I always hear people mentioning the limits of the stock internals of our Z's. They always seem like guesses. I never hear anything concrete. My question is, is there any scientific way of testing the strengths of certain individual internal components? I.e. Test A shows the limits of our valve springs, Test B etc., etc. You get my point. Cuz we can't really trust Nissan can we? They're gonna lie on certain specs for warranty/reliability reasons. If we could obtain this info, it seems we as a community could better understand the limits of our cars before making a serious purchase (like a turbo). I know comapnies like greddy have warranties, but it still seems like very valuable information.

Thanks for listening to my rant. I have only very superficial knowledge of how an engine works, so if any part of this seems..dumb, please forgive me.

 

basicly, push it till it breaks. not much else you can do... every engine is different anyway.

 

I know every engine is different. Just seems like someone could have came up with some methods to test components for durability under stress. Cuz each part gets stressed in a different way...How do engineers do it? There is a way.

 

I'm not entirely sure how bigtime auto manufactures design specific components but I'd bet money they have empirical formulas from years of testing. They also have access to high price FEA (finite element analysis) computer programs that can predict stresses, strains, and dynamics. I know Porsche used Ansys to solve a pre-production problem they had with the Boxster's intake manifold. It hit a bad resonance frequency. Nothing like paying 50K for a german sports car that sounds like a pinto.

To get to the point, if you don't have a degree in engineering and the resources to put that knowledge to use I think you will have to rely on the manufacturer's claim. Or there's always destructive testing.

 

Yeah, I figured as much. Some nice neat simple formulas would be cool though. I don't expect any however.

 

There are no neat simple formulas. It's not outrageously complicated though on the individual component level, but when combined into a system, the second- and third-order effects make stuff get really complicated really fast.

It's not just about strength. There's fatigue, thermal cycling, vibration, temperature effects, etc., etc., etc.

Don't worry about sounding dumb . It's fascinating stuff and the only way to learn is to ask questions. I was a mechanic for years, and eventually got sick of wondering all this stuff and went and got a mechanical engineering degree. Now I design spacecraft structures and mechanisms for a living.

You never know where your curiosity is going to take you...

 

if you don't mind me asking, how old were you when you decided to get the degree, and how old are you now?

 

I've seen stuff written about chevy engines and drivetrains that seems to come mostly from empirical experience, usually from engine and tranny builders who have learned the limits from rebuilding. There doesn't seem to be enough experience with the VQ and Z drivetrain to have that kind of empirical experience. But, there are probably builders who have seen enough that they can guess where the limits and problems lie if they have the specs or can see the arrangement. I doubt theoretical analysis will be of much help, because of the variables listed by reen and the fact that you are pushing performance to their limits.

Phile, if you think you would enjoy engineering - go for it. The math is usually the toughest hurddle to get over, but it can be done. Engineering schools with night programs are generally geared for people who are working, they take it a step at a time and generally aren't as theoretically oriented (less calc etc). I'm a civil (unless you really make me mad ), but CEs and MEs take pretty much the same courses for 2+ years. Go in to your local engineering school and check it out.

 

Mechanical Engineer here, too.

I always like building things, as well as science, so I decided mechancial would be cool because it could be both extremely theoretical, but also very hands-on, depending what you are interested in.

Some very cool classes, as well as poopy ones.

Currently I'm doing robotic designs for semiconductor wafer handling robots.

As far as engine testing goes, reen made very good points.

Just take a connecting rod for example. First, you have your material choice, which will determine the basic strength characteristics. Then you have any finishing processes, which can chage many of the properties.

Now take your load characteristics such as compression force due to gasoline explosions, rotational effects due to the inertia of the rod, tensile force when stopping the mass of the piston.

Finally take your life characteristics. For all materials, fatigue will lower the amount of stress a given type of material can take. Certain materials, like steel, have a theoretical limit of stress, that if never exceeded will allow the material to last "forever". Other materials, such as aluminum, have no such limit and will theoretically eventually fail no matter how low the forces are.

By knowing two of these three characteristics, you can figure out the third. In design, you usually will have a reliability goal and a power goal. The power goal will determine the forces and the reliability goal will determine the amound of stress the parts can take. Then you need to pick materials and figure out how to make the shape requried to keep the stresses low enough to meet the reliability goal.

In this case, we know the shape, since the parts are already designed, and we can try to calculate loads based on torque and engine speed. We could then estimate the life based on the stresses.

Because of the complex shapes involved, the easiest way to do this would be to either take the parts and push on them until they break, or make some computer models and test them with an FEA program. Some simpler shapes can probably be done with hand calcs.

That might be an interesting project for a science class. Try to get the student to figure out how much power we can handle, hehe.

