Piers Cam Update
10-06-2002, 11:48 AM
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Piers Cam Update
Here is an update on the Piers cam I installed back in July. As you guys may remember I was impressed with the Piers 24v cam that was installed in my truck. Fuel mileage was up, egt's down, and top end power increased slightly. The one thing that didn't change much was spoolup time for the turbo.
Well..... I must now happily update the spoolup issue! Seems that when the cam was installed the valve lash was not set correctly. On Thursday night I set the lash to the correct specification and boy did the truck come to life! Spoolup is very much improved. In fact just cruising down the road at 65 mph on level ground I always showed 0 psi on my boost gauge, now it reads 3-4 psi. Also when I dynoed this weekend during the MD-TDR Fall Brawl the charts confirmed that I was in fact producing more HP and torque at a lower rpm. Peak #'s were just up slightly but prior to the cam install I reached 750 HP at 3100 rpm and 1200 lbs torque at 2550 rpm. After the cam install I obtained 750 HP at 2600 rpm and 1200 lbs torque at 2200 rpm! The two dyno runs compared were identical setups on the truck except for the cam.
As for driving the truck I can really feel the increased low end! Another benefit from getting the valve lash set correctly is a further decrease in egt's. Turbo cooldown time is almost nonexistant when the outside air is around 75*. For anyone considering a cam change I HIGHLY recommend Piers' Cam!
Doug
Well..... I must now happily update the spoolup issue! Seems that when the cam was installed the valve lash was not set correctly. On Thursday night I set the lash to the correct specification and boy did the truck come to life! Spoolup is very much improved. In fact just cruising down the road at 65 mph on level ground I always showed 0 psi on my boost gauge, now it reads 3-4 psi. Also when I dynoed this weekend during the MD-TDR Fall Brawl the charts confirmed that I was in fact producing more HP and torque at a lower rpm. Peak #'s were just up slightly but prior to the cam install I reached 750 HP at 3100 rpm and 1200 lbs torque at 2550 rpm. After the cam install I obtained 750 HP at 2600 rpm and 1200 lbs torque at 2200 rpm! The two dyno runs compared were identical setups on the truck except for the cam.
As for driving the truck I can really feel the increased low end! Another benefit from getting the valve lash set correctly is a further decrease in egt's. Turbo cooldown time is almost nonexistant when the outside air is around 75*. For anyone considering a cam change I HIGHLY recommend Piers' Cam!
Doug
10-06-2002, 08:07 PM
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Re:Piers Cam Update
The torque numbers are different than in my signature because until recently the dyno I use did not have software capable of reading torque above 1200 lbs. Since the dyno runs I had made prior to the cam change were limited to 1200 I had to compare runs based on a known factor which was when I reached and dropped below 1200 lbs.
10-07-2002, 08:12 AM
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Re:Piers Cam Update
The DD cam is not installed for 1500. That is over the counter with self install. If I am correct the Piers camshaft is 6-700 dollars, OTC.<br><br>Some differences are: the Piers cam is a re-ground shaft and comes with re-ground lifters. The stock 12 and 24 valve engines use a press on gear and the material is different.<br><br>The DD camshaft is a New Marine camshaft that uses the bolt-on gear and the high ductile iron material for strength and comes with new lifters. The bolt that holds the gear to the shaft goes all the way to the second bearing journal. Cummins had some experience with breakage with a governed engine at 3000rpm. This was with loads much higher than ours in most cases though. DD felt the extra strength of the marine cam that was engineered into the design from Cummins was a good insurance policy for long term durability and to lessen the breakage potential. <br>As far as I know, camshaft breakage is a very very small problem at the power levels and the loads we are at now.<br>I have heard of breakage problems from truck pullers. I feel the load and rpm both are playing a part in this. <br><br>I still believe that as we increase power levels, valve spring rates, lobe lift, overall cylinder pressure (especially on the exhaust events), boost levels, etc that the strongest components that we can use will only help. Finally, nitrous can induce harmonics that Cummmins and others have found inherent in the valvetrain that could cause a failure. The sudden shock and very fast twist up of the engine make it hard to keep the lifters on the shaft. <br><br>Don~<br><br><br>
10-07-2002, 10:26 AM
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Re:Piers Cam Update
Sounds sweet man. I just got done installing a cam on my friends V6 stang. .495/.525 lift 218/225@.050 It sounds wicked and idles nicely. What's yours sound like? You think you may be able to get a sound clip or something of it? Does it lope and all at idle? I can't wait to do a cam on mine (in like 4 years 
).
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10-07-2002, 02:14 PM
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Re:Piers Cam Update
BigBlue<br><br>The truck actually idles smoother and quieter than before the cam change.<br><br>Don~<br><br>Nobody at Cummins that I can find says they have done any testing on the ISB using N02. I also have never heard of any guys using N02 to have a cam failure. As for keeping the valves on the lifters, engine ramp speed ramp up is not a problem. The problem comes from an engine being operated at higher engine rpm than what the stock valve spring tension will allow for.
