Cam Profile - Regrinding

[oldcorollas]

OK I did a research. I suggest you too.

http://www.camshafteng.com.au/conclobe.htm

that profile was used for very low revving engines..
Horsepower 70.00 BHP (51.5 KW) @ 3500.00 RPM
Compression Ratio 5.3:1
from 3 litres.

they could get away with such sharp nosed cams because of the low rpm, and strong springs.

the reason manufacturing moved away from the concave lobes in the 1920's was that engine speeds increased, and valves could not follow those profiles for very long.

[kylestyleup]

Yeah cool, I didn't know that EARIST was a tech school, i thought it was an IT college or something. Thats the one near Nagtahan? I'm always interested to know whereabouts all the car nuts go for go fast bits coz no one seems to know, lol.

Yes it's before Nagtahan bridge, coming from UST via Lacson, right under the flyover.
Automotive, Diesel, Ref & Air-Con, Welding, etc., all are in their separate 4 year college degree.

[kylestyleup]

the reason manufacturing moved away from the concave lobes in the 1920's was that engine speeds increased, and valves could not follow those profiles for very long.

Yes. you explained it to me back in page 1.
This cam profile produces a powerful torque.
Now being used for industrial engines.
Folks here have rumors that this is being used to some Jeepneys
that uses a 2 liter diesel engine with a 24 passenger capacity.

What I like from this profile is the snap at the closing part.

But thanks to this thread I can now redirect my project.
I would try to simulate first from a model.

.

[styler]

hey seems that the old concave cam setup is limited to very old motors
eg bently, rolls royce

but a new convcave cam setup with roller follower is now being used the lexus IS

http://www.worldcarfans.com/2051128....us-is-in-depth

and camshaftengineering says it can be used on some chev v8's

http://www.camshafteng.com.au/conclobe.htm

but isky probably sums it up the best

http://www.iskycams.com/techtips.php#2007

[oldcorollas]

you may find that the use of roller rockers and their geometry in the lexus motor results in a valve lift curve that approximates a more normal camshaft if the valve had flat faced lifters or buckets..
the shape of the ramp is not so important.. only the resulting valve movement curves.. and the ability of the components to follow such a curve.

good finds tho

[amichie]

Yes it's before Nagtahan bridge, coming from UST via Lacson, right under the flyover.
Automotive, Diesel, Ref & Air-Con, Welding, etc., all are in their separate 4 year college degree.

My sister in-law lives near there. I think its called dela santos. Quezon city anyway. Just a few kms from cubao

[ed]

This cam profile produces a powerful torque

no... this cam is used for a specific kind of follower system where the funky profile of the cam is transformed through the follower system, into a NORMAL sinusoidal (or thereabouts) valve action

randomly whacking a cam meant for a strange follower assembly into your engine is just dumb

its like putting a flat plane crank into your engine because you like the sound of a Ferrari, but do nothing to your ignition or valve timing - just makes zero sense whatsoever

[kylestyleup]

no... this cam is used for a specific kind of follower system where the funky profile of the cam is transformed through the follower system, into a NORMAL sinusoidal (or thereabouts) valve action

randomly whacking a cam meant for a strange follower assembly into your engine is just dumb

its like putting a flat plane crank into your engine because you like the sound of a Ferrari, but do nothing to your ignition or valve timing - just makes zero sense whatsoever

Ferrari? Who said I like that?
I like Toyota more than any other brands.

I have talked to some Mechanical Engineer from EARIST in Sampaloc Manila.
This cam profile can give you a good airflow and so it can at low RPM.

At the intake timing point of the cam, it'll restrict air and then releasing it with a snap
that creates greater vacuum, (which I'm not convinced yet).
As ISKY said... "Unfortunately these cams are not a wise choice considering their major drawback: the undesirable hidden side effect of reduced valve train life expectancy!"
(It's because of the entry point or opening point of this cam profile.)

Then at the closing point, the valve is delayed open for more air... and timely snaps to close that gives greater compression. (which I like the most).

Also he said even with or without rollers, at high RPM, the exit / closing point will be useless or will be bypassed if you don't have a stronger springs.
Strong springs will be heavy for the engine and we'll lose rpm.

We are now studying to resolve this with not caving it in too much and with the help of a convex intro...

[kylestyleup]

My sister in-law lives near there. I think its called dela santos. Quezon city anyway. Just a few kms from cubao

So one of your brother / sister got married to a Filipino? Yes Cubao is around 6 or 7 kms from EARIST.

