24V motor out Rebuild.....what suggestions....HOT truck needed!
09-09-2004, 10:11 AM
#31
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Oh, by the way...
Here's the link to all of Panic's tech papers:http://victorylibrary.com/mopar/mopar-tech.htm
He focuses on Mopars and Harleys, but the principles are more specific to general internal combustion engine theory.
It's a GREAT education and FREE, too
jlh
Here's the link to all of Panic's tech papers:http://victorylibrary.com/mopar/mopar-tech.htm
He focuses on Mopars and Harleys, but the principles are more specific to general internal combustion engine theory.
It's a GREAT education and FREE, too
jlh
09-09-2004, 11:03 AM
#32
DTR Advertiser
Forged aluminum is stronger than cast aluminum per mass. Even squeezed cast or hyper pistons. Stronger material lets you use less material for the same strength. This gives a huge savings in weight. Those kinds of percentages are great.
Forgings are nice to save weight and add durability for short bursts of high power. They cant take the heat better, but they swell more from the heat. This added swelling needs a wider piston to wall clearance. Where we use around .0045-.005 clearance with stock pistons in mild apps..we go higher for higher EGT engines, but again even higher with forgings. More clearance is not the greatest thing for long term durability, cylinder gas sealing, and the noise of the pistons is louder. Luckily we have basically no skirt below the piston pin and this reduces noise for the Cummins.
The cast piston have a ni-resist iron insert in the ring lands. This adds long term durability when the rings are constantly being pounded back and forth in a diesel engine that is producing abrasive soot particles that make their way into the ring grooves on every power stroke. Forgings try to combat this with hard anodized coatings that are applied after the piston is finish ground. Generally these coatings are applied pretty thick and the piston is ground slightly undersize and then built back up with the anodizing. Top fuelers used this coating back in the 90's when I still drag raced. I dont know if it used now. The old "Green Coat" is what they called it back then. The coating is good, but will not last nearly as long as a ni-resist insert of iron that is cast into the the pistons when they are manufactured.
Forgings are the greatest thing we can do for competitive engines that will see massive EGT's, wind higher RPM's, and need that extra short term durability.
Castings are much better suited to long term durability street engines that want maximum cylinder wall sealing, ring land durability, and a cost savings of nearly 300%. Cast pistons are not the sheek or cool thing that most racers wanted throughout the hot rod years in gassers, but they do a remarkable job in Diesel engines. The RV pistons are squeeze cast to avoid any tiny openings or voids while being cast and they are fiber re-inforced to add strength and reduce swelling. Cummins also adds a skirt coating of Teflon to again lower scuffing. Its great piston for a great price. When considering the 24 valves with limited RPM ability are not seeing RPM ranges that high and the EGT's are totally controlable with the right set-up...the cast piston just makes the most sense.
On the subject of weight, here are the number I have for the 12 valve piston used in the 97 215 engine from Cummins.
Stock cast piston: 1256 grams ( this is with no rings, pin or tru-arcs ) John maybe your piston had the tru-arcs and rings installed when it was weighed at 1326 grams?
Stock piston pin: 636 grams
The pistons I am using weigh in at under 1100 grams and the pin is lighter yet at 574 grams.
The rod I am using is still top secret, but will be available soon enough after some testing. It is lighter than stock too.
I dont agree with a lower top ring in most applications but in an all out race app...its better to help protect them from heat. The bad thing about doing this is...it also increases the volume or area you can leave behind residual gas trapped in that clearance area after the exhaust stroke. Not a problem for a race engine, but for a streeter you are going to raise emissions and give that soot a better chance to attack the ring lands.
The major causes I have seen from EGT is wall scuffing that gets out of control. This is from swelling the pistons in their bores. It wipes the oil film away or bakes it off the cylinder wall and scuffing begins. The stock Cummins engine is not set-up lose enough to deal with the amount of swelling the pistons will encounter in high EGT applications. When building a high EGT engine the clearance should be increased. When using forged pistons you need to take that clearance up even higher. Coatings for heat control and scuffing can help lower that, but these are considered crutches and if the coatings fail from either flaking off or the just plain wearing through you are back in the danger area again.