10-07-2002, 05:05 PM
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Re:Piers Cam Update
I guess if you read that post it might seem I was trying to say that Cummins found harmonics with the use of Nitrous. I did not mean to say or imply that.
Let me clarify, the harmonics that are inherent in the "B" series engine were dealt with by Cummins in the following manner over the years after they had failuers of the components.
The older and lower HP engines used a casting of chilled iron. It was ok for the low power and lower loads of that era. After the power was increased the castings went to a chilled ductile iron for more strength and more wear durability. The lobes were also widened and the tappet faces were hardened by induction methods. Induction hardening is not a "completly through the metal process" The outer layer is the benefactor of the process only. Finally, the cam lobes were widened again when the ISB was introduced. This design still was adequate for the lower power engine and lower loads they encountered.
Of course the marine "B" series is rated at a higher HP output and is used for larger loads. Cummins decided to go with a camshaft that bolts the gear to the shaft and has made the casting a larger and stronger material yet again over the standard "B" engine. Further, the entire shaft is shot-peened to relieve stresses that can cause cracking from those dern harmonics again. The lobe seperation is a bit wider and the lobes are of course larger as well. This camshaft IMO makes the best factory part available to begin a regrind process for several reasons:
First, you need to grind a fair amount of material away on either camshaft to get the desired lift and duration you need. The larger lobe on the marine cam is a plus because the induction hardening wont be ground into as far as it would be on a standard "B" camshaft. Second, the gear that bolts on and uses the extra large keyway to hold it to the shaft is important IMO for guys who really want to crank the power up and the extra strength is only going to help everyone else as well. The added strength will help those who twist up their engines to 4200-4500rpm like I do from time to time as well.
Nitrous allows the engine to "twist up" much faster than normal and increases the inertial load faster. Of course the highest loads are compressive and this a good thing, but the size of the loads generated are proportional to the engine rpm squared. So if rpm is increased 3 fold the load increases 9 times. At 4000 rpm the loads are enormous and IMO way past a solid design limit for longevity/durability. When I have the tach at 4000rpm on my truck I would hate to have the cam snap off on the number 2 journal. The barrel springs we have (even the 60 lb'rs) are not my idea of a high performance spring either. Just because Isky designed them does not mean they are the best in our applications now. Did anyone ever weigh the collets and the retainers? They are plain heavy...way tooo heavy. Talk about inertia to overcome.
Actually, most of the harmonics is a direct result of the crankshaft transfering it through the drive gears. As the crankshaft rotates the resonance frequency of vibration is usually considered to be equal to two times the engine speed, with periodic excitation created by the compression and combustion events. Nitrous makes the frequency change even again with the acceleration being faster. Starting with the compression stroke, the crankshaft first slows as a result of the work required to compress the charge into a fixed volume at TDC. As the fuel/air charge ignites and the flame expands against the piston, the crankshaft is loaded down toward the main bearings and deflects toward the oil pan. During the exhaust or pumping loop, the inertia of the reciprocating mass of the connecting rod and piston wants to pull the crankshaft up toward the deck of the block. The intake stroke now creates a rapid change in direction that at first brings the crankshaft to its natural position, but then experiences inertial bending as the piston stops and dwells at BDC.
Even the most effective damper still allows a large majority of the crankshaft's harmonics to be transferred to the camshaft and in turn the valvetrain. Eventually this leads to premature component wear, a variation in valve events and broken camshafts in high rpm and high load conditions. Most gassers use a chain and much of the harmonics is absorbed up to certain rpm ranges. We have the solid drive gears that the higher rpm gassers got rid of years ago. There are not many cost effective alternatives to the gears at this time. The best thing is a strong cam and applying good valvetrain technology to dampen harmonics.
Don~
Let me clarify, the harmonics that are inherent in the "B" series engine were dealt with by Cummins in the following manner over the years after they had failuers of the components.
The older and lower HP engines used a casting of chilled iron. It was ok for the low power and lower loads of that era. After the power was increased the castings went to a chilled ductile iron for more strength and more wear durability. The lobes were also widened and the tappet faces were hardened by induction methods. Induction hardening is not a "completly through the metal process" The outer layer is the benefactor of the process only. Finally, the cam lobes were widened again when the ISB was introduced. This design still was adequate for the lower power engine and lower loads they encountered.
