Hey folks, I got tons of questions I have been saven up while skimmen these boards. Some are quit newbish questions while others are pretty technical. If you only know a single answer, go for it. Don't need to answer them all, but I would be greatly appreciated with any help.

1.) I see people talking about 2.8 pulleys or other numerical values. What does the value mean and what is meant by pulleys?
2.) When someone installes a PSI gauge, it measures the amount of boost that the turbocharger, supercharger, or blower adds right?
3.) "Wheel hop" - The term was used when talking about an 03 Cobra “wheel hopping” when there was too much rwhp for the type of tire. What does it mean and why would it do this because of too much rwhp?
4.) How do you port a supercharger and why would this physically help... as in how does it increase the HP?
5.) What is a heat exchanger and where does it "extract heat" from? Where does the heat go?
6.) What's an intercooler and how does it cool off a supercharger?
7.) Ok, this one took me a little muster to type out. This just seems explicitly newbie to me, but here it goes - how exactly do you "burnout"? The way I thought you do it is you rev hard while holding down the breaks. Since all Stangs are rear wheel drive, the front brakes will stick but the rear ones won't. Thus, you can still spin the tires while standing in place. Please correct me if i'm wrong. Lastly, wouldn't that desimate your brake pads?
8.) What’s the fuel economy of the 03 / 04 Cobras?
9.) What’s a twin-screw?
10.) Is it possible to put a turbo and a supercharger? If so, why has no one doen it? Fitting it all under the hood maybe?

 

ill try to answer a few.

1)When they are talking size of 1 pulley, they are talking about improving boost by changing out the stock blower pully

2)Yes

3)Dont know too much about wheel hop

4)Dont know much on that either.

5)I think you are thinking about an intercoller which is a heat exchanger, the heat goes through basically a rad.

6)Intercoolers cool the air after the blower cause when air is compressed it heats up. Colder air is more dense so you can get more air in the motor at a given time if its cooler.

7)Yes if you step on the brakes and put it in gear and floor it you will do a burnout. Rear wheel driven cars, front wheel drive cars you would use the e brake.

8)Wish i owned one to tell you

9)Twin screw is a super charger, its positive displacement so it can really put out some boost, others are usually centrifugal.

10)Dont know on that one, but if your thinking these things you definetly got more money than me

Sorry i didnt know them all, someone will jump in here though.

 

9....is 2 girls that look alike screw'in you

 

1) A 2.8 pully refers to the size in diameter of a supercharger pully. The smaller the pully the faster it turns the blower. 2.8 pully is the most common for Cobra's

2) Thats correct. Its commonly refered to as a boost gauge.

3) '03/'04 Cobras get wheel hop because of the Independent Rear Suspension. Im pretty sure that rwhp has no affect on wheel hop or over powering your tires. Wheel hop is when traction is lost and regained in rapid cycles after power is applied to the rear wheels. It indicates a need for different tires, better shock absorbers, better springs, better axle control, different driving technique, or all of the above.

4) Im not to big on the porting thing right now but I do know you do it to lower intake temperature and colder air means more boost because the air is more dense.

5) Have to get back to you on that one...

6) An intercooler acts like a radiator of sorts, except that instead of being used to remove heat from engine coolant (by running the heated coolant through tubes in a core and moving outside air through and across that core), it's used to cool the compressed air from a supercharger or turbocharger.

7) You are correct for the most part. When you apply the brakes you get 70% stopping power from your front brakes and the rest from the rear. So when you're doing your burnout, its a good idea to just barely hit the brake... just enough to hold the car still.

8) I have no clue on this one. Havent taken one on a long trip.

9) A twin screw is a type of blower. There are 2 basic types of superchargers used in kits today, centrifugal and positive displacement. Centrifugal superchargers build boost relative to engine RPM. The higher the RPM, the more boost they build. Most of the 6psi to 9psi centrifugal kits don't build any measurable boost until about 3,000 RPM. The higher pressure kits will start to build boost at lower engine speeds. Higher pressure, inter cooled, centrifugal superchargers work OK in full race applications on an engine with a high RPM power band. The street kits can be disappointing. There are good reasons that very few professional race teams in only a few types of races select centrifugal blowers. They are certainly better than no blower and they will give you the peak power gains.

