Amazing, Chevy builds a 330 HP engine with 28mpg Options

[Dr. Roger]

QUOTE (jniemeier @ Sep 26 2005, 06:19 PM)

This is the first thing Google found about Pogue, and it seems about right. http://www.mikebrownsolutions.com/fish3.htm Jim N.

That's alright Jim, (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

IMHO, I feel that when there is so much engineering and so little progress regarding MPG numbers, that indicates the need for a fundamental paradigm change in the way engines operate. But that is just me.

I did make a little 4 stroke motor idle using my own bubbler device. Crude is an understatement as to it's engineering but I know it works.
I even brought a friend and his mom to witness just in case of doubters. =-)

Keep up the good work and hope to see pics of that 2.0.

Roger
just another "out of the box" thinker, amateur engineer, designer, builder, 914 owner.

PS. A little better data on the Pogue. See Data B.
http://www.himacresearch.com/books/crisis1.html

This post has been edited by rogergrubb: Sep 26 2005, 11:43 PM

[bare 1]

Could one of you kind intelligent gentleman please explain to me why my rear wheel bearing died before I even got the brake rotor completely on . please Pretty please. Thanks In the aaaaaaaaaaiiiiiiiii what did I do wrong post. I'm just a simple fellow. And frustrated. (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) and perhaps a bit crude for you enginners.

[MattR]

QUOTE (phantom914 @ Sep 26 2005, 09:15 PM)

QUOTE (MattR @ Sep 26 2005, 06:16 PM) QUOTE (jniemeier @ Sep 26 2005, 05:19 PM) Cam design programs calculate four derivatives: (you paid attention in math class, right?) displacement, velocity, acceleration, and jerk. Jim, Your posts are very interesting. Ive read them all once and Im going to read through them again. Having just taken a quarter of thermodynamics, all this stuff is freash on my mind. My impression on the Fish carburator; its not based on science, because it obviously fails, but its based on skepticism of science. I do have a question about this statement though. You say 4 derivatives, now what are these derivatives? My math skills are sufficient (6 quarters of college calc.) but not necessarily proficient, but I obviously dont have much experience with this knowledge being a 3rd year mech e student. Displacement is dVolume/dt, velocity is dDisplacement/dt, acceleration is dVelocity/dt. Does this mean jerk is dAcceleration/dt? If so, wont having a cam profile of x^5 mean jerk is always smooth? And any exponential value of 4 or less will have 0 jerk? Im not sure how Im communicating my ideas, but I dont have a piece of paper in front of me. Matt, On the derivatives, you are on the right track. First, I'm not sure, but I think Jim may have meant third derivative? I will explain a little based on that assumption, but if he meant fourth derivative, you can carry this example just one step further. The third derivative is also called jounce (at least when referring to a vehicle's wheel motion). I believe you want to have the third derivative be a constant in the case of suspension movement to have a perceived good ride. In other words, acceleration should be to cx^1 (c is a constant). If the third derivative is not constant, that means acceleration is changing wrt time and that is what supposedly is the most objectionable sensation in a car's ride. I would guess it is similar in the case of valve movement that Jim describes. Oh, just noticed. There is a slight mistake in your statement. Regarding motion, displacement has nothing to do with volume, it relates to motion (distance travelled). So displacement is 'x'. Velocity is dx/dt. Acceleration is dv/dt and jounce is da/dt. And to go back to your statement, if the diplacement as a function of time is third order, the third derivative is constant. If it is second order, jounce is zero. If displacement is fourth order or higher, jounce varies with time which I think is a bad thing. But I'm just guessing. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) Andrew

Okay Andrew. That clears some things up. Im not quite sure why I wrote the displacement and volume statement. Rereading that, you're totally right. I'm still have a bit of trouble visualizing jounce and jerk. I'll break out the good book when Im not so tired (RCVD).

[phantom914]

Matt,

In your sleep deprived state, you confused the idea of displacement with volume because you were thinking of engine displacement. (IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif)

Think of jounce like this. If you were experiencing a constant acceleration (zero jounce), you would feel a contant force being exerted against you. If the acceleration were changing over time (non-zero jounce), the force you felt being exerted on you would change over time.

Again, this may have nothing to do with what Jim was saying, but is only to explain some things about derivatives, at least up to the third derivative.

