Dumb and Dumber

H

HardScrabble

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Okay we got Jeff Gordon accidently hitting his kill switch, so the team replaces all of them with the Rouxh system.

Now we got Ryan tripping his kill switch and managing to kill his engine and any chance of winning the race (which he had a demmed good shot at) at the same time. Although it should be noted that it may have been the regular ignition switch in Ryan's case, not sure from what I have read so far.


Anyways, these are bright people allegedly. How many teams are waiting til it happens to them to make a change. Seems the least they could do is rig some kinda big ol' signal light that indicates the switch has been tripped. This ain't rocket science.
 
HS,

Didn't you ever wonder about all the "rocket scientists" getting invoved in auto racing lately?

What ever happened to good old-fashioned "shade tree" engineering?

Making do with whatever you could find on the dealership or the local jobber's parts shelves?

Before all the wind tunnels, templates, plain vanilla engines and even plainer vanilla drivers?

Before two-way radios, spotters, anger-management classes, and politically correct everything?

OR big fancy pitcarts, bigger fancier haulers and still bigger and fancier motorhomes?

Multi-million dollar purses, mega-multi-million dollar championships and all the sponsors to answer to?

TV deals and media folks who feel that the sport should be run solely for their benefit?

I could go on here, but for the sake of brevity will drop the whole subject for now.

In short, it would simply make too much common sense to install some sort of indicator light on the dash telling the driver that the kill switch had been activated.
Of course, there is also the possiblity that an excited driver, in the heat of competition, merely overlooked the switch being turned off. I thought the kill switch was just a button that when pressed shorted out the ignition and when released would allow the engine to be restarted. Must have thought wrong, again.
 
Or, how about Ryan's crew members beat the ever loving snot out of him for making them push the car, what 5 times, when he had tripped the kill switch. I bet he would remember the next time to check...
 
It is amazing how technology and engineering has replaced good old common sense. I agree with boB, more making due with what you have and less technology interference.
 
Ya know, it ain't the speed that's exciting, it's the competition. I've had as much enjoyment out of watching a race between stock four cylinder engine cars as I have watching the late models that turn up all that dust.
(If ya ain't got dirt in yer beer yer not at a real race)

The more complicated things get the less fun there is. I could cite many examples in nearly every phase of life, but to what avail.

I mean, geesh, kids "graduating" from kindergarten ??

Eighth grade class trips going to Disney World ???

Senior class trips to some foreign country ??

Mom and Dad screaming at the kids in a little league game ???

Why, back when I was a lad............................................................ :rolleyes:
 
It probably has something to do with Ryan's engineering background, he never even thought to look for the simple solution (I deal with electrical and mechanical engineers on a daily basis and they tend to complicate the most simple problems!)
 
It's my understanding a water bottle passed through the window net hit the kill switch. ...and some things are, in fact more complicated than what common thinking is prepared to handle.

e.g. In a natuarly aspirated engine, when the intake valve opens and the piston is on it's way down, what acts on the air to move it into the cylinder?
 
Originally posted by mlitefan01@Sep 2 2003, 04:06 PM
It probably has something to do with Ryan's engineering background, he never even thought to look for the simple solution (I deal with electrical and mechanical engineers on a daily basis and they tend to complicate the most simple problems!)
Click to expand...
I can relate to that one!
 
Originally posted by Windsor377@Sep 2 2003, 04:07 PM
It's my understanding a water bottle passed through the window net hit the kill switch. ...and some things are, in fact more complicated than what common thinking is prepared to handle.

e.g. In a natuarly aspirated engine, when the intake valve opens and the piston is on it's way down, what acts on the air to move it into the cylinder?
Click to expand...
wouldn't it be pressure differential. a negative or low pressure in the cylinder combined with the positive 14.7 psi (at sea level)
I think I have the right idea just don't know how to express it.
I think most people call it vacuum.
 
Very good. Excellent, you're on the right track! Now, there is one more component adding to this. I'll give a hint (and don't ask Nate...Nate, no cheating!). A fella named Harry Miller took advantage of this many years ago. In fact some call it the Miller Cycle, others call it the Miller effect (don't ask boB or HS either!)
 
Originally posted by Windsor377@Sep 3 2003, 03:02 PM
Very good. Excellent, you're on the right track! Now, there is one more component adding to this. I'll give a hint (and don't ask Nate...Nate, no cheating!). A fella named Harry Miller took advantage of this many years ago. In fact some call it the Miller Cycle, others call it the Miller effect (don't ask boB or HS either!)
Click to expand...
Well I'm lost at this point. but I will guess that it might have something to do with valve size and possibly the angle of the valve to the cylinder. If I'm wrong please educate me.
 
Well, what you're saying has an influence on what is happening, but does not create the active force. Mind if we see if someone else has any ideas?
 
Hope I'm not answering too soon here. I'll start by clarifying your first answer. The pressure differential is the key.

