B16b/B18c R cam which 1 better?

dcloo

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dcloo

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from what i gets thats was b18cr better then b16b
its cause of valve lifting more higher so engine can take more air compare to b16b type r

B16b will get a bit better respond on b4 vtech engage cause of torque lower then b18cr
just my 2 cents no heart feeling :regular_smile:

urs guys have any idea on it?

 

shiroitenshi

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shiroitenshi

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from what i gets thats was b18cr better then b16b
its cause of valve lifting more higher so engine can take more air compare to b16b type r

B16b will get a bit better respond on b4 vtech engage cause of torque lower then b18cr
just my 2 cents no heart feeling :regular_smile:

urs guys have any idea on it?

Not sure I agree, because the most B16Bs I know have not so good low end power with the stock ECU. It's where the vtec kicks in that there's a difference between the B16A and B16B.

B18CR and B16B lift numbers differ by few decimals of an mm only. The duration, I'm not sure, as the numbers listed are a bit on the low side on that pic you scanned. (the primary secondary and mid lobes numbers)

The duration numbers are more accurately reflected under the action angle numbers, which looks about right for true duration at 1mm lift.

Rather than looking at lift numbers, I noted another difference, which I think says a lot more about how 'better' each cams are. Which is the valve overlap. It does seem that Spoon has bigger valve overlap than B18C, which has bigger valve overlap than B16B. (see the centre angle on the sheet, also called lobe centers, minus duration for IN and EX, then add the two values, and there's your valve overlap duration.)

There could be more to that, but I don't have access to my formula that calculates timings of opening and closing of the valve so I can calculate exactly the overlap, so don't use that formula for practical applications yet. I think I might have missed something in the above formula to calculate valve overlap.

Edit... I did miss something.. haha.. thank god I write everything down, or I'd forget it in a second.
BRB with the update.. gonna check my notes.

I don't claim to be very knowledgable in this, but from what I've studied and experiment, valve overlap seems to be the key in getting more power out of high compression engines (stock honda's are considered high comp engines, due to their static 10.5 = B16A, 11.0 = B18C, B16B = ????, I think 11 also.)

Which is why that 1-2 degree retard or advance on your cam pulleys can make a big difference in where you make power and where you kill power.

And that's where that 1-2 degrees difference can make or kill power depending on cams you use.

This is what I've found out though, so if you have different results, maybe I should do a retest sometimes.

Oh, for something interesting, check out various cam manufacturers.. Although some of them have nearly same durations and lift, their cam spec sheet results in different valve overlap durations. Interesting why this is so, no?
 
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acuralover

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acuralover

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i read in those american forums that you will get the best out of those aftermarket cams like toda/jun/buddyclub if your compression is done higher..e.g a b20 with stock pistons with toda C cams might not bring out the potential in the cams with versus b20 forged pistons with higher compression ratio and using toda C cams....not sure if its true...maybe some experts can shed some light here...

i was infact advise to go for dc2 cams with my b20 stock block rather than a set of toda C...my mech was fair enuff to tell me to come back for toda or jun when im ready to lup forged pistons in my block...
 

moshpit21

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moshpit21

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just some thoughts from me,

if the b18cr cams are better, why would honda changed the b18cr cams spec of year 2000/2001 to the same profile as the b16b cams?

i have a very lil knowledge in this area... phew glad to finally post something here again in zth.

-peace-
 

shiroitenshi

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shiroitenshi

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Well, here are the numbers I got from your picture, but do note that I have different numbers on file for B16B.. about 2 degs less.

But I think there will always be slight disparity as .5 mm wear on cam followers/cam lobes = near 1mm of valve lift loss, so I can accept that as a reason why the durations and the numbers on that paper and mine are different. Anyway, I've never measured a new cam with new rocker arms, so maybe that's why I'm getting numbers that are less than what's usually printed.

Also it could be due to different years of cams, like moshpit noted, as my B16A intake cams are giving me 10.44 valve lift instead of 10.34 as noted in your picture. But it could be the cam dial as well, since it only measures up to 10mm of lift, so I had to get creative and extend it, so that might have given me some errors as well.

Thanks to Seong from Bukit Kemuning for teaching me how to lock the midlobe in position to do this.

The valve overlap are always larger for high comp engines, so that's probably why you're seeing high overlap numbers for B16B and C2 cams, so maybe B16B do have higher compression than a B18CR. If someone has measured them before (when stock) please let me know.

The intake closing timing affects your dynamic CR, which is why some setups seem to run fine on normal fuel even with high compression.

If you think this is confusing, yeah.. I am too.. hahaha... (O_o)
Well, this is my ongoing research, so my opinions will change as I find out more. Before plonking 3K-4K for valvetrain, I'm gonna make sure what I need. I think that since I'm aiming for a street setup, those Mat Salleh stage2s should be good enough I think. Thinking of BC cams, but well, until I finish this and do some more research and saving up money, it's still a long way off.

Edit: Oh, just noted, it's 'exhaust opens after TDC on combustion stroke.' not stated in the screencap I did. The exhaust valve actually opens while the piston is moving down on the combustion stroke.

BTW, the intake centerline numbers are the suggested setting from the manufacturers so that you have ample valve to valve clearance. So your mech usually tweaks them for power by using those cam pulleys, and that's how they can manipulate the overlap.

Which is also one reason (I think) why two cars with the same similar setup may not get the same numbers on the same dyno.
 
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dcloo

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dcloo

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toda power better hahah... until can blow every engine....
 

harpoon

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harpoon

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there's a good write-up on this overlap thingy, cam duration and also cam lift.
EK9.org: VTEC Camshafts Specs / Comparison for Honda B series Engines

this site talks bout the b-series specs, with overlap value but no valve centre no
Specs for B series Honda Engines

and lastly this site also bout the same info on cam, no overlap info but with degrees of cam open and close
B-Series Motor Specs

shiroitenshi, do update on us from all that i can get on the net.

from my observation, b16b have extra overlap on the intake due to earlier valve open angle before TDC.... does that play much part for its power?

besides, how if a person with b18cr to use b16b intake cam, will that make the b18cr generate more power??
 

shiroitenshi

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shiroitenshi

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there's a good write-up on this overlap thingy, cam duration and also cam lift.
EK9.org: VTEC Camshafts Specs / Comparison for Honda B series Engines

this site talks bout the b-series specs, with overlap value but no valve centre no
Specs for B series Honda Engines

and lastly this site also bout the same info on cam, no overlap info but with degrees of cam open and close
B-Series Motor Specs

shiroitenshi, do update on us from all that i can get on the net.

from my observation, b16b have extra overlap on the intake due to earlier valve open angle before TDC.... does that play much part for its power?

besides, how if a person with b18cr to use b16b intake cam, will that make the b18cr generate more power??
Hey, finally someone into the tech aspect as well.

I think if you read through all that, you have understand it roughly like me.
The thing about cams are that they can help control the static compression ratio.

Remember the intake valve closing at XX degrees ATDC?

Our static compression test gives us compression values that are larger, because they consider the intake and exhaust valves are closed during the compression stroke.

In real life, this is not the case, and as you notice, like 20 degrees ATDC the intake valve closes, your 11:1 compression has been reduced by 20degs/180deg = 11.1%, which means the 11comp - 11.1% = (11 - 1.221) = 9.779.

However, the actual volume of air going in the engine is dependent on the flow rate/speed which at the moment, is anyone's guess. Futhermore, as one of your link noted, the speed which the valves open (the lobe ramp angle) determines this also. So in other words, would 9.779 comp ratio cause knocking? it's probably dependent on engine speed, and of course the ignition timing I think, but well... that's anyone's guess, as most people don't keep track of why their engine makes power, or why it doesn't.

So if you ask whether plonking in B16B cams in a B18CR would give different performance, I think it may or may not, and there's no definite answer because you can play with the actual opening and closing timing (within tolerances, before vavle meets valve on overlap, which is why the cam spec specifices the lobe seperation angle or sometimes the mid lobe angle, at the point where there is maximum clearance).

You can tweak it a little by 2-4 degs, I think, depending on how aggressive the cams are.

A high ramp rate usually gives better performance for high comp engines, I'm sure you noticed it when you look at toda, spoon, etc, performance cams where the cam lobes are nowhere teardrop shaped like stock cams. It gives higher rocker arm wear (at the cam follower part), so that's why they don't make it too aggressive, just slightly more than stock, and which is also why they want valvesprings that are hard so that the valves won't float.

One set of cams I saw get around this by making the lift higher. like really high.. either 13.9 or 14mm of lift.

But still, much to learn about cams.

The summary of what I've learned so far comes to the following. (this is my opinion, they could be wrong, so consider that I'm just sharing what I'm thinking.

1) high rpm power need high compression,
2)high compression needs high duration cams to manage the compression at low and mid rpm.

As to exactly why.. hmm.. that one I'm not sure at all.

I need to study the how the air is going in the engine at low/mid/rpm and see how they differ to find out.

