MelloYellow

Now.. I know Forged are stronger, but was reading Corky Bell's(?) SC book. He noted that Hyperteutetic were better than cast and even superior to Forged Pistons when it came to dissapating heat from Forced Induction.

Now, I know Forged would be stronger when detonating, but maybe our stock pistons aren't so bad if you keep your setup tuned & monitor detonation closely?

Opinions? (Other than just forged is better) <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> Might Hypertuetetic pistons have some advantages?

MelloYellow

Anyone want to compare Hypertuetetic pistons to cast or forged? Might they be better in some ways than just thinking stock pistons are junk?

chasgiv3

iTrader: (1)

I also read the same book. However in reading some engineering data there are different hardness levels in the hypereutectic pistons. Some of the designs are simply not good for FI applications. You really have to do your homework on this subject.

Honestly the stockers aren't designed for FI and I wouldn't trust them for too long in a racing application. Running them in low boost applications would probably work ok if like you mention you completely stay away from any detonation.

Gold Phoenix

iTrader: (1)

Hypers are generally light weight and tighter sealing like a cast piston, but are a little stronger due to the higher silicon content. But not near as strong as forged. Engine knock is like a steel hammer, a forged piston will deform after a series of blows where a cast or hyper will crack and shatter. I own a supercharing and a turbocharging book. They both state that for standard cast pistons, which the LS1 doesn't have, will be alright for boosts between 5 to 7psi. As for the rods and crank, if not seeing more than 9psi of boost and high RPM, the stock units would be ok. All this for a STREET forced induction motor. I believe that the LS1 will handle up to 9psi and rev up to 6500rpm without too much problems as long the tuning is right and maintain the motor. Although I haven't look lately, I haven't heard anyone breaking the stock shortblock with mild boost setups. I have seen cars crank out over 700RWHP on the stock crank. My car has had at least a dozen runs on 150HP wet shot of nitrous on the track and many more on the street. I want to go to a T-76, but I am not too sure how my motor will hold after the abuse of nitrous. My car has 48K on it and I installed the system at 22K. It's never knocked, because I always had it rich and used high octane fuel. I am just tired of running out of the bottle. I think if I am going to rebuild my motor, I will use Diamonds boost pistons, Lunati Pro Mod Rods, and stock crank and cam. The pistons are lower compression and are good to 20psi.

MelloYellow

Slightly off-topic, but weren't the Gen1/2 Viper Pistons cast and all Mustang pistons cast until the '03 Cobra?

MIGHTYMOUSE

iTrader: (59)

lots of 5.0's came factory with forged pistons... definitely 87 and definitely not 94, other years im not sure of.

as far as i know cast IS hypereutectic.

AzzHauler

iTrader: (3)

I think mustangs dropped the forged pistons in 91-93 time (90% sure 93 was the first year with hyper pistons).

SJH

93 is when Ford went to hyper pistons on the 5.0.
I managed to crack 4 of them under boost.
Stock ls1 pistons are pretty fragile.
I cracked 2 completely in half when I pressed them off the rods.
They crack real easy.Hyper pistons are cast, only with added silicon.
You won't find any serious engine using them.
And there are several different alloys used in forged pistons also.
A 2618 no silicon alloy is generally used in a serious poweradder piston.
That's what's in my motor.
Steve

Boosted LS1

I like hypers because they're nice & tight in the bore, like 001" and don't rattle. They seem strong enough for 10lbs boost and maybe more as long as they have a solid skirt. I like the stock LS1 piston also. It looks like a performance item even if it is a production car and cast. LS1 pistons do break when pressing them off the rods but that is because of the sideways load being applied across the bosses. That wouldn't happen in use. Mind you, the top ringland isn't exactly thick and this could be the boost limiting factor for higher then stock cylinder pressures?

MelloYellow

Thx for the opinions. Any more?
I do hear the stock LS1 piston ringlands are one of the weaker points.

SJH

I already cracked a 2nd ring land on a stock ls1 piston.
That's why I was pressing them off the rods <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
I was just illustrating how they crack clean when subjected to certain forces.
Detonation will crack them faster than you could ever do with a press.

