Questions about rebuilding
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From: on a hilltop in Ky
Questions about rebuilding
The engine in my sig needs rebuilt, it's using to much oil (quart in 450 miles).
This truck is a dd - work - tow vehicle with gcvw from 24000 to 35000 lbs, sees very little interstate and 30% of the time it's pulling a gn trailer.
My questions are what pistons to use and cam recommendations. I've read in other forum's about what pistons are best to use (non ic, marine, stock) but no one say's why one is better than the other. Would I see a benefit using a after market box cam (what brand and size), custom grind (who to use)or just stay with stock.
With the way this truck is used will pistons or cam other than stock help improve mpg, lower egt, improve over all performance, increase durability and are they worth the cost.
This truck is a dd - work - tow vehicle with gcvw from 24000 to 35000 lbs, sees very little interstate and 30% of the time it's pulling a gn trailer.
My questions are what pistons to use and cam recommendations. I've read in other forum's about what pistons are best to use (non ic, marine, stock) but no one say's why one is better than the other. Would I see a benefit using a after market box cam (what brand and size), custom grind (who to use)or just stay with stock.
With the way this truck is used will pistons or cam other than stock help improve mpg, lower egt, improve over all performance, increase durability and are they worth the cost.
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Well, I haven't seen any responses so I'll throw my $0.02 in...
I've never rebuilt a 6bt, but I think I'd be wary of marine pistons in case they result in lower compression. I think the race/tractor pull guys like the lower compression because they can run higher boost safely. In a daily driver though, lower compression would probably suck due to the harder starting if nothing else.
The cam would be interesting to look at though--I was looking at Hamilton cams for a while but never did it. I've heard complaints of aftermarket cams hurting the effectiveness of exhaust brakes, maybe because of the change in valve overlap.
Hopefully someone with real experience will chime in.
Mike
I've never rebuilt a 6bt, but I think I'd be wary of marine pistons in case they result in lower compression. I think the race/tractor pull guys like the lower compression because they can run higher boost safely. In a daily driver though, lower compression would probably suck due to the harder starting if nothing else.
The cam would be interesting to look at though--I was looking at Hamilton cams for a while but never did it. I've heard complaints of aftermarket cams hurting the effectiveness of exhaust brakes, maybe because of the change in valve overlap.
Hopefully someone with real experience will chime in.
Mike
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From: Brightwood, Oregon
a friend has a combine with the non turbo B engine that started snapping up a gallon of oil every day, we just pulled the pistons slapped new rings on them and honed it up really good. adjusted the valves and its running like new again, very little oil usage over a entire week of 15 hour days!
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Well ! I was told I would get a lot of replies on this forum. I know these engines are getting a little old and most every one is running the newer electric engines now days but I was hoping there were a few old die hard 12v builders still around.
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Yea I know about the cpl numbers I've used them for years on stock rebuilds. I would like to know if changing things up a little (different pistons or cams) would gain me anything for the way I use this truck (towing and local hauling).
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After reading some old post I've decided to go with non ic pistons, so now what inj to run 145* or 155*. Can you get a 5x.010 or 5x.011 in 155* or would I be better off with 145*
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From: Holly Ridge, N.C.
The engine in my sig needs rebuilt, it's using to much oil (quart in 450 miles).
This truck is a dd - work - tow vehicle with gcvw from 24000 to 35000 lbs, sees very little interstate and 30% of the time it's pulling a gn trailer.
My questions are what pistons to use and cam recommendations. I've read in other forum's about what pistons are best to use (non ic, marine, stock) but no one say's why one is better than the other. Would I see a benefit using a after market box cam (what brand and size), custom grind (who to use)or just stay with stock.
With the way this truck is used will pistons or cam other than stock help improve mpg, lower egt, improve over all performance, increase durability and are they worth the cost.
This truck is a dd - work - tow vehicle with gcvw from 24000 to 35000 lbs, sees very little interstate and 30% of the time it's pulling a gn trailer.
My questions are what pistons to use and cam recommendations. I've read in other forum's about what pistons are best to use (non ic, marine, stock) but no one say's why one is better than the other. Would I see a benefit using a after market box cam (what brand and size), custom grind (who to use)or just stay with stock.
With the way this truck is used will pistons or cam other than stock help improve mpg, lower egt, improve over all performance, increase durability and are they worth the cost.
DestrokedF450:
Sorry you haven't had more replies on your questions Sir.
Let me see if I can help you some. I have done several rebuilds on my 1996 Dodge CTD 12 valve with higher H.P./TQ. being the goal each time. My truck is right at 800+ H.P. now which I do not recommend for a "daily driver."
I do not feel that a "hotter cam" is going to help your mileage much in fact on mine the numbers went down each time I went hotter. Pistons are another issue on the Cummins 12 valve engines which there is alot of disagreement.
