Hypereutectic vs Forged?

ThePidler · #1 (**permalink**) 04-03-2002, 06:23 AM

I'm building a 393W Stroker for my LS427, I know that the hypereutectics are cast with just more silicon in them, but are forged THAT much better? For 95% Street driving? I mean, it may see the tree a few times down at Ennis, but not much. My cousin, who's sciencing out my motor, is a forged man, period. But he's also a bracket racer...all he does.

I can save about $500 if I go hypereutectic, (AND HOW IN THE HADES DO YOU SAY THAT WORD?)

greg

CobraEd · #2 (**permalink**) 04-03-2002, 06:36 AM

AN INTERESTING PERSPECTIVE FROM KEITH BLACK

http://www.kb-silvolite.com/page11.htm

PSB · #3 (**permalink**) 04-03-2002, 07:05 AM

I have been researching this also. As I understand it, hypereutectic pistons can be manufactured to closer tolerances than forged pistons, so they "fit" better in the block. This means less ring wear and a longer life engine. However, they are more brittle than forged pistons and may not be a good choice if you are planning on running NOS or a blower. I'm going with hypereutectic pistons on my 396W.

Pete B

CobraEd · #4 (**permalink**) 04-03-2002, 07:10 AM

HERE IS SOME OTHER CONVERSATIONS I FOUND ON THIS

http://www.camaros.net/forum/Forum1/HTML/002797.html

ERA535 · #5 (**permalink**) 04-03-2002, 09:18 AM

Hyper - u - tec - tic

427sharpe · #6 (**permalink**) 04-03-2002, 09:35 AM

Forged and Forged ONLY!
The forged piston will stand up better in the long run and provide better service. And you you really think that you Cobra will only see race stress 'every now and then'? Once you get it rolling, your right foot takes on an odd weighted feeling....

ThePidler · #7 (**permalink**) 04-03-2002, 08:52 PM

CobraEd: Good links, Keith Blacks Stroker Kits are what got me started thinking about the hypers. Thanks for the input!

Pete: I will have NOS, eventually...don't know if I'll ever hit it

ERA535: Thanks, I needed that. Now if I can just remeber it during conversation...

427sharpe: You know, you may be the closest to the truth I've heard all year. Is that what everyone really does? Right now, I'm just building the frame, and I can't imagine really dragging it, but you sound like my cousin..."Greg, I knew you when you were a kid, you'll be in it all the way all day"... I'm assuming you're a forged crank guy too?

Thanks guys...I love this hobby!!!

greg

427sharpe · #8 (**permalink**) 04-04-2002, 11:25 PM

Pidler:
I haven't seen a single owner resist the urge to beat their car yet---even the waxers!

In my case, I started out YEARS ago to build a hammer...very light with something very simple as motivation...a decent 302 to be exact ( I got my car WAY before the stroker craze!). During the build, one thing led to another and I wind up with a 535 ci stroker with a lot of overkill! I had the same idea..just cruise, maybe a bit of speed 'every now and then'...HA! Reality is the car is JUST TOO DAMNED MUCH FUN! Go out at night, and see how fast it takes you to get to 90 without even realizing it! I dont street race, but I have been known to burst a few bubbles every now and then....and I run down to Ennis a lot more than I ever thought I would for the Friday Night Run Whatcha Brung races! Finally, no, I dont use a forged crank..I run a billet steel because it was more expensive!

Dennis Mosley · #9 (**permalink**) 04-10-2002, 02:33 PM

May be chiming in late here but if you are talking about $500 and you think you "might" want the forged, go with them. That kind of thought leads to cost overruns but just think how much it will cost you to tear it all apart and put the forged ones in after everything is put together and you decide you "must' have them.

justa6 · #10 (**permalink**) 04-11-2002, 08:34 PM

A question. Have you ever had the hypereuteptic pistons in one of your cars?

My "other" car is a Buick Grand National that will give my 10.8 second Cobra a very hard time and weighs 3600 lbs.

That Buick goes that fast because it runs the boost up over 22psi and it can do that on NON Forged "Hypers".

Forged pistons are very strong but they can not match the consistancy of Cast. IF you are not going to run 13 to 1 compression they will work fine. Detonation is what will kill pistons, especially on a blown motor. If it were me I'd be VERY comfortable with a set of Non Forged for street and strip.

By the way "427 Sharp" what kind of times are you getting out of that Big Block?

Regards,

ThePidler · #11 (**permalink**) 04-11-2002, 09:48 PM

Bob,

AAhhh, a 10 second car! $hi!, when I was kid, Dandy Don's folks lived right around the block, and he was just barely into the 10's...and today we got street v6's doin' it all day long...and takin' momma to the store for groceries that night, DANG IT'S GOOD TO BE AN AMERICAN, (or anyone else with the freedom to love these cars!)

I'm guessin you run it a lot, what about the Hypers when they go, being more silicon, are they not more brittle? Do they grenade? Colatteral damage much worse?

Dennis, you're right about the $5 or 6 hundred bucks....not a lot of difference, but why waste it if you don't need too...

427Sharpe: Yea, I know, but standin' on it once in a while, and racing it are two different things. The hypers fit better, make less noise, can rev higher...I hear they just grenade when they go, no broken skirt, no chnck outta the top, they blow...

120 horse shot of juice should get me close....

justa6 · #12 (**permalink**) 04-12-2002, 07:42 AM

The Grand Nationals came with hyperuteptic pistons, stock.

They don't blow UNLESS you have massive detonation. I'm talking about something you'll never hear in a normally aspirated motor. Detonation that actually feels like a rod just went through the block. There are a lot of GN's around with 150-200 thousand miles and never lost a piston. And they aren't exactly babied.

