A&Q about 350Z
Q:
BLASPHEMY!! Okay that was a great post but I still don't know the difference between mechanical eng and automotive eng. let alone backyard engineering. But instead of asking you guys...uhhh, well you can still answer it but you've jolted me into looking it up myself.
Just the other night I was fed up with people saying an F1 car has less torque than a sports car's engine. The first place I started looking was to find an f1 car (I chose the Renault R25/26 models) and it's torque numbers. That wasn't easy, but only because I still had the mind set that if it had 1200 horsepower, it should have a lot of torque. So I looked around and after an hour of frustration, I found the formula Power(hp) = Torque(lb-ft)xRPM/5252, which means a 1200 hp F1 car has about 600tq. Okay well then why is it the fastest race car in the world? That part was easy to find out. The F1 engines are designed to redline upwards of 20,000 rpms. The horsepower translates to the engine and it accelerates 3 times as fast as most engines, assuming a 6-7k redline. I still don't know why it has half as much torque, possibly rules and regulations have to do with it. Oh, and my point was that I like to learn all I can.
A:
uhhhhhh...that's impossible...but controlling it is doable. I need a social life, and...it's college!!!
Truth Formula = Best Years of My Life >= X <= Making lots of Money where X represents the present time.
Do I get a lifeline?
A:
you're focusing on the torque as if it means something. Its just a variable involved in calculating the HP.
Not to completely hijack the thread, but 250 ft/lb's at 25K RPm's is roughly 1200HP. Acceleration potential is HP, not torque.
A:
I said 20k, what the, the math isn't working out...
Do you mean that V8s have high torque because they have a lower redline? Now that you've said it, follow through with it!
A:
very good. I said 25K.
Not sure what V8's or redline has to do with it. Its a simple formula as you stated.
Its the end result that matters. HP = acceleration potential. Not torque. If that was the case, then diesels would be the ultimate drag race engine, since they are the masters of torque.
A:
By that formula, it means that the higher the redline the less torque it has. 315tq for a 20k limit engine and 252tq for a 25k limit engine. Why do I hear all around that it's torque that puts power to the wheels?
A:
the higher the red line doesn't really matter, its at what RPM you make peak HP that matters. (and a little bit after that, assuming it falls off gradually)
As you've pointed out above, the higher the RPM, the less torque to make the same HP.
As for the "why do I hear"...you hear that from people that don't understand how power is applied to the ground. Many people confuse torque with HP. Its easy to do since they are part of the same formula. But one is static and one is dynamic. In american measurements, on a low-reving motor, a high torque reading is a sure sign of a high HP reading, so its easy to confuse the two. But when you look at rediculously high reving engines, (20K or 25K RPM's) that simplistic view doesn't hold water anymore. You can't look at a F1 engine and say "its fast because it makes a whopping 250 ft/lb's of torque!", because thats really not impressive vs many stock street engines. But the HP definitely IS impressive....which is why its so fast
A:
what? vectors are easy.
i did them, i don't know how i did them and i never really understood any of it. but i did them easily.
A:
If you learn to work in metric (which you should), you can get rid of all those crappy factors like 5252.
Power = Torque * rotational speed (in radians/second).
Torque and horsepower are different ways of representing the same thing.
If you know the torque curve, you can draw the power curve from it.
If you know the power curve, you can draw the torque curve from it.
If two engines have similar power, the one with a fatter torque curve will always be faster. Peak power means little.
My old corolla:
Approx 70kW (5afe engine) and maybe 800kg, time to 100km ~ 25 seconds.
My 4wd truck:
Approx 100kW (turbo diesel) and 2300kg, time to 100km ~ 22 seconds.
As for Automotive vs Mechanical engineering.
Automotive is a specialized area of mechanical engineering.
Other specialized areas are metallurgy (material science), HVAC (heating, ventilation, air con), Manufacturing, Product Design, Stress Analysis, Control Systems, Pneumatics, Hydraulics etc.
How stressed you'll be at eng school depends on your time management skills.
For my last three years of my degree I was running one university club (with approx 130 members and weekly events), on the committee of another (90 members), represented my uni at snow sports and had a girlfriend who lived 400km away who I managed to see every 2-3 weeks.
I never pulled an all-nighter either. They're just stupid.
The people who are at the computers when you leave to sleep at 5am, are still there at 8am trying to replace the project they accidentally deleted at 6.30am.
A:
assuming your tranny sucks anyway
There is definitely truth to this. But it depends on the application. Peaky engines can be taken advantage of.
A:
that is painfully slow...
A:
painfully slow enough to make you wonder about all the parameters involved in these two vehicles.
Turbo diesels aren't known for their wide power bands (percentage of redline).
Maybe with vehicles this slow, we should compare 0-50kph, because if they take that long to get to 100kph, I have to wonder what their top speeds are
A:
You couldn't be farther from the truth. Well the make friends with other engineers part is correct, but that'll naturally happen because you take all your classes with them. Thats besides the point. I have the highest level of academic scholarship available at my college. I do a varisty sport (Track and Field) at the Division 1 level (with no scholarship, my school did not give athletic scholarships until this current year's freshman). I am a mechanical engineering major with a minor in business and economics. I'm very involved with several student groups like the executive board of the student board of ASME and our school's ski race team. I still work part time (one afternoon a week) at the internship I had this past summer. Also, I am a member of one of the fraternities on campus. As you can imagine, being part of a fraternity leads to a rather fulfilling social life, since we do throw several parties every week. I do all of this while maintaining a GPA high enough to graduate Magna cum Laude (over 3.6). To top it all off, I just received a job offer doing a job I will like with a company I like, paying $62K/year to start WITH full benefits. I apologize if I come off as bragging, but if that isn't combining success with a life, I think everyone is in for a world of dissapointment. It is all about how well you can apply yourself during those times you do have to study, and being able to sacrifice going out every once in a while to complete an assignment. If you try to focus on just school work, or just having a life, your life will be MUCH more stressful.
A:
Or they break for coffee at 3am at a diner and on the way back their car breaks down in the intense fog, 4 in the morning and the alternator dies on the highway, which then it takes a stress filled hour and a half to get back to their dorms and 3 hours to sleep till class,
I mean yeah.
A:
Thank you for bragging because now I feel a whole lot better about it. I have to bring up my GPA big time though.