M cam vs. B cam vs. K cam

[isaac]

A week ago my B cam in my '83 245DL (NA) decided to shear it's pin off, so I've had my M back in my car for a week. I was allowed in this period of time to remember the fondness I had of it's smooth, even idle, and imperviousness to being killed by a zero throttle clutch dump from a stop. Thats right, I can't make my car shut off by accidentally dropping the clutch at a stoplight with my foot off the gas.

Something I didn't realize from my M cam to K cam swap 2 years ago was the K cam (as well as the B cam) makes the car noticeably louder. Granted this is because my 2.25" single muffler exhaust allows the K to take advantage of increased airflow, as well as it's having bigger lift and longer duration than the M. So thats something to take into account: If you've got a performance exhaust in your NA volvo, swapping cams will make it louder under most conditions. It's just flowing more gas volume overall, so it's gonna be louder. I'm not talking jet take off loud, it's just a few decibels, but it's noticeable, particularly in a wagon.

Anyway, so I can't stand this M cam's top end anymore, so I decided I'd swap my B back in today after I drill out the broken off pin inside. I decided I might as well repeat the tests I ran a couple months ago with the B and K cams, and do it with the M in my car, timed straight up of course. As part of my third edit of this post, I will note that my car is a 1983 245DL, M46 tranny, 3.31 gears, approx 3195 lbs w/o driver. Mods are: Airbox mod, 2.25" single turbo style muffler cat back exhaust, ignition timing advancement, electric fan conversion, knife-edged throttle plate, and accel superstock coil.

Though I can't say this is a perfect test, I tried to keep variable change to a minimum. There is no way this test could be the same as the last in every way. The K cam and B cam specs were tested at the same time last time, so I stand fully by my conclusions regarding those cams in comparsion to each other. The gas tank is at about the same level as the last test. No weight saving measures were taken. It's about 70 degrees out today like last time. Its not very windy. The car has a few more miles on it and I've changed an air filter in between, but everything else is the same. I used the same flat stretch of road, going the same directions: once up, once down, then once up again. I took the 3 runs of each of the 3 styles of tests and averaged them.

Here are the results, plus a reposting of the results taken from the last test with the K (6 degrees advanced) and B (straight up) cams for comparison:

20-60mph all out acceleration (1st 3,800-6,000rpm, 2nd 3,000-6,000rpm, 3rd 3,450-3,750rpm ) -

M cam - 10.233 seconds
B cam - 9.673 seconds
K cam - 9.57 seconds

30-50mph (1,450-2,300rpm) 4th gear only acceleration -

M cam - 10.66 seconds
B cam - 10.356 seconds
K cam - 11.59 seconds

50-70mph (2,300-3,100rpm) 4th gear only acceleration -

M cam - 12.6325 seconds
B cam - 12.04 seconds
K cam - 12.536 seconds

Needless to say, I really really love the B cam now. I'd been living with the B for the time since the last test, about 2-3 months, and knew it was the ultimate no compromises cam from the last test, but this just says it that much more. It kicks ass.

 

[skastel]

I'm impressed!
How hard is it to get a B cam and which car does it come from?

 

[Captain Bondo]

Thanks for the testing Isaac, it's greta to get real numbers but I have to say,these are really misleading imo. You have to use the cam in its powerband.

If you were gearing down with the K it'd be killing all of those cams- it wants to be run from about 4500-6500. The only semi-revealing test is the first one since it repsents more "real conditions. Pulling out to pass someone when running a K cam at only 1500-2300 rpm is rediculous. You just would not do it. An H cam probably would have been slower yet in those tests.

Keep in mind this is coming from a Canadian who has had the opportunity to drive plenty of K cammed cars, I'm not saying it isn't great to test cams or that i don't appreciate it, but they need to be tested at the rpm they were DESIGNED for. Know what I mean? You could set up tests to make a T cam car look faster than a K cam car. Do all the tests from 1200-2100rpm.

You should do those tests via gearing down 1 or even 2 gears and see what happens.

 

[towerymt]

20-60mph all out acceleration (1st 3,800-6,000rpm, 2nd 3,000-6,000rpm, 3rd 3,450-3,750rpm ) -

M cam - 10.233 seconds
B cam - 9.673 seconds
K cam - 9.57 seconds

This is a good test. I'd run mine with the VX3 except that I have snow tires on, and with short summer tires, I don't know where 60mph really is.


