B16A Camshaft Question
10-26-2003, 10:38 PM
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B16A OE Camshaft Lobe Question
When I was doing a valve adjustment on my SiRII engine, I noticed that one camshaft lobe is always wider than the other for the companion valve on the same cylinder. Why is this? One is narrow and one is fat, but the rocker arm's surfaces where the lobes ride are the same width. What's up with that?
-zelifcam
-zelifcam
10-27-2003, 03:11 PM
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Re: B16A OE Camshaft Lobe Question (zelifcam)
Assuming you are referring to the primary cam lobes. The VTEC lobe is the biggest one.
As for the primaries, there is one primary cam lobe that is smaller than the other primary cam lobe.
Why?
It's for low and smooth idling purposes. As for aftermarket cams, that is a different story.
As for the primaries, there is one primary cam lobe that is smaller than the other primary cam lobe.
Why?
It's for low and smooth idling purposes. As for aftermarket cams, that is a different story.
10-27-2003, 03:47 PM
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Re: B16A OE Camshaft Lobe Question (poison)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by poison »</TD></TR><TR><TD CLASS="quote">Assuming you are referring to the primary cam lobes. The VTEC lobe is the biggest one.
As for the primaries, there is one primary cam lobe that is smaller than the other primary cam lobe.
Why?
It's for low and smooth idling purposes. As for aftermarket cams, that is a different story.</TD></TR></TABLE>
I know that the two lobes (intake side) have different lifts, this is to create a mixture swirl in the cylinder during intake. I am talking about, if you look at the cam shaft, one lobe is physically WIDER than the other. One is skinny and one is fat. I'm not talking about lift or duration. Any ideas?
As for the primaries, there is one primary cam lobe that is smaller than the other primary cam lobe.
Why?
It's for low and smooth idling purposes. As for aftermarket cams, that is a different story.</TD></TR></TABLE>
I know that the two lobes (intake side) have different lifts, this is to create a mixture swirl in the cylinder during intake. I am talking about, if you look at the cam shaft, one lobe is physically WIDER than the other. One is skinny and one is fat. I'm not talking about lift or duration. Any ideas?
10-28-2003, 12:45 PM
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Re: B16A OE Camshaft Lobe Question (advanracing62)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by advanracing62 »</TD></TR><TR><TD CLASS="quote">who F'in cares? this is a pointless ? to ask..
IBTL</TD></TR></TABLE>
Why is it pointless? I'm only asking this because if I figure this out, then maybe it will somehow be related to why one of your mom's ******* is more bouncy than the other.
IBTL</TD></TR></TABLE>
Why is it pointless? I'm only asking this because if I figure this out, then maybe it will somehow be related to why one of your mom's ******* is more bouncy than the other.
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10-29-2003, 02:19 PM
#12
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Re: B16A OE Camshaft Lobe Question (zelifcam)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by zelifcam »</TD></TR><TR><TD CLASS="quote">When I was doing a valve adjustment on my SiRII engine, I noticed that one camshaft lobe is always wider than the other for the companion valve on the same cylinder. Why is this? One is narrow and one is fat, but the rocker arm's surfaces where the lobes ride are the same width. What's up with that?
-zelifcam</TD></TR></TABLE>
This is actually a really good question.
Obviously, the primary & secondary lobes work together before vtec, then when vtec kicks on a pin locks-in the middle rocker pad allowing the MID lobe (or vtec lobe) to take over. While looking at the skunk2 camshaft image, you can see how the intake & exhaust cams have offset lobes, flipped 180 for each cam. I have a feeling they're designed opposite like that, along with being wider/thinner for some lobes, because the cams should sit one way in the head...so you can't accidently put an exhaust cam on the intake side of the head. But I really think there's more dynamics to it than just that...
Looking at the cam lobes in the skunk2 image more, it looks like the PRI + SEC lobes, combined would match the width of the MID/VTEC lobe. Leads me to think that the thinner PRI & semi-thicker SEC lobes are designed like that for strengthening purposes (low rpm range), while the MID lobe is purely bigger for strength while in high rpms. Makes me wonder why Honda even split up the PRI + SEC lobes (if thats the case), but i'm guessing it has to do with fitment of making eveyrthing work within the size of the vtec head.
...just my edumacated guess
[edit]
after looking more at the skunk cams even more and pondering, the PRI + SEC lobes are obviously switched on either cam, so I'm guessing at TDC before VTEC during a stoke, only 1 valve per intake & exhaust side, per cylinder opens up, almose like a criss-cross pattern which (I think) contributes to more of a swirling effect when air & gas enter the cylinder on top of making the motor run more effeciently; but when in VTEC, both valves per side of the head would open up normally on the stroke. Why would you need both valves opening at lower rpms when it doesn't quite need that...right? Its more effecient to have both valves open later on rather than early in the powerband. I'm beginning to see the light....
thanks for making me think
, interesting **** no doubt
Modified by Katman at 3:39 PM 10/29/2003
Modified by Katman at 3:39 PM 10/29/2003
-zelifcam</TD></TR></TABLE>
This is actually a really good question.