I'd do some work on it, but I'm just too lazy and am still working on a stupid license plate frame (it's been six months, and I have some sketches, but no drawings yet). Also, my head hurts now.

I think I've spilled just about everything I remember from school.

-D'oh!

 

I don't mind at all. I started the degree at 24, and now I'm 30. I busted *** and got it done in 3.5 years. Amazing how much more motivated you are when you're a bit older, going because you want to, and paying for it yourself. I know that's not that old; I had a buddy there who started at 28 and another at 30. Hell, my Ma got her architecture degree at like 45.

Good post, D'oh! Said all the things I was thinking but couldn't get motivated to type.

 

Hey D'oh -- you don't work for Fortrend do you? I have a good buddy who used to do the same thing.

 

Im pretty sure there are formulas for all of this. BUT, if you paid attention in high school physics. In order for the formulas to work, it has to be in an IDEAL situation. Where there would be no heat lost due to friction, No gravity, constant speed, going in a straight line, etc.... Thats why you pretty much have to guess at it most of the time. Too many factors to make it work all the time, just have the basic understanding of it and tune accordingly.

Oh, I'm no mechanical engineer, just an electrical engineer

 

Thanks for entertaining my questions guys It is interesting stuff indeed. My motivation for posting in the first place was that it bothers me to read so much speculation. It seems like almost everything I read in a technical/performance forum is "what if", "maybe", "I heard", "I think". And I blame no one, because obviously i'm not motivated enough to figure things out at the moment.

I'm 22. I'm currently getting a business management science degree. I graduate in a year. The only reason I went for a management science degree is because I half own a family business, and I satand to inherit the rest very soon. In 1998, I went to RIT (Rochester Institute of Tech) to be a computer engineer. Shortly after I switched to electrical engineering (more broad applications), and I left the school at the end of the year. I originally wanted to take a year off, so I was pissed I had to go to school (parents forced me). I did ok at RIT. I never studied, did no hw, and still pulled off 3.4's. At the end of the year, I skipped all of my tests and got like a 1.80. I didn't want to be there and that's how I made my point (very stupid of me). Anyhow, I took a year off after that and went back to school at a local state college, and I entered into the business field...and here I am. I have disliked school all my life, so it's really hard to do anything school oriented, even if I am motivated/interested in a particular field.

 

Ha! I had the EXACT same story after high school, and did the EXACT same thing, at RIT as well!!! 1991-1992. Small world. I opted out of the family business though and went out west. I didn't get truly motivated until I was 24, so maybe you'll come around yet.

Funny -- when my kid brother wanted to take a year off after high school, my folks let him. Guess they learned. He moved out to AZ into my place, and working minimum wage for a year motivated the hell out of him to get his butt to college heheh.

 

...........

wow. That's pretty damned amazing That's eerie! HA! Well I'm glad things are going well for you. Good to hear other people have taken my path :thumbsup:

 

Nah, but I'm familiar with them. The semicondoctor industry is pretty small, and unfortunately, it's been getting quite a bit smaller over the last couple years.

The company I work for is called Brooks Automation.

Luckily I like to hear myself talk, so my posts usally end up being a big, rambling, nightmare for everyone else. I'll keep this one short, though.

-D'oh!

 

Actually, I've enjoyed reading your posts. They are well reasoned, well written and clear enough for a lay person to understand. Keep the rambling on.

 

To the other ME's:

I am currently working in a small R&D facility in the lakes region of NH-where I have been for the past 3+ years. I would like to know how the job market is on the west coast because I would like to find more challenging work and a more Z friendly climate. Any information you can pass along?

-Murry

 

We just laid off a ton of mechanical engineers, but other places in the aerospace world out here are hiring. Many of our guys went to TRW and Northrup-Grumman. It's kinda hit-or-miss depending on what exactly you do and, frankly, how good you are

Biggest ME job pool in SoCal is aeroispace, and aerospace is super cyclical.

Plus, cost of living is a gazillion times more than in NH.

Good luck! 300+ perfect Z days a year await!

 

SF area is also pretty tight on jobs right now.

Most of our market is semi, defense, and medical.

All have been in the crapper for the past six months to a year, but defense may be picking up given the current world events.

Semi is extremely cyclical, with violent peaks and valleys. Quite a harrowing experience and not for those who like security. I think in another year the semi should be starting an upswing, but we'll see. That may be a good time to start looking out here.

Of course, much depends on how picky you are. There are often jobs out there, but they may be far from where you live (not a prob. if you are just moving out here though) or they may not pay very well, or they may not be very interesting.

I would think that an R&D job would be really cool. I would also think that many jobs would be even worse than the one you currently have, although, I guess it depends on what you are used to. Sometimes a change of pace is what is required to get back some motivation.

It is tough to beat the weather out here though! Even in the SF area, it is quite mild.

-D'oh!