The Miller Cycle is continued cylinder filling after the piston passes bottom dead center (bdc) and is on it's way back up. These days, the intake valve remains open for a pretty long period during this event onb a race engine. Sometimes as much as 90 degrees of crank rotation (picture now, the crank is now only 90 degrees away from top dead center (tdc)). You would think this would push the air right back out of the cylinder. Inertia is the force that makes the air continue to work in a direction opposite of the piston. This actually overfills a cylinder on a race engine by as much as 15% and even more. The engine n this case has a volumetric efficiency of 115%. Cool, huh? This can also be called Ram Charging (re, the Ramchargers back in the 60s).

And while I'm thinking of it, I skipped right past the very first thing that begins the flow of the intake charge into the cylinder. This effect is also from inertia and uses sound pulses as well. Even before the piston reaches tdc and while the intake valve is just begining to open, there is a period called overlap. The is the end of the exhaust cycle and continues into the intake cycle. During this period, the exhaust charges are plowing out of the exhaust still and can create a pull on the inatke charge even before the piston starts it's way down, to create a pressure drop.

So, to sum it up there are 3 factors:

1. During overlap, exhaust scavenging can create a pull on the intake charge to get it started moving,

2. The downward movement of the piston during the intake cycle creates a pressure differential whch results in the "high pressure" atmospheric air pushes it's way into the lower pressue cylinder, and

3. Inertia in the incoming air column continues to fill, and even over fill the cylinder even as the piston is moving back up.

There, now how simple can it get?...lol...
 
That is great stuff. I have always heard of overlap but never knew what it did. it also makes sense that the cylinder can continue to take in atmospheric pressure on the up stroke if cylinder pressure is still low pressure.
after over 20 years as a mechanic I still learn something new everyday.
all the shops I have worked in never cared about this stuff, It was just fix the damn car and get it out.
Thank you for the education. beers are on me.
:cheers: :cheers: :cheers:
 
Great posts !!!!!! It is interesting to see there are people who post and have actual knowledge of a technical nature.

Of course I tend to think of the movie, "My Cousin Vinnie" when the gal is describing something and says, "It's a technical toim", whenever these things are discussed, but that is my way of covering my ignorance, through humor, poking fun at ........................me !!!!!

Keep up the good stuff though. It is really interesting and enjoyable.

And for the Miller cycle ????? I always thought that was when you changed from drinking Yuengling or Coors and went began drinking Miller Lite, IOW, "the Miller cycle".
 
This a great direction this thread has taken!!

Perhaps Windsor or Nate will take the "scavenging" one step further on the exhaust side. Windsor mentions the "inertia scavenging" of the exhaust gases during the valve overlap. There is another scavenging effect called usually either "wave" or "impulse" scavenging. The basic concept is that ahead of the exhaust gas flow out of the cylinder into the exhaust system, there is another force traveling through the system as well. It is a wave of pure energy, traveling much faster than the exhaust gases themselves. It has no mass and studies claim it travels at around 1200 to 1500 feet per second. (exhaust gases travel at between 150 and 300 fps as a rule). Having no mass, this wave tends to change direction rapidly and often. When it reaches a low pressure area of the exhaust system, say in the collector of a header, it will reverse direction and head back towards the cylinder. This puts it in direct opposition to the exhaust gas flow and if it reaches the cylinder while the exhaust valve is still open, can actually repressurize the cylinder creating a significant loss of pumping efficiency. Since the timing of this reverse flow of energy varies with engine rpm, exhaust headers are generally at their maximum efficiency only at specific rpm ranges.

Which also leads to the effect of "X" pipes, "crossovers" and "360 degree" header systems not to mention equal and unequal length tube headers............

It is a concept I know about but lay absolutely no claim to being able to put into practice it uses and mis-uses. I do hear that recently theories of valve overlap and "back pressure" are being argued with new ideas opposed to older ideas.
 
Wow! Great stuff. Been up for an hour and already learned something.
 
Just to confuse the issue a little more:

Consider that while the exhaust charge has an effect on the incoming charge, that incoming mixture also is going to have an effect on the exhaust charge as well.

While HS mentioned the pulse waves in the exhaust and the fact that headers could be tuned for a specific RPM range, nothing was mentioned about using that pulse wave by pairing cylinders with the header design to obtimize its effects. (HS did however, mention X-pipes, cross-overs and 180 degree headers.)

Should we get into the effects of the shape and size of valves, seat angles, port length, shape and size, manifold pleniums and even the surfaces of those items as well?

Then we need to consider camshaft design, lift and duration, lobe-centers, acceleration ramps, closing speeds and how best to utilize all of these things with all the other components in our engine as well as exactly what we want that engine to do, when we want it to do it, and how long do we want it to continue doing it.

Racer8,

I know exactly what you are talking about when you say that most shops just want the car fixed. I was lucky enough to spend several years at VW dealerships and nearly 12 years working for a very progressive BMW dealer who wasn't afraid to spend money on training. BMW at that time was, and as far as I know, still is, about 10 years ahead of the rest of the industry with their engineering.
It was a great educational experience to say the least.

Both of those organizations have been setting the standard for technician training since bringing their products to this country.

