BADSZ28

iTrader: (39)

I know that high lift does not mean more aggressive accel. I am saying you can be more aggressive with less lift and durration with the same power and better running. What I am trying to do is get the same amount of total air into the chambers with less durration and overlap. Heads flow better at higher lift, we all know that. So we need to get these valves at higher lift faster to take advantage of the higher flow.

I see. The higher ratio is putting more material over the stem which in turn can cause float. OK. I am still learning here.

Alright then, lets say we have $1Million. Now we get the lightest strongest
material (say titanium) and make 1.9:1 rockers. Now implement this into my concept. Does this do what I think or is it the same with a different cam and rockers. I wish I had a program that draws up cam profiles and knew what the limmits were of the valve train (cam lobe to lifter clearances and loads and such). I am betting I can get more aggressive with accel with less lift on the cam. I guess I am trying to make the cam profile more square like is what I am saying.
This make sence?

Side Note: I do not mean to hijack, I am simply looking more into Vincis idea and mine. So sorry.
Also I am not bashing or arguing. Just learning.
Later.

ta02zx10r

iTrader: (19)

Hey no offense taken here as far as thread hijacking. You guys are coming up with some good points. But the idea of making the same power with less lift and less duration (on the cam alone) vs. a big cam is basically like having your cake and eating it too ain't it? The way they explain their idea does seem to reason out though if you envision how the whole valve train moves and apply their ideas. I would be interested to see what kind of numbers we would see with that g5x3 and those rockers. I bet it is pure hell on those springs though! Thanks for the info guys. Looking forward to reading some more. thanks Chris

nuzee

iTrader: (2)

That is the first time I heard someone say that the weight over the lifter doesn't make a difference. I was under the impression that the weight difference between solid and hydraulic lifters was one of the reasons why solid-lifter valvetrains are more stable at higher rpms. Am I just misunderstanding your statement?

Gman2002Z06

For you guys talking about the higher ratio rockers being more prone to valve float...You need a quick rocker lesson...

First off...A higher ratio rocker DOES NOT put more rocker weight over the valve stem...For example...Stock 1.70 rockers vs. SLP 1.85 rockers...From the rocker pivot to the tip that actuates the valve...The two rockers are identical...

The increase in ratio comes as a result of moving the pushrod cup closer to the rocker pivit...Think of a teeter-totter...both sides of the pivot point move the same distance up and down as the teeter-totter pivots...Now shorten one side by half the length...The short side now only moves half of the distance up and down, while the opposite, long side, still moves the full range...

Follow that...

Also, because you are shortening the fulcrum lenght on the lifter/pushrod side vs. the valve/valvesrping side...You effectively increase your spring pressure...

Ex.
A 100# seat pressure with 1.7 rockers, will effectively see aproximately 9% increase in spring seat pressure as seen by the lifters...

This will reduce valve float, not increase the likelyhood of it...

I am running the 1.72 accelerated lift roller rockers from CraneCams...The ratio starts off at 1.79, then at approx. .300" of lift the ratio backs off to the net max. of 1.72 ratio...

The rockers did make a noticeable difference compared to he stock rockers...Both down low and up top...And I am running the G5X3 also...

Peace...Gman

ta02zx10r

iTrader: (19)

Right on Gman. Thats basically how I understood their whole theory on their rockers. thanks for the info chris

Do you happen to have a before and after dyno from the rockers?

Gman2002Z06

I don't have a dyno of the before and after...But After the cam install, I put maybe 1500 miles on the motor before switching to the CraneCams lifters...But, the seat of the pants meter says they are doing their job...

Maybe its just that they are reducing the valvetrain frictional losses...The car does feel much stronger...Maybe its the combination of a little more power and the lower friction that makes the engine wind up much quicker...

Peace...Gman

GrannySShifting

iTrader: (10)

TA02ZXR... doesnt matter what you do with teh rocker/cam combo. if the end result is the same valve motion the motor doesnt know any difference it makes same power.

Solid rollers make more power because they are SOLID, they dont pump up, nor collapse. Ask guys doing solid roller stuff how heavy their pushrod is compared to stock.. its not lighter Id prefer to have a stiff (and likely heavier) 3/8 pushrod in my 7500 rpm hyd motor then a lite as I could get it 5/16 prod. I could see a reason for restricting the amount of oil in the pushrod, but i wouldnt trade some things for pushrod weight

If cranes variable ratio rockers work like that.. they they are the anti-thesis of valvetrain stability in my opinion. they close the valve faster (1.79) ratio making them more prone to floating the valves off the seat. Ask guys what rocker ratio they are using when they are taking their hydraulic cams into the 8000 rpm range SUCCESSFULLY, Id have to say usally a lower ratio

Gman I was talking about actual weight.. more correctly I should have said perceived load... being ccelerating the valve quicker is going to be more perceived load. Like the same way a T400 transmission becomes more parasitic the faster the car goes. The harder you try to accelerate an object, the more it will resist you.

I dont have a million dollar budget to test this out for msyself in every instance, but these are how my thinking works around subject, and i havent seen anything to the contrary. if I do, then Ill change my mind fo shizzle!

mrr23

iTrader: (3)

i have before and after results of using the VHP/Crane 1.89 accelerated lift rockers on the wife's stock cam 99 formy. here' you go.

hp graph


tq graph. do not pay attention to the tq peak number for the after result. if you look, there was a spike at the beginning of the run.

Squintz Palladoris

iTrader: (1)

[QUOTE=GrannySShifting]TA02ZXR... doesnt matter what you do with teh rocker/cam combo. if the end result is the same valve motion the motor doesnt know any difference it makes same power.

Solid rollers make more power because they are SOLID, they dont pump up, nor collapse. Ask guys doing solid roller stuff how heavy their pushrod is compared to stock.. its not lighter Id prefer to have a stiff (and likely heavier) 3/8 pushrod in my 7500 rpm hyd motor then a lite as I could get it 5/16 prod. I could see a reason for restricting the amount of oil in the pushrod, but i wouldnt trade some things for pushrod weight
QUOTE]

I Plan on using a 3/8 pushrod in my next hydraulic motor. The 5/16 may be lighter but the 3/8s will be much less likely to flex and cause a loss of stability at higher RPM.
I will probably still be running the Vinci 1.79 rockers with this combo

Brad

nuzee

iTrader: (2)

I was just using the lifters as an example of weight difference. Same could be said for pushrods, rocker arms, etc. From the lifter to the valve, all of that is a reciprocating mass. It doesn't matter if the mass is before the rocker arm or after. If some of that mass wants to go in one direction and the other wants to go in a contrary direction, you'll get instability.

In other words there is no difference between mass over the valve vs. mass over the lifter. All reciprocating mass should be considered to produce a stable valvetrain.

GrannySShifting

iTrader: (10)

Ok... explain why some of these rockers marketed as being lightweight still cause valve float sooner? I always was under the impression it was due to the weight over the valvestem

Gman2002Z06

For all you "engineers" out there that think that there is no difference between weight over the valve or weight over the lifter...I'll give you a very simplistic example to prove you wrong...

Ex:
Take an 8# sledge hammer with a 30" handle as our being our "rocker" and your wrist as the rocker fulcrum...

Now take the sledge hammer in your hand and grab it 10" from the head and hold the handle horizontal in front of you...That puts the 8# head 10 inches to one side of your wrist and the 20" of handle to the opposite side...

Now rotate the sledge hammer back and forth, mimicking the motion that a real rocker makes about its pivot point...

NOW...do the same test as above, except grab the handle 10" from the without the head attached...This gives you 10" of handle to one side of your wrist and the 8# head 20" from your wrist...

Now tell me which one was easier to rotate and mimick the motion of a real rocker...

Total weight of the sledge hammer did not change...But the perceived load realized to rotate the hammer sure changed...The closer you move the head to the pivot point, your wrist, the lower the perceive weight that there is to rotate...

This is exactly how the effect of a higher ratio rocker can work...The distance between the pivot point and the top of the valve does not change, but the distance from the pivot point to the pushrod cup gets shorter with higher ratio rockers...This is how the perceived load on the lifter increases and thus aides in reducing valve float...

Peace...Gman

nuzee

iTrader: (2)

Gman
Granny appears to advocate that weight from the pushrods and lifters does not matter in valve train stability. I am in disagreement with that. I've reread your post and find it hard to make a connection between your example and what I am in disagreement with. It seems that you took my words out of context when I say there is no difference in weight over the valve vs. weight over the lifter. When you apply those words to whats only happening at the rocker arm and do a valve-side vs. lifter-side comparison(totally out of context from what I am saying), then I would tend to agree with you. However, I'm still digesting your point "This is how the perceived load on the lifter increases and thus aides in reducing valve float..."