As you said they frag when they fail but as you also said the forged loose a skirt so to me when a piston fails it makes little difference in the outcome. Rebuild time.

As far as the Cobra goes the Buick V6 in it is not the same as the Grand National motor by a long shot. Its the same block as the Menard Indy motor and was used in Busch racing for a number of years. ie its a pure race motor that doesn't even have an internal oiling system. It only uses a Dry sump system.

Its fine on the street though, for a little motor (274"). 390 ft/lb of torque and 473 HP. Runs 10.8 and it will probably get down to mid 10's when its completely dialed in. (Hope so anyway)

Regards,

ThePidler · #13 (**permalink**) 04-12-2002, 09:52 AM

Bob,

Nice car, awesome looking engine! What tranny are you running? Is it special too? Man, the more I read and talk to folks, the more I am leaning towards the hypers... I think they'll fit the bill just fine.

greg

blykins · #14 (**permalink**) 04-12-2002, 10:41 AM

I agree with 427sharpe. I would only used forged. Hypereutectic refers to a point in the metal phase diagram when creating forms of steels. As you know, steel has different forms...martensite, austenite, etc. If you plot all of these on a graph and show where they fall vs. heating and annealing, etc...you can see the differences. The hypereutectic point refers to the point where you get a carbon shift. Hypereutectic refers to a steel with more than .6% carbon in it than the other forms.

Now, there are probably a million arguments to which is better or when you should use which. My dad's 1997 Mustang Cobra has hypereutectic pistons in it, and it's a stoutly build motor....6-bolts mains, piston oil squirters, etc.

However, I would always choose forged. It's kinda like the thoughts you get in the back of your mind when someone asks you whether you'd rather have a cast or a forged crank....Forged all the way baby.

CobraEd · #15 (**permalink**) 04-12-2002, 10:53 AM

But all pistons are ALUMINUM.

justa6 · #16 (**permalink**) 04-12-2002, 11:14 AM

Thanks for the comments. The trans I'm using is the Road Race version of the Tremec TKO. Its got a heavier 3rd gear and some other small changes and its got a little lower Overdrive ratio.

I'm running a 4.10 Ford 9" rear with a Powertrax center section.

Scattershield, clutch, hydraulic throwout bearing from McCloud in California. McCloud had done a lot of work on the Stage II Buick motor years ago so they were a natural to get everything to bolt up to my "Big" block 4.5 liter motor

As to the comments about forged pistons. Obviously they are a good choice. But they are not as exact in their dimensions as a cast piston. The sizes will tend to be slightly different as will the weights (which can be fixed).

One last comment. I knew a young guy in Florida that would buy Chevy 350's out of the junkyard (two bolt mains, cast pistons, cast crank) and put the motor in an old 4 door Impala, hook up a HUGE shot of nitrous (he knew what he was doing) and the car ran high 10's. Once in a while he blow a piston (not hyperuteptic) and simply bolt in a new (old) motor then go race again. VERY inexpensive and he NEVER broke a 2 bolt main cast crank. Never...

So a lot of this stuff is overkill especially in a light car like the Cobra.

Regards,

wilf leek · #17 (**permalink**) 04-12-2002, 11:20 AM

I have hypers in my 408 windsor stroker, chose them because of their low thermal expansion rates, allowing a smaller piston/bore clearance for less noise and to reduce piston rocking on this stroker.
Since the piston fpm limit of 4000 means I can't run above 6000rpm anyway, and since I have no intention of either blowing the engine or fitting Nitrous, they seem a good deal to me. Also I am on a street - gas compression ratio.
If you ever think you might blow your engine, or make it ready for NO2 in the future, or want a racegas CR, then the extra for forged pistons is worth it.

Of course, bragging rights might come into it as well!!
Lastly, I believe the hypers are lighter than the forged items - am I right??

427sharpe · #18 (**permalink**) 04-12-2002, 05:02 PM

justa6;
Yes I have run Hyper pistons before..and they have not held up as well as forged. There is a reason that most professional engine builders use forged pistons...
As for times, in street trim (at the Texas Motorplex in Ennis) I go to the Friday night Street Heat races, which are rung whatcha brung street legal races, I run in the high 10's to lo 11's. When I change over to slicks and beat the car a bit harder I can get to the lo 10's. The absolute best I have ever run was a 9.97, with slicks and 5.36 gears..and twisted an axle doing so! You can granny the car and run mid 11's all day...

I've also had the pleasure of running at Hallet Raceway a few times and put in respectable lap times, although it meant looking over the doors so that I could see where the car was actually going quite often!

justa6 · #19 (**permalink**) 04-13-2002, 07:33 AM

Sounds like your car runs very well...Ever think about going to Run & Gun?

As far as the "hypers" go no one ever said that the Forged were not stronger. However, as I said, the hypers can take fairly high boost on a turbo motor they should be just fine for any normally aspirated "STREET" car with an occasional trip to the track.

If the car is going to be raced a lot or the owner simply wants the extra strength of forged that is what they should do.

Regards,

ThePidler · #20 (**permalink**) 04-13-2002, 03:24 PM

Interesting conversations, people doing 10's, (and 9's....), on both "hypers" and forged. Got Blown "Hypers" in justa10second6, an old Impala, runnin stock 350 bowties with about a 400 horse shot of juice, (yea, I'm guessin' here).

Guess this is a good example of what makes this a great hobby... all of you guys are right!! Fordged, (couldn't resist), are stronger, "Hypers" are quieter and fit better. It boils down to what the owner wants to do...

Wilf Leek, you got a good point, ain't it all about Braggin Rights?

I got a heck of a lot of info here from you guys that are running both, and I appreciate the hades out of it. May you always see 'em in your mirror!

greg