Superchargers 101 - Introduction to Superchargers

[ttocs]

if I am not mistaken the intake of the supercharger is under vacuum when the supercharger is turning?

 

[MustangChris]

Clear, thanks. But as long as there is vacuum, the supercharger is not doing it's job.

Reason why I'm asking: my car isn't tuned properly and it takes an effort to get it to boost. I'm getting more convinced to do something about this.

correct. Although it's not doing its job at that exact moment. Some blowers (centrifical or turbo) require boost to "build" or climb. Then they peak out at a certain PSI. Before the blower can fully "catch up" to the demand of the motor, you will still be in vacuum.

if I am not mistaken the intake of the supercharger is under vacuum when the supercharger is turning?

the supercharger will always "be spinning" so long as the belt is still attached. Some cobra owners have snapped a belt and the vacuum of the engine is strong enough to rotate the lobes of the blower and run as a poorly-built naturally aspirated car ... lol.

 

[warthogdriver]

Ok...newb question.
I am planning on running m112 on stock 99 v6 with a 25%udp to keep boost down. Will i really have a heat issue at the low boost i will be running?

 

[MustangChris]

Under-drive, or over drive?

OEM M112 pulley size for 03/04 cobra is 3.65" -- a 25% over drive would put you at a 4.57" top pulley (or you would have to change the lower pulley.) This would lower boost, lower heat, lower RPM, etc.

An under drive on the blower would put you at a 2.74" upper pulley (or you would have to change the lower pulley.) This would increase boost, raise heat, raise RMPs, etc.

to lower the heat of the mighty eaton you need to ensure the lobes are heat-coated (black coating), the *blower* is equipped with over-drive pulley (or crank is equipped with an under drive pulley), or use artificial cooling methods (Meth.)

 

[warthogdriver]

Ok...sorry left out some info.
Eaton has the stock pulley
crank will be the 25% udp
the coating has been removed...guy i got it from was running meth so he removed the protective layer on the eaton.
If i get what your saying is i should be ok for now till i build the engine up down the road.

 

[Orange 94]

Ok...newb question.
I am planning on running m112 on stock 99 v6 with a 25%udp to keep boost down. Will i really have a heat issue at the low boost i will be running?

Ok...sorry left out some info.
Eaton has the stock pulley
crank will be the 25% udp
the coating has been removed...guy i got it from was running meth so he removed the protective layer on the eaton.
If i get what your saying is i should be ok for now till i build the engine up down the road.

This sounds like my setup except I have 4.2 splitport.
How low is low boost?

I removed the coating (which btw will reduce boost), then I put a 2.93 pulley on the m112 because of the reduced boost from removing the coating and hood clearance. I have a 25% under drive pulley. My bottom end is stock. Its running at 9psi.

I ran with out meth for a year. It was fine, but after the first pull you lost a ton of power from heat retarding. If I put my hand on the supercharger it would be very hot.
I put on meth and it made a huge difference. I can do a bunch of pulls, pop the hood and place my hand on the supercharger. Not hot at all.
I strongly recommend putting meth on.

In the future I want to put on a different underdrive pulley to reduce boost slightly which will decrease temp and result in an increase of power.

 

[Orange 94]

This is for pro charger, but it gives a really great animation for centrifugal superchargers for people who are new to superchargers!

[video=youtube;ImvM5N-H-10]http://www.youtube.com/watch?v=ImvM5N-H-10[/video]

 

[D3VST8R96GT]

Spraying meth before on a roots....

The meth will cool the rotors and if you have intercooler it will sap anything left.

Id spray it in the lower intake with dual nozzles ... maybe have a third nozzle per blower. Lots of Lightning and cobra people doing that.

The D3V

 

[ttocs]

I thought I had heard people doing a small shot of NO2 on blowers? What is too all know there good/bad. Again thanks for all this info perfect time as I am looking for the near future.

 

[95opal]

I thought I had heard people doing a small shot of NO2 on blowers? What is too all know there good/bad. Again thanks for all this info perfect time as I am looking for the near future.