Of course the marine "B" series is rated at a higher HP output and is used for larger loads. Cummins decided to go with a camshaft that bolts the gear to the shaft and has made the casting a larger and stronger material yet again over the standard "B" engine. Further, the entire shaft is shot-peened to relieve stresses that can cause cracking from those dern harmonics again. The lobe seperation is a bit wider and the lobes are of course larger as well. This camshaft IMO makes the best factory part available to begin a regrind process for several reasons:
First, you need to grind a fair amount of material away on either camshaft to get the desired lift and duration you need. The larger lobe on the marine cam is a plus because the induction hardening wont be ground into as far as it would be on a standard "B" camshaft. Second, the gear that bolts on and uses the extra large keyway to hold it to the shaft is important IMO for guys who really want to crank the power up and the extra strength is only going to help everyone else as well. The added strength will help those who twist up their engines to 4200-4500rpm like I do from time to time as well.
Nitrous allows the engine to "twist up" much faster than normal and increases the inertial load faster. Of course the highest loads are compressive and this a good thing, but the size of the loads generated are proportional to the engine rpm squared. So if rpm is increased 3 fold the load increases 9 times. At 4000 rpm the loads are enormous and IMO way past a solid design limit for longevity/durability. When I have the tach at 4000rpm on my truck I would hate to have the cam snap off on the number 2 journal. The barrel springs we have (even the 60 lb'rs) are not my idea of a high performance spring either. Just because Isky designed them does not mean they are the best in our applications now. Did anyone ever weigh the collets and the retainers? They are plain heavy...way tooo heavy. Talk about inertia to overcome.
Actually, most of the harmonics is a direct result of the crankshaft transfering it through the drive gears. As the crankshaft rotates the resonance frequency of vibration is usually considered to be equal to two times the engine speed, with periodic excitation created by the compression and combustion events. Nitrous makes the frequency change even again with the acceleration being faster. Starting with the compression stroke, the crankshaft first slows as a result of the work required to compress the charge into a fixed volume at TDC. As the fuel/air charge ignites and the flame expands against the piston, the crankshaft is loaded down toward the main bearings and deflects toward the oil pan. During the exhaust or pumping loop, the inertia of the reciprocating mass of the connecting rod and piston wants to pull the crankshaft up toward the deck of the block. The intake stroke now creates a rapid change in direction that at first brings the crankshaft to its natural position, but then experiences inertial bending as the piston stops and dwells at BDC.
Even the most effective damper still allows a large majority of the crankshaft's harmonics to be transferred to the camshaft and in turn the valvetrain. Eventually this leads to premature component wear, a variation in valve events and broken camshafts in high rpm and high load conditions. Most gassers use a chain and much of the harmonics is absorbed up to certain rpm ranges. We have the solid drive gears that the higher rpm gassers got rid of years ago. There are not many cost effective alternatives to the gears at this time. The best thing is a strong cam and applying good valvetrain technology to dampen harmonics.
Don~
10-07-2002, 07:01 PM
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Re:Piers Cam Update
You know, there are speed shops that sell bolt on parts, then there are engine builders and tuners. I think we are already starting to see this in the diesel industry! Hurry up and build us an aluminum block Don!
10-07-2002, 07:08 PM
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Re:Piers Cam Update
[quote author=DieselSport Promotions link=board=7;threadid=5607;start=0#49587 date=1034035315]
Hurry up and build us an aluminum block Don!
[/quote]
Would you like a nice cast iron head to go with that.
Kind of a Dura-whatever in reverse. ;D
Good to see 'ya out on Staurday, we coulda used one more truck in the OHMYGAWD class.
Hurry up and build us an aluminum block Don!
[/quote]
Would you like a nice cast iron head to go with that.
Kind of a Dura-whatever in reverse. ;D
Good to see 'ya out on Staurday, we coulda used one more truck in the OHMYGAWD class.
10-07-2002, 07:09 PM
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Re:Piers Cam Update
Yes , yes...I would love that Man. Billet block, heads, crank, etc.... ;D I actually spoke with a guy over the last few weeks about having some billet cylinder heads made. Too bad the market is not there for them. Yet! <br><br>I have a cam guy that can now make us up some billet camshafts too. Not a bad price either. Less than 1700 dollars and the thing is frickin bullet proof. All kinds of grinds too, even roller for the higher rpm guys like us 12 valvers.<br><br>Don~<br><br>
10-07-2002, 10:42 PM
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Re:Piers Cam Update
So we have gear drive, solid roller, cams? How nice. Got a buddy with a 73 Camaro with a 409 solid roller and gear drive. Talk about responsive. Guess our trucks really are built to withstand a lot. Fully forged (or super strong) rotating assembly, shot-peened cams, gear drive. I love our engines. Now, if only I could find some cam specs.
10-11-2002, 05:58 PM
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Re:Piers Cam Update
[quote author=Don M link=board=7;threadid=5607;start=0#49396 date=1033996322]<br> <br>I have heard of breakage problems from truck pullers. <br><br>Don~<br><br><br> <br>[/quote]<br><br><br>Really?<br>What truck pullers are those? Dodge Cummins? ???<br><br>I like to know details on carnage, in hopes I can avoid the same.