[quote:2bbe1c42af]30-50mph (1,450-2,300rpm) 4th gear only acceleration -

M cam - 10.66 seconds
B cam - 10.356 seconds
K cam - 11.59 seconds[/quote:2bbe1c42af]

I never drive in 4th gear below 50mph, so this doesn't do much for me.


[quote:2bbe1c42af]50-70mph (2,300-3,100rpm) 4th gear only acceleration -

M cam - 12.6325 seconds
B cam - 10.356 seconds
K cam - 12.536 seconds[/quote:2bbe1c42af]

It would be nice to see these 30-50 and 50-70 tests in 3rd gear. I've pulled 3rd to around 80, so this should be within the rev limiter.

Try a T cam on those last 2 tests, and I bet you find a "better" cam.

BTW, for the person who asked, a B cam comes in the B21F, but not all since I think some got the M cam late in the run.

 

[isaac]

[quote:8d970b3ba5]You should do those tests via gearing down 1 or even 2 gears and see what happens.[/quote:8d970b3ba5]

I did do those tests via gearing down 1 or 2 gears. See the 20-60mph test where the K was run from over 3,000rpm all the way to redline in 1st and 2nd gear. 3,000rpm-6,000rpm encompasses the same powerband whether it's done at 20mph or done at 100mph. Doing 3,000rpm to 6,000rpm testing at higher speeds would have been of little importance and unnecessarilly dangerous considering my testing procedures.

Though this is self explanitory: I did the tests of 30-50mph and 50-70 mph in 4th gear to show how these cams react in day to day conditions. Everybody on here, including you, should know how a cam reacts as you are driving it at cruise and at light throttle conditions at lower rpm. We drive our cars (including in passing situations) at less than 4,500rpm about 80% of the time we're on the road, if not more. If everybody drove the K from 4,500rpm plus most of the time, then there wouldn't be dozens of posts on here asking about how it does at idle and how much low rpm torque it has. At least half the people on turbobricks have NEVER been to a racetrack, let alone gone habitually enough to necessitate high-rpm-only testing. These tests represent how fun these cams are to drive in many conditions, not just when you're going nutballs with the gas and shifting like mad. Had I not tested the low rpm capability of these camshafts, the K would seem like the perfect camshaft, which it isn't even close to being.

This is ridiculous that I have to defend having performed these tests for the reasons that I did.

 

[Captain Bondo]

"I did do those tests via gearing down 1 or 2 gears. See the 20-60mph test where the K was run from over 3,000rpm all the way to redline in 1st and 2nd gear. 3,000rpm-6,000rpm encompasses the same powerband whether it's done at 20mph or done at 100mph."

agreed. Why didn't you reference those tests or the results of?

"Doing 3,000rpm to 6,000rpm testing at higher speeds would have been of little importance and unnecessarilly dangerous considering my testing procedures."

agreed. Just test the cam under the conditions each was designed for.
You might as well have rented a Viper and tested its ability to tow a 5th wheel.

"I did the tests of 30-50mph and 50-70 mph in 4th gear to show how these cams react in day to day conditions. Everybody on here, including you, should know how a cam reacts as you are driving it at cruise and at light throttle conditions at lower rpm."

And everybody here here who knows anything about anything GEARS DOWN if they're trying to accelerate under those "day to day conditions" hence doing tests without gearing down is a little irrelevant.

"We drive our cars (including in passing situations) at less than 4,500rpm about 80% of the time we're on the road, if not more."

Yes, but you aren't trying to accelerate during those times are you? Whenever I'm trying to accelerate I am at 3000-6000, who cares how a cam performs while you aren't accelerating?

"If everybody drove the K from 4,500rpm plus most of the time, then there wouldn't be dozens of posts on here asking about how it does at idle and how much low rpm torque it has."

Most people who ask those questions are noobs who have never learned to shift and have driven American, Automatic, V8 Oldmobiles their entire lives.

"At least half the people on turbobricks have NEVER been to a racetrack, let alone gone habitually enough to necessitate high-rpm-only testing."

Well, it's not my fault they don't know how to drive. maybe you should explain what cam offers the best ALL OUT performance, and then explain how to drive it.

"These tests represent how fun these cams are to drive in many conditions, not just when you're going nutballs with the gas and shifting like mad."

you just shift down into the powerband. no nutballs, no madness.