If your looking at nitrous as a cooling agent yes been done over and over but not very cost effective for a street car. You can slap a 50 shot on there to see how it goes but meth is a better bet for sure

 

[Win]

If your looking at nitrous as a cooling agent yes been done over and over but not very cost effective for a street car. You can slap a 50 shot on there to see how it goes but meth is a better bet for sure

Agreed way way more cost effective... We have a member/former mod that works for Devils own and can get you a good deal on a kit!

 

[mcglsr2]

Nice write-up! A couple corrections/suggestions/clarifications:

Superchargers 101 - Introduction to Superchargers


And because of the way superchargers work, they provide power only when the engine is under full throttle or under load... not under normal cruising conditions. This means that the supercharger will not affect the engine's reliability, longevity, or fuel economy under normal driving conditions.

For the most part, true. However, the engine is still rotating the pulleys/gears, so some N/A power is being used regardless. Depending on your driving style, it might not be noticeable, but it is not a free lunch. There is additional friction there, boost or no boost.

Supercharger Impeller Boost is created at the point when the supercharger's internal impeller pushes enough air through the blower to overcome the vacuum force naturally created by the engine's air intake, so air is being forced, rather than pulled, into the air intake. Boost is measured in pounds per square inch, or psi. More boost equates to a more dense air charge into the engine's combustion chamber, which allows the engine to burn more air and fuel and create more horsepower. Most street superchargers produce somewhere in the range of 6 to 9 psi, meaning they produce 6 to 9 additional pounds of pressure over the atmospheric pressure at that elevation (at sea level atmospheric pressure is 14.7 psi).

You mention it here regarding atmospheric pressure - typically this is expressed as psia (psi atmosphere). A gauge shows psig (psi gauge), which is the boost OVER atmosphere. It is typically accepted that when someone talks about the boost they are making and psi, they are really talking about psig - though it's usually expressed as psi.

Another concern some people have towards using a supercharger is that they think it will increase the engine's compression to the point that it will cause detonation inside the combustion chamber. Detonation exists when the combustion pressure is raised so high that the inlet charge ignites itself before the spark plug fires.

What actually causes detonation is heat, not necessarily the pressure. Heat is a function of pressure, and the efficiency of the boosting mechanism (supercharger or turbocharger). As air is compressed, heat is generated. In a low boost situation, the denser air easily compensates for the added heat to the intake air temp, so one sees a positive effect of boost. As boost is increased (or the boosting mechanism strays out of it's efficiency range), more and more heat is imparted into the air stream. So even though the air is denser, it's much much hotter. The hotter air, coupled with less room in the combustion chamber to move around (because of denser, thus more, air in there) is what causes detonation. If one could cool the air (via an intercooler for example), then much higher boost pressures can be used (and thus higher pressure) without fear of detonation. There are limits of course.

Vortech, Paxton, and ATI (except ATI's and the new Vortech SL self-contained systems) all use the engine's oil to lubricate the step-up gears and keep heat and friction to a minimum.

For systems that use the engine's oil, it's a very good idea for the owner of these vehicles to use synthetic oil (if possible) and increase the frequency of oil changes. The oil is used to lubricate the supercharger, but also some heat from the supercharger will transfer to the oil, heating it up more. This will cause the oil to break down faster over time. In boosted applications that use engine oil (superchargers and turbochargers), oil is the life blood. Change it more frequently.

Intercoolers and aftercoolers cool the air after it has been discharged from the head unit and before it enters the intake manifold. The cooler air provides a denser air charge which can make added horsepower, especially under higher boost conditions. Intercoolers and aftercoolers, while popular for racing applications, are not normally needed for street drivers running 6 to 9 psi of boost.

Personally, I wouldn't say it this way - rather, the plumbing challenges with adding an intercooler are typically the reasons an intercooler is left off (and cost of kits). If one was made out of money, ALWAYS use an intercooler. The enemy is heat. Even at 6 to 9 psi, heat is being generated. If you could run this through an intercooler, you would reduce the heat (and probably pick up some power for "free"). It's *safe* to not use an intercooler at 6 to 9, on a low compression engine like ours (around 9:1). But if you raise the compression ratio, or you run more boost, you will have more heat, and potentially more problems. You can handle this via the engine tune and timing (as newer cars with higher compression ratios and no intercooler do) or via an intercooler. Any car that is serious about boost really should have an intercooler or some other form of cooling the intake charge.


Good job man, thanks for taking the time to write this up :thumbsup: