Contour Enthusiasts Group Archives Forums Modifications Forced Induction blower options

Originally posted by Alphatour:

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I was wondering how turbos work, is it just the air flow? Would there be a way to install a high powered fan, i know they make fan blowers with 400cfm and more, could you just hook one up and run it like that with a switch or something?

Alpha

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Its a logical question, but the answer is NO and it is not altogether simple to understand. If you aren't exposed to turbo technology then you aren't going to know all the ins and outs about it. Do a little reading of the old posts in this forum to help you understand. Search on the internet.

The bottom line is that turbos are spun by the exit of the exhaust through a pipe as it goes out the engine. This is supposedly wasted "free" power.
Simply put the exhaust has momentum and you can harness that energy to compress air on the intake.

Now look at your electric blower. It moves a lot of air, 400 cfm, but it does it at very low pressure. If you put that air into a pipe it will create pressure on the fan and the fan will no longer be able to flow the 400 cfm.
The motor will have a voltage and a current requirement and we can use that to estimate the power capability of the electric fan.
If an electric fan pushes 400 cfm at 1 psi and runs on 12 volts at 50 amps, then it will use 600 watts of power. Thats about 0.8 HP to get 1 psi of boost.
If you have an engine that produces 200 HP at atmospheric pressure = 14.7 psi, then you boost it by 1 psi, what is the gain? 15.7/14.7 = 1.068 this is the ratio of pressure increase. All else being proportional, you would get a 6.8% increase in power, for a grand total of ~213HP.

Now take the drivetrain loss of 18% (1-.18=.82) * 200 and you get 175 HP to the ground. What did you have before?
200 * 0.82 = 164 HP.
Remember, this is highly optimistic and you will likely gain less than ~6-7% power.
You had to add the extra fuel to go with the extra air going into the engine in order to make the power.
You have to decide if more wear and tear on your alternator is worth a net gain of 6.7% and at a cost of $250.
The problem with the electric fans is they cannot push the required amount of air at the required amount of pressure.
I used 1 psi because that is the average pressure of the eRam and others that I have seen. Two eRams at a cost of $500 nets you 1.5 psi, and so on and so forth, to the point where more money is pointless for the gains it gives you.
All that money is better spent on an exhaust that is always there, doesn't take horsepower from the motor, wear the electrical system, etc. and can make considerably more than 11HP in many cases.

So read up, I'm not in the mood to do any more instruction tonight. I'm tired!