Acceler8

Blower: 2100
No injector change
Chip: 600
No intercooler change
plumbing: 400
mounting: 500

now thats for 5psi
roughly 415 whp.
If you go above 5 its recommended to adjust timing, upgrade to a 2core intercooler($1000+), and move to higher lb injectors.

PaulW

First off, you have 310 flywheel HP, your calcs show 519 HP, that's a pressure ratio of 1.67.

14.7 PSI time 0.67 = 9.95 lbs of boost

So you'll never get 519 flywheel HP out of your 5 PSI of boost.

BTW, you state that you'll have an additional 34% increase in HP, but what you didn't tell the program is that 310 HP is your flywheel HP, not your wheel HP....that's why it came up with 5 PSI (1/3 of an atmosphere) for a 100 HP increase.

Do you know what the fuel pump flows? It's got a shut off head of 60 or so PSI, so you can't use a rising rate fuel pressure regulator.

Stock injectors are about 20lbm/hr, and that will support about 300 HP, maybe a little more. So right now they are at a 85% + duty cycle.

How are you going to increase the fuel flow to the cylinder? That's the only way that you'll get more power is to shove more air in there, which will require more fuel.....but your stock injectors won't flow the fuel because they are too small. They need to be replaced.

No Intercooler? You have a 11:1 CR engine. On a 90F day, the heat generated from CR alone puts you at about 1076 degrees absolute. You have very little margin above that to prevent detonation.

If you put 4 PSI of boost in there with a roots style blower, you'll probably add about 50 degrees absolute and you'll be in detonation land.

And detonation is the DEATH OF ALL FORCED INDUCTION MOTORS.

A centrifugal compressor has a higher efficiency, use a 85% efficient intercooler, and you can blow 7 PSI with a 5-8 degree absolute temperature rise, which will keep you safe.

Can you tell I've researched this a little?

Acceler8

A rough starting estimate to calculate HP gain is to take boost (say 5psi) and multiply it by 7% (a constant) to get your approximate power gain (in our example 35%). Why 7%? Because 7% is approximately how much more air and fuel gets into the motor with each pound of boost that is added by the blower. To get a more exact figure, take 1psi boost and divide by normal atmospheric pressure, 14.7psi at sea level. 1 divided by 14.7 equals 6.802%. Under ideal conditions, you can expect to burn 6.802% more fuel and air per pound of boost.
Im not saying you arent well versed in the relm of 4.2L engines. Im just throwing out something that i havent seen yet.

Acceler8

Your Entries:
Existing horsepower: 310 flywheel HP

Planned level of boost: 5

Planned fuel octane rating: 92

Intercooler / Aftercooler None

Estimated Results:
HP Loss due to timing adjustment: 0
Est. flywheel HP with supercharger: 415.4
Est. rear wheel HP with supercharger: 332.32
Total HP Gain: 105.4 flywheel HP
Percentage Gain: 34 %

Acceler8

Forget this crap. the car is great ..... buy a Subaru WRX STi

PaulW

I did not take into account the loss of boost from not having an intercooler into your calcs....

You can't do this project for $3K in parts, there is just no way.

Acceler8

the cost and work seems excessive due to the limited reward.

docmusolf

studied their requirements. I was planning on building a 951 track car before I bought the 8. In many cases turbos are harder to design. But the design work has already been done with the RS6. I think that to replicate that you would be way over the 8K range that Paul is talking about, may be double that. Paul is on the right track and the cost are spot on.

Acceler8

was switch my intake manifold(aan), replaced my cams and cam gears(schrick), installed s2 ecu, changed exhaust(scorpion cat back) w/custom downpipe. I added custom wastegate and BOV (dahlback). I did nothing to my intercooler but change my plumbing. Almost all of this is problematic for the A8 because the S8 isnt a turbo car. The S2 was almost a carbon copy of the CQ. In total, it cost me around $3000. I was hoping someone found a way to transplant the rs6 turbos. Its the same engine, isnt it? Im still relatively new to the car. I had my CQ for two years before i did anything other then suspesion to it.