Andrew

[snflupigus]

while we're on efficiency and alternatives in combustion engine design...

wrench going in....

quasiturbine?

http://www.quasiturbine.com/ETheoryEngineP...Problematic.htm

[jniemeier]

OK, you guys are already finding my mistakes... which I'm willing to admit I make quite a few of. Including ending sentences with prepositions.

First, yes, jerk is the third derivative of cam lift, isn't it? You got me there.

Andrew, very interesting to read about constant accel in wheel control motion being required for a good feeling ride. Leave it to the engineers to make a mathmatical equation for feeling quesy. I've got as many questions about suspension design as you guys have about engines, so maybe we can go in that direction next.

Back to cams: acceleration is definately not constant in a typical cam profile, so jerk is non-zero. I've seen production profiles where there's a sharp bend in the accel curve, therefore a step or discontinuity in the jerk curve. A cam like that could have acceptable durability, but it puts a heck of a load spike into the valve train. And, I should have explained before that the reason we calc all those crazy derivatives is to predict the forces in the valve train and therefore the stress at various critical points in the components. It's tough to sum it up in a sentence, but let's try: smooth jerk curves lead to better fatigue life, which allows the parts to survive the most stress, and we'll put our stress capability to good use by snapping the valve open as quickly, but smoothly as possible. To fill the cylinder with the most mixture possible (filling! (for max torque)) you would want to be as close as possible to the ideal, which would be a rectangular lift profile (instant open and close) but since that would give infinite stress (generally bad), we do the best we can. How quick you can pop open the valve depends on the weakest link (lowest load capability) in the chain (valve train).

No one bit on the Ferrari question, so here's another: In a typical pushrod V8 at redline, how much force exists in the valve train? Like if you could grab the pushrod, how much force would it be pushing upward with? (Another trailing preposition!! Urgh)

Matt, where are you going to school? Any engine classes yet? What sort of field do you want to work in?

(IMG:http://www.914world.com/bbs2/html/emoticons/driving.gif) Jim N, who wishes he knew how to make quotes appear in those cool green boxes...

[Mueller]

QUOTE

Pop quiz: How does a Ferrari valve get a larger lift profile than the what's ground into their cam?

at least for one motor, they a few different profiles on one lobe, the cam shaft moved back and forth to increase/decrease the lift..more than likely not what you are talking about (IMG:http://www.914world.com/bbs2/html/emoticons/sad.gif)

pushrod force? 3.5K#'s???

[Dr. Roger]

QUOTE (Mueller @ Sep 27 2005, 07:16 PM)

QUOTE Pop quiz: How does a Ferrari valve get a larger lift profile than the what's ground into their cam? at least for one motor, they a few different profiles on one lobe, the cam shaft moved back and forth to increase/decrease the lift..more than likely not what you are talking about (IMG:http://www.914world.com/bbs2/html/emoticons/sad.gif) pushrod force? 3.5K#'s???

Ferrari uses something like a V-tec engine. V-TEC stands for Variable Valve Timing and Lift Electronic Control.

The Vtec solenoid pumps fluid into a small pinion, which engages a different lifter which makes 2 valves work off of 1 cam lobe instead of each valve having it's own lobe..In essense in a DOHC(Dual Overhead Cam) car you get the benefits of 4 camshafts.. 2 different intake cams and 2 different exhaust cams (due to the profile change.

QUOTE

From Honda - i-VTEC The 'intelligent' VTEC Since the creation of the revolutionary VTEC system, Honda has advanced engine efficiency even further, with the invention of i-VTEC. The 'i' denotes an even more 'intelligent' power-plant. This evolution of Honda's renowned VTEC technology employs Variable Timing Control (VTC), which allows the engine to vary its intake camshaft phasing. This means that the intake ports are able to open and close earlier or later, providing precisely the right amount of fuel and air at exactly the right time for driving requirements. The result is better fuel economy and low emissions because the system virtually precludes the exhaust of unburned fuel. Now that's intelligent! i-VTEC is found in Honda's CR-V, Integra, Odyssey, Accord and Accord Euro cars.

Is this what you were thinking about Jim? (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

[messix]

the push rod would have as much force as it would take to bend or break the push rod, lifter or cam/ cam drive.

[phantom914]

QUOTE (jniemeier @ Sep 27 2005, 05:45 PM)

................. Jim N, who wishes he knew how to make quotes appear in those cool green boxes...

You mean like this? Just go to the post you want to quote and click the "quote" button in the upper right hand corner.