Obviously, the primary & secondary lobes work together before vtec, then when vtec kicks on a pin locks-in the middle rocker pad allowing the MID lobe (or vtec lobe) to take over. While looking at the skunk2 camshaft image, you can see how the intake & exhaust cams have offset lobes, flipped 180 for each cam. I have a feeling they're designed opposite like that, along with being wider/thinner for some lobes, because the cams should sit one way in the head...so you can't accidently put an exhaust cam on the intake side of the head. But I really think there's more dynamics to it than just that...
Looking at the cam lobes in the skunk2 image more, it looks like the PRI + SEC lobes, combined would match the width of the MID/VTEC lobe. Leads me to think that the thinner PRI & semi-thicker SEC lobes are designed like that for strengthening purposes (low rpm range), while the MID lobe is purely bigger for strength while in high rpms. Makes me wonder why Honda even split up the PRI + SEC lobes (if thats the case), but i'm guessing it has to do with fitment of making eveyrthing work within the size of the vtec head.
...just my edumacated guess
[edit]
after looking more at the skunk cams even more and pondering, the PRI + SEC lobes are obviously switched on either cam, so I'm guessing at TDC before VTEC during a stoke, only 1 valve per intake & exhaust side, per cylinder opens up, almose like a criss-cross pattern which (I think) contributes to more of a swirling effect when air & gas enter the cylinder on top of making the motor run more effeciently; but when in VTEC, both valves per side of the head would open up normally on the stroke. Why would you need both valves opening at lower rpms when it doesn't quite need that...right? Its more effecient to have both valves open later on rather than early in the powerband. I'm beginning to see the light....
thanks for making me think
, interesting **** no doubt Modified by Katman at 3:39 PM 10/29/2003
Modified by Katman at 3:39 PM 10/29/2003
10-29-2003, 04:48 PM
#13
Honda-Tech Member
maybe the thinner one is just to balance the offset of hte other side. what i mean is since there are 2 valves being controlled and with the vtec lobe on there maybe they just decided that it would be stronger to have some support on the other side. damnit idk and i have more important questions that i need answered.
10-29-2003, 08:35 PM
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Re: B16A OE Camshaft Lobe Question (Katman)
Ah, finally someone willing to think about this with me!
w00t!
That wouldn't stop you from putting the cams in wrong. You would know if you reversed them because the intake cam has the slot for the distributor on the end of it. (Actually, in the Skunk2 photo, the INTAKE camshaft is in the FRONT, see the distributor keyway?)
I buy the thickness of the VTEC lobe for strength (it has twice as many valve springs to compress as a normal cam lobe would, but can't see why a thin non-vtec lobe would provide any strength.
The two valves (on intake) for one cylinder actually have different lifts and possibly durations (I have measured this with a micrometer) this is, as you theorized, to provide a swirl-effect in the chamber to better atomize fuel to keep it in suspension during intake and compression. I don't think the exhaust valves have different lift, but I haven't checked it. I can't see why they would.
Both valves always open, but to different extents.
I kinda lost you here. Both valves always open. At 4,000RPM, you better believe it needs both the valves to be operating. By the way, the rocker arm surfaces that the non-vtec cam lobes ride on are all the same size! The thin lobe does not ride on a thin rocker arm "pad". Perplexing!
Thanks for your reply. Please share any more thoughts you may have on this subject!
-zelifcam
Originally Posted by Katman
This is actually a really good question.
Originally Posted by Katman
Obviously, the primary & secondary lobes work together before vtec, then when vtec kicks on a pin locks-in the middle rocker pad allowing the MID lobe (or vtec lobe) to take over. While looking at the skunk2 camshaft image, you can see how the intake & exhaust cams have offset lobes, flipped 180 for each cam. I have a feeling they're designed opposite like that, along with being wider/thinner for some lobes, because the cams should sit one way in the head...so you can't accidently put an exhaust cam on the intake side of the head.
Originally Posted by Katman
Looking at the cam lobes in the skunk2 image more, it looks like the PRI + SEC lobes, combined would match the width of the MID/VTEC lobe. Leads me to think that the thinner PRI & semi-thicker SEC lobes are designed like that for strengthening purposes (low rpm range), while the MID lobe is purely bigger for strength while in high rpms.
Originally Posted by Katman
Makes me wonder why Honda even split up the PRI + SEC lobes (if thats the case), but i'm
guessing it has to do with fitment of making eveyrthing work within the size of the vtec head.
guessing it has to do with fitment of making eveyrthing work within the size of the vtec head.
Originally Posted by Katman
[edit]
after looking more at the skunk cams even more and pondering, the PRI + SEC lobes are obviously switched on either cam, so I'm guessing at TDC before VTEC during a stoke, only 1 valve per intake & exhaust side, per cylinder opens up, almose like a criss-cross pattern which (I think) contributes to more of a swirling effect when air & gas enter the cylinder on top of making the motor run more effeciently;
after looking more at the skunk cams even more and pondering, the PRI + SEC lobes are obviously switched on either cam, so I'm guessing at TDC before VTEC during a stoke, only 1 valve per intake & exhaust side, per cylinder opens up, almose like a criss-cross pattern which (I think) contributes to more of a swirling effect when air & gas enter the cylinder on top of making the motor run more effeciently;
Originally Posted by Katman
but when in VTEC, both valves per side of the head would open up normally on the stroke. Why would you need both valves opening at lower rpms when it doesn't quite need that...right? Its more effecient to have both valves open later on rather than early in the powerband. I'm beginning to see the light....
