Piston Issues Confirmed..I Think.

Prof said:
We need some one to put a micrometer on a diamond piston to see what distance they have between the two compression rings...it looks (in my pictures to be about the same (http://www.vtcoa.com/forums/showthread.php?t=24264&highlight=Diamond+Pistons)...the stock pistons have two metals in the divider...I will take a close up later to show that...that could be a possible cause too...but the distance seems to be about the same...just being forged and stronger may be enough...but I don't know the engineering ramifications here...where the hell is Silverback when you need him?

Has anyone seen this piston land destruction in forged pistons????
Click to expand...


Finally got my engine man to take a good look at our stuff and his opinion is
close to ours, the difference being that he said our pistons will only take a
tiny amount of detonation and its over. He said a set of good forged pistons
and rings properly gapped (with a correct tune) shoud do the trick. Another
problem is the inconsistent quality of pump gas at this time is not helping
matters.
He is very well connected with piston manufacturers, and is waiting on a call
back from them on their best pistons for our app.





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tell them to check with wiesco, a little unknown piston for the viper engines that kno one runs;)

I've had them in mine for about 7000 miles, the first 3000 of those miles were on a questionable tune,yes some detonation........and ask FStjack at bradenton fla, I honestly did everything I could to blow it up, even continusly running it to 6500rpms at the end of the quarter and holding it there, and sstill have the same cylinder pressure that I had to begin with:p


they must be one tough set of pistons:rock:
 
Just a little note here I saw that someone mentioned increasing the gap between the top 2 rings, in reality you want to do just the opposet decrease the distance in between the rings. also yes about seeing this problem in other forged pistons. The 03-04 Ford Cobra's that came supercharged from
the factory also have this same problem. They also have a ring gap of 3.5thousandths thus causing the "lifting" or "sticking" of rings and land. basically on the cobras you get a couple of high load pulls then you must let teh engine cool down and let teh cylinders cool as well. then you can go back to playing. I stick a ring on my old cobra about 3 yrs ago and had to put a motor in it. this is also where i recieved some of my experience.
 
Blaine@PSI said:
Just a little note here I saw that someone mentioned increasing the gap between the top 2 rings, in reality you want to do just the opposet decrease the distance in between the rings. also yes about seeing this problem in other forged pistons. The 03-04 Ford Cobra's that came supercharged from
the factory also have this same problem. They also have a ring gap of 3.5thousandths thus causing the "lifting" or "sticking" of rings and land. basically on the cobras you get a couple of high load pulls then you must let teh engine cool down and let teh cylinders cool as well. then you can go back to playing. I stick a ring on my old cobra about 3 yrs ago and had to put a motor in it. this is also where i recieved some of my experience.
Click to expand...
would more distance from the top of the piston to the first ring land be the fix? just trying to understand this
 
eddie102870 said:
would more distance from the top of the piston to the first ring land be the fix? just trying to understand this
Click to expand...



Yes somewhat many things need to happen. lower the top ring on the piston yes this will also lower the compression level as well as the amount of high heat able to reach the ring, gas paths should also be applied to the top of the piston pushing the ring to seal against the walls, gap should be opened up on the top rings and piston to wall clearance should be in 5-7thousandths range.

now onto ruel 93 octane should be used for no more than 8-10lbs of boost anyting more and step up to some race gas depending on the amount of boost. the number above are based on intercooled applications. go atleast 2 heat ranges cooler on the plugs.
 
Blaine@PSI said:
Yes somewhat many things need to happen. lower the top ring on the piston yes this will also lower the compression level as well as the amount of high heat able to reach the ring, gas paths should also be applied to the top of the piston pushing the ring to seal against the walls, gap should be opened up on the top rings and piston to wall clearance should be in 5-7thousandths range.

now onto ruel 93 octane should be used for no more than 8-10lbs of boost anyting more and step up to some race gas depending on the amount of boost. the number above are based on intercooled applications. go atleast 2 heat ranges cooler on the plugs.
Click to expand...
i see, i wonder, and this is just tossing shit up for discussion, the total seal rings would they be useful in our application. im running colder plugs now. will probably take them out next week just to see what they look like. and do a leak down test just for kicks so ill know what im up against. havent ad any problems so far and the truck still runs fine so far as i can tell. actually runs better since i put 3in exhaust and a new tranny and torque converter
 
I had a leak down test done on mine after the impact on #3 and it was fine. Even though there was some damage.
 
Stinker said:
tell them to check with wiesco, a little unknown piston for the viper engines that kno one runs;)

I've had them in mine for about 7000 miles, the first 3000 of those miles were on a questionable tune,yes some detonation........and ask FStjack at bradenton fla, I honestly did everything I could to blow it up, even continusly running it to 6500rpms at the end of the quarter and holding it there, and sstill have the same cylinder pressure that I had to begin with:p


they must be one tough set of pistons:rock:
Click to expand...
did you do anything to address the oiling issue in your rebuild ?
 