All this makes no difference in racing or sled pulling apps. The engines in sled pulling have very short duty cycles and turn a very limited number of revolutions total. The ultra high powered engines should have a forged piston.
Street engines turn more revolutions going up to the grocery store than sled pulling engines turn at a dozen sled pulls. This long and extended duty cycle needs a piston that is designed to last in this application. The only one that will is a cast piston with ni-resist lands.
Don~
Forgings are nice to save weight and add durability for short bursts of high power. They cant take the heat better, but they swell more from the heat. This added swelling needs a wider piston to wall clearance. Where we use around .0045-.005 clearance with stock pistons in mild apps..we go higher for higher EGT engines, but again even higher with forgings. More clearance is not the greatest thing for long term durability, cylinder gas sealing, and the noise of the pistons is louder. Luckily we have basically no skirt below the piston pin and this reduces noise for the Cummins.
The cast piston have a ni-resist iron insert in the ring lands. This adds long term durability when the rings are constantly being pounded back and forth in a diesel engine that is producing abrasive soot particles that make their way into the ring grooves on every power stroke. Forgings try to combat this with hard anodized coatings that are applied after the piston is finish ground. Generally these coatings are applied pretty thick and the piston is ground slightly undersize and then built back up with the anodizing. Top fuelers used this coating back in the 90's when I still drag raced. I dont know if it used now. The old "Green Coat" is what they called it back then. The coating is good, but will not last nearly as long as a ni-resist insert of iron that is cast into the the pistons when they are manufactured.
Forgings are the greatest thing we can do for competitive engines that will see massive EGT's, wind higher RPM's, and need that extra short term durability.
Castings are much better suited to long term durability street engines that want maximum cylinder wall sealing, ring land durability, and a cost savings of nearly 300%. Cast pistons are not the sheek or cool thing that most racers wanted throughout the hot rod years in gassers, but they do a remarkable job in Diesel engines. The RV pistons are squeeze cast to avoid any tiny openings or voids while being cast and they are fiber re-inforced to add strength and reduce swelling. Cummins also adds a skirt coating of Teflon to again lower scuffing. Its great piston for a great price. When considering the 24 valves with limited RPM ability are not seeing RPM ranges that high and the EGT's are totally controlable with the right set-up...the cast piston just makes the most sense.
On the subject of weight, here are the number I have for the 12 valve piston used in the 97 215 engine from Cummins.
Stock cast piston: 1256 grams ( this is with no rings, pin or tru-arcs ) John maybe your piston had the tru-arcs and rings installed when it was weighed at 1326 grams?
Stock piston pin: 636 grams
The pistons I am using weigh in at under 1100 grams and the pin is lighter yet at 574 grams.
The rod I am using is still top secret, but will be available soon enough after some testing. It is lighter than stock too.
I dont agree with a lower top ring in most applications but in an all out race app...its better to help protect them from heat. The bad thing about doing this is...it also increases the volume or area you can leave behind residual gas trapped in that clearance area after the exhaust stroke. Not a problem for a race engine, but for a streeter you are going to raise emissions and give that soot a better chance to attack the ring lands.
The major causes I have seen from EGT is wall scuffing that gets out of control. This is from swelling the pistons in their bores. It wipes the oil film away or bakes it off the cylinder wall and scuffing begins. The stock Cummins engine is not set-up lose enough to deal with the amount of swelling the pistons will encounter in high EGT applications. When building a high EGT engine the clearance should be increased. When using forged pistons you need to take that clearance up even higher. Coatings for heat control and scuffing can help lower that, but these are considered crutches and if the coatings fail from either flaking off or the just plain wearing through you are back in the danger area again.
All this makes no difference in racing or sled pulling apps. The engines in sled pulling have very short duty cycles and turn a very limited number of revolutions total. The ultra high powered engines should have a forged piston.
Street engines turn more revolutions going up to the grocery store than sled pulling engines turn at a dozen sled pulls. This long and extended duty cycle needs a piston that is designed to last in this application. The only one that will is a cast piston with ni-resist lands.
Don~
09-10-2004, 07:51 AM
#33
Administrator
HOHN:
Thanks for all that math you did on page #2!
It is
very interesting to say the least.