There are 2 types of positive displacement superchargers used in kits today. The older and more common type is the Roots. This uses 2 counter rotating lobed rotors to force air into the engine. The 2 rotors are either identical or mirror images of each other. The other type is a Lysholm, or screw type. They use 2 counter rotating rotors much like those in a Roots except the 2 rotors are different than each other and the lobes are twisted from one end to the other (like a screw). One is male and the other female. Both of these superchargers types (Roots and Lysholm) act much alike as far as boost characteristics. Both force air from the inlet to the outlet in a positive way, not just from centrifugal force. These superchargers build boost right off idle and keep that boost all the way through the RPM range. They will give you large torque gains and you will get these gains throughout the RPM range. These kits are great for daily drivers and tow vehicles, as well as race applications. In fact, top fuel dragsters use Roots or Lysholm blowers. Historically, more supercharged race applications use Roots blowers than any other type. Ford, GM, Mercedes, Aston Martin, and Jaguar all chose Roots or screw blowers for their OE applications as well. As you can probably tell by now, my personal preference is a positive displacement supercharger. Eaton makes the best Roots supercharger for late model applications and kits. See my Superchargers page for Eaton based kits. Autorotor makes Lysholm superchargers used in Kenne Bell and older Whipple kits. Eaton began making Lysholm (screw) blowers and Whipple is not the distributor for those blowers to the aftermarket. The Lysholm blower is more efficient under boost than the Roots. This results in lower exit air temperatures and less ping. However, they will typically draw more power that a Roots when not in boost assuming both types incorporated a bypass valve in the system. A bypass valve should always be used with any positive displacement supercharger for street applications.

10) Probably not im guessing. I dont know if it has or hasnt been done but im sure it takes a lot of money and time. Most people go for one or the other.

 

JD Nice definition for #9.

#10) yes it is possibly. Detroit Diesel use to make turboed supercharged 2 stroke diesels. The supercharger was a gear driven (instead of belt) roots supercharger. There was an intercooler on top of that, then a turbo. I think it would require quite a bit of math to figure the correct amout of boost to run on each to make them efficient, nevermind the stress on the motor that amount of boost would create. I don't think having both would be practical, but it can definately be done.

 

Wow, thanks for both replies you guys. Jdaniel, your twin screw explenation was immaculate, thanks.

And by the way, no way on earth I have enough money to invest into trying to use a turbo and supercharger. I am just a curious person into this type of stuff (the perks of an engineer at heart). I was however talking with my dad on how to physically but both types on. Obviously there would be simply be a room problem. But, if you can somehow synchronize the two systems to always put out the same pressure, then maybe you could connect the two outflows into one tube. The diameter of the two would need to be the same as well. Now is this even feasable? After all, you can only force so much air into the chamber. I would think this would simply be overkill and a waste of money. Correct me if i'm wrong.

 

Any time.

 

I'm not going to say this hasn't been done either. However, there is no point in it. While street cars seem to run the popular SC like avortec, that hangs off the engine. It is my understanding that turbo's make the most overall horse power. It takes extra time to spin them up, and benifit from the boost, unlike a roots type SC. But since the exhaust gas is driving it. It is as close to free horse power in a forced induction, that you can get. No parisitic drag like any thing belt driven.

Anyway, for cost and simplicity, I plan to go the belt driven route. With the Mustang already torque heavy low end. The vortec style systems seem my best choice.

Best of luck !!

 

What do you mean by "parasitic drag"? And by the way, if I had an 03 Cobra for example, I would certainly put a SC on instead of a turbo as well. From what I have read, they seem like the right fit for me.

 

parasitic drag refers to any device driven by the engine crankshaft that takes power away from the driving wheels, this includes things like water pumps, engine cooling fans, alternators, power steering pumps, smog pumps, superchargers, external oil pumps, etc etc.