Currently, I know how to go about it, by using the Auxbox, but I need to take out the IAT and measure it at 3 different temps for calibration purposes,
The Map sensor too, and therein the problem lies. I don't have time at the moment to do so.
 

shiroitenshi

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shiroitenshi

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Yes.. the aftermarket cam gears are for you to compensate for the key wear on the crank and the camshaft. But I can confirm the DC2 cams work without the aftermarket pulleys.

Anyway, if you have the aftermarket pulley, how are you going to set the cams? The stock cam specifications are not available (at least none that I believe to be the exact same as the cams on hand), and to do it alternatively would require a lot of work (manually measuring duration and lift, or claying for clearance check, which I should get around to, sometime.)

The stock cam pulley will work, they might be a bit retarded/or advanced.. but they will work.
 

harpoon

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harpoon

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Hey, finally someone into the tech aspect as well.

I think if you read through all that, you have understand it roughly like me.
The thing about cams are that they can help control the static compression ratio.

Remember the intake valve closing at XX degrees ATDC?

Our static compression test gives us compression values that are larger, because they consider the intake and exhaust valves are closed during the compression stroke.

In real life, this is not the case, and as you notice, like 20 degrees ATDC the intake valve closes, your 11:1 compression has been reduced by 20degs/180deg = 11.1%, which means the 11comp - 11.1% = (11 - 1.221) = 9.779.

However, the actual volume of air going in the engine is dependent on the flow rate/speed which at the moment, is anyone's guess. Futhermore, as one of your link noted, the speed which the valves open (the lobe ramp angle) determines this also. So in other words, would 9.779 comp ratio cause knocking? it's probably dependent on engine speed, and of course the ignition timing I think, but well... that's anyone's guess, as most people don't keep track of why their engine makes power, or why it doesn't.

So if you ask whether plonking in B16B cams in a B18CR would give different performance, I think it may or may not, and there's no definite answer because you can play with the actual opening and closing timing (within tolerances, before vavle meets valve on overlap, which is why the cam spec specifices the lobe seperation angle or sometimes the mid lobe angle, at the point where there is maximum clearance).

You can tweak it a little by 2-4 degs, I think, depending on how aggressive the cams are.

A high ramp rate usually gives better performance for high comp engines, I'm sure you noticed it when you look at toda, spoon, etc, performance cams where the cam lobes are nowhere teardrop shaped like stock cams. It gives higher rocker arm wear (at the cam follower part), so that's why they don't make it too aggressive, just slightly more than stock, and which is also why they want valvesprings that are hard so that the valves won't float.

One set of cams I saw get around this by making the lift higher. like really high.. either 13.9 or 14mm of lift.

But still, much to learn about cams.

The summary of what I've learned so far comes to the following. (this is my opinion, they could be wrong, so consider that I'm just sharing what I'm thinking.

1) high rpm power need high compression,
2)high compression needs high duration cams to manage the compression at low and mid rpm.

As to exactly why.. hmm.. that one I'm not sure at all.

I need to study the how the air is going in the engine at low/mid/rpm and see how they differ to find out.

Currently, I know how to go about it, by using the Auxbox, but I need to take out the IAT and measure it at 3 different temps for calibration purposes,
The Map sensor too, and therein the problem lies. I don't have time at the moment to do so.
you did talk about the dynamic compression, does it increase the actual compression or reduces it?? because the air that goes into the combustion chamber have to go through the intake manifold, and the ecu monitors this vacuum pressure inside the manifold.... via few small ducts.

so does the manifold help to increase the air pressure and obviously the flow? and how does that affect the dynamic compression

latest invention that i saw, put it that manifold don't need to have butterfly flap anymore, it uses individual flap just before exiting manifold towards the valve, does that improve anything?? it's like using individual throttle for every combustion chamber right???

then only we come to the cams part.....if i'm not wrong, most aftermarket cam are designed to be much wilder than stock (if the same why change??), obviously it will have sharper teardrop design, to increase the valve lift for more opening and longer opening duration.... perhaps they don't make it too wild to avoid valve hitting piston phenomenon but it will still be more than stock.... how much, it depends on the manufacturer research.... so the other thing that we can adjust would be ignition advance or retard and cam angle adjustment.

from your summary

((The summary of what I've learned so far comes to the following. (this is my opinion, they could be wrong, so consider that I'm just sharing what I'm thinking.

1) high rpm power need high compression,
2)high compression needs high duration cams to manage the compression at low and mid rpm.))


obviously high rpm power need high comp, or else it won't sustain the rpm and won't be able to generate enough power

on the second one, the low cam on vtec engine manages all this, but all the talk about this only on vtec cam, how about the low cam? don't anybody wants to study that too?
 

shiroitenshi

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shiroitenshi

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you did talk about the dynamic compression, does it increase the actual compression or reduces it?? because the air that goes into the combustion chamber have to go through the intake manifold, and the ecu monitors this vacuum pressure inside the manifold.... via few small ducts.
Well.. definitely reduces static compression, that one I'm positive.

