Considering adding a supercharger in the spring..

SC is a big project and you must be careful. when you detonate with a blower it is near death of that engine. Because you have more air in the chamber you will need more fuel. you entire fuel system needs to be upgraded. Injectors, regulator, pump. Ignition I hear can become an issue also but I'm not an expert.

Two guys garage installed a Kenne Bell twin screw on one of their shows and they put out 500 ponies. That is with a profession tuning that computer on the dyno. I think a dyno tune is a must when it comes to superchargers.

by additional do you mean 400 on top of the 300. You need a turbo and a race motor with a solid bottom end. Not to mention what your tranny will look like after a pass with that power.

Saleen sells their S/C for 5K. It only needs 5 to 6 PSI to produce 400+ HP and 400+ Ft/lbs. It's a postive displacment style blower so the boost will be there sooner than a centrifugal style blower (not that centi style blowers are bad). It also mounts where the current intake manifold sits so it looks a little more factory. (I am currently saving my extra pennies for one)

You really need to decide what your goals and use is going to be to make this decision. If you want to make big HP numbers at the top end and are primarily interested in drag racing the you may want to seriously consider on of the Centifugal S/C out there like a Vortech or ATI. If you are more of a occational drag racer but want to have the extra power available in a braoder RPM range then consider a positive displacement screw type S/C like a Bell, Whipple or a Saleen Unit. All these S/C will make good power they just do it differently - determine what you want to make for power and how you are going to use the car, then determine what you budget is and go from there - obviously to higher the goals the more extensive the modifications will have to be in the supporting systems of the car like Intake, Exhaust, Cams, Fuel System and Ignition.

It is a very rewarding endevour and you can have a lot of fun along the way but be sure you have access to a good tuner no matter which path you choose

Good Luck!!!

Hi Blairster,

This began as a quick reply but it quickly turned into a full blown (no pun intended) novel since every week someone seems to have the same question.
First of all don't believe everything you hear. For example the vortech factory 05 which puts out 575hp is running $25.00 a gallon fuel and ice water in the intercooler for a reason. A production vortech kit puts out 390-410hp

Sorry for the long post.

I have been researching a blower install since I received my 05 in April. At first I thought 500hp was possible on a stock bottom end.
Since then more and more stories of how many blown up 05's are out there have begun to to appear. It has dawned on me that the question is when rather than if you'll blow it up.

If you're serious about adding a blower you'll need a plan of attack.

Here is mine.

I will probably be building an 05 block with forged internals topped off with a Kenne Bell 2.4 either next winter or the following one.
This will allow me enough time to upgrade all the necessary items before adding more power.

It is foolish to add horsepower without increasing the cars braking and handling abilities.
I have already overheated and warped one set of stock GT brake rotors with my minimal mods.

I am thousands of dollars into my suspension already and still have a little ways to go before I am done.

Over the winter I'll be installing a Centerforce dual friction clutch and Fidanza aluminum flywheel to handle the additional horsepower.
Mine is already slipping even with my minimal mods.

My next upgrade will be 18 X9.5" wheels and tires. This is so that a Wilwood 14" big brake kit can be installed to stop the car with the additional power it will be making.

Once all these mods are performed then I'll be ready to install a blower.

This is the breakdown of my upgrades present and future in US Dollars.

Suspension $5,000.00
Wheels $2,000.00
Tires $1,300.00
Brakes $4,000.00
Exhaust $2,000.00
Clutch $ 320.00
Flywheel $ 320.00
Shortblock $5,000.00
KB Blower $5,500.00

Blairster said:

1) If I increase boost with a SC do I not also increase compression? And if this is the case do I not need a higher octane fuel?

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The opposite is true. You will need to reduce the compression ratio to somewhere in the neighborhood of 8.5 to 1 if you want to make big boost. With 94 octane you can probably make between 700-800rwhp with proper tuning and built bottom end.

Blairster said:

2) As I hope to own the car for a few more years what is the general consensus on a “reasonable” boost pressure to horsepower ratio?

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Keep reading and the answer will come to you.

Blairster said:

3) With the greater torque does it make sense to install heavy duty (Steeda has some) engine mounts to make up for that?

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The steeda engine mounts are recommended for higher horsepower applications as well as headers,centerpipe,upgraded clutch and flywheel,upgraded brakes, and upgraded suspension.

Blairster said:

4) is a rwhp goal of an add ional 400hp practical without toasting the motor?

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Just to be sure this is what you're looking for you want an additional 400HP?

There have been many discussions on the limits of the 05 engine and I will recap for those who don't want to put any effort into searching for answers.

The hypereutectic pistons and the cracked powdered metal concecting rods on the 05 are good for around 450hp. Even at these relatively low power levels they have been known to self destruct. It doesn't mean that they all will self destruct or that it will happen the first time you put your foot in it but there's a good chance you'll be replacing your engine sooner or later. I have even heard of one self destructing on it's second pass down the 1/4mi even though it was tuned on a dyno with close attention paid to air/fuel ratio.

At power levels over 450hp the fuel pumps are maxed out which can lead to a lean condition and detonation. Adding fuel pressure isn't the answer it's maintaining fuel differential pressure at all boost levels that's the key. Here's a tech paper on the Kenne Bell Boost-A-Pump theory of operation. It's an interesting and very informative read.

At power levels over 450hp the MAF runs out of voltage and a MAF such as the Diablosport Mafia or the Ford Lightning MAF is required.

At power levels over 450hp the stock crankshaft should be replaced for a forged cobra crank and at over 600hp a billet steel crank is required

Stock 05 aluminum engine blocks have been known to split at power levels over 600hp so a Teksid block which is good for 1200hp will be required. Custom engine mounts will need to be made to bolt the Teksid block into the 05.

Blairster said:

5) My preference is for the additional power to be spread evenly across the gears (that is how it is set up now), is this possible with a SC?

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Did you mean across the powerband from low to high rpm because you cannot change the way power is delivered depending on which gear you're in.
A twin screw supercharger is more linear than a centrifugal supercharger and is my personal preference.

I hope this answers all of your questions