Note: EARIST don't do works. Professors refer you where their x-students at.
Me, I sell ideas to the graduating students and offer my cars for application.
The supervising prof. was my former coach during my varsity days. lol

[amichie]

Is there any relation between EARIST and the university Ateneo. My office mate used to be head of physics dept there

[kylestyleup]

Is there any relation between EARIST and the university Ateneo. My office mate used to be head of physics dept there

No, Ateneo is a private school specialize academics, business, philosophy, literature, etc.
Any they hurt packets and wallets. lol

EARIST is a government school specialize Industrials and Technological expertise.

[oldcorollas]

At the intake timing point of the cam, it'll restrict air and then releasing it with a snap
that creates greater vacuum, (which I'm not convinced yet).
As ISKY said... "Unfortunately these cams are not a wise choice considering their major drawback: the undesirable hidden side effect of reduced valve train life expectancy!"
(It's because of the entry point or opening point of this cam profile.)

Then at the closing point, the valve is delayed open for more air... and timely snaps to close that gives greater compression. (which I like the most).
.
Strong springs will be heavy for the engine and we'll lose rpm.

We are now studying to resolve this with not caving it in too much and with the help of a convex intro...

restricting and then "snap" will not increase the volumetric efficiency.. it will just restrict.
the rpm you are talking abotu with these cams is maybe less than 2000rpm. those bentley race cars went to 3500rpm? that was with "race reliability"... do you realyl want to restrict your motor to only 3000rpm to have a reliable valve train?

to take advantage of these cams, you will also need to maybe halve the diameter of your intake ports, so that you get back some lost velocity.
your intake ports are designed for maybe 6-7000rpm.. and running engine at 3000rpm means air will be too slow.

as isky meant, this cam is TERRIBLE for valve train components. even at low engine rpm, the valve train forces are so high on opening that things will break. the transition from ramp to peak is so sudden that you will have valve float. and then when you go to the trailign ramp, you also get float...
every time you get float, it is like hitting the valve and cam with a hammer.. it will destroy the cam and follower, and it will make the valve lift strange, because it will nto follow your strange profile.

to make the valve follow the lobe, maybe you will need springs that are usualyl required for much higher rpm... for example, to run at 3000rpm, you need springs strong enough for 9000rpm. this means that your valve train forces are same as at 9000rpm.
this means that your POWER LOSS from valve train is same as at 9000rpm... ie, you are wasting power to turn your camshaft, and you won't get it back from a strange cam lobe profile, even if you do make your intake ports realyl small to make up for the loss in velocity...

but please take a video of the car running it will be interesting to see, even if it does or doesn't work. even better would be a members ride thread with information abotu each step of your process to make these cams...and then the results in testing!

[kylestyleup]

Hi Oldcorollas,

I have read your explanation. You are correct on the part that the cam will destroy the valve train (assembly) as ISKY mentioned. That is also why I noted on the line "At the intake timing point of the cam, it'll restrict air and then releasing it with a snap
that creates greater vacuum, (which I'm not convinced yet)."

Thanks... We will not use the concave profile on the entry / opening flank.
But we will use the concave on the exit / closing flank which said to increase air to be compressed.

We are also going to use strong valve springs to follow on the concave exit / closing flank.
To reduce resistance on turning the cam and gain RPM, we will use a convex entry / opening flank.

About the video... yes sure think but as I've said this will take use a year or so, it's because this is a Thesis I am selling to a graduating student. And there will be tons of paper works.

But I'll do video it... also for my documentation.

[oldcorollas]

maybe it is a good idea to recommend to the student to look up why they are a bad idea before you sell them the idea?

to have the valve follow a convex exit, you need a stronger spring.. and this automatically increases the load on the opening as well.

please do the calculation, including acceleration rates, and inertia of valves, followers and the springs themselves, before you sell anything to anyone

edit: why are you selling ideas to thesis students? i have never heard of such a thing
unless by "selling" you mean "convincing"??

edit2: then again, a thesis doesn't always need to have a positive outcome. if the process of analysis is good, then it doesn't matter if the end result is not good... and these calculations could form a good part of the thesis, combined with various springs etc and the results of real world testing.
however, it may not be easy to measure if the valve is following the lobe, unless you can have vibration detection to detect the slap, or high speed camera to see when the follower leaves the lobe?

[kylestyleup]

edit: why are you selling ideas to thesis students? i have never heard of such a thing
unless by "selling" you mean "convincing"??

edit2: then again, a thesis doesn't always need to have a positive outcome. if the process of analysis is good, then it doesn't matter if the end result is not good... and these calculations could form a good part of the thesis, combined with various springs etc and the results of real world testing.
however, it may not be easy to measure if the valve is following the lobe, unless you can have vibration detection to detect the slap, or high speed camera to see when the follower leaves the lobe?

I am in a circle of people who do crazy things. lol
I am "convincing" them in a way...
But literally selling the idea. We sell them half way done.

It'll work... A friend simulated a 3D.
Like you said, we need to test it in the real world.