Used parts
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Registered User
Joined: Sep 2002
Posts: 1,942
From: kitchener/Ontario
Used parts
Yes used parts...We all no all to well every year we up gread in some way and there is a ton of used parts for sale on this board.
My question is for used crank , rods. I can here every engine builder saying no right now but,
Dose a crank have a duty cyl (life frame)
Rod's have a duty cyl but what is it (life time)
Is there a way to build a stocker or rebuilt eng with used parts and get a good life out of that eng and make some good power..
Money is the key thing here ...if youy could buy a 500hp rated crank/rods for X amount of $ or you could buy a set of 700hp rated used crank/rods for the same amount of money, An eng builder cheaked out the crank/rods and they are good would it be ok to buy the used crank/rods here or am i missing somthing here..
If the eng only makes 500rwhp, the used 700hp crank/rods are under the limit here ....
My question is for used crank , rods. I can here every engine builder saying no right now but,
Dose a crank have a duty cyl (life frame)
Rod's have a duty cyl but what is it (life time)
Is there a way to build a stocker or rebuilt eng with used parts and get a good life out of that eng and make some good power..
Money is the key thing here ...if youy could buy a 500hp rated crank/rods for X amount of $ or you could buy a set of 700hp rated used crank/rods for the same amount of money, An eng builder cheaked out the crank/rods and they are good would it be ok to buy the used crank/rods here or am i missing somthing here..
If the eng only makes 500rwhp, the used 700hp crank/rods are under the limit here ....
Banned
Joined: Oct 2002
Posts: 6,518
This is a post my father is going to be all over like flies on ****.
A famous saying is that metal is like a woman, it remembers every stress ever put on it and once it has had enough blows up like Hiroshima. That's paraphrasing a bit but you get the picture.
Yes both rods and crankshafts have a duty cycle.
Personally I will not re-use "used" parts unless either I or the customer know their past life, and even then they need to be checked and fixed.
For example on a recent rebulid the crankshaft and rods are both forged brand name parts, and knowing the life they have lead already they will be ok, they are going back in the same owners hands. The bad thing was the block needed to be junked, but the pistons had very little wear. The problem lies in the work needed to get the parts back up to par. The crank at minimum needs to be polished if it's used, and ground .010 if it's at all tappered or has heat marks. Magnafluxing both the rods and crank is also a good idea. Looking at piston pins in that motors case, they need to be polished on the external hone if they pass inspection or replaced if they don't. The rods should be inspected for roundness in the big end and small end and for tapper. If they need to be fixed you have to buy either new bushings for the pin end or hone them cylindrical again and get pins to fit them. If the big ends are out on a aftermarket rod it is much harder to fix.
So used parts can look cheap to start, or turn out to be junk needing more time and money to get them right again, plus you are taking into account the fact that they are down on life and down on rebuilds left in them.
Duty cycle is hard to tell when the life the parts lead is unknown, and the ONLY way you know is that the parts were in your hands when the use was happening or in your customers hands.
Crankshafts don't wear out as fast on the street, but a 400-500hp circle track motor needs a new 4340 crank every other year to be safe, and that's with light bobweights.
Connecting Rods with good bolts will last longer, but bolts can be costly. Usually they have a certain number of revolutions until they go boom also. Circle track stuff can be run a season or two at the most.
Pistons, all depends on the heat they see and detonation. Worn out pin bores due to high rpm and detonation or badly machined rods, ringlands that get beat on heavily and go out of spec can really not be replaced, so pistons are not the best thing to reuse.
Well that's what I have to add to that, again the old man is probably going to add to that considerably.
Bret
A famous saying is that metal is like a woman, it remembers every stress ever put on it and once it has had enough blows up like Hiroshima. That's paraphrasing a bit but you get the picture.
Yes both rods and crankshafts have a duty cycle.
Personally I will not re-use "used" parts unless either I or the customer know their past life, and even then they need to be checked and fixed.
