Technical Questions about cars...

[trophymaker]

Norton can probably answer these, and they have been bugging me for quite some time now.

I know a lot about cars, but cannot figure out:

1. What is a dry-sump oil delivery system?
2. What is the difference between Roots-type superchargers and Lysholm-type? Which is better?
3. What are the different differential types? (For 4WD and RWD cars)
4. What constitutes "AWD" as opposed to "4WD"? Are they simply interchangeable?
5. Why the hell does everyone buy front-drive Civics, Integras, Preludes, etc., and think that they are sports cars? Are front-drivers really viable for speed? Or does torque-steer and strange transitional behavior make them pretenders?

Thanks.

 

[BrianCNorton]

whew, these are all good questions, and I dont know all the answers, regardless of what my signature says.

1) Supposedly there is a horsepower improvement amongst other things
read this http://www.howstuffworks.com/question331.htm

2) I had to look this one up. Ive never had a supercharged car. http://www.sportcompactcarweb.com/archives/tech/tech02_0701.jsp

3) There are a bunch of differential types, but they fall into a couple categories. Open and Limited slip are the most common on street cars.
full time 4wd cars like subarus have a wierd differential that actually uses really thick goo to transfer power from "the wheels that slip to the wheels that grip" as they claim. Its kinda cool. race cars use some kind of hydraulic differential, but who knows how that works.

4) All wheel drive is all wheels spinnig all the time. 4 wheel drive has the connotation of part time 4 wheel drive. Trucks like my old blazer switch between 2wd and 4wd when they need the extra traction. You would do this in the snow, sand, or mud, but that's all. It generally puts out a 50-50 power distribution. They dont run 4wd full time because they are designed to operate in low speed high torque mode for "when you need it." All wheel drive is seen as a saftey feature, as it provides increased stability at the expense of some cornering ability. Power is usually distributed at somewhere around 85-15 (r/f) to maintain favorable weight distribution.

5) ten years ago, people thought exactly what you are saying, but some VERY talented people started playng with the imports and come out with some amazing results, but mostly on the drag strip. Dont get me wrong, rear wheel drive is still the way to go for ANY kind of racing by virtue of laws of physics of weight transfer. The FWD import crowd has however achieved unbelieveable results with small engines. Go to an SCCA event some time, and you will see a bunch of rice-boys with go-fast parts and big tips, and usually there is one old guy with a CRX or something that really knows how to drive, and shows up everybody else. One of those guys lives everywhere and goes to every event. So yes, FWD is viable for speed, but RWD still owns the track. Dollar for Dollar the RWDs are light years ahead because of their generally larger engines, and thus less sophisticated parts.

Hope that helps
Brian Norton

 

[BMW///M3]

well looks like someone beat me to the answers!

 

[trophymaker]

Originally posted by BrianCNorton
whew, these are all good questions, and I dont know all the answers, regardless of what my signature says.

1) Supposedly there is a horsepower improvement amongst other things
read this http://www.howstuffworks.com/question331.htm

2) I had to look this one up. Ive never had a supercharged car. http://www.sportcompactcarweb.com/archives/tech/tech02_0701.jsp

3) There are a bunch of differential types, but they fall into a couple categories. Open and Limited slip are the most common on street cars.
full time 4wd cars like subarus have a wierd differential that actually uses really thick goo to transfer power from "the wheels that slip to the wheels that grip" as they claim. Its kinda cool. race cars use some kind of hydraulic differential, but who knows how that works.

4) All wheel drive is all wheels spinnig all the time. 4 wheel drive has the connotation of part time 4 wheel drive. Trucks like my old blazer switch between 2wd and 4wd when they need the extra traction. You would do this in the snow, sand, or mud, but that's all. It generally puts out a 50-50 power distribution. They dont run 4wd full time because they are designed to operate in low speed high torque mode for "when you need it." All wheel drive is seen as a saftey feature, as it provides increased stability at the expense of some cornering ability. Power is usually distributed at somewhere around 85-15 (r/f) to maintain favorable weight distribution.

5) ten years ago, people thought exactly what you are saying, but some VERY talented people started playng with the imports and come out with some amazing results, but mostly on the drag strip. Dont get me wrong, rear wheel drive is still the way to go for ANY kind of racing by virtue of laws of physics of weight transfer. The FWD import crowd has however achieved unbelieveable results with small engines. Go to an SCCA event some time, and you will see a bunch of rice-boys with go-fast parts and big tips, and usually there is one old guy with a CRX or something that really knows how to drive, and shows up everybody else. One of those guys lives everywhere and goes to every event. So yes, FWD is viable for speed, but RWD still owns the track. Dollar for Dollar the RWDs are light years ahead because of their generally larger engines, and thus less sophisticated parts.

Hope that helps
Brian Norton

1. Interesting... the article explained it all really. I asked because I read that the new M3 and M5 have racecar-derived dry-sump oil systems that greatly improve oil delivery during hard driving/cornering...

2. Another great article. I wanted to know, because in reading car mags, I would hear about Eaton-type blowers in Benzs, Roots-type in Jaguars, Lysholm-type in Milenias(?), etc. and not have a clue what seperated them.

3. Differentials are insane. I have a Torsen (Torque Sensing) limited-slip on my Camaro. I went over my interval for changing the diff fluid, and it started to lockup... my inside tire would spin as fast as my outside, and when making turns it wouuld actually spin...

4. Understood. I have frequently argued with people that claim AWD helps cornering because of the greater ultimate grip... Do you know why AWD isnt beneficial in cornering? Or actually a bit harmful?

5. I am becoming more and more impressed by front-drivers, but having driven both, the sensation and mannerisms of rear-drive simply feel built for speed. Probably the physics.

Thanks a lot Norton.

 

[BrianCNorton]

Originally posted by trophymaker


4. Understood. I have frequently argued with people that claim AWD helps cornering because of the greater ultimate grip... Do you know why AWD isnt beneficial in cornering? Or actually a bit harmful?

Thanks a lot Norton.

Well, awd is going to hurt your overall performance by adding weight to the car. Lots of it. (300-500lbs?) Two turning hits occur. one is an enlarged turning radius, bucause you have to have a drive axle attached. (low speed only) The other is that the force of the rear tires can overcome the grip of the front tires due to a forward weight shift when the car starts a turn, thus making your car understeer. (high speed only) For everyday driving, I dont think you'd notice, and subaru WRXs do quite well at the autox