maxspool cams
09-10-2007, 08:18 AM
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Greg Hogue and as far as which one is a better cam that's hard to determine, as one cam in two different trucks might have alot different results. Maxspool is a core regrind cam. And Helix's are ground from a UGL Blanks
09-10-2007, 10:07 PM
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That would depend on the heat treatment and such that's applied to the cam.
The typical concern with a regrind is that you grind through the surface hardening on most cams, and the lobes are softer than they should be, which can be catastrophic.
Anyone remember the infamous GM "soft cam"' problems of the 80s?
Another concern with a regrind is not so much the metallurgy as it is just general strength. To regrind a cam with more duration and/or lift, you MUST decrease the size of the "base circle", or the diameter of the imaginary circle that is the part where the tappet is just "along for the ride"- in other words, no valve lift.
Smaller base circle has a couple big negatives. The first is strength-- not so much breaking strength, but flexing strength. A camshaft that isn't stiff will lose a lot of valve motion and hence HP. Another big negative is rate-of-lift: that larger base circle of the camshaft, the faster the valves can be opened or closed, allowing either more lift for a given duration, or less duration (i.e. more tq) for a given amount of lift.
That's why you see so many race engines have the cam journals bored out and larger 50mm roller cam bearings are installed. The larger cam diameter lets you use much more aggressive cams and still have the reliability and durability you want. This is really common in race classes that require a flat tappet cam (i.e. no roller cams).
Justin
The typical concern with a regrind is that you grind through the surface hardening on most cams, and the lobes are softer than they should be, which can be catastrophic.
Anyone remember the infamous GM "soft cam"' problems of the 80s?
Another concern with a regrind is not so much the metallurgy as it is just general strength. To regrind a cam with more duration and/or lift, you MUST decrease the size of the "base circle", or the diameter of the imaginary circle that is the part where the tappet is just "along for the ride"- in other words, no valve lift.
Smaller base circle has a couple big negatives. The first is strength-- not so much breaking strength, but flexing strength. A camshaft that isn't stiff will lose a lot of valve motion and hence HP. Another big negative is rate-of-lift: that larger base circle of the camshaft, the faster the valves can be opened or closed, allowing either more lift for a given duration, or less duration (i.e. more tq) for a given amount of lift.
That's why you see so many race engines have the cam journals bored out and larger 50mm roller cam bearings are installed. The larger cam diameter lets you use much more aggressive cams and still have the reliability and durability you want. This is really common in race classes that require a flat tappet cam (i.e. no roller cams).
Justin
09-10-2007, 10:16 PM
#5
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Here's a link to a 500+ post bantering back and forth about the two
http://www.competitiondiesel.com/for...ad.php?t=12481
Best I can figure from what I have read.... anyone that has used either has been happy? I like my Helix II but I'm pretty confident I would be just as happy with one of the Maxspool cams.
http://www.competitiondiesel.com/for...ad.php?t=12481
Best I can figure from what I have read.... anyone that has used either has been happy? I like my Helix II but I'm pretty confident I would be just as happy with one of the Maxspool cams.
09-11-2007, 12:47 AM
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Justin, see if this means anything to you, straight from a Banks man:
Originally Posted by Greg
The MaxSpool II cam is 174 in 207 exh @ .050 14 degrees bigger then stock , but this same cam is 3 degrees shorter then stock at .006 or seat timing and at .200 lift is 31 degrees larger then stock . .200 lift is the point that air flow really starts to move, this profile is quick in its acceleration of the valve train , and doesn’t bleed off precious cylinder pressure
09-11-2007, 04:23 AM
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Sounds good to me. Basically he's saying the cam accelerates the valves at a much higher rate than stock.
The "seat timing" at .006" inches basically how many degrees of engine rotation (not cam rotation, remember cam turns half of crank speed) that the valve is lifted .006" off it's resting place (base circle).
The "duration at .050" is the same thing, just measured at .050" lift (usually measured at the valve, not at the cam, so account for any rocker ratio).
Likewise with duration at .200".
Think of it this way. If you could make a square cam lobe work, that would be ideal as the valve would instantly go from closed to open without wasting time in between. But we can't do this.
So if a cam has a "duration at .050" of 210º, it means that the crankshaft spins 210º of rotation when the valve passes the point of .050" lift on the way open and again on the way closed.
The "advertised duration" you'll typically see with a hydraulic cam is measured at .006" lift, and for mechanical cams at .020 (due to lash of the valves).
This Banks cam is a "dual pattern" cam, meaning the exhaust lobes and intake lobes are different. When this is the case, typically the exhaust duration is larger than the intake (look at any Crane Cams product and you'll see this with almost the entire line).
So the Banks cam is 174º duration on the intake (at .050" lift) and 207º on the exhaust.
This is more typically done on a naturally aspirated gasser, because the intake breathing relies so heavily on the vacuum created by the exhaust. Basically, the exhaust "sucks" on the intake and that's responsible for a large portion of the engine's breathing ability.
