so here is my question I had a built gsr that spun a bearing and I decided to just use a b16 short block I had in the garage to get my car back on the road. im gonna use my gsr head which has skunk2 flat face valves springs retaineers and skunk2 tuner 2 cams. with the gsr head flat face valves and a lil milling no more then 10 thousandths I should be close to 11:1 compression with the b16 block and my gsr head, should I keep my tuner2 or sell them and get smaller cams say itr cams, and before ppl ask im rebuilding the gsr block down the line but im gonna sleeve it and bore to 84mm and that's gonna take some time for me to get done, the b16 block is a very cheap alternative to get my car back on the road for now

 

cam choice and compression being directly related is a myth in my opinion.

So if you can take the time to degree the new engine with the cams you already have, you should be ok.

Since you said "cheap alternative" I am guessing that it does not matter what the engine makes as long as it runs.

Another question you are indirectly asking is basically how these 2 sets of cams will perform on your future/potential engine tuner 2 vs itr cams.

No matter what that answer is, I don't think its worth it to sell the cams you already have just to get the engine running.

One more thing to consider is that flat faced valves do not really affect compression as much as you think. I don't think its enough to affect your compression. That is mostly for marketing, again in my opinion.

Good luck getting her running again

 

please elaborate on that...i happen to disagree
its really not a matter of opinion. either it does or it doesnt

 

I could consider elaborating but it would be beyond the scope of this forum and thread.

My competition also reads this public forum, I would rather I don't have to do their homework.

Cams for the most part, generally speaking sent commands for opening and closing valve events.


Take a stock engine with stock cams and dyno it. It makes 200whp.

Take the same engine and bump the compression, it will make more power. On average the rule of thump of 10whp per point of compression.

So there you have it, the stock cams made 10whp more power when compression was increased. I believe this is a simple way to look at it without writing a book on the subject.

Another test would be to find a 300whp race engine with race cams and replace them with stock cams. So chances are, it made less power. The reason for the power loss, some might see as "the cams are designed for less compression"

Engine building and tuning is a multi dimensional thing and its nothing is usually as easy as it seems.

 

Compression is important in cam choice. However, for Honda's or most setups, the power is in the head.

Everything effects camshaft choosing, you can't say anything is important then the next, I believe Displacement will play a bigger role then compression but i feel they are both equal in some way.

Head flow, Intake manifold/intake setup, Exhaust flow, bore/stroke... its a book obviously...

It's important to look at all aspects of your cylinder head and total engine performance. I tend to focus heavily on the cylinder heads Intake to Exhaust flow percentage. That's the amount of air the exhaust port can flow vs. the intake port. A head with a higher percentage can use a cam with more matched intake and exhaust lobe figures or more of a bigger intake, Conversely, a head with a poor ratio needs more exhaust duration to work well. A small change in head flow is usually worth more of a power increase than a large change in cam timing.

People typically forget, the camshaft is probably THE most important aspect of building a motor because you're suppose to build your motor around your camshaft profile, not the other way around.. It controls EVERYTHING in and out of the motor.

 

i think they mean dynamic compression not static.
where its slightly affected by the opening and closing times of the valve. no?

just red wikipedia im full of knowledge, come at me

 

well my actual plans for the future build would probably be something a lil bigger then the tuner2 since I already have done a b20v with tuner2 but that's not set in stone. as far as the b16 setup of course im going to get it tuned but not really looking for a specific hp goal on this setup but Im gonna keep the tuner 2 for now then once the new build is done id probably hit Derek up for some custom grinds

 

 

the supporting mods of course are skunk2 intake mani 68mm throttle body toda rep header kteller 2.5 inch exhaust no resonator no cat itr trans with 4.9 final drive and as far as the compression goes what I came up with on zeal calculator was 10.8:1 with just the head milled 7 thousandths didn't really add in the flat face valves as far as raising compression with 10 thousandths would be about 11:1

 

when its all said and done, it comes down to the lobe design(s) No matter the specs, they deliver or they will not deliver if the design is a hack. A hack means that its not a pure design but based on something else that was derived by a cam doctor.

 

this the heart/core of the cam design problem, gmsii asked about



to design a cam for a roller, you have to go backwards

what these curves represent, is cam lift, velocity, acceleration and jerk

but guess what? Cam lift. acceleration and jerk does not mean anything because you need the valve lift, velocity, acceleration and jerk!

So to get to the cam design, finished product..

you have to design valve motion with good jerk, good acceleration and good velocity to satisfy the valve motion model. Then your finished design, gets reduced to cam lift through a huge pain in the *** procedure.

What people do is they just take a cam design lift profile like CAM XXX,

add more area to get a bigger cam and come up with what they think is a new design



but when you do this, you are creating other problems that will rob power from your engine and as seen in kseries over and over gain, your chain or tensioner will go boom eventually.

 

this is just for one lobe.

There are 4 lobes in each set of cams. 2 for intake and 2 for exhaust. VTEC for exhaust, non vtec for exhaust, vtec for intake and no vtec for intake.

 

last post before I go back to work, doing BMW M5 cams today

this is not really my theory, I am just going by what my mentor taught me.

He did all these designs here



the ones with the DOT are the SVM designs.

the ones without the DOT are the IPS original designs for k2, kme, k10, kxv, k6h, kt1, kt2, ksc1 and ksc2.

I deleted the real duration at 0.050 because without the real duration , the competition cannot copy or attempt to copy based on the seat duration. Not bseries specs, but its how most R and D is made, so I am showing you how real deal engineering in cam design field is.

If I had to name one factor that matters, that is duration. But duration is tied with the cam / valve motion model so here we go again, its really beyond the scope of any forum..

 

dayem wikipedia fail
interesting stuff tho

 

blah blah blah....i feel sorry for the poor bastards that actually think you are saying something meaningful...this kind of hand waving and smoke and mirrors is typical of people that know little but pretend to know much

here is a very basic example...two cams with identical valvemotion/lift curves above 1mm can have very different performance due to different profile designs off the seat to 1mm....why?....dynamic compression characteristics

another very basic example....dyno an engine, lash the cam tighter and then looser....power is not the same. why? do you think its because of the difference in a few thousandths lift? or because of the effect that lash has on seat timing and consequently dynamic compression

seems to me you should do your homework before you tell others to do theirs

 

Looks like Nikos studies seismology.

 

This is something i learned a few years back from another guy, known as robert martin, interesting 3 way call we had going with Donf, I and him, and that was a very informative conversation about how lash was important and over looked by many.

 

What did you "learn"?

 

why would you use valve lash when its only there to adjust for metal expansion not for changing seat timing.

 

Lash is important.

Imagine getting punch in the face with a "three inch" Bruce Lee punch. Now imagine getting punched in the face allowing the person a full back swing.

 

Feel sorry for honda racing team running my cams, I designed on my own.. oops..

What you see as dynamic compression, cannot be measured. It changes with conditions, RPMS because VE (volumetirc efficiency) changes as well.


Unless you can design from scratch your own cam profile and manufacture it on the spot, what you think about me does not really matter. lol

 

Lash could give effective duration to a point, it'll effect valve timing events etc etc.

Not to mention, it has alot to do with cam health in general and wear.

 

That would hurt.. BL's style of fighting was very unique. He was able to drop people like 3rd period french with a 3 inch punch, imagine if he actually hay makered it lol

 

You're lucky this forum is moderated.