I have tried several different types, those being, stock, Arias Forged (Open Bowl) and now Mahle Forged (Stock "Keyhole" style Bowl like stock pistons.)
If you are daily driving your truck, I DO NOT recommend using a marine or open bowl type piston in your Cummins 12 valve!
On my truck, the engine constantly smoked, at idle, at midrange and at WOT. I feel that the stock Cummins design of the 12V piston, with the "hole" at the top greatly helps to atomize the fuel going into the cylinder. After my try with the AriasForged (Open Bowl) pistons, we went back to the stock pistons and all the smoke etc. was GONE! the truck ran better, it didn't smoke much at all an the performance was very good. I now have the Mahle Forged Pistons (Hole in piston top like the stock piston) and they have worked well but there is more smoke than what I had with the stock piston. Now, with that being said, I am now running around a 15:1 compression ratio, so that adds to the smoke issue.
On injectors, I would recommend a 5X.013 Cummins Injector. They are clean, offer good performance and the pressures can be adjusted to your needs.
For your information, my diesel shop and engine builder is Scheid Diesel. Dan Scheid has been in business for over thirty (30) years and has three full service shops, two in Indiana and one in Illinois. Dan also has two high performance sled pulling trucks which run the PPL, ITPA circuit every year and they are top finishing trucks. He also has the fastest diesel rail dragster in the U.S. right now running low 6's at over 220 MPH! All of his engine products are thoroughly tested on his race engines in addition to him being a full Cummins/Bosch service center. I would recommend you calling one of his head technicians by the name of Brad Ingram @ the Effingham, Illinois shop.
His toll free number is: 1-800-669-1934. Brad is a great guy, he is very
knowledgeable on these engines and can help you with what would work best for you. Tell him John P. referred you. He has done ALOT of work on my
1996!
Good luck Sir!
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John_P
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From: on a hilltop in Ky
John-P thank you for your reply
After a fair amount of research I believe the early 89-91 non ic piston will work best for me. It has slightly larger bowl than the 94-97 ic pistons but still has over 17-1 compression ratio for better cold starts and less haze. With the larger bowl there should be less chance of spraying outside the bowl which cause's high pressure waves against the head gasket.
I talked to Scheid Diesel at the farm machinery show in Feb and after some discussion between 5x010's and 300 marines they recommended 5x010s. When I read non ic engines used 155* inj I considered 300's but have decided to stay with 145* inj to insure not spraying outside of the bowl.
A well known member on another forum uses a PDR Quick Spool cam in his tow vehicle with good results. (idk the specs) PDR no longer does cams and referred me to Colt. They recommended their Big Stick over the Stage 2 but idk, don't what to get too big. After you mentioned Schied I remembered they are doing regrinds know so I'll check back with them.
A cam and lifters adds a lot to the cost of a rebuild so I'll have to see what the stock cam looks like before I made that decision.
After a fair amount of research I believe the early 89-91 non ic piston will work best for me. It has slightly larger bowl than the 94-97 ic pistons but still has over 17-1 compression ratio for better cold starts and less haze. With the larger bowl there should be less chance of spraying outside the bowl which cause's high pressure waves against the head gasket.
I talked to Scheid Diesel at the farm machinery show in Feb and after some discussion between 5x010's and 300 marines they recommended 5x010s. When I read non ic engines used 155* inj I considered 300's but have decided to stay with 145* inj to insure not spraying outside of the bowl.
A well known member on another forum uses a PDR Quick Spool cam in his tow vehicle with good results. (idk the specs) PDR no longer does cams and referred me to Colt. They recommended their Big Stick over the Stage 2 but idk, don't what to get too big. After you mentioned Schied I remembered they are doing regrinds know so I'll check back with them.
A cam and lifters adds a lot to the cost of a rebuild so I'll have to see what the stock cam looks like before I made that decision.
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If I was you, I would start with a solvent motor flush. If you get the pistons hotter the rings can push back into the carbon buildup in the pistons causing compression/oil consumption problems. Since the pistons are oil cooled and directly exposed to the combustion, they can have aluminum expanding temperature spikes semi-regardless of coolant temperature. The solvent flush cleans out a remarkable amount of this carbon and brings back compression, oil delivery to oil control rings, and raises oil pressure. IE it unsticks stuck rings.
With gassers, you pretty much go buy a rebuild kit regardless, they are just cheaper to buy the whole kit. With diesels, usually it is more practical to inspect what you have and buy what you need. Unless you have hot seized or have 800k on the engine, the pistons will probably spec out- feeler gauge against the rings in the lands. The metal doesn't know if it's new or not and neither does the engine. It either has slop or not.