But we are dealing with a turbodiesel, and in my uneducation opinion, this changes everything. First, the turbocharger poses quite a restriction to the exhaust. The typical thought here is that the restrictive exhaust "needs more help" so the cam is slanted in that favor by giving it longer duration.
But a turbodiesel has much higher compression ratio. That means the expansion ratio is much higher. That means that there's much less cylinder pressure to bleed off so you don't need a very effective exhaust to get the job done.
So at first blush, I'd actually thing favoring the intake lobe would work better. But a TON of this depends on the turbo you are running-- just how restrictive it is.
What I'd really like to know more than duration specs are specs of overlap and Lobe Centerline Angle (aka Lobe sepration angle). A cam for these engines should have a little overlap to help get the charge going, but huge overlap won't help you "overlap breathing" only works when your exhaust has little to no backpressure--obviously not the case in a turbodiesel!
I'd like to know how Banks tested these cam profiles and with which tappets and turbos.
Even given these comments, I'd bet the Maxspool cam would be a pretty noticeable improvement over stock.
Finally, the comment that ".200 is where the airflow really starts to move" is ridiculous because who'd defining the meaning of "really starting to move?" .050" is where you'll typically see the first stages of airflow in the port, but the full port size won't be seen by the flow until the valve is open as far as 25% of the valve's diameter. Once the valve is open this far, you're "really getting things moving"in the sense that the PORT is actually contributing to the restriction the flow experiences, while at valve lifts lower than this, the primary restriction is the valve itself.
Remember a closed valve is a closed port, and a valve that's barely open is the same as having a port breathing through a soda straw.
I know a lot more about gasser cams than about diesel engines, so I could be drawing conclusions that are completely wrong. But general principles are valid-- higher compression needs less exhaust breathing, etc.
Justin
The "seat timing" at .006" inches basically how many degrees of engine rotation (not cam rotation, remember cam turns half of crank speed) that the valve is lifted .006" off it's resting place (base circle).
The "duration at .050" is the same thing, just measured at .050" lift (usually measured at the valve, not at the cam, so account for any rocker ratio).
Likewise with duration at .200".
Think of it this way. If you could make a square cam lobe work, that would be ideal as the valve would instantly go from closed to open without wasting time in between. But we can't do this.
So if a cam has a "duration at .050" of 210º, it means that the crankshaft spins 210º of rotation when the valve passes the point of .050" lift on the way open and again on the way closed.
The "advertised duration" you'll typically see with a hydraulic cam is measured at .006" lift, and for mechanical cams at .020 (due to lash of the valves).
This Banks cam is a "dual pattern" cam, meaning the exhaust lobes and intake lobes are different. When this is the case, typically the exhaust duration is larger than the intake (look at any Crane Cams product and you'll see this with almost the entire line).
So the Banks cam is 174º duration on the intake (at .050" lift) and 207º on the exhaust.
This is more typically done on a naturally aspirated gasser, because the intake breathing relies so heavily on the vacuum created by the exhaust. Basically, the exhaust "sucks" on the intake and that's responsible for a large portion of the engine's breathing ability.
But we are dealing with a turbodiesel, and in my uneducation opinion, this changes everything. First, the turbocharger poses quite a restriction to the exhaust. The typical thought here is that the restrictive exhaust "needs more help" so the cam is slanted in that favor by giving it longer duration.
But a turbodiesel has much higher compression ratio. That means the expansion ratio is much higher. That means that there's much less cylinder pressure to bleed off so you don't need a very effective exhaust to get the job done.
So at first blush, I'd actually thing favoring the intake lobe would work better. But a TON of this depends on the turbo you are running-- just how restrictive it is.
What I'd really like to know more than duration specs are specs of overlap and Lobe Centerline Angle (aka Lobe sepration angle). A cam for these engines should have a little overlap to help get the charge going, but huge overlap won't help you "overlap breathing" only works when your exhaust has little to no backpressure--obviously not the case in a turbodiesel!
I'd like to know how Banks tested these cam profiles and with which tappets and turbos.
Even given these comments, I'd bet the Maxspool cam would be a pretty noticeable improvement over stock.
Finally, the comment that ".200 is where the airflow really starts to move" is ridiculous because who'd defining the meaning of "really starting to move?" .050" is where you'll typically see the first stages of airflow in the port, but the full port size won't be seen by the flow until the valve is open as far as 25% of the valve's diameter. Once the valve is open this far, you're "really getting things moving"in the sense that the PORT is actually contributing to the restriction the flow experiences, while at valve lifts lower than this, the primary restriction is the valve itself.
Remember a closed valve is a closed port, and a valve that's barely open is the same as having a port breathing through a soda straw.
I know a lot more about gasser cams than about diesel engines, so I could be drawing conclusions that are completely wrong. But general principles are valid-- higher compression needs less exhaust breathing, etc.
