calling all mechanics/tuners

hi. im doing a research project for school involving automotives. as part of this project i was supposed to conduct an interview, but the people around my area have all had schedule conflicts with my own.

so now i have to turn to the internet. i already have found most of the answers on my own, but some expert/professional opinions would also be of help.

if there is anyone who is willing to answer any of my relatively simple questions, any and all help is greatly appreciated.

-(to those who've worked on both) What differences have you seen between domestic and import (Japanese) automobiles engines, in terms of their structure, build quality, etc.?
-What can be done to add horsepower to an engine?
-How does the material an engine is made of affect its performance/fuel economy?
-How have the aftermarket and import scenes affected the demand for each other?
-What seem to be the top picks for consumers, judging from what you have worked on?
-What are examples of cars with low displacement engine and are 'high performance' and how is this achieved?
-What exactly is 'octane' and how does it affect a car's performance?
-How would one explain horsepower and torque in layman's terms?
-How does the softness/stiffness of the suspension parts affect the car's ride quality/handling?


thanks to anyone who offers helpful answers, no matter how simple or short (:

I am by no means a mechanic or a tuner but here ye go.

-(to those who've worked on both) What differences have you seen between domestic and import (Japanese) automobiles engines, in terms of their structure, build quality, etc.?

Haven't worked on Imports much so can't say, but as far as any manufacturer everybody uses cheap little parts at some point in time but I'd have to say European cars are the best as far as build quality...but I'll go with American for reliability. I think imports are kind of in the middle.

-What can be done to add horsepower to an engine?

Many many many things. um....I'm not going to create a list but basically everything and anything. The most simple being "bolt ons".

-How does the material an engine is made of affect its performance/fuel economy?

I know that aluminum is lighter and has better heat dissipation, and iron lasts longer, but I dont think the material it's made of affects peformance, maybe for the parts being lighter but it's more about how much friction, balancing, and all sorts of things.

-How have the aftermarket and import scenes affected the demand for each other?

Well we all know because of TF&TF, well not directly but it definately aided in the growth of the aftermarket, not just for imports either. But I think because of the import cars in those movies that they are the ones that kinda started the whole thing.

-What seem to be the top picks for consumers, judging from what you have worked on?

Not sure what you mean. What's the easiest to work on or what's the best car to have? Because you could pick up a Consumer's report for that almost. As far as what's the easiest to work on, boy....I think most mechanics would have different opinions.

-What are examples of cars with low displacement engine and are 'high performance' and how is this achieved?

Lotus Elise, Honda S2000, RX8 maybe, I know there are more.

-What exactly is 'octane' and how does it affect a car's performance?

Best way I think of explaining is octane is the resistance to pre-detonation. In higher compression, or higher boost cars you need higher octane, but running a 110 octane in your stock Chevy ain't gonna do a damn thing.

-How would one explain horsepower and torque in layman's terms?

Um....I'll take this from Neutrino, Horsepower is your top speed and torque is your accleration. Horsepower is a derivative of torque, can't have on without the other right? Imo torque is far more important, down low too.

-How does the softness/stiffness of the suspension parts affect the car's ride quality/handling?

Sports cars and trucks generally have stiffer suspension for their handling/hauling reasons but you can't say that the better it is at cornering the stiffer the suspension will be. I know a Viper can corner at over 1G and has some stiff suspension compared to a Lotus Elise that has a less stiff suspension and corners at almost the same, but I cannot comment on either's ride quality. I'd say that it's more the design of the suspension and compenents used that suspension traits rely on but there are also more factors. Handling also rely's on low center of gravity and obviously tires.

-(to those who've worked on both) What differences have you seen between domestic and import (Japanese) automobiles engines, in terms of their structure, build quality, etc.?

While domestic motors are catching up, foreign car companies tend to have more stringent tolerances as well as acceptable metalurgy which accounts for higher reliability. Also, foreign car companies generally have smaller displacement engines while domestic car companies rely on higher displacement to aquire their power.

-What can be done to add horsepower to an engine?

Think of an enine as an giant air pump. The idea to make an engine more powerful is to be able to get more air through it. In this you can either make it flow better or force more air through it. There are countless ways to make it flow better (intake, exhaust, cam, port/polishing). Forcing air through a motor is relayed to forced induction (turbo, supercharger, any other means)

-How does the material an engine is made of affect its performance/fuel economy?

The material doesn't so much affect either but it does effect reliability. Certain materials have certain properties. For example, aluminum expands considerably when heated. In this sense, forged aluminum pistons are good for strength, but as they expand and contract they wear the bore of the engine. Eventually this increases to a point so that when the engine is started cold, there is a little 'play' between the piston and wall making a distinctive 'slapping' sound. This is common on GM's LS1 engines. Cheap materials flooded with weaking contaminants also create weak spots in the metalurgy leading to premature failure.

-How have the aftermarket and import scenes affected the demand for each other?

Its more towards the need for more power. Import cars were used for cheap and reliable transportation. Eventually they were handed down to a son or daughter for transportation. It was only a matter of time before someone said "How can I make this faster?" (This situation holds true for the hot rodding scene as well)

-What seem to be the top picks for consumers, judging from what you have worked on?

No definitive answer, consumers of what? Automobiles? While there is no definitive pick, as far as the import scene goes, I've seen a lot of civic's as well as integras. Leading close behind is DSM (Diamond Star Motors-Mitsubishi) and Subaru for all wheel drive traction.

-What are examples of cars with low displacement engine and are 'high performance' and how is this achieved?