Fancy designation for pistons such as forged are very misleading. I'll wager that all the pistons you will find in these engine are "forged" as are most diesel pistons. Soft cast pistons using hypereutectic alloy to limit swell and thus piston taper are way to soft to survive in a diesel. Thus the use of precipitate hardened (t6 probably) alloy. The differences will be in shape, not material strength. Or not significantly unless you go steel pistons which are beyond awesome in all ways, but also beyond expensive in all ways.
Cams are unlikely to be helpful unless you are a SERIOUS racer. In gassers, compromising idle for more top end can help, but in a turbodiesel, you want very little (or no) valve overlap since the turbo moves the gasses, not flow compromises. If you want better flow, I'd port the head first personally. Higher lift puts more stress on the components due to abrupt rise and more spring squish and the FIRST thing performance cam manufacturers do usually is limit the set down ramp of the cam. Most stock cams have a point right when the valve closes that the cam slows the closing to gently set the valve on the seat. This dramatically improves wear characteristics and is not worth compromising unless you are racing.
The place to make power outside of racing is not in the long block at all. Fuel, timing and turbo. Leave the engine alone unless you are genuinely racing imo. *Edit: except for studs and O-ringing and perhaps porting, that is.*
Don't forget the killer dowel pin (KDP) issue. And inspect valve protrusion and stem *and face* deflection carefully.
With gassers, you pretty much go buy a rebuild kit regardless, they are just cheaper to buy the whole kit. With diesels, usually it is more practical to inspect what you have and buy what you need. Unless you have hot seized or have 800k on the engine, the pistons will probably spec out- feeler gauge against the rings in the lands. The metal doesn't know if it's new or not and neither does the engine. It either has slop or not.
Fancy designation for pistons such as forged are very misleading. I'll wager that all the pistons you will find in these engine are "forged" as are most diesel pistons. Soft cast pistons using hypereutectic alloy to limit swell and thus piston taper are way to soft to survive in a diesel. Thus the use of precipitate hardened (t6 probably) alloy. The differences will be in shape, not material strength. Or not significantly unless you go steel pistons which are beyond awesome in all ways, but also beyond expensive in all ways.
Cams are unlikely to be helpful unless you are a SERIOUS racer. In gassers, compromising idle for more top end can help, but in a turbodiesel, you want very little (or no) valve overlap since the turbo moves the gasses, not flow compromises. If you want better flow, I'd port the head first personally. Higher lift puts more stress on the components due to abrupt rise and more spring squish and the FIRST thing performance cam manufacturers do usually is limit the set down ramp of the cam. Most stock cams have a point right when the valve closes that the cam slows the closing to gently set the valve on the seat. This dramatically improves wear characteristics and is not worth compromising unless you are racing.
The place to make power outside of racing is not in the long block at all. Fuel, timing and turbo. Leave the engine alone unless you are genuinely racing imo. *Edit: except for studs and O-ringing and perhaps porting, that is.*
Don't forget the killer dowel pin (KDP) issue. And inspect valve protrusion and stem *and face* deflection carefully.
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Joined: Mar 2002
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From: Holly Ridge, N.C.
If I was you, I would start with a solvent motor flush. If you get the pistons hotter the rings can push back into the carbon buildup in the pistons causing compression/oil consumption problems. Since the pistons are oil cooled and directly exposed to the combustion, they can have aluminum expanding temperature spikes semi-regardless of coolant temperature. The solvent flush cleans out a remarkable amount of this carbon and brings back compression, oil delivery to oil control rings, and raises oil pressure. IE it unsticks stuck rings.
With gassers, you pretty much go buy a rebuild kit regardless, they are just cheaper to buy the whole kit. With diesels, usually it is more practical to inspect what you have and buy what you need. Unless you have hot seized or have 800k on the engine, the pistons will probably spec out- feeler gauge against the rings in the lands. The metal doesn't know if it's new or not and neither does the engine. It either has slop or not.
Fancy designation for pistons such as forged are very misleading. I'll wager that all the pistons you will find in these engine are "forged" as are most diesel pistons. Soft cast pistons using hypereutectic alloy to limit swell and thus piston taper are way to soft to survive in a diesel. Thus the use of precipitate hardened (t6 probably) alloy. The differences will be in shape, not material strength. Or not significantly unless you go steel pistons which are beyond awesome in all ways, but also beyond expensive in all ways.
Cams are unlikely to be helpful unless you are a SERIOUS racer. In gassers, compromising idle for more top end can help, but in a turbodiesel, you want very little (or no) valve overlap since the turbo moves the gasses, not flow compromises. If you want better flow, I'd port the head first personally. Higher lift puts more stress on the components due to abrupt rise and more spring squish and the FIRST thing performance cam manufacturers do usually is limit the set down ramp of the cam. Most stock cams have a point right when the valve closes that the cam slows the closing to gently set the valve on the seat. This dramatically improves wear characteristics and is not worth compromising unless you are racing.