"Had I not tested the low rpm capability of these camshafts, the K would seem like the perfect camshaft, which it isn't even close to being."

Assuming you are trying to accelerate at low rpm. But you have to add that little tidbit.

"This is ridiculous that I have to defend having performed these tests for the reasons that I did"

You SHOULD have to defend your testing because obviously it doesn't make sense to some of us. And if you did other tests, refer to them or include them. Include the WHOLE picture, that's all. If you had included that you would not have to be defending yourself. You are being forced to defend yourself because you weren't playing all of the cards imo.

When I'm booting around town I gear down all of the time without thinking about it. Revving the engine IS real world conditions for many of us. These are 4 bangers and that is how they make power. Learning to hit that 4th to 2nd gear change is the key to getting these cars to even halfways get out of their own way.

I'm done with this one. If nobody wants to actually drive their car where the power is and would rather have something that makes no power but will grunt along at 1500rpm then all the power to you. It's the american way. [/code]

 

[700mopareater]

Hey, the more research the better. There can never be enough #'s out there on volvos for me. I love doin my homework, and it's tough because not a lot of people take the time (or have the resources) to go out and run tests like this. So cheers to you! :beer2:

 

[gtlover]

I agree, most of us aren't hitting the redline most of the time. I'd actually do more redline shifts in first and second, but between squishy motor mounts and wet roads it doesn't happen much.

But your tests do illustrate difference in the powerbands between the cams, which is useful.

 

[isaac]

Kenny, I am now convinced that you didn't read my test, and I mean really read it, because every single thing you just derided, insulted, or questioned me about was in there.

This is the 2nd time that I will repeat that I DID do at test from 20-60mph that started at 3,800rpm in 1st gear until redline, continued in 2nd from 3,000 until redline, and finished in 3rd gear. This was an all out acceleration test, like a normal person would do, through the gears.

Here is a direct paste from the original post of that exact test which you ignored and which I then referenced in my response to you, which you then acted like I had omitted:

"20-60mph all out acceleration (1st 3,800-6,000rpm, 2nd 3,000-6,000rpm, 3rd 3,450-3,750rpm ) -

M cam - 10.233 seconds
B cam - 9.673 seconds
K cam - 9.57 seconds "

About the other stuff, are you seriously telling me you've never attempted to accelerate above your current speed without changing down a gear first? You're telling me that, cruising 50mph in 4th gear, you've never just pressed the gas to get up to 70mph? BTW stop making personal references relating to your driving habits if you're going to make your arguments objective. I don't know anyone who downshifts even half the time they feel like speeding up a bit. I'm no talking about going 4th gear at 50mph, flooring the gas and then wondering "whats going on its not going very fast!" I'm talking part throttle, just accelerating, not flooring it and driving fast all the damn time. Nobody drives like that. Nobody just downshifts and floors it every time they want to speed up.

About your 'explain what cam give the best all out performance' comment. Once again, did you read my post? I DID do that! I did it in my last post with only the B vs. K cam test as well. Thats what the 20-60mph test is. Don't you get it? It's 3,000rpm plus, full throttle, all the time, shifting at redline. What the f'ck more do you want, a 4th gear 5,500-6,500rpm test at 115mph? I can't do that, and like I said before, if I'm testing the cam's powerband between 3,000-6,000, 4,000-6,000, or 5,000-6,000, it's utilizing the same powerband, no matter what gear its in, no matter what speed the car is going. Don't you get how that works? If I do a single test which tests high rpm running from 20-60mph, thats ALL the tests I need. For the purposes of showing that the K cam is the best all out cam (which my test DID show and you've hence ignored) the test did exactly what it was supposed to do.

About the "you should add that little tidbit" remark: I DID add that little tidbit about low rpm acceleration! It's in the damn test! Didn't you read the 30-50mph test that showed the K cam was 'far from perfect' in the low rev department? Wasn't that obvious enough without me having to 'add that little tidbit'? WTF?

Kenny Wrote: "You SHOULD have to defend your testing because obviously it doesn't make sense to some of us. And if you did other tests, refer to them or include them. Include the WHOLE picture, that's all. If you had included that you would not have to be defending yourself. You are being forced to defend yourself because you weren't playing all of the cards imo."