Originally Posted by Katman
thanks for making me think , interesting **** no doubt
, interesting **** no doubt Thanks for your reply. Please share any more thoughts you may have on this subject!-zelifcam
10-30-2003, 12:38 AM
#15
Solbros Owns Me
Re: B16A OE Camshaft Lobe Question (zelifcam)
I don't think there is enough room to have both small lobes be the same size.
That's the only thing I could figure.
So instead of having both be small and having a big gap between vtec lobe and small lobes, they just made one of the lobes small
That's the only thing I could figure.
So instead of having both be small and having a big gap between vtec lobe and small lobes, they just made one of the lobes small
10-30-2003, 09:43 AM
#16
Honda-Tech Member
Re: B16A OE Camshaft Lobe Question (zelifcam)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by zelifcam »</TD></TR><TR><TD CLASS="quote">
That wouldn't stop you from putting the cams in wrong. You would know if you reversed them because the intake cam has the slot for the distributor on the end of it. (Actually, in the Skunk2 photo, the INTAKE camshaft is in the FRONT, see the distributor keyway?)
-- Yep, I know about the distr. key slot on the intake cam and how that skunk2 image has the int. cam in the front of the exh. cam...dunno why they placed them like that for the picture *scratches head*. But other than that, you can place the exhaust cam on the intake side of the head and int.cam on the exh. side of the head, but you won't actually be able to bolt down the cam journals if you do misplace the cams in the head. Have you ever personally installed b-series vtec cams?
I buy the thickness of the VTEC lobe for strength (it has twice as many valve springs to compress as a normal cam lobe would, but can't see why a thin non-vtec lobe would provide any strength.
-- same here. I'm really thinking its for fitment issues though, but who knows
The two valves (on intake) for one cylinder actually have different lifts and possibly durations (I have measured this with a micrometer) this is, as you theorized, to provide a swirl-effect in the chamber to better atomize fuel to keep it in suspension during intake and compression. I don't think the exhaust valves have different lift, but I haven't checked it. I can't see why they would.
Both valves always open, but to different extents.
I kinda lost you here. Both valves always open. At 4,000RPM, you better believe it needs both the valves to be operating. By the way, the rocker arm surfaces that the non-vtec cam lobes ride on are all the same size! The thin lobe does not ride on a thin rocker arm "pad". Perplexing!
-- makes sense to me. On the intake side for instance, looking at one cylinders valve operation before vtec kicks on, the smaller lobe (PRI) + medium lobe (SEC) would open the valves that they control to their most highest points, but the opening of each valve would be staggard because the PRI + SEC lobes are different in lobe height specs. So yeah, both valves would definitely be opening per cylinder (staggard though), not just one...I stand corrected.
Thanks for your reply. Please share any more thoughts you may have on this subject!
-zelifcam</TD></TR></TABLE>
That wouldn't stop you from putting the cams in wrong. You would know if you reversed them because the intake cam has the slot for the distributor on the end of it. (Actually, in the Skunk2 photo, the INTAKE camshaft is in the FRONT, see the distributor keyway?)
-- Yep, I know about the distr. key slot on the intake cam and how that skunk2 image has the int. cam in the front of the exh. cam...dunno why they placed them like that for the picture *scratches head*. But other than that, you can place the exhaust cam on the intake side of the head and int.cam on the exh. side of the head, but you won't actually be able to bolt down the cam journals if you do misplace the cams in the head. Have you ever personally installed b-series vtec cams?
I buy the thickness of the VTEC lobe for strength (it has twice as many valve springs to compress as a normal cam lobe would, but can't see why a thin non-vtec lobe would provide any strength.
-- same here. I'm really thinking its for fitment issues though, but who knows
The two valves (on intake) for one cylinder actually have different lifts and possibly durations (I have measured this with a micrometer) this is, as you theorized, to provide a swirl-effect in the chamber to better atomize fuel to keep it in suspension during intake and compression. I don't think the exhaust valves have different lift, but I haven't checked it. I can't see why they would.
Both valves always open, but to different extents.
I kinda lost you here. Both valves always open. At 4,000RPM, you better believe it needs both the valves to be operating. By the way, the rocker arm surfaces that the non-vtec cam lobes ride on are all the same size! The thin lobe does not ride on a thin rocker arm "pad". Perplexing!
-- makes sense to me. On the intake side for instance, looking at one cylinders valve operation before vtec kicks on, the smaller lobe (PRI) + medium lobe (SEC) would open the valves that they control to their most highest points, but the opening of each valve would be staggard because the PRI + SEC lobes are different in lobe height specs. So yeah, both valves would definitely be opening per cylinder (staggard though), not just one...I stand corrected.
Thanks for your reply. Please share any more thoughts you may have on this subject!-zelifcam</TD></TR></TABLE>
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