Andrew

[phantom914]

QUOTE (jniemeier @ Sep 27 2005, 05:45 PM)

.......No one bit on the Ferrari question, so here's another:  In a typical pushrod V8 at redline, how much force exists in the valve train?  Like if you could grab the pushrod, how much force would it be pushing upward with?  (Another trailing preposition!! Urgh) ..........................

I don't know. If there is valve float, there might be very little force (zero?) as the pushrod "falls off" the back side of the lobe? When opening the valve, I'm sure there is a lot. (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif) that's a slightly longer way of saying "I don't know". (IMG:http://www.914world.com/bbs2/html/emoticons/huh.gif)


Andrew

[snflupigus]

"Chromoly 4130 is a tough material with a tensile strength that varies from 140,000 psi up to 240,000 psi depending on the heat treatment. For all out racing applications such as Top Fuel, Pro Stock, Pro Modified, Blown Alcohol, NASCAR Cup racing, marine racing and tractor pulling, 4140 chromoly tubing can provide up to 275,000 psi of tensile strength. "

from

http://www.aa1car.com/library/2004/eb30431.htm

[jniemeier]

Ok, here's my quiz answers, although you may find someone else who says something quite different. YMMV as they say.
Before I can go on though, just how the heck does one pronounce "snflupigus"? Not only do I not have any cool green boxes, I don't have a cool pic on the left, or a cool signoff stamp, or,... I'm going to have to quite writing posts and figure out how the site works a bit more.

Ferrari have a system called "Ballistic Lift". We call it "Toss and Catch". I imagine it started on race motors, but I think even the 360 uses it. I'll tell my one cool Ferrari story below. Anyhow, they have this cam profile that works normally at "low" speeds, but at a certain point, the lift curve overcomes the springs and it literally throws the cam follower off the cam and therefore gets the valve open further (I think) and longer (I'm sure) than what is ground into the profile. Then the tricky part is that it "catches" the follower again in such a way as to not put a huge impact load into the valve train. Kinda like valve float on purpose, but without the impending-doom part.

Our lifter engineer says that a Chevy small block at 6000rpm or so puts about 5000 N (1100 lbf) through it's pushrods. Considering that this happens about every 20 milliseonds, I think it's pretty impressive. (The 4130 stress numbers were great. I don't know how hard the production pushrods are- but I can tell you that you can bend them if you try hard enough.) Andrew, you're right, when a valve floats, the force in the pushrod would be a lot less, only the spring load. Keep in mind, that the inertial loads in the valve train get to be much larger than the valve spring load once you get some revs. Anyhow, I can say that designing a hydraulic lifter that doesn't leak down too much under 5000N loads requires some pretty tight tolerances. Like if you pick up the inner part and hold it in your hand a few seconds, it will no longer fit in the outer part. Roger, good info about VTEC. The "i" version is one of the newer derivatives. What they call VTC, we call Cam Phasing. Pretty common, but in combo with all their other VT controls, they must have pretty good oil pump capacity to run it all. Most engines barely have enough pump capacity to run the phasers at idle, which is definately required.

What else... Quick Ferrari Story: In about '98 or so, I was working out of our European office (Luxembourg) and we went to Maranello to sell evap canisters to Ferrari for their US market cars. Hey, somebody has to do these things, you know. Before the meeting, (since I'm a big F1 fan) I suggest lunch at Restorante Montana, which is a famous little place right alongside the test track in Fiorano. Sure enough while we're eating our pasta, Micheal walks in with his Indian trainer/dietician guy and they shake hands with all the old Italian men and go into the back to eat. As we're getting our bill paid, they walk back through, so naturally we followed them out. Just as we get to the end of the sidewalk, Micheal comes wheeling around the little driveway in a Alfa 164 and comes within a meter of driving over my foot! He gives a little wave and guns it back towards the track. David Letterman used to do "A brush with greatness". This was a "Brush-back from Greatness"! The guy's pretty short in real life...

(IMG:http://www.914world.com/bbs2/html/emoticons/driving.gif) Jim N.
'73 Bahia Red 2.0
'84 Camaro Z28 HO (First new car)
'96 Kawasaki GPZ1100 (When you feel the need for real speed)
'81 Ducati 900SS Mike Hailwood (When you feel the need for a back ache)

[MattR]

Very interesting stuff Jim.

Did you get the PM I sent you? I wasnt sure it was sent because the club site went down right after.