Jesus Christ man! I DID include the whole picture! It's in the tests! The tests covered all the revs from 1,450 all the way to 6,000 rpm, including a torque test, a low-mid rev test, and a high rev test, and it was all on the same page! I even referenced the past post to look at! I even repeated it in my last post!

Kenny, you'd better have done this as a joke, and tell me so privately or publicly. If not, and you don't apologize after this crap, I'm emailing you my phone number, and I'm gonna give you one hell of a talking to. I don't want any of that "calm down" crap either. Via being a jerkoff and not reading my post, or just pulling a prank on me, you did this on purpose.

 

[isaac]

BTW Michael, I just got done doing a 30-50mph and 50-70mph test in 3rd gear with the M, and I'll do the B and the K later tonight and report back. Seems as if you were at least nice-ish about your criticisms.

 

[linuxman51]

daaaaaayyyaaammm....

reminds me of some "discussions" i had with some of the t-brickers on the mailing list a year ago...

 

[700mopareater]

Wow kenny, you must've posted just as i was putting mine up. I gotta go w/ Isaac on this one. There's a HUGE difference between performance track and performance street driving. How often do you find it feasible to usefully heel to toe downshift on the street? What about city driving, doesn't it seem a little relevant that a car that rarely sees above 40 mph would like to have a little low end grunt?

I'm not trying to be a wise ass, but seriously dude, everyone's style is a little different. I was brought up on alfas myself, not exactly low end lovers there. Those twin cams suck you up to 6 grand like it was nothing. I frequently drive my volvo in a similar style. However I travel long distances and through varying situations that requires a cam w/ varying personalities (i sure wish these things had variable valve timing ) which is part of the reason i'm looking to ditch my M cam. For a person that does a lot of varied highway/city driving such as myself, i find Isaac's information really informative. I really do push my car to it's higher limits, believe me i was extatic when i pushed it to limit on third gear and hit a little above 90 mph. However i also need lots of low end in the city to get my ass around, or else i wind up spending more time shifting gears to keep the powerband available than i do actually driving. Hi-rev = maddd fun, but it's just not always practical

 

[Captain Bondo]

Well , I apologize for disagreeing with your testing, it's just that in my opinion 2 out of the 3 tests were way out of what the K cam is meant for- I never mentioned the first test because it was fine. My bone to pick was with the other 2. The 0-60 test is much more definitive regarding overall power and good on ya for doing it.

It's just that you need to understand that how fast my car is below 3000rpm means nothing to me- and most people around here who have manual cars are are really looking for performance will tell you the same thing. If I want to go fast, I rev it. So FOR ME, I disagree with your conclusion. Different person, different goals, etc. I do just accelerate from 50-70 in 4th, but I could care less how fast it does it. If I wanted to get there fast I'd gear down, that's when it counts.

Put it this way, what will smoke more ricers? Gearing down with the K cam, gearing down with the B cam, or not gearing down with the B?
Gearing down with the K. As long as it's drivable when not gearing down then who cares? I'm not trying to beat anything.

I just want to go as fast as possible when i really want to, and the best cam of the ones you tested for that is the K. That's all I'm saying. I'm sorry if that pisses you off, I don't intend to. I think you could have actually summarized this as noobs just look for the numbers in seconds and make a judgement, I know that's not your fault though.

I know many have never raced or been to a track or whatever, but instead of catering, why not help them by suggesting what the K really does and how it is to be used responsibly?

This all brings out the point of how important it is to learn a car's powerband and learn to drive for it. The numbers are very useful for this end and you get a big ATTA BOY from me for all your hard work.
Again, I am sorry I disagree.

 

[Hank Scorpio]

Another good thread destroyed.

You can see the K cam out performs in the all out tests, but the other cams were better suited for daily driving.

Funny, a car company spends god knows how much money making these cams for just this (daily driving) and all anyone does is sit around a say how crappy they are.

lol, your tests do remind me of tests you see in trailer/camping magazines when they test new trucks. Real world info. Seriously, if I had an N/A I wouldn't be looking at it as an all out track car, just needs something to get out of its own way on the freeway.

Good info isaac

 

[Captain Bondo]

This is just insane.

"How often do you find it feasible to usefully heel to toe downshift on the street"

?What? We're talking about ACCELERATING! Why would you heel-toe? Push clutch in as you move the shifter, blip throttle as shifter slides home while dumping the clutch. Heel-toe is when you're braking and has nothing to do with going from 50-70. Why would you brake while gearing down so you can speed up?