Justin
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09-12-2007, 02:47 AM
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OK, I read a good chunk of that cam thread.
what a waste of my time.
And now I know that it's not Banks, but rather Greg Hogue, the (in)famous Comp461.
Greg's done some neat things, but if words were hp, he'd have been 2 seconds quicker in the 1/4! Still, he's a great guy, and I'd recommend that people look past all the talk to get to know him a bit.
That said, my shopping list for cams is shallow: Helix 2.
JMO
what a waste of my time.
And now I know that it's not Banks, but rather Greg Hogue, the (in)famous Comp461.
Greg's done some neat things, but if words were hp, he'd have been 2 seconds quicker in the 1/4! Still, he's a great guy, and I'd recommend that people look past all the talk to get to know him a bit.
That said, my shopping list for cams is shallow: Helix 2.
JMO
09-12-2007, 04:21 AM
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Just from reading numerous cam post here and there, mostly from the F1 side of the fence, because they were close to the only game (of which was only releasing any information to general readers) in town (PDR exempt). The difference between gas non-super charged cams and turbo charged diesel cams is night and day.
According to F1, the Helix optimize air in and exhaust out. Basically increasing lift, no overlap and adding duration. With very little timing change.
If you continue reading the Competition Diesel thread, some where in that mess F1 and MaxSpool agreed to due some dyno runs stock vs Helix vs MaxSpool and to publish the results. So far, no results.
From my opinion, there were close to equal supporters of both cams that posted up. Reading through the muck, I concluded that both cams are good products that the companies making them will stand behind their products.
The MaxSpool seemed more about custom grinds and specific applications while the Helix seemed more about one size fits all and general application.
Jim
According to F1, the Helix optimize air in and exhaust out. Basically increasing lift, no overlap and adding duration. With very little timing change.
If you continue reading the Competition Diesel thread, some where in that mess F1 and MaxSpool agreed to due some dyno runs stock vs Helix vs MaxSpool and to publish the results. So far, no results.
From my opinion, there were close to equal supporters of both cams that posted up. Reading through the muck, I concluded that both cams are good products that the companies making them will stand behind their products.
The MaxSpool seemed more about custom grinds and specific applications while the Helix seemed more about one size fits all and general application.
Jim
09-12-2007, 11:31 AM
#12
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Obviously, both cams perform well, but in relation to each other - I would choose the Helix for it's superior construction and lobe profiles, which IMO are designed specifically using the turbo-diesel school of thought.
Since the power stroke in a CTD is so long in terms of crankshaft degrees, I favor a cam profile with large LSAs, enough lift to register-mark the piston crowns minus "a little bit"
and all the duration ramp-wise that won't: 1. cause the tappets to defeat the lobes' oil film 2. create more reciprocal inertia than the valvesprings can reliably control.
My prototype:
LSA 114*
In .355"
Ex .355"
In 202*
Ex 213*
Ground from a new blank, requires F1 springs, MLS gasket and bottom-tapped studs. It should be installed straight up, and not crutch anything else.
Since the power stroke in a CTD is so long in terms of crankshaft degrees, I favor a cam profile with large LSAs, enough lift to register-mark the piston crowns minus "a little bit"
and all the duration ramp-wise that won't: 1. cause the tappets to defeat the lobes' oil film 2. create more reciprocal inertia than the valvesprings can reliably control. My prototype:
LSA 114*
In .355"
Ex .355"
In 202*
Ex 213*
Ground from a new blank, requires F1 springs, MLS gasket and bottom-tapped studs. It should be installed straight up, and not crutch anything else.
09-12-2007, 11:36 AM
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Obviously, both cams perform well, but in relation to each other - I would choose the Helix for it's superior construction and lobe profiles, which IMO are designed specifically using the turbo-diesel school of thought.
Since the power stroke in a CTD is so long in terms of crankshaft degrees, I favor a cam profile with large LSAs, enough lift to register-mark the piston crowns minus "a little bit" and all the duration ramp-wise that won't: 1. cause the tappets to defeat the lobes' oil film 2. create more reciprocal inertia than the valvesprings can reliably control.
My prototype:
LSA 114*
In .355"
Ex .355"
In 202*
Ex 213*
Ground from a new blank, requires F1 springs, MLS gasket and bottom-tapped studs. It should be installed straight up, and not crutch anything else.
Since the power stroke in a CTD is so long in terms of crankshaft degrees, I favor a cam profile with large LSAs, enough lift to register-mark the piston crowns minus "a little bit"
and all the duration ramp-wise that won't: 1. cause the tappets to defeat the lobes' oil film 2. create more reciprocal inertia than the valvesprings can reliably control. My prototype:
LSA 114*
In .355"
Ex .355"
In 202*
Ex 213*
Ground from a new blank, requires F1 springs, MLS gasket and bottom-tapped studs. It should be installed straight up, and not crutch anything else.
09-12-2007, 12:08 PM
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