For example on a recent rebulid the crankshaft and rods are both forged brand name parts, and knowing the life they have lead already they will be ok, they are going back in the same owners hands. The bad thing was the block needed to be junked, but the pistons had very little wear. The problem lies in the work needed to get the parts back up to par. The crank at minimum needs to be polished if it's used, and ground .010 if it's at all tappered or has heat marks. Magnafluxing both the rods and crank is also a good idea. Looking at piston pins in that motors case, they need to be polished on the external hone if they pass inspection or replaced if they don't. The rods should be inspected for roundness in the big end and small end and for tapper. If they need to be fixed you have to buy either new bushings for the pin end or hone them cylindrical again and get pins to fit them. If the big ends are out on a aftermarket rod it is much harder to fix.
So used parts can look cheap to start, or turn out to be junk needing more time and money to get them right again, plus you are taking into account the fact that they are down on life and down on rebuilds left in them.
Duty cycle is hard to tell when the life the parts lead is unknown, and the ONLY way you know is that the parts were in your hands when the use was happening or in your customers hands.
Crankshafts don't wear out as fast on the street, but a 400-500hp circle track motor needs a new 4340 crank every other year to be safe, and that's with light bobweights.
Connecting Rods with good bolts will last longer, but bolts can be costly. Usually they have a certain number of revolutions until they go boom also. Circle track stuff can be run a season or two at the most.
Pistons, all depends on the heat they see and detonation. Worn out pin bores due to high rpm and detonation or badly machined rods, ringlands that get beat on heavily and go out of spec can really not be replaced, so pistons are not the best thing to reuse.
Well that's what I have to add to that, again the old man is probably going to add to that considerably.
Bret
Registered User
Joined: Oct 2002
Posts: 2,931
From: Upstate NY
Bret about said it for me...almost.
Rotating or reciprocating parts (flywheel, rods, pistons) are the things that fatigue from repetative stress. That's total revolutions in anger. It detonation occurred, which is difficult to learn from inspecting a crank or rods, there were some loads perhaps well above the design loads for the "700 hp", which shortens it's life dramatically. Detonation is that really bad incident with a woman, like when she found you with someone else.
Other parts like blocks, heads, etc. are rebuildable up to a point. If they aren't cracked (and you can prove this), and there's meat left for a rebore or redeck, they might be worth it. If it was a CNC 8620 main cap Bowtie block which cost $2500 new, I'd consider it. If it was an LT1 already @ 4.030 and decked to 9.000 I'd pass.
The reason Nextel Cup rotating parts are for sale is that after one race they are "senior citizens" and ready to retire. You don't find many Cup blocks, and if you do it's because they are out to max bore size which isn't much use to us anyway.
Sure, you might buy used rotating parts which have lots of life left in them, and which don't need refurbishing, but hey, you never know!
If you're budget isn't up to 700hp, rethink your goals. 500 fwhp on Scat 9000 $250 stroker cranks is safe, and the crank is new. Match the parts for where your power goals are, and spend all you can afford on airflow.
OK, IF I was building a show car that never ran in anger and wanted to brag on the having exotic (Nextel Cup, etc.) parts in it, sure I'd consider used rotating parts. Of course you could iceskate in hell before I'd do that kind of a car.
My $.02
Rotating or reciprocating parts (flywheel, rods, pistons) are the things that fatigue from repetative stress. That's total revolutions in anger. It detonation occurred, which is difficult to learn from inspecting a crank or rods, there were some loads perhaps well above the design loads for the "700 hp", which shortens it's life dramatically. Detonation is that really bad incident with a woman, like when she found you with someone else.
Other parts like blocks, heads, etc. are rebuildable up to a point. If they aren't cracked (and you can prove this), and there's meat left for a rebore or redeck, they might be worth it. If it was a CNC 8620 main cap Bowtie block which cost $2500 new, I'd consider it. If it was an LT1 already @ 4.030 and decked to 9.000 I'd pass.
The reason Nextel Cup rotating parts are for sale is that after one race they are "senior citizens" and ready to retire. You don't find many Cup blocks, and if you do it's because they are out to max bore size which isn't much use to us anyway.
Sure, you might buy used rotating parts which have lots of life left in them, and which don't need refurbishing, but hey, you never know!
If you're budget isn't up to 700hp, rethink your goals. 500 fwhp on Scat 9000 $250 stroker cranks is safe, and the crank is new. Match the parts for where your power goals are, and spend all you can afford on airflow.
OK, IF I was building a show car that never ran in anger and wanted to brag on the having exotic (Nextel Cup, etc.) parts in it, sure I'd consider used rotating parts. Of course you could iceskate in hell before I'd do that kind of a car.