---------
Don:
Thanks for the good discussion! As I had said in my
earlier post, I was not trying to "interfere" with you
on your help to "Mudinford." I respect you very much
and all the R&D you have done concerning our trucks
and I think you know that! All I was trying to do
was give another "viewpoint" on this piston issue.
As you said, for Mudinford, the Cummins RV 275
piston may be the best bet, but I do feel that the
Scheid Arias Pistons are also a very good choice
for high H.P. applications be it street or strip. I
know that "Throttle Jockey" also has them in his
daily driver (24V) and is getting up there in mileage.
The weights I listed on my stock piston were with
the rings still in the piston, so your noted weight
of 1256 grams on the Cummins Piston is probably
pretty close. You mentioned the lower ring grooves
and "an increased volume or area where residual
gases can be trapped after the exhaust stroke."
IMO, that would be so slight it would make hardly
any difference at all.
While these Scheid Arias Pistons may be be new to
diesel "street trucks", I intend to run them as long
as I did my stock Cummins 12V pistons. When I get
about 230,000 miles on them we will see how they
look compared to my old stockers.
-----------
John_P
Thanks for all that math you did on page #2!
It isvery interesting to say the least.
---------
Don:
Thanks for the good discussion! As I had said in my
earlier post, I was not trying to "interfere" with you
on your help to "Mudinford." I respect you very much
and all the R&D you have done concerning our trucks
and I think you know that!
All I was trying to dowas give another "viewpoint" on this piston issue.
As you said, for Mudinford, the Cummins RV 275
piston may be the best bet, but I do feel that the
Scheid Arias Pistons are also a very good choice
for high H.P. applications be it street or strip. I
know that "Throttle Jockey" also has them in his
daily driver (24V) and is getting up there in mileage.
The weights I listed on my stock piston were with
the rings still in the piston, so your noted weight
of 1256 grams on the Cummins Piston is probably
pretty close. You mentioned the lower ring grooves
and "an increased volume or area where residual
gases can be trapped after the exhaust stroke."
IMO, that would be so slight it would make hardly
any difference at all.
While these Scheid Arias Pistons may be be new to
diesel "street trucks", I intend to run them as long
as I did my stock Cummins 12V pistons. When I get
about 230,000 miles on them we will see how they
look compared to my old stockers.
-----------
John_P
09-10-2004, 01:07 PM
#34
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This added swelling needs a wider piston to wall clearance. Where we use around .0045-.005 clearance with stock pistons in mild apps..we go higher for higher EGT engines, but again even higher with forgings. More clearance is not the greatest thing for long term durability, cylinder gas sealing, and the noise of the pistons is louder
The coating is good, but will not last nearly as long as a ni-resist insert of iron that is cast into the the pistons when they are manufactured.
The bad thing about doing this is...it also increases the volume or area you can leave behind residual gas trapped in that clearance area after the exhaust stroke. Not a problem for a race engine, but for a streeter you are going to raise emissions and give that soot a better chance to attack the ring lands.
The only one that will is a cast piston with ni-resist lands.
09-10-2004, 01:42 PM
#35
DTR Advertiser
Spewing out large clouds of black smoke is what I try hard to avoid. We still manage to make 600 plus HP without doing that.
Watch Brandons video!
The lower the ring groove the higher the amount of abrasive soot can get into the volume. Just like a simple shovel for dirt. The larger the shovel the more it will hold. Its just harder to clear soot particles from that clearance volume.
IMO, the best thing we can do for a street driven engine is to use a cast piston. For 600 bucks a set VS a cost approaching 2000 dollars for Forged Arias pistons in a street driven engine...the choice becomes easier to make. As you stated the noise involved with the rattling from forged pistons is a moot point in a high HP smoke spewing competitive engine. This is certainly not the case in street driven engine. 600 HP or even as high as 800 or more HP is eay to make with a cast piston.
I have used the hard anodized pistons in a racing applications myself and they do hold up well. They are not however a long term street engine solution. We would wear them out in a season of racing. This goes back to duty cycle.
If you are suggesting that a forged and hard coated piston is a better solution in a street driven engine this is where we will have to disagree.
Lets not let anyone forget that the Enterprise Engine trucks are still running cast pistons. Dave Mitchell with his claimed 1000 HP is still running them and has been since the begining.
Don~
Watch Brandons video!
The lower the ring groove the higher the amount of abrasive soot can get into the volume. Just like a simple shovel for dirt. The larger the shovel the more it will hold. Its just harder to clear soot particles from that clearance volume.
IMO, the best thing we can do for a street driven engine is to use a cast piston. For 600 bucks a set VS a cost approaching 2000 dollars for Forged Arias pistons in a street driven engine...the choice becomes easier to make. As you stated the noise involved with the rattling from forged pistons is a moot point in a high HP smoke spewing competitive engine. This is certainly not the case in street driven engine. 600 HP or even as high as 800 or more HP is eay to make with a cast piston.
I have used the hard anodized pistons in a racing applications myself and they do hold up well. They are not however a long term street engine solution. We would wear them out in a season of racing. This goes back to duty cycle.
If you are suggesting that a forged and hard coated piston is a better solution in a street driven engine this is where we will have to disagree.
Lets not let anyone forget that the Enterprise Engine trucks are still running cast pistons. Dave Mitchell with his claimed 1000 HP is still running them and has been since the begining.
Don~
09-10-2004, 01:58 PM
#36
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If you are suggesting that a forged and hard coated piston is a better solution in a street driven engine this is where we will have to disagree.
I have used the hard anodized pistons in a racing applications myself and they do hold up well. They are not however a long term street engine solution. We would wear them out in a season of racing. This goes back to duty cycle.
Lets not let anyone forget that the Enterprise Engine trucks are still running cast pistons. Dave Mitchell with his claimed 1000 HP is still running them and has been since the begining.
09-10-2004, 02:56 PM
#37
DTR Advertiser
I see you are nearing the 600 HP mark in yor truck. Will you be installing the Arias forged pistons soon? LOL!
Or do you think the stock cast pistons will be ok in your 556 HP engine that you drive on the street daily?
Its funny to see the trucks running around now with 600 plus HP. None of them are in dire need of a forged piston. None have lost pistons. Building an engine that will last includes more than throwing high dollar parts at it.
There is an old adage that is used around here: " there is no end to concern"
Learing how to handle that concern and make the right moves is where the seperation takes place.
Don~
Or do you think the stock cast pistons will be ok in your 556 HP engine that you drive on the street daily?
Its funny to see the trucks running around now with 600 plus HP. None of them are in dire need of a forged piston. None have lost pistons. Building an engine that will last includes more than throwing high dollar parts at it.
There is an old adage that is used around here: " there is no end to concern"
Learing how to handle that concern and make the right moves is where the seperation takes place.
Don~
09-11-2004, 08:23 PM
#38
Administrator
Don:
A set of Scheid Arias Pistons are not $2,000.00 a set! I won't
put the exact price here, but if you doubt me on this Kent
Crowder @ Scheid Diesel (Lafayette) can confirm that for
you. His number is: 1-800-669-3533. My decision to have
them put in my engine was because by the time I bought
the stock Cummins pistons (be it stock Cummins 12V,
Cummins 12V Marine or the RV's) and had them coated
(which I feel I need); I was almost up to the price of what
a Scheid Arias cost! And again, for me, I feel that was the
best choice, but it may not be for "Mudinford." I think in the
future you will see more of the high H.P. diesel "street
trucks" going to these Arias Pistons. Nothing against
anybody or anything, but I do have to agree with
"banshee" about your comments concerning Dave
Mitchell @ "Enterprise Engine!"
-----------
John_P
A set of Scheid Arias Pistons are not $2,000.00 a set! I won't
put the exact price here, but if you doubt me on this Kent
Crowder @ Scheid Diesel (Lafayette) can confirm that for
you. His number is: 1-800-669-3533. My decision to have
them put in my engine was because by the time I bought
the stock Cummins pistons (be it stock Cummins 12V,
Cummins 12V Marine or the RV's) and had them coated
(which I feel I need); I was almost up to the price of what
a Scheid Arias cost! And again, for me, I feel that was the
best choice, but it may not be for "Mudinford." I think in the
future you will see more of the high H.P. diesel "street
trucks" going to these Arias Pistons. Nothing against
anybody or anything, but I do have to agree with
"banshee" about your comments concerning Dave
Mitchell @ "Enterprise Engine!"