I have seen damage like that in many factory pistons. Much more so in the past ten years or so. This is mainly due to design changes to help a couple things. First, by moving he top compression ring closer to the top of the piston you reduce the amount of unburned gases from combustion. That helps with emissions controls. Secondly, moving the rings up also helps reduce the amount of carbon buildup on the lands above the top ring. That helps reduce cylinder wear, blow-by gases and helps improve emission controls. Since the top rings on the newer engines are so close to the piston top, they get exposed to more pressure and heat from combustion.

Now take for instance a diesel piston...The piston is considerably taller and the rings are located about one third the way down from the top. Since most diesels are designed for massive amounts of torque and longevity, the rings are protected more from the heat and higher cylinder pressures.

Look at the profile of a true performance piston and they are not very tall (less surface area touching the cylinder wall, the less friction). Top ring is farther down from the top of the piston (usually both compressions rings are just above the pin), and the oil control rings will be right at the pin. The head of the piston has more material behind it to handle the higher pressures of FI and performance use. Of course the alloy's are much better.

Another thing to keep in mind is he design of the piston is only half of it. The other is what it is made of. You can have a casting and forging from the same alloy. The forging will be stronger because it has a more uniform molecular structure from being formed under high pressure and temperature. The casting is just poured into a mold and then finish machined to shape. All billet means is they took a forged block of metal and machined it to its final shape. Not necessarily better than a forging. So the alloy used is important and how it is used to make the piston is important. Then there are a number of coatings that can be applied for further improvement in performance.

Stock pistons are designed to do hold up to stock HP and pass emissions. That is name of the game for manufactures. Make the cheapest possible part that will survive long enough for the warranty to run out. It is sad, but often true.

-Muzzy
 
Prof said:
Has anyone seen this piston land destruction in forged pistons????
Click to expand...


I think Chuck Tator stopped using Diamonds for this same reason. He mentioned this as we were discussing my rebuild. He recommended another brand I think CP . These pistons were custom made. He has basically been doing nothing other than installing Roe units on Viper engines 10+ years
 
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Muzzy, I was wondering if you would pop in for this discussion. I am always happy to read your input...thanks again for sharing your knowledge.
 
moparracing said:
did you do anything more than forged rods & pistons ?
Click to expand...
billet mains, bearings, oliver rods, wiesco pistons, stock bore and stroke, stock heads, cam bearings, nuttin else bro, jsut a basic forging, and dude I honeslty beat the pooh outta this thing,

it has 14,000 miles on it, probably 7000 since build, 6000 of those have been to GTG's and the strip, maybe 1000 around the house, she mostly sits, unless a GTG comes up, but Eddie and Jack will tell ya, i dont baby the ol girl too much:D
 
Stinker said:
billet mains, bearings, oliver rods, wiesco pistons, stock bore and stroke, stock heads, cam bearings, nuttin else bro, jsut a basic forging, and dude I honeslty beat the pooh outta this thing,

it has 14,000 miles on it, probably 7000 since build, 6000 of those have been to GTG's and the strip, maybe 1000 around the house, she mostly sits, unless a GTG comes up, but Eddie and Jack will tell ya, i dont baby the ol girl too much:D
Click to expand...
billet mains, bearings, oliver rods, wiesco pistons ? that's it ?:)
 
moparracing said:
billet mains, bearings, oliver rods, wiesco pistons ? that's it ?:)
Click to expand...


serious as a heart attack, nothing in my engine is even coated, just plain ol rods, pistons and mains, nuttin special
 
Prof said:
Muzzy, I was wondering if you would pop in for this discussion. I am always happy to read your input...thanks again for sharing your knowledge.
Click to expand...

Muzzy provided a lot of good input. Pay attention to what he has to say.

Super... whatever is a complete idiot in my opinion. I'm surprised he can really type. Ignore him.

Roy,

As I stated in my PM, I have to work some this weekend, and my daughter and her husband just signed the papers on their first house. So between work, and helping them move, I will be a busy ape this weekend.

If I get the time I'm going to run some calculations on the deltas in cylinder pressures between a stock engine, and an engine with 5.6 pounds of boost. Now you will have to remember that this will be all theoritical (Yes, I'm drunk, and can't spell worth a shit). Cam profiles can have a dramatic affect on cylinder pressures. But still it may amaze you.

By the way, I'm not surprised by your pictures. You have to remember that head design dictates the flame travel within the cylinder, and you will have areas of the piston that are hotter than others. That is why you are seeing that pistons all failed in the same area.

Take care my friend. Hopefully I will get back to you later.
 
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