Lotus elise is one example. It uses the same motor as a Celica GT but is uncommonly light in weight. This with a well tuned suspension creates for an extremely nimble and well handling car. Generally, lower displacement cars that excel are light and have a well implimented/engineered suspension. Driving conditions (such as rally cars) also effect what could be considered a high performance car.

-What exactly is 'octane' and how does it affect a car's performance?

howstuffworks gives an excellent explanation for this, visit:http://auto.howstuffworks.com/question90.htm

-How would one explain horsepower and torque in layman's terms?

torque is measured in foot lbs. HP is a derivitive of torque. HP is calculated as: HP=(torque*rpm)/5252. In this, HP will equal torque at 5252 RPM and surpass it at higher RPM's. Again visit http://auto.howstuffworks.com/horsepower1.htm for more information.

-How does the softness/stiffness of the suspension parts affect the car's ride quality/handling?
It would take far more than a paragraph to discuss this but I'll try to summarize. Generally stiff suspension is better for turns. HOWEVER this is not entirely true. In rear engine cars for example, the weight is generally located in the rear of the car. This makes the front light, and thus when you go into a turn, if you have stiff front suspension, the car will just want to 'push', 'be tight' or understeer through the turn. On front engine, rear wheel drive cars, stiff rear suspension will cause the car to spin out easily. Also referred to as, oversteer, or 'being loose'. Even though these cases can be true, stiff suspension helps the car transfer weight quicker from side to side, making for better cornering. With this stiffness though, ride comfort is drastically reduced. (This is why when I see those hondas riding on bumpstops I want to cry.)

Hope this helps
Joe

-(to those who've worked on both) What differences have you seen between domestic and import (Japanese) automobiles engines, in terms of their structure, build quality, etc.?
The main difference is where they were desinged and built. Anything from north america is domestic anything else is an import. Domestics, in my opinion, tend to focus on higher displacement and heavier cars, generally pretty good in a straight line but have some cornering issues. That's not to say that there aren't exceptions, the corvette is a powerful car and handles well whereas the monte carlo is a more straight-line/nascar oval focused car. Imports, the ones desinged for performance/tuning rather than economy cars, are more focused on efficiency. Their cars will rev higher, be lighter, and be more efficient (both volumetrically and fuel consumtion wise) and therefore be better for the track. This is my oppinion and probably not all of it is entirely correct.

-What can be done to add horsepower to an engine?
There are plenty of things. The idea is to get as much air and fuel into the cylenders as possible, get the most out of that air/fuel, and rev higher because horsepower, with torque kept constant, will be higher at a higher rpm. The first thing most will do is make the car breath better (intake/exhaust), not just by adding a huge muffler but upgrading the whole exhaust (headers, downpipe, cat, cat-back) and the whole intake (free-flowing intake tubing, intake manifold, port and polish heads, throttle body). The next thng on peoples mind is, in many cases, forced induction, or FI. Forced induction is cramming more air and fuel into the engine by means of a supercharger. A supercharger is anything that forced more air into the engine, thus a turbocharger is a type of supercharger. blowers are belt driven and are less efficient than turbochargers but produce more low-end torque and are usually better for daily driving IMO. You can also bore out the cylenders and increase the stroke of the engine, this will give you more displacement and allow more air into the engine. Increased compression will make the fuel burn quicker and allow your engine to rev higher. A higher reving cam will allow the engine to suck in more air at higher rpms but sacrifice some low-end power. High rev cams will provide more valve overlap(the time when both valves are open at the same time) to allow the fast moving exhaust to suck in air/fuel while it's exiting. This will hurt low engine speed performance because the exhaust gasses aren't moving as fast and the exhaust scavengine effect will not be there(exhaust scavenging=when the exhaust sucks in the air).
-How does the material an engine is made of affect its performance/fuel economy?
Two very common materials are iron and aluminum. Aluminum is lighter than iron but, I believe, not as strong. Lighter components will allow your car to accelerate quicker and turn better. In terms of fuel economy, a lighter car will need less of a force to accelerate and require less fuel, it will increase gas mileage.
-What are examples of cars with low displacement engine and are 'high performance' and how is this achieved?
Formula 1, their cars are 3L V10's that have around 1000Hp. This is achieved through extremely good flowing intake and exhaust, high compression, very light internals, and by tuning everything extremely precisely. these cars also include some technologies not available to the general public, such as pneumatic valve somethings(i dunno, i saw something about it somewhere on this site). They also rev very high, up to, i think, 15,000RPM, something you generally will not even come close to on a road car.
-What exactly is 'octane' and how does it affect a car's performance?
Octane is a hydrocarbon, C8H18, that burns slower than gasoline. This allows it to reduce the chance of knocking and detonation. This is when the fuel/air mix ignites prematurely because it became to hot. Increased octane in fuel will burn slower and, if you do not need it, decrease horsepower slightly (emphasis on slightly because you won't even notice it) some cars require it because they run on high compression or are equiped with superchargers.
-How would one explain horsepower and torque in layman's terms?
Torque is the rotational force of the engine, horsepower is the application of torque. The way I see it is torque is how much of a force the engine makes at a certain rpm and horsepower is the overall power at that rpm. Horsepower is derived from torque with this equation: Hp=(Torque*RPM)/5252.
-How does the softness/stiffness of the suspension parts affect the car's ride quality/handling?
I'm in no way an expert on this so i will provide you with my limited knowledge on this subject. Harder springs will stop the cars body from rolling to one side in a turn and allow you to turn better. softer springs will absorb bumbs better and provide a more comfortable ride. On off-roading softer springs are rquired to absorb the big bumps that, with hard springs, could damage the car.

I hope this helped, I'm no mechanic but I think much of this is correct. If someone corrects me they are probably right and probably have more experience in that field.

thank you all so much for your help (: