Comp XFI Lobes for Carbureted Application?

[mopowers]

Have any of you guys run Comp XFI hydraulic roller lobes in a carbureted application? I've read that they're designed for fuel injected applications, whatever that means.

Are these lobes relatively hard on valve train components in an application that's driven quite a bit?

 

[MidnightSwinger]

Have any of you guys run Comp XFI hydraulic roller lobes in a carbureted application? I've read that they're designed for fuel injected applications, whatever that means.

Are these lobes relatively hard on valve train components in an application that's driven quite a bit?

Usually an EFI cam just keeps the duration shorter than typical for a high performance cam. Helps keep all the sensors happy. In a carbureted application? More vacuum and smoother idle, but no ill effect imo. But I have no experience with the XFI cams personally.

 

[Bewy]

Go to the Comp Website & look at the lobe families for hyd roller. There are quite a few & good info on the lobes sduch ss:
- adv duration @ tappet lift
- lobe lift
- duration @ 050 & 200
- lift @ 106 & 110 centre lines.

Compare them all at the 050 duration you intend to use & compare the specs. I do not see why FI lobes would have to be different from lobes used on a carbed engine.

 

[360duster]

at the moment i run a cam with their QNX lobes, will upgrade to a custom hyd. roller with the QXI Lobes (these are a little more intense). So i also see no reason to not use these in a carbureted application.

from the comp catalog:

XTREME ENERGY XFI™ HYDRAULIC ROLLERS
The Xtreme Energy XFI™ series is designed for use with modern induction systems, heads, springs and rockers. The XFI™ intake lobes have more lift than the
base Xtreme series, and the XFI™ exhaust lobes have more area under the curve, for better exhaust flow, than the base exhaust series. These are the first hydraulic
roller profiles designed for use with COMP Cams® Beehive™ Valve Springs such as the #26915, #26918 & #26120. The combination of these profiles,
the springs and our very stiff Ultra Pro Magnum™ Rocker Arms in higher ratios, makes for the most revolutionary improvement in hydraulic roller design to date
by bringing the latest race winning technology to the street.
CAMSHAFT TYPE LOBE # RATED
DURATION

 

[mopowers]

at the moment i run a cam with their QNX lobes, will upgrade to a custom hyd. roller with the QXI Lobes (these are a little more intense). So i also see no reason to not use these in a carbureted application.

from the comp catalog:

XTREME ENERGY XFI™ HYDRAULIC ROLLERS
The Xtreme Energy XFI™ series is designed for use with modern induction systems, heads, springs and rockers. The XFI™ intake lobes have more lift than the
base Xtreme series, and the XFI™ exhaust lobes have more area under the curve, for better exhaust flow, than the base exhaust series. These are the first hydraulic
roller profiles designed for use with COMP Cams® Beehive™ Valve Springs such as the #26915, #26918 & #26120. The combination of these profiles,
the springs and our very stiff Ultra Pro Magnum™ Rocker Arms in higher ratios, makes for the most revolutionary improvement in hydraulic roller design to date
by bringing the latest race winning technology to the street.
CAMSHAFT TYPE LOBE # RATED
DURATION

Thanks. I was was comparing lobes from their catalog last night and was looking at the XFI lobes specifically. It looks like from what I can see the Comp shelf retrofit roller grinds are marketed as Xtreme Energy, even though the specs line up with the XFI lobes.

The XFI lobes specifically seem like they have pretty aggressive ramps whereas the Xtreme Energy lobes are a little softer. I wonder if the XFI lobes beat up springs and seats causing longevity issues in an application that's driven regularly, or how noisy they are, given the lobe design.

 

[360duster]

my personal experience: i ran the qnx lobes with the stock magnum hyd. roller lifters without any trouble. No significant noise, but the car is not a quiet cruiser also.....the xfi lobes are a little bit more intense than the qnx, but with less lift. I´d think since everything is cushioned by the hydraulic lifter these should run pretty smooth, too. And since there is no need for extreme spring pressures i see no problem for the valvetrain parts. Of course expect not sth. like a stock motor.

Michael

 

[TT5.9mag]

Have any of you guys run Comp XFI hydraulic roller lobes in a carbureted application? I've read that they're designed for fuel injected applications, whatever that means.

Are these lobes relatively hard on valve train components in an application that's driven quite a bit?

I’m curious why you’re doing a deep dive into lobe profiles. Just an interesting topic for you or are you searching for some lost HP? Are you unhappy with a current cam?

 

[mopowers]

I’m curious why you’re doing a deep dive into lobe profiles. Just an interesting topic for you or are you searching for some lost HP? Are you unhappy with a current cam?

I was talking with Mike (I think it was) at 440source planning out my BB build and started talking cams with him. Super nice guy by the way, and very knowledgeable. Turns out, a while back I had ordered a custom Comp cam with XFI lobe profiles for a 408 build (still waiting on that one), and based on what Mike was saying I'm second guessing that choice.

I'm just wondering if folks have any direct experience with the XFI lobe profile series and if it was hard on springs and valve seats. I can't imagine it'd be any worse than a solid street roller. But I honestly have no clue. I'm thinking the BluePrint 408s may use those profiles.

 

[mopowers]

my personal experience: i ran the qnx lobes with the stock magnum hyd. roller lifters without any trouble. No significant noise, but the car is not a quiet cruiser also.....the xfi lobes are a little bit more intense than the qnx, but with less lift. I´d think since everything is cushioned by the hydraulic lifter these should run pretty smooth, too. And since there is no need for extreme spring pressures i see no problem for the valvetrain parts. Of course expect not sth. like a stock motor.

Michael

Thank you. Those QNX profiles look like they have quite a bit of lift for the given duration. I'm curious - was your cam with QNX lobes on a SADI core, or billet?

 

[middleagecrisis]

Thanks. I was was comparing lobes from their catalog last night and was looking at the XFI lobes specifically. It looks like from what I can see the Comp shelf retrofit roller grinds are marketed as Xtreme Energy, even though the specs line up with the XFI lobes.

The XFI lobes specifically seem like they have pretty aggressive ramps whereas the Xtreme Energy lobes are a little softer. I wonder if the XFI lobes beat up springs and seats causing longevity issues in an application that's driven regularly, or how noisy they are, given the lobe design.

The Comp Cam description above makes it sound like an aggressive profile with fast ramp rates. beehive springs and very stiff heavy duty (or whatever) pro-magnum rockers caught my eye. FI cams always have higher LSAs (e.g. 114) to mimize overlap. I’d like to see the same specs, but with 106-110 LSA on a carbuerated engine.

 

[360duster]

Thank you. Those QNX profiles look like they have quite a bit of lift for the given duration. I'm curious - was your cam with QNX lobes on a SADI core, or billet?

with cams i´m pretty much the guinea pig where i am (Germany), so i´m kinda careful with my decisions - slowly working towards my goals. I had two custom cams with these QNX lobes, one was a SADI core, the next one was a standard cast core (this one is currently installed). The newest version (not installed yet, engine is getting a CR upgrade before) is also a standard cast core comp #20-000-9, but with the QXI Lobes and more duration / less LSA.

 

[mopowers]

with cams i´m pretty much the guinea pig where i am (Germany), so i´m kinda careful with my decisions - slowly working towards my goals. I had two custom cams with these QNX lobes, one was a SADI core, the next one was a standard cast core (this one is currently installed). The newest version (not installed yet, engine is getting a CR upgrade before) is also a standard cast core comp #20-000-9, but with the QXI Lobes and more duration / less LSA.

I didn't realize you were in Germany. That's pretty neat. I'm getting parts is probably a total pain in the ***.

I believe the SADI cores are still technically cast iron, aren't they? Do they even have another type of cast cores they use?

 

[360duster]

think so, afaik it´s the heat treatment that makes the difference. Ironically i got these cams with different cores, but the part no. is the same 20-000-9. Comp does not list different cores for SBM, so i have no clue how to get the SADI Core when custom ordering.

 

[mopowers]

think so, afaik it´s the heat treatment that makes the difference. Ironically i got these cams with different cores, but the part no. is the same 20-000-9. Comp does not list different cores for SBM, so i have no clue how to get the SADI Core when custom ordering.

From what they told me, 20-000-9 is just the pricing code they use, not necessarily the core part number. They do have a code for a billet piece too - 20-000-11 if I recall.

Now you got me curious - if they do have distinct cores that are SADI and standard cast, would you be able to tell the difference by appearance? From what they told me, their shelf grinds (e.g., 20-812-9, etc.) are SADI, which has me questioning why they'd make a roller cam on a standard cast core.

 

[Newbomb Turk]

From what they told me, 20-000-9 is just the pricing code they use, not necessarily the core part number. They do have a code for a billet piece too - 20-000-11 if I recall.

Now you got me curious - if they do have distinct cores that are SADI and standard cast, would you be able to tell the difference by appearance? From what they told me, their shelf grinds (e.g., 20-812-9, etc.) are SADI, which has me questioning why they'd make a roller cam on a standard cast core.

A SADI core is usually 8620 bar stock with a pressed on cast iron distributor gear.

If I was doing a roller for the street and I could get a SADI core that’s what I’d be doing.

BTW, every SADI core I used cam from Cam Motion. Do other companies May use a different steel for the cam core or different heat treating so the appearance may be different.

Of course, there are just a couple of cam core manufacturers out there so options may be limited.

 

[mopowers]

A SADI core is usually 8620 bar stock with a pressed on cast iron distributor gear.

If I was doing a roller for the street and I could get a SADI core that’s what I’d be doing.

BTW, every SADI core I used cam from Cam Motion. Do other companies May use a different steel for the cam core or different heat treating so the appearance may be different.

Of course, there are just a couple of cam core manufacturers out there so options may be limited.

Thank you.

Do you have any experience with comps XFI lobe profiles? I'm curious what your thoughts are on those in an application that sees a bunch of miles.

 

[Newbomb Turk]

Thank you.

Do you have any experience with comps XFI lobe profiles? I'm curious what your thoughts are on those in an application that sees a bunch of miles.

I do not but I’d love to try them.

 

[360duster]

From what they told me, 20-000-9 is just the pricing code they use, not necessarily the core part number. They do have a code for a billet piece too - 20-000-11 if I recall.

Now you got me curious - if they do have distinct cores that are SADI and standard cast, would you be able to tell the difference by appearance? From what they told me, their shelf grinds (e.g., 20-812-9, etc.) are SADI, which has me questioning why they'd make a roller cam on a standard cast core.

yes, the SADI core was machined everywhere where as the cast one has got rough surfaces between the lobes. And the SADI core had copper paint surfaces between the lobes - don´t know if it´s just paint or sth. else.

 

[Newbomb Turk]

yes, the SADI core was machined everywhere where as the cast one has got rough surfaces between the lobes. And the SADI core had copper paint surfaces between the lobes - don´t know if it´s just paint or sth. else.

That’s the heat treating. Do you have a picture of that cam core?

 

[mopowers]

yes, the SADI core was machined everywhere where as the cast one has got rough surfaces between the lobes. And the SADI core had copper paint surfaces between the lobes - don´t know if it´s just paint or sth. else.

Thanks, that's interesting. Yeah, I'd like to see a picture if you've got one. I was told by the guy at Comp (whatever that's worth) that their iron roller shelf grinds are all SADI. Like this one I had acquired and sold earlier this year. Sounds like it isn't?

 

[Newbomb Turk]

Thanks, that's interesting. Yeah, I'd like to see a picture if you've got one. I was told by the guy at Comp (whatever that's worth) that their iron roller shelf grinds are all SADI. Like this one I had acquired and sold earlier this year. Sounds like it isn't?

View attachment 1716489054

View attachment 1716489055

That called that a SADI core? It’s 100% cast iron. I do not run cast iron cores with roller lifters. I’ve been burned by it twice.

 

[mopowers]

That called that a SADI core? It’s 100% cast iron. I do not run cast iron cores with roller lifters. I’ve been burned by it twice.

Thanks. That's what I thought, which is why I was confused. Lots of misinformation being thrown around out there. But technically, isn't a SADI cam still a cast iron (cast ductile iron) that's just been heat treated?

Do you have a picture of an austempured ductile iron cam for comparison purposes?

 

[Newbomb Turk]

Thanks. That's what I thought, which is why I was confused. Lots of misinformation being thrown around out there. But technically, isn't a SADI cam still a cast iron (cast ductile iron) that's just been heat treated?

Do you have a picture of an austempured ductile iron cam for comparison purposes?

Ok, I stand corrected. What used to be called a SADI core has changed. When I bought my first SADI core it was a steel cam with a pressed on iron gear.

Evidently that was too expensive or guys couldn’t figure out what cam gear to use so they are now calling a heat treated iron core as a SADI core.

I won’t run any iron core cam regardless of heat treating with a roller lifter.

Being retired makes it hard to keep up with running changes.

 

[mopowers]

Ok, I stand corrected. What used to be called a SADI core has changed. When I bought my first SADI core it was a steel cam with a pressed on iron gear.

Evidently that was too expensive or guys couldn’t figure out what cam gear to use so they are now calling a heat treated iron core as a SADI core.

I won’t run any iron core cam regardless of heat treating with a roller lifter.

Being retired makes it hard to keep up with running changes.

Thanks for clarifying.

 

[PRH]

SADI = Selectively Austempered Ductile Iron