Pro Stock John

iTrader: (34)

All hypereutectic pistons are not the same QUALITY and strength.

Our stock h.. pistons are not as good as an aftermarket forged piston.

I like the Diamond pistons a lot, their FI piston works out to being ~8.9:1 with a 70cc 6.0 truck head, ~9.5:1 with a 62cc head.

2k2z28

I am seriously considering picking up the ati procharger 5# intercooled kit. With this boost level and proper tuning, is there still a large change of piston failure? Also, how long can I expect the engine to remain intact, as long as I dont beat the sh** out of it, and race it at the track once in a while? How much dammage cost would I be looking at if I cracked a piston (worst / best case scenario)? If this did happen what would I have to do to fix this with aftermarket products? would I need springs, pushrods, retainers, pistons, everything? and finally, how much would this complete rebuild cost? thanks.

<small>[ December 10, 2002, 11:40 PM: Message edited by: 2k2z28 ]</small>

SLPFireChicken

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MelloYellow:
<strong>Now.. I know Forged are stronger, but was reading Corky Bell's(?) SC book. He noted that Hyperteutetic were better than cast and even superior to Forged Pistons when it came to dissapating heat from Forced Induction.

Now, I know Forged would be stronger when detonating, but maybe our stock pistons aren't so bad if you keep your setup tuned & monitor detonation closely?

Opinions? (Other than just forged is better) <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> Might Hypertuetetic pistons have some advantages?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">They dont dissipate heat. they prevent it from moving through the piston as easily, in order to prevent thermal expansion, which, when manufactures try to compensate for in piston design and tolerancing, can result in some pistons being too small, causing piston slap.

Here, read this!

A website for a company that makes the pistons and the material. Read them in order, from top to bottom. Basically, hypereutectic pistons are ordinary cast aluminium pistons that are uniformly doped with a super high amount of silicon (16% of total mass). Silicon mainly acts as a heat insulator. Because it prevents heat from traveling through the piston as quickly, it has the effect of reducing the amount of thermal expansion below the levels of a eutectic piston (12% silicon), or hypoeutectic piston (less than 12%). Because you have a piston with less thermal expansion/contraction, you have a smaller range of actual dimensions during startup and steady state operation. This actually helps to discourage piston slap!!! However, these KB pistons are still made in a mold, and with some specialized heat treating procedures, are actually stronger than traditional cast pistons, and stronger than non-heat treated hypereutectic pistons. While not as strong as forged components, they are ideal for factory OEM high performance applications.

http://www.kb-silvolite.com/page02.htm

http://www.kb-silvolite.com/page03.htm

http://www.kb-silvolite.com/page04.htm

http://www.kb-silvolite.com/page05.htm

Just thought I would share.

SLPFireChicken

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by 2k2z28:
<strong>I am seriously considering picking up the ati procharger 5# intercooled kit. With this boost level and proper tuning, is there still a large change of piston failure? Also, how long can I expect the engine to remain intact, as long as I dont beat the sh** out of it, and race it at the track once in a while? How much dammage cost would I be looking at if I cracked a piston (worst / best case scenario)? If this did happen what would I have to do to fix this with aftermarket products? would I need springs, pushrods, retainers, pistons, everything? and finally, how much would this complete rebuild cost? thanks.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Well, for one thing, if you have stock pistons, even hypereutectic, they arent going to last long. The higher horsepower is going to wear and tear everything, pretty much. For the most part, you have to understand that piston failure (Im including piston AND rod AND pin AND journals as one unit), occurrs because of tensile and compressive forces that act on it every cycle of engine operation. This means that at TDC, the piston is being stretched, and at the point of ignition, the piston is being compressed. THese forces are called generally termed stress. Stress does not occurr without side effects. A certain amount of damage is done to the material on the microscopic scale every time its exposed to stress. This damage is comprehensive. Every time you run your engine, you increase the damage due to stress. Most engines have a piston stress life of over 100,000 miles. Some last longer, depending on operating conditions, type of driving, etc. When you increase the energy output of the engine, you also increase the amount of stress, and therefore damage, that is inflicted on pistons. This accelerated damage rate is what causes pistons to fail more quickly in a modified engine than a stock engine. To compensate for the increased damage, you must install high strength components that will allow you to extend the life of the engine beyond what stock components are able to do with forced induction.