The actual volume of air is theoretically dependent on how well the engine flows (the ports, the manifold, exhaust, etc.. something like, if exhaust easy to get out, then intake will be better.) But until I get around to the IAT and manifold pressure measurements, and how they can be used to estimate airflow.. this one still my THEORY only..

so does the manifold help to increase the air pressure and obviously the flow? and how does that affect the dynamic compression
It doesn't affect dynamic compression. The reason it's called dynamic compression is because it changes as valve closing timing changes during compression stroke.
The manifold in theory doesn't really change pressure. At full throttle opening for NA engines, it will read atmospheric pressure, which is about 14.xpsi at sea level, less when at higher than sea level (there's the ram air effect, but doesn't seem to be a big of an effect for street car speeds). For some gauges they will put this as zero vacuum. Boosted, will be different, as your manifold pressure will see more than atmospheric pressure.

What the intake manifold does is increase the volume capacity. I think this is for part throttle purposes, but it's a guess on my part.

Part throttle??.. Hmmm.. this one, I don't know yet.. I'm still on the stock intake manifold, so I'm logging all the stuff I can for the stock stuff, so when I swap, I have a baseline to compare to.

latest invention that i saw, put it that manifold don't need to have butterfly flap anymore, it uses individual flap just before exiting manifold towards the valve, does that improve anything?? it's like using individual throttle for every combustion chamber right???
I haven't seen this new invention, but it does sound like a slide carb though. (O_o)

then only we come to the cams part.....if i'm not wrong, most aftermarket cam are designed to be much wilder than stock (if the same why change??), obviously it will have sharper teardrop design, to increase the valve lift for more opening and longer opening duration....
Sharper teardrop design? Maybe it does seem that way to you, but for me, it looks nothing like the original teardrop design of stock cams. they are usually fatter, so don't look much like teardrop anymore. They are shaped like that so that they will spend more time at peak lift.

The teardrop shape is something that is a compromise to ensure the valvetrain works for a long long while, IMO.

Perhaps they don't make it too wild to avoid valve hitting piston phenomenon but it will still be more than stock.... how much, it depends on the manufacturer research.... so the other thing that we can adjust would be ignition advance or retard and cam angle adjustment.
Yup, agree with this.

obviously high rpm power need high comp, or else it won't sustain the rpm and won't be able to generate enough power
Yes, that is the conclusion so far, but why?

For me, sustaining the RPM is the work of the valvesprings so that valvefloat doesn't happen to the extreme..

The generating enough power part is understood, but exactly 'how' is the question.

Studying cams, it seems like the big durations actually makes high rpm compression a lot less than the static. But I understand the big duration needed part, because at high rpms, the valves would close too fast for proper filling of the engine cyclinders.

So the idea seems to be like yours, that high compression makes power.. The question is how, which I'm still researching now.


on the second one, the low cam on vtec engine manages all this, but all the talk about this only on vtec cam, how about the low cam? don't anybody wants to study that too?
Actually there was a discussion a while back on this. in a "1.8L with 200whp" thread.

Seems like for high compression engines, big duration primary/secondary lobes (not the VTEC) are needed to enable the engine to run higher ignition timing without knock at low/mid rpms.
 
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harpoon

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harpoon

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Part throttle??.. Hmmm.. this one, I don't know yet.. I'm still on the stock intake manifold, so I'm logging all the stuff I can for the stock stuff, so when I swap, I have a baseline to compare to.

I haven't seen this new invention, but it does sound like a slide carb though. (O_o)

Studying cams, it seems like the big durations actually makes high rpm compression a lot less than the static. But I understand the big duration needed part, because at high rpms, the valves would close too fast for proper filling of the engine cyclinders.

So the idea seems to be like yours, that high compression makes power.. The question is how, which I'm still researching now.
about the throttle valve... you can have some reading here
BMW World - Technology

about the higher compression makes power, to me i guess it's because of the higher compression pressure, makes the combustion more powerful (ie higher pressure equal to bigger fire equals to higher push equals to piston move downward faster equal to extra enrgy produced)

make sense right??

besides higher compression, there is also need to ensure the intake could suck in more air and fuel.... job of the camshaft.

higher air pressure entering.... job of the intake manifold

better breathing through exhaust pulsing... job of the exhaust system

nice discussion here bro