the option of ordering them oversized; not for us V6 Mustang enthusiasts to build strokers. However, the numbers are what counts, and the principle is the same.

A standard 3.8 V6 block has a bore of 3.810"

The pistons I posted in the link have a diameter of 3.850". Whenever a block is bored over, the machine shop uses the PISTONS as a reference. In other words, rather than bore each cylinder .040" over, each cylinder is bored to 3.850" exactly.

But to answer your question, standard pistons aren't modified (because that would be impossible), but rather the manufacturer produces a set of pistons that are x requested amount over the standard specs.

g36 monkey · Mar 25, 2013

Why not just see how much the block actually needs to be bored out before boring it 40 or 50 over?

Hoseitdown · Mar 25, 2013

Thanks for that bit of info. I did not understand.

sixstanger00 · Mar 25, 2013

g36 monkey said:
Why not just see how much the block actually needs to be bored out before boring it 40 or 50 over?

Because I WANT it bored .050 over. Or .040 over.

The only problem I'm running into now is compression ratio. Using 4.2 pistons is going to yield 4.2 CR, which is about 9.2:1.

This is too low, and too close to stock. I'm aiming for 10:1 compression, so I may be doomed to order custom made pistons. Yay.

No prob, Hoseitdown

It's my understanding that 4.2 pistons will NOT work with the SCAT long rods, because at TDC the piston would overshoot the top of the deck about 0.125".

For the SCAT long rod use, the wrist pin is located higher up in the piston to compensate for the rod's extra length. This apparently improves engine geometry, but other than that it does nothing for power or displacement.

So basically I can use the Eagle 5.956" forged rods and be OK. These will mate with the 4.2 pistons, but as I said, there's the question of CR....

g36 monkey · Mar 25, 2013

Deck the heads. Compression goes up

sixstanger00 · Mar 25, 2013

Any idea how much $$ that runs? I was planning to do a self port-to-match on both heads and IMs

g36 monkey · Mar 25, 2013

It shouldn't be much trouble for any machine shop to do. It's basically a resurface, just cutting off a loooot of material hhaa

sixstanger00 · Mar 26, 2013

g36 monkey said:
It shouldn't be much trouble for any machine shop to do. It's basically a resurface, just cutting off a loooot of material hhaa

Hmm...might send the heads then when I send the block. After some power shopping on Summit Racing, I've pretty much got everything for the bottom end except for the cam listed for $800.
That's pistons, rods, rod bearings, main bearings, rings, wrist pins, cam bearings and crankshaft.

g36 monkey · Mar 26, 2013

Nice!

rz5.0 · Mar 26, 2013

You shave the heads and you pvc decreases.. You can get your pistons fly cut with bigger reliefs for your valves..

sixstanger00 · Mar 27, 2013

rz5.0 said:
You shave the heads and you pvc decreases.. You can get your pistons fly cut with bigger reliefs for your valves..

Yeah, that much I figured out. lol Decking the heads is pretty much shaving off a layer on the undersides of the heads, thus bringing the top of the combustion chamber closer to the top of the piston.

One bit of information I can't seem to track down is what the OEM pvc is....if I knew that, I would atleast know what I'm working with...

sixstanger00 · Apr 24, 2013

sixstanger00 said:
Orange,

I'm aiming for about 300 hp at the crank (that's an estimate of course.)

Here's a breakdown of the build:

3.8 block bored .50 over
Forged SCAT rods
4.3 crankshaft
Hypereutectic pistons (3.860 dia.)
SSM camshaft
Ported-to-match upper/lower intake manifold
Ported-to-match heads
CompCam beehive valve springs
CompCam hardened pushrods
CompCam lifters
CompCam aluminum rocker arms
Accufab 70mm throttlebody
SPEC aluminum flywheel
F1 Stage III clutch
ASP underdrive pulleys
24# fuel injectors
Aeromotive 310 lph fuel pump
hi-flo fuel filter
Re-tune on the ECU (of course)

UPDATE!!!!!!

In case anyone's planning on a similar build, the hypereutectic pistons WILL NOT WORK.

Both the SCAT forged rods and the Eagle rods (which I ended up getting) have a pin diameter of 0.912", and are floating style.

The hyper pistons are made to be direct replacements for a 4.2 V6. All OEM ford engines had PRESS FIT pins with a pin diameter of 0.906"

No manufacturer makes a piston off the shelf that meets the spec requirements for the build:

Diameter: 3.860"
Pin Type: Floating
Pin Diameter: 0.906"

Since the rods are actually intended to be used in the 351w, the pin end is made to fit 351w pistons, which obviously is a much bigger bore than the v6.

Does this make sense?

The only way to use hyper pistons for a 4.2 is to use 4.2 reconditioned rods, which aren't forged and aren't floating type.

The only way to build the 4.3 stroker WITH forged rods is to get a set of Eagle or SCAT rods (rod length 5.956" or 6.125" respectively) and nab a set of custom made pistons from SSM or Morana.