After I had to quit working in the shop a few years ago, I volunteered at the local Vo-Tec, which is affiliated with General Motors. They wasted time using teaching methods totally unrelated to the industry today. While they are teaching the use of computers for certain operations, they are years away from teaching the technicians how best to optimize them.
Their whole program is based on finding the bad component and replacing that part, not on trying to determine what caused the failure intially or what measures may be needed to prevent a re-occurrence. Get the car out of the shop and get on to the next one.

It seemed as though any original thought and common sense were unwelcome intruders to the curriculum dictated by the General and the General was, after all, paying the bills.
I didn't last very long in that atmosphere.

I can only wonder if this is an isolated instance or if this is the case with technician trainging throughout the industry today.
I most certainly hope that the former is true.
 
It all works together,,,,,,,,,,,,,,when it's done right.

I can tell ya that when the exhaust system is dem near perfectly tuned to the cam and rpm range it is one mighty sweet sound. Melodious, smooth as silk, and strangely quiet................
 
The exhaust stuff sounds to me like basically tuned exhaust.
In my younger years I rode 2 cycle motocross bikes for years and remember very well just how much different exhaust systems would change things. back then they were called expansion chambers. one good healthy dent in your pipe could really change things.
As far as training goes. even at my age I just recently completed 2 1/2 years of engine performance and advanced engine performance at a local college which is very well known for their program. It was probably the best time I have ever invested in anything in my life. The instructors there are really sharp.
 
Thanks all...and I'm in the Miller Cycle as we "speak"! I touched on the energy pulsing through the system. It's sound.

HS and boB mentioned how these pulee can enhance or hamper the performance of an engine. It is very critical to have both the intake and exhaust systems tuned to match the characteristics of the engine. If not, your engine will never see it's true potential.

But this puts us in a "what came first, the chicken or the egg" situation to some extent. In the world of custom fabricated headers/exhaust and intake systems, how do you know what is right for your combination. Well, you could play hit and miss by trying this or that, OR you could have a set of predictors that allow you to very closely predict what your combination should do and then calculate the correct inatke and exhaust systems from there.

The engine is an complete package. Change one aspect and every other aspect is altered one way or they other (for better or worse). Because of this I tend to shy away from street engines. Too many uncontrolled factors. When I do a race engine, I need to control all aspects. So I can be sure every component will work in sync with every other component.

It's nice going into a project with a knowlege of the eventual outcome before you begin ordering and fabricating parts, vs crossing your fingers, closing your eyes and hoping it will work!

Nate and I had some discussions over on the Drag Race board. They go into a little more detail. If you are interested, take a look at the "sticky" threads.

P.S. Racer8, Overlap is also a by product of another necessity. If the inatke valve didn't begin to open until the piston began it's downward travel during the intake cycle, the valve would lag way behind it's ability to feed the cylinder as the piston opened up cylinder displacement.
 
Enough of this "he said, she said" stuff. We've talked a little bit about overlap with regard to breathing. Thered is another area where overlap becomes a by product. This area is another tuning tool for the over all combinations.

Any ideas?...Nate, sorry I have to ask you to let others answer first...sorry...
 
The first thing which comes to my mind is ignition timing. Gotta get the combustion done before the exhaust valve opens to take advantage of all the fuel/air in the cylinder.

First "high tech" device I ever had was a distributor machine. Spent hours working with weights and springs to get the curve where we wanted it, then even more time trying to get rid of point bounce.
 
...just got back from Back to School Night. I'll update tomorrow...keep thinking...
 
H.S. you are correct that ignition timing is a tuning tool, however it has no affect on overlap. How about valve timing? Is that what you were thinking about? Any ideas how valve timing affects the an engines state of tune and how it can have an impact on overlap?

OK Nate...if you are reading this, go for it!
 
Henry,

Without going to deeply into this, I used to either advance or retard the cam timing in very small amounts for different tracks or even track conditions sometimes. Advance it if we needed a bit more coming off the turns and retard it if we needed a bit more at the end of the straights. Always carried a few cam bushings for the sbc or used a crank gear with multiple keyways on the Fords we ran.

Another "tuning" tool was valve clearance which has a very real effect on valve timing and duration and can be used as mentioned above although if any large adjustments in either direction seem to be working too well with either method, it's a pretty good indication that it's time for a different camshaft.

Of course we had to use the same engine for several weeks in a row at whatever tracks we chose to run at. It wasn't like today where the teams have a different engine for every track and a new or rebuilt every week.
 
boB,

You're speaking from a been there, done that perspective all right. Another thing is lobe separation angle. A closer LSA gives you the ability to boos torque by allowing the tuner to advance the inatke lobe while keeping the exhaust valve on it's seat until the last possible moment. On the other had, a wider LSA works real well with stratospheric CRs and rpm. It flattens out and extends teh torque curve and sustains it it the higher rpm ranges (from a basic rule of thumb approach). Interestingly (and I think HS touched on theis earlier when mentioning rethinking that old theories and how new theories are changing "conventional" wisdom). We are approaching/are at a point where valve train design is now capable of supporting very radical lobe profiles. The new designs allow wide LSAs but still produce low end grunt...technology can be a wonderful thing!
 
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