Do you understand what my point is?

RevGTO

iTrader: (12)

Is anyone else besides me still interested in learning more about the Vinci cams? I take it as obvious that Crane doesn't have any "magic lobe" design beyound the standard Comp Cams XE and XE-R. But the advertized powerband for their cams doesn't show it being pushed up 4-500 rpms like a typical 224. So the inference is that these cams put out more torque under the curve rather than max HP. Do any Vinci users have dynos or track results to demonstrate what these cams can do?

GrannySShifting

iTrader: (10)

Advertised numbers are just that. Like the original post stated, lets see a 225 duration well tuned put together combination vs vinci rocker cam setup on dyno to see if claims pan out.

Or a cam with same overlap as 226/224 112 LSA cam, outrun a 3600-3700 lb stock head car trapping 119. Theory is good and all, but people wan to see results.

Gman2002Z06

nuzee...

The perceived load being applied to the lifters, as a direct result of using a higher ratio rocker can and does relate directly to my example...Let me explain...

Lets take the sledge hammer for our example again...Now lets use for arguements sake, some easier numbers...Weight of hammer head is still 8lbs., but make the handle 4ft long...

Now if you were to hold hammer in the center of the 4ft handle, the torque, that the head would be exerting on your wrist, would be 8lbs x 2ft = 16ft.lbs.

Now, lets say you put your other hand at the handle end without the head and try to keep the handle from rotating...you would have to exert the same 8lbs. of force to counteract the 16ft.lbs of torque being generated by the head...

OK...Now lets say you try to resist the head from rotating by using your free hand at only 1ft from your wrist...Now you would have to physically exert 16lbs. of force to match the 16ft.lbs of torque being generated by the head (16lbs. x 1ft = 16ft.lbs)...

That is how the higher ratio rockers give a higher perceived pressure exerted on the lifters, even though you didn't change any other valvetrain item, i.e. stronger spring...

Peace...Gman

nuzee

iTrader: (2)

Gman
I clearly understood the principle you have stated from your other post. No disagreement there. The part I'm digesting is how the perceived additional load reduces valve float.

Do you understand my original point? The reason that I ask is that I'm not sure if your intent is to make me understand something else that is not apparent to me. In a nut shell my point is that reciprocating mass, regardless of whether it is before, at, or after the rocker arms affects valvetrain stability (& rev-ability).

RevGTO
Sorry to have side tracked this thread. I just didn't want something posted by a highly-respected member that may have been a misstatement to have gone unchecked.

mrr23

iTrader: (3)

has been there for a long time. not a new cam. but as you can see, it's at the bottom for a reason. reason for standard split design is because it works. remember all those cam suggests that were given for my combo. all 6 companies went with a standard split. hmmm...

what makes them different is the accelerated lift design. nothing like the comp XE and XE-R that everyone else is following.

people wanted the 224/224. so, they made one.

Gman2002Z06

It reduces the chance of valve float due to being able to push down with greater force on the pushrod (shorter fulcrum to pushrod cup distance), in effect, making the perceived weight that the spring sees on the pushrod side less...

Now, I do agree that total mass does affect revability, but the total mass is not nearly as important as where the mass is located relative to the rocker fulcrum...i.e. the sledge hammer example...Moving the 8lb end closer to the fulcrum, it becomes easier to rotate (good for higher revs), move the 8lb away from the fulcrum, it becomes harder to rotate (bad for high revs)

Lets look at this in another way...Lets say the only thing that we change in the valvetrain are the springs...Higher rate springs that weight the exact same as the stock springs...So, what we have is a total valvetrain that did not change weight, but the higher spring pressures allow higher rpms, because they force the rocker, pushrod, lifter and valve through there motions with greater force...

In essence, the effect of moving the pushrod cup closer to the fulcrum point, makes the pushrod, lifter and rocker easier to push back down on the return of the spring even though the actual weight did not change...

Peace...Gman

nuzee

iTrader: (2)

digested ....... burp*.......

Now back to the original subject.......