I have been researching FI for the past two months or so, and while I have a little time before I am going to make my decision, I've got a few questions for some people with first-hand experience.

At first I was leaning the turbo route, but I think SC'ing is the way to go (at least for me). I do not need extraordinary power gains and I want to stay as stock as possible. Tuning is another thing that scares me.

My question is related to SC tuning, specifically with the Comptech unit. How much tuning is involved? From what I understand, it is plug and play but we all know that is too good to be true. With the hardware that comes with the kit, what can be tuned? Is it necessary to get an AEM EMS or an Emanage? I understand the huge importance of properly tuning a turbo setup, but how about a SC? Any advice would be greatly appreciated!

 

If you use only what comes out of the box, there is very little (if anything) that you need to do for either the Comptech or the Vortech. About the only thing you can do with the Comptech is to adjust the fuel pressure regulator if you determine that the A/F is not quite right. The vast majority of stock kit owners just bolt the thing on and drive away, never to look back.
If you intend to track the car and use it at or near its limits, then you are well advised to put it on a dyno and know how it's working. To do further "adjusting", you'd have to get either a stand alone ECU or a piggyback.

 

Another option would be additional injectors and an independent controller for them as seen here.

 

Absolutely not necessary whatsoever. I am sure this is not a commericial post by any means

 

So I strap on the supercharger, fire it up, and assuming my mechanic skills are worth something, it should run smoothly...no additional tuning, no need to worry about an A/F ratio of 18?

I also have a question about the drivability. I am familiar with a turbo setup, where boost is completely variable at all rpms, depending on throttle position. A ton of tuning is necessary to get the right mixture at all rpms and throttle settings. How about with the supercharger? No matter the throttle position, the blower is always providing x amount of pressure at y rpm. How is this handled at part throttle conditions. How and when does the system know to vent out the BOV?

Also, when I am cruising along at 80 mph in 6th at 4500 rpm with barely any throttle application, what is the system doing. A turbo wouldnt be doing much, spinning of course but not significantly boosting. With the supercharger setup, the blower is spinning at a constant speed but is the BOV open venting the unneccesary pressure?

Sorry for the abundance of questions. I've got about 50 more I could ask but I'll wait for some responses. Feel free to write a book-length response back to me...i need some nice posts to read here at work.

 

If anything the Comptech kitswill run rich at the settings they come with. 10-11:1
Partial throttle is smooth with the SC.
BOV vents back into the system.

At barely any throttle you will not be building much boost if any at 4500.
BOV on the SC is not really necessary like it would be on a turbo as you cannot overboost. They do however help with partial throttle driveability. You will not see more boost that what you get at WOT and max RPM.

 

Is that needlessly rich? How does gas mileage fare after installing the kit with these numbers compared to stock. (Highway mileage).

How does the system control boost at partial throttle conditions? I've seen most pics of installs with a BOV venting to the atmosphere. Curiosity is my middle name today.

 

Stock = 240 miles per fillup

Comptech SC = 210-220 miles per fillup

Definite hit, but not too bad.

The sound is incredible. Sounds like a Boeing jet taxiing to the gate.

 

Yes it is. All in the name of safety. Listen to the great Xviper. Get your stuff tuned

Boost is not controlled like it is in turbo, it is only hidden from the MAP sensor via the ESM.

BOV to atmosphere is a 'style' thing for SC. It looks cool, sounds cool some would say. I think it is unnecessary and I have no room for it.

Xviper, please correct any incorrect statements I have made sir.

 

Asura, you know your stuff, too. No need for me to correct anything.
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An engine under boost develops added heat internally. It's important to richen up the mixture under boost to help keep the temps down to a reasonable level or you start to melt all kinds of things inside the combustion chamber. Fuel acts as a "quencher" (or cooling agent). You lose power whenever you diverge from stoich (14.7:1 a/f), where you have the most ideal combustion conditions to extract the most power from gasoline. However, this makes for a dangerously hot environment, so you richen it up to around 12:1 for safety.
Keep in mind that when there is little to no boost, the a/f mix is not too rich. It's boost, via the fuel management units, that cranks up the fuel when pressure is evident in the intake manifold.
If you drive sedately, out of significant boost, you still run fairly lean.
For example, when I put in 4.44 gears (an 8% change in final drive) and added the S/C, my highway mileage decreased by about 10%. I'm not saying that an increase of highway cruising rpm of 8% will decrease fuel economy by 8% but for the time being, let's just say it does for ease of calculation. So where did that other 2% disappear to? S/C? Well, hard to say. At highway speeds, my rpm is around 4500. This is just at the threshold of significant boost. I'll leave you to make any conclusions.
Boost in a turbo car is determined by the amount of exhaust gases, however, this is directly proportional to the throttle position. Therefore, in a sense, boost that gets to the engine is controlled by throttle position.
Boost in a S/Cd car develops by engine rpm spinning the blower. At any given rpm, the boost pressure will always be the same. Again, the amount of boost that gets into the engine is controlled by the throttle position.
I think what you're asking is how is the excess pressure handled, right? In a turbo, you have a wastegate and a BOV. The wastegate takes care of the amount the turbo spins and the BOV takes care of excess pressure before the throttle plate.
A Comptech uses a bypass valve to shunt the excess back into the pre-blower area. A Vortech uses a BOV to shunt the excess to atmosphere. In both cases, these valves are actuated by pressure build up in the pre-throttle plate area. Whenever the throttle plate is closed or almost closed, the pressure before it rises.

The two S/C kits are designed to only boost so much max (around 7 psi). Their respective relief valves are calibrated in a very specific way as is their fuel management units to see to adequate fuel pressure (and hence, a/f). Comptech uses a computer box that hides boost from the ECU. Vortech uses an extra computer box to also alter timing. All together, both kits were designed to work on an S2000 without further modification. Common sense would suggest that any owner of such a car take the time to ensure that all parameters are as they should be before driving into the sunset.