-----------
John_P
09-12-2004, 10:35 AM
#39
DTR Advertiser
The 12 valve Marine pistons are 600 bucks. They are coated from the factory. An Arias piston is over 1650.00 bucks a set. Nearly three times the cost for something that will not last as long in a street engine.
In your 12 valve twin turbo application, you wont have massive EGT's. Stock Cummins Marine pistons would have better suited for long term wear.
In the mid to late 80's I ran forged pistons in most of my hi-po gasser engines. We would wear out a set of forged TRW pistons in 15- 25 thousand street miles. That was a terrible waste of time and money back then. This is the reason that high silicon hyper pistons became so popular. A stronger piston that was more heat resistant, but would last as long as a standard cast piston.
A street driven hyper or standard alloy cast piston in a Cummins would last 10 to 15 times longer if the EGT's were controlled than a forging.
There is a reason other than cost that Cummins does not use a forged piston. Some of the reasons are spelled out in my posts. They are looking for long term durability.
Don~
In your 12 valve twin turbo application, you wont have massive EGT's. Stock Cummins Marine pistons would have better suited for long term wear.
In the mid to late 80's I ran forged pistons in most of my hi-po gasser engines. We would wear out a set of forged TRW pistons in 15- 25 thousand street miles. That was a terrible waste of time and money back then. This is the reason that high silicon hyper pistons became so popular. A stronger piston that was more heat resistant, but would last as long as a standard cast piston.
A street driven hyper or standard alloy cast piston in a Cummins would last 10 to 15 times longer if the EGT's were controlled than a forging.
There is a reason other than cost that Cummins does not use a forged piston. Some of the reasons are spelled out in my posts. They are looking for long term durability.
Don~
09-12-2004, 09:48 PM
#40
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Don,
I'm not planning on rebuilding my engine anytime soon, so no, I'm not going to put a set in. Where did I say or John_P say they are "required" for over 600hp??? Once again, you have derived this "requirement" when I haven't said anything like that. The only thing I strongly disagree with is your statement that forged pistons will last only 20,000 miles. No, forgings aren't cheap, and hyper cast is a good alternate for less money. Powder metal Sintered parts are also gaining popularity in the gasser world, but not because they're better.... they're just cheaper and "good enough". Do you not think that you can forge a high silicon aluminum?? LOL! You need to catch up to the technology of today on coatings and forgings. What was standard in the late 80s is not the case today!!!
I'm not planning on rebuilding my engine anytime soon, so no, I'm not going to put a set in. Where did I say or John_P say they are "required" for over 600hp??? Once again, you have derived this "requirement" when I haven't said anything like that. The only thing I strongly disagree with is your statement that forged pistons will last only 20,000 miles. No, forgings aren't cheap, and hyper cast is a good alternate for less money. Powder metal Sintered parts are also gaining popularity in the gasser world, but not because they're better.... they're just cheaper and "good enough". Do you not think that you can forge a high silicon aluminum?? LOL! You need to catch up to the technology of today on coatings and forgings. What was standard in the late 80s is not the case today!!!
09-13-2004, 07:57 AM
#41
Administrator
Don:
As in past threads you and I disagree about this and have
our own opinions and viewpoints and that is good. We
can "agree to disagree". Time will tell how these Scheid
Arias pistons last and I will keep the members and you
informed on how they do. As "banshee" pointed out
earlier, this issue reminds me a little of the "ATS TripleLok
Converter" battles a few years ago. The "so-called experts"
at that time said the lock-up clutches would eat right through
the front covers and "locked-to-locked" shifting would never
work! Well, none of that happened and as it turned out
the TripleLok has proven to be a very tough, reliable
TC with thousands of miles to their credit under some
very grueling conditions with both of my trucks included
in that!
Thanks for all your input and for the good discussion on
all the points concerning this piston issue.
----------
John_P
As in past threads you and I disagree about this and have
our own opinions and viewpoints and that is good.
Wecan "agree to disagree". Time will tell how these Scheid
Arias pistons last and I will keep the members and you
informed on how they do. As "banshee" pointed out
earlier, this issue reminds me a little of the "ATS TripleLok
Converter" battles a few years ago. The "so-called experts"
at that time said the lock-up clutches would eat right through
the front covers and "locked-to-locked" shifting would never
work! Well, none of that happened and as it turned out
the TripleLok has proven to be a very tough, reliable
TC with thousands of miles to their credit under some
very grueling conditions with both of my trucks included
in that!
Thanks for all your input and for the good discussion on
all the points concerning this piston issue.
----------
John_P
09-13-2004, 10:08 AM
#43
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One thing for sure forged were the word in the 70s....we thrue stuff at our rods (just kids cars) put them in my Harley Davidson and the funny thing is,, they did not last!!! .The piston collapsed as best as I can understand ..the comp. rings would get squished and not able to do thir job.
Thermodynamics= big subject and big word To quote Qurky Bell " dont run out and spend you cash on forged pistons".......If you know this dude it lends some creedence......if you dont mabe you ought too......
Thermodynamics= big subject and big word To quote Qurky Bell " dont run out and spend you cash on forged pistons".......If you know this dude it lends some creedence......if you dont mabe you ought too......
09-14-2004, 10:17 AM
#44
Administrator
thumper:
I wouldn't compare a forged piston made in the 70's for
a Harley Davidson to what is made now for cars and trucks.
IMO, this would apply to not only Arias but to other big
piston manafacturers such as: JE, Speed Pro or Keith Black.
Arias has been buiding pistons for over 35 years now and
while they may be new to the diesel world, they are not
new for gas engines like some of those found in drag racing.
If you go to their website (www.ariaspistons.com) you can
see the variety of vehicles they are in now. FWIW, I have
never seen an Arias piston "collapse" as you described.
As I said in my earlier post, "time will tell on these Scheid
Arias Pistons!" So far they are doing very well in my truck,
"Throttle Jockey's" 24 valve and a few others. Many of the
members have already seen how well they are doing in a
few of the midwest pulling trucks!!
---------
John_P
I wouldn't compare a forged piston made in the 70's for
a Harley Davidson to what is made now for cars and trucks.
IMO, this would apply to not only Arias but to other big
piston manafacturers such as: JE, Speed Pro or Keith Black.
Arias has been buiding pistons for over 35 years now and
while they may be new to the diesel world, they are not
new for gas engines like some of those found in drag racing.
If you go to their website (www.ariaspistons.com) you can
see the variety of vehicles they are in now. FWIW, I have
never seen an Arias piston "collapse" as you described.
As I said in my earlier post, "time will tell on these Scheid
Arias Pistons!" So far they are doing very well in my truck,
"Throttle Jockey's" 24 valve and a few others. Many of the
members have already seen how well they are doing in a
few of the midwest pulling trucks!!
---------
John_P
09-14-2004, 11:00 AM
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Don,
I am planning on rebuilding my engine this winter currently it has 106k miles on the stock bottom end. I already bought the RV pistons FWIW. I want to lighten the crank in a timely manner when I tear the motor down. Which brings up the how much question. Roughly how much weight would you think could be safely shaven off? How much turn around time is required to do it if I sent it out of state, lets say TX?
MCummings,
I have the same feelings you do on the cryo job that was done in the pic you posted.
John_P,
Have you raced this year? I am looking forward to hearing how that new Scheid motor of yours does or is doing.
Mudinford,
600 hp would be mass more fun/practical with an automatic.
Opie
I am planning on rebuilding my engine this winter currently it has 106k miles on the stock bottom end. I already bought the RV pistons FWIW. I want to lighten the crank in a timely manner when I tear the motor down. Which brings up the how much question. Roughly how much weight would you think could be safely shaven off? How much turn around time is required to do it if I sent it out of state, lets say TX?
MCummings,
I have the same feelings you do on the cryo job that was done in the pic you posted.
John_P,
Have you raced this year? I am looking forward to hearing how that new Scheid motor of yours does or is doing.
Mudinford,
600 hp would be mass more fun/practical with an automatic.
Opie