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Re: Building a 360 magnum question
[Re: volaredon]
#3142980
05/07/23 08:47 AM
05/07/23 08:47 AM
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Joined: Jan 2006
Posts: 8,162
USA
360view
Moparts resident spammer
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Moparts resident spammer
Joined: Jan 2006
Posts: 8,162
USA
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Working from a fuzzy memory...
If you look at the 1994+ Ram Field Service manual be aware of a mistake that never seemed to be corrected, at least up to 1998:
The technical drawing and specs for Magnum 5.9 V8 pistons are wrong: they incorrectly left in the 1992 TBI 360 piston data.
Drawing shows a round dish in the piston top, not at all the new “soapdish” of the 5.9 Magnum v8.
Fortunately in the 1995 FSM the V10 pistons of that year where identical to the 5.9 V8 as a Chrysler “money saving” decision, and this is confirmed in former chief engineer Willem Weertman’s later book “Chrysler Engines.”
So use the V10 section piston specs and drawing.
Seems like the compression height was 1.61 to 1.63
I think Magnum 5.9/8L piston weight was 480 grams, not positive.
I measured 1994 soapdish to be 11 cc, but around 1998 Chrysler enlarged it because Ram owners were complaining of pinging, which was mainly due to carbon deposits filling up the soapdish in the piston top. Chrysler also did the terrible “bandaid” TSB that retarded ignition timing - this became known as the “Deathflash.”
Magnum 5.9 piston tops average about 55 thousandths “in the hole” with about another 47.5 thousandths from the head gasket, which creates a “quench clearance” well above the recommended 60 thousandths.
The “blueprint specification” for for 5.9 V8 combustion chamber size is 62 cc but is typically bigger with the largest one of the four on a cylinder head typically 65 cc.
The 5.9 soapdish cavity in the piston top is there to create “mixture tumble” to reduce NOx emissions.
The 1992+ Magnum 5.2 piston top is flat, and is more like 20 thousandths in the hole, for ballpark 60 thousandths clearance which is recommended max for measureable quench action benefits to actually occur..
This 5.2 piston is all about “Squish” mixture motion improvement.
Magnum 5.9/5.2 connecting rods are lighter than 360 rods.
One of the later Chrysler performance books, I think the one with “Stoker” or “Big Inch” in the title
helpfully informs that later year V10 connecting rods are both lighter and longer.
These V10 rods might help you use the heavier 360 pistons you already own,
or you could offset bush factory Magnum rods and add external balance weight.
If your already owned 360 pistons have thick enough flat tops
one might consider grinding in “heart shaped” dishes on each piston top
that exactly matches the Magnum cylinder head combustion chamber bottom outline.
This would lighten those pistons closer to Magnum balance specification
and create both tumble and squish action.
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Re: Building a 360 magnum question
[Re: 360view]
#3143208
05/08/23 02:29 PM
05/08/23 02:29 PM
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Joined: Jan 2005
Posts: 12,423
Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,423
Kalispell Mt.
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Working from a fuzzy memory...
If you look at the 1994+ Ram Field Service manual be aware of a mistake that never seemed to be corrected, at least up to 1998:
The technical drawing and specs for Magnum 5.9 V8 pistons are wrong: they incorrectly left in the 1992 TBI 360 piston data.
Drawing shows a round dish in the piston top, not at all the new “soapdish” of the 5.9 Magnum v8.
Fortunately in the 1995 FSM the V10 pistons of that year where identical to the 5.9 V8 as a Chrysler “money saving” decision, and this is confirmed in former chief engineer Willem Weertman’s later book “Chrysler Engines.”
So use the V10 section piston specs and drawing.
Seems like the compression height was 1.61 to 1.63
I think Magnum 5.9/8L piston weight was 480 grams, not positive.
I measured 1994 soapdish to be 11 cc, but around 1998 Chrysler enlarged it because Ram owners were complaining of pinging, which was mainly due to carbon deposits filling up the soapdish in the piston top. Chrysler also did the terrible “bandaid” TSB that retarded ignition timing - this became known as the “Deathflash.”
Magnum 5.9 piston tops average about 55 thousandths “in the hole” with about another 47.5 thousandths from the head gasket, which creates a “quench clearance” well above the recommended 60 thousandths.
The “blueprint specification” for for 5.9 V8 combustion chamber size is 62 cc but is typically bigger with the largest one of the four on a cylinder head typically 65 cc.
The 5.9 soapdish cavity in the piston top is there to create “mixture tumble” to reduce NOx emissions.
The 1992+ Magnum 5.2 piston top is flat, and is more like 20 thousandths in the hole, for ballpark 60 thousandths clearance which is recommended max for measureable quench action benefits to actually occur..
This 5.2 piston is all about “Squish” mixture motion improvement.
Magnum 5.9/5.2 connecting rods are lighter than 360 rods.
One of the later Chrysler performance books, I think the one with “Stoker” or “Big Inch” in the title
helpfully informs that later year V10 connecting rods are both lighter and longer.
These V10 rods might help you use the heavier 360 pistons you already own,
or you could offset bush factory Magnum rods and add external balance weight.
If your already owned 360 pistons have thick enough flat tops
one might consider grinding in “heart shaped” dishes on each piston top
that exactly matches the Magnum cylinder head combustion chamber bottom outline.
This would lighten those pistons closer to Magnum balance specification
and create both tumble and squish action.
I too have noticed the bad info they kept putting in the service manuals, really annoying. I have never noticed any significant CC difference in any 5.9 pistons but in the later ones (I think starting aroun 2000 or so) the pistons wet from a raw cast top to a CNC top but the dish size, weight and compression height was not changed but was slightly more consistent. On the 5.2 magnums I usually end up taking around .037 off to get zero deck and close to the same on 5.9s, maybe a couple thousands more but not .055. As far as balance is concerned if you want to redneck it and run LA pistons you should run LA TQ converter and Balancer as the lighter piston is where most of the balance difference comes from (the rods are a tiny bit lighter in the mgnum because it is narrower on the small end). I have heard people say the v10 used the exact same piston but have heard the rod is different and that it is the same, seems I need to get on fleabay and buy a set to confirm it for myself...
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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