My $.02
Registered User
Joined: Jul 2000
Posts: 520
From: MD
2 big things are being left out here:
- if the parts are sufficient for a certain cycle life at a rated load, as you lessen the load you reach a point where cycle life becomes just about infinite. I have graphs of this somewhere but with most metals it is much higher then most people believe it is.
- road/oval track use is VERY different then street or even street/strip use. There's plenty of drag cars out there that see quite a few passes a season using oem parts and living for considerable time in an engine making 5, 6, 7 even 800hp. This same engine would most likely self destruct the first time it spent a few minutes on a road course. There's a lot of people out there getting away with taking a stock short block, adding some cheap TRW pistons, adding a power adder and then running 9's for a few seasons without any major carnage. As long as you understand that these crappy parts need to be torn down once in a while and freshened up…
- if the parts are sufficient for a certain cycle life at a rated load, as you lessen the load you reach a point where cycle life becomes just about infinite. I have graphs of this somewhere but with most metals it is much higher then most people believe it is.
- road/oval track use is VERY different then street or even street/strip use. There's plenty of drag cars out there that see quite a few passes a season using oem parts and living for considerable time in an engine making 5, 6, 7 even 800hp. This same engine would most likely self destruct the first time it spent a few minutes on a road course. There's a lot of people out there getting away with taking a stock short block, adding some cheap TRW pistons, adding a power adder and then running 9's for a few seasons without any major carnage. As long as you understand that these crappy parts need to be torn down once in a while and freshened up…
Banned
Joined: Oct 2002
Posts: 6,518
How about this......
Used 4340 Forged Rods Rods $300, rated for 600hp has a unknown life
Used 4340 Forged Crank $300, rated for 800hp has unkown life
New 4340 Forged Rods $500
New 4340 Forged Crank $600
Now$600 vs $1100...
The problem is that after the parts are inspected, the crank regound or polished, magnaflux both the crank and rods, hone the rods to size, fix pin bores if need be (very likely) you are going to eat up that $500 savings in labor (paying a engine builder so it's not like i'm not stepping on my own dick here) and have a part that has a unknown life and unknown life span that is already partially used up.
Now granted they could have a long life span left if they are not over stressed, personally I don't belive in HUGE overkill on engine parts because most times that just adds weight to the setup, added strength is not bad but added weight is. Most times guys are trying to save a few bucks here and there to get more parts that will make more power and stress the parts more and more.
Just because people do something doesn't mean it's a good idea or it's the right thing to do. It may save you money at first and that's the reason people buy used parts. When something breaks it's going to cause problems far beyond the money savings. It's like a high quality CNC machined aftermarket block, you can get the thing perfect with tons of room for overbores and it's going to be more accurate and stronger than a stock block fully preped and machined up to the same standards. The couple of bucks you save are not worth the loss of strength and extended life a aftermarket block gives you since it has more overbores and better inital quality.
Bret
Used 4340 Forged Rods Rods $300, rated for 600hp has a unknown life
Used 4340 Forged Crank $300, rated for 800hp has unkown life
New 4340 Forged Rods $500
New 4340 Forged Crank $600
Now$600 vs $1100...
The problem is that after the parts are inspected, the crank regound or polished, magnaflux both the crank and rods, hone the rods to size, fix pin bores if need be (very likely) you are going to eat up that $500 savings in labor (paying a engine builder so it's not like i'm not stepping on my own dick here) and have a part that has a unknown life and unknown life span that is already partially used up.
Now granted they could have a long life span left if they are not over stressed, personally I don't belive in HUGE overkill on engine parts because most times that just adds weight to the setup, added strength is not bad but added weight is. Most times guys are trying to save a few bucks here and there to get more parts that will make more power and stress the parts more and more.
Just because people do something doesn't mean it's a good idea or it's the right thing to do. It may save you money at first and that's the reason people buy used parts. When something breaks it's going to cause problems far beyond the money savings. It's like a high quality CNC machined aftermarket block, you can get the thing perfect with tons of room for overbores and it's going to be more accurate and stronger than a stock block fully preped and machined up to the same standards. The couple of bucks you save are not worth the loss of strength and extended life a aftermarket block gives you since it has more overbores and better inital quality.
Bret
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