This is where forged components come in. Stronger pistons, and piston rods, are a necessity. You may also want to think about reinforced pushrods, rocker arms, etc, since you are already going to have the motor torn apart anyway, and its better to do these things now than later. As far as general tuning goes, you will probably want to lower the compression ratio (shorter piston rods), to compensate for the fact that you will be running forced induction. This will slightly reduce your power output, but because of the charger, you will still have much more power than a naturally aspirated engine. The lower compression ratio will help prevent detonation, because sometimes high octane gasoline just isnt enough on blown engines, unless you want to put a $5 bottle of octane booster in every tank.

As for how long it should last, as long as you replace the internals with forged components, and dont have any supercharger failure, you should have a life expectancy that is almost as long as the normal engine (you will have increased the power, but also increased the durability of the internals to match the increase power).

If a piston did break, best case scenario, it just scores the inside of the cylinder wal, and maybe nicks the cranshaft, or bumps the valves.

Worst case scenario, it will destroy the engine beyond repair, where you have to buy a crate motor and put in to replace.

Middle case, you will have piston destroyed, and need to replace head(s) or intake manifold.

A little suggestion. If you get the charger:

1. Replace EVERYTHING in the engine with teh highest strength, most expensive FORGED components you can find. That means even the crank shaft.

2. Get different pistons and rods to lower the compression ratio.

3. Get the intercooler. That, combined with the lower compression ratio will help reduce your chance of detonation

4. A complete rebuild, excluding cost of supercharger, will probably run you a couple of grand for the parts alone. If you do the work yourself, maybe $1500-$2000 or so. Then add the supercharger cost. If you dont do it yourself, but have a shop do it, your looking at somewhere around $1500 or so, for a rebuild and supercharger install. Then, there will also be costs involved in tuning, etc. You may need PCM program-modification to alter air fuel mixtures, and maybe even fuel injector upgrades.

Best thing to do is ask ATI what they reccomend for their charger on your type of engine, they can give you specific numbers about compression ratio reduction, needed fuel delivery requirements, and can probably reccomend what components need replacement.

Pro Stock John

iTrader: (34)

Hi JAS@Pace, how are you...

I am running Ross pistons in the 422ci but I have been talking to Diamond (Chris G) and their customer service is much better then when I dealt with JE on the last motor. And I like the fact that Chris is behind their product line, since he is none other than Chris Gelineau formerly of Katech, and he ran Katech's engine program including the C5R program.

SJH

yes, that top pic is of my old piston.
I caught it right away from plug checks last year.
I noted that cylinder's plug had a sooty weak reading.
Then ran a compression check and leakdown and it confirmed a problem.
I then pulled the motor as I knew it had to be cracked.
Once I removed the piston the chunk fell out in my hands.
The cyl bore was holding it together.
I had light scoring from very small pieces of the piston that managed to get caught between the rings. They cleaned up totally with a .005 hone.

The pics show the grain structure and why these things just are not suitable for any sort of heavy poweradder use.
Steve

Pro Stock John

iTrader: (34)

JAS@Pace, I think you read into my comment, I never said I was running the blower pistons but I have have been running various forged pistons since 1999.

The 8.9:1 compression info was straight from Chris I like how i can get a hold of him not like the JE folks.

Pro Stock John

iTrader: (34)

JAS@Pace, I have seen folks quote you should they not do that?

Back on topic, I'd run some aftermarket forged pistons...

MelloYellow

Anyone think it's a bad philosophy to run a stock engine 'til you crack a stock Hyper ringland or catch a problem when reading plugs, then just forging then? Worst case, if you go nuclear or score the block past usable, stock blocks aren't that expensive. I hate breaking up a stock rotating assembly with no problems.

I'm seeing stock Vortech setups on the C5 for our engine putting down 585rwhp right now. At least this is my approach. With a good tune a stock bottom end may take 8-9# for 1-2 years I think.

How often should I leak test an FI stock engine?