The place to make power outside of racing is not in the long block at all. Fuel, timing and turbo. Leave the engine alone unless you are genuinely racing imo. *Edit: except for studs and O-ringing and perhaps porting, that is.*
Don't forget the killer dowel pin (KDP) issue. And inspect valve protrusion and stem *and face* deflection carefully.
With gassers, you pretty much go buy a rebuild kit regardless, they are just cheaper to buy the whole kit. With diesels, usually it is more practical to inspect what you have and buy what you need. Unless you have hot seized or have 800k on the engine, the pistons will probably spec out- feeler gauge against the rings in the lands. The metal doesn't know if it's new or not and neither does the engine. It either has slop or not.
Fancy designation for pistons such as forged are very misleading. I'll wager that all the pistons you will find in these engine are "forged" as are most diesel pistons. Soft cast pistons using hypereutectic alloy to limit swell and thus piston taper are way to soft to survive in a diesel. Thus the use of precipitate hardened (t6 probably) alloy. The differences will be in shape, not material strength. Or not significantly unless you go steel pistons which are beyond awesome in all ways, but also beyond expensive in all ways.
Cams are unlikely to be helpful unless you are a SERIOUS racer. In gassers, compromising idle for more top end can help, but in a turbodiesel, you want very little (or no) valve overlap since the turbo moves the gasses, not flow compromises. If you want better flow, I'd port the head first personally. Higher lift puts more stress on the components due to abrupt rise and more spring squish and the FIRST thing performance cam manufacturers do usually is limit the set down ramp of the cam. Most stock cams have a point right when the valve closes that the cam slows the closing to gently set the valve on the seat. This dramatically improves wear characteristics and is not worth compromising unless you are racing.
The place to make power outside of racing is not in the long block at all. Fuel, timing and turbo. Leave the engine alone unless you are genuinely racing imo. *Edit: except for studs and O-ringing and perhaps porting, that is.*
Don't forget the killer dowel pin (KDP) issue. And inspect valve protrusion and stem *and face* deflection carefully.
totalloser:
Man,.....what an interesting User Name you have!
No offense but I don't agree with your assessment on the forged piston issue Sir! For what it is worth, the stock pistons in the Cummins 5.9/6.7 Engines are cast pistons, not forged. And the point I was trying to make to the OP was to go with the "original" design of the older Cummins 12V Piston which has that off-set "keyhole" to better atomize the fuel with the location of the stock injectors which are also "offset" and not directly over the top of the piston.
For your information, "forged" pistons like those designed and made by companies such as "Arias" or "Mahle" are built to withstand much more heat than a stock cast Cummins Piston. If that was NOT the case, then why do you see all the top diesel sled pullers and drag racers going to forged pistons?
Because they are tougher due to the better metal and can withstand MUCH more heat than a stock cast Cummins Piston. The other advantage of a forged piston is the beefier underside where the wrist pin goes through the piston to connect to the rod. I can assure you there is NO comparison between the two types of pistons in either strength or durability even though you say they are the same!
I would say that the OP has pretty much "made up his mind" as to what he will do so much of this is really a moot point anyway.
---------
John_P
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From: Holly Ridge, N.C.
greendodge:
Thanks for your kind words Sir and you are welcome on the posts!
I am waiting for totaloser to get back in here so we can continue this
"debate."
Should be alot of fun!
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From: on a hilltop in Ky
In the mechanical world one's mind is never made up until purchased parts are installed and can not be returned.
With that said, yes I have a very good idea on what pistons I'd like to use but parts haven't been purchased yet so keep the opinions coming.
I've tried motor flushes in the past and found that most of the time it was a tempary fix to a larger problem. Besides I've already pulled an inj and bore scoped a cylinder where I found a lot a clearance between the piston and cylinder. I know it's not a true way to check but when it looks like you can drop a nickle between the piston and cylinder thats a lot a clearance.
From what I've read and some what understand keeping the injector spray inside the bowl lowers the pressure spikes against the head gasket (less head gasket problems). Larger bowls lower compression which for proformance use allow for more boost and fuel, but for normal use off idle torque and mpg's suffer from low compression.
Someone jump in and correct me if i'm wrong.
With that said, yes I have a very good idea on what pistons I'd like to use but parts haven't been purchased yet so keep the opinions coming.
I've tried motor flushes in the past and found that most of the time it was a tempary fix to a larger problem. Besides I've already pulled an inj and bore scoped a cylinder where I found a lot a clearance between the piston and cylinder. I know it's not a true way to check but when it looks like you can drop a nickle between the piston and cylinder thats a lot a clearance.
From what I've read and some what understand keeping the injector spray inside the bowl lowers the pressure spikes against the head gasket (less head gasket problems). Larger bowls lower compression which for proformance use allow for more boost and fuel, but for normal use off idle torque and mpg's suffer from low compression.
Someone jump in and correct me if i'm wrong.