You guys wonder why I sound riled up...

The very fact that you said that shows that you have no idea what I'm talking about.

To get out of your own way on the freeway as Doug said, you select the correct gear to be in the powerband. Simple concept. Nothing to do with racecars or heel-toe or anything else.

 

[Hank Scorpio]

With 3.31 gears, its nice to have down low torque.

THATS WHAT I SAID. Nothing about being in the correct gear. Who wants to have to downshift to 2nd gear on the freeway (for an auto) and 3rd (or lower depending on speed) for a stick?

gosh, nothing like proving my point about this thread once again

 

[Captain Bondo]

You drive a performance car and you're complaining about shifting? WTF?
Shifting to 3rd from 4th is about 0.25 seconds and maybe 2 calories. IT AIN'T HARD, and the rewards are great. the 4-3 downshift is one of the best things the M46 has going for it.

You'd rather be slower and shift less. Great. You have now proved my point. In that case a B cam is probably for you I won't argue that.
I don't mind shifting if it means more power. And that equals K cam.
Hence I disagree with his choice. now I have people who complain about shifting and don't know what a heel-toe is attacking me.

So it just depends on wether you want to actually DRIVE your car or not. And if you would rather not actually drive it and be slower, I don't want to ever hear you dissappointed with a timeslip.

 

[700mopareater]

[quote:187fcc8091]What? We're talking about ACCELERATING! Why would you heel-toe? Push clutch in as you move the shifter, blip throttle as shifter slides home while dumping the clutch. Heel-toe is when you're braking and has nothing to do with going from 50-70. Why would you brake while gearing down so you can speed up?
[/quote:187fcc8091]

Sorr you took that in the wrong context. When i mentioned httds i was just making it a point that you're basically saying you drive like a track driver. Httds being a race technique to keep your power band up and weight distributed properly on a corner to make up for the loss of speed. With that in mind, i was just saying that most people don't and can't use race bred techniques on a day to day basis, it's just not pracitcal.

Ok, lets all just drop the argument part of this and chill, not worth it, i mean, there's no point in arguing to no end when there can be benchraces!

 

[Hank Scorpio]

Good lord, why don't you read before you speak?

Case in point, I clearly stated that for a daily driver and what not (NON TURBO) like my DL was, I'd rather have a cam that would help the car out for the driving style that I most likely encounter (freeway, passing, moutain roads).

THIS IS DIFFERENT from my 242t, where I don't give a shit about driveabilty.

Kenny, you have a real knack for taking information, misreading it and getting pissy over it. So I'll try to make it clear:

FOR MY DL, OR ANYOTHER CAR THAT I AM NOT INTENDING ON RACING, JUST FOR DAILY DRIVING, I think thats a great test of those cams. AND NO, I do not want to spend all my time downshifting a DAILY DRIVER just to get through a yellow light. NOTE: My daily driver is a LOW PRESSURE turbo, not the high pressure T5, which was laggier. AND AN AUTO! Not the fastest, but hands down the nicest driver motor you could ask for. Loads of torque, 0 turbo lag (well, very unnoticable) and just the perfect powerband for long freeway trips, yet still runs a 15.5 in the quater. And, were talking about a car with Leather, 17" wheels, the good sound system, ect ect.

 

[700mopareater]

[quote:58ac18c81a]Hence I disagree with his choice. now I have people who complain about shifting and don't know what a heel-toe is attacking me.
[/quote:58ac18c81a]

Wow dude. Watch what you say about what i do and what i do not know. I may be young, but i'm no fool w/ diamond plate floors getting blown out and computers telling me my nawz is gonna blow up my intake in a built motor. Just because you don't take the time to think about what something might mean doesn't mean you have to be insulting. I take a huge amount of pride that i spend a lot of time learning what to and what not to do to push my car to its limits, and learn the proper techniques associated with that. My car may not be fast, but i sure as hell know how to drive it and what's involved with doing that, whether it be on the street or the track.

If you still think that i've no clue what i'm talking about, come for a drive with me. You're more than welcome, i'd honestly love to see your project car. Just don't make assumptions aboutme. Remember, when you assume you make an ass out of u and me (get it, hehe )