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[Barry]

Greg,where are you? lets get going with all this.....

What is efficiency in turbo`s,intercoolers and plumbing??
What is better,small weezy turbos or big bad ones??
For that matter,superchargers as well??
How big a diameter must the piping be??
How long should the piping effectively be??
What is the more effective intake manifold to use on turbo`s??
What is the best grade of oil to use??
Forged pistons or cast pistons??
Std rods or fancy high dollar jobs??

I think we have all read Corky Bell`s book -Boost-So lets be original here-Nothing like first hand experience.

Let the games begin.......

[Mats]

Are you joking? We have like ten of these threads on the old forum...

I think it is very important to point out that there is no difference in the basic mechanics behind the process of maiking power, just that with boost there are a few factors that are a bit higher then usual.
So, the same stuff applies. forged rods/pistons is a good thing but may not be needed. Plumping is very much depending on the power output.

Keep all the "active" piping short and compact though, manifolds are really important to keep small, i.e. small exposed cooling area. Diameter can be kept smaller then similar N/A, you will have backpressure anyway so you might as well keep the gas speed up. equal length primaries are important and also a good collector.

size of turbo is very much depending what you are going to use the engine for, I use a small OEM turbo because I want the response and am ready to sacrifice the top end, I drive a lot of tight roads. If you ONLY drive between 4k and 8k with lots of full throttle you might wanna chose some other (larger) turbo...

I've thought about alternative fuels lately, here we have something called E85, (85% Ethanole and 15% gas/petrol) , there are many benefits such as higher octane rating, around 104 RON, cooler burn and such.
You need about 40% more fuel though, this means your tank is virtually a lot smaller and you need bigger pumps and injectors.

[Greg Gordon]

Mats, we can't continue the discussions in the old forums so it's a good idea to start this topic here and avoid hijacking other threads with forced induction tech stuff.

[Greg Gordon]

I get a lot of questions via e mail, one of the most common is regarding supercharger sizing so I guess I will start there. I will use Eaton superchargers for reference. Not because I am trying to advertize but because I am very familiar with them. Plus they provide great charts and stuff to help determine boost levels, power gains, losses, etc.

I don't plan to discuss my kit here, there are other threads for that.

In the case of the Eaton supercharger there are 4 sizes available. The M45, M62, M90 and M112. These numbers refer to the cubic inch displacement per supercharger revolution. Keep in mind since the number refers only too the internal rotor group displacement not all M62s, M90s etc are the same. There are 4 generations of the smaller units and 5 of the M112. Plus there are many variations within each generation. In other words a 4th generation M62 off of some production car is not the same supercharger as say the 4th Gen MP62 used in most aftermarket applications. Of course it's a lot different from a 3rd generation M62.

What size supercharger will you need? There are a lot of factors that come into play here. First of all how big is the engine and how much of a power increase are you hoping for?

Eaton provides very general guidlines about supercharger selection. They say the M45 is good for 1.0-2.4 liter engines, the M62 for 2.0-4.0 engines, the M90 for 3.0-5.7 engines and the M112 for 4.8-6.0 motors.

As a general rule you want to use the smallest supercharger you can for the required level of boost on your engine. This is because it's usually more efficient to spin a small supercharger fast than it is to spin a bigger one slow. Of course this is only true within certain limitaions. For one thing at a certain point the extra RPM of the smaller supercharger starts to cost too much in terms of power drain and heat build up. The bigger problem is the supercharger's RPM limit. For example if you have to spin it at a 3:1 drive ratio to get 10 pounds of boost and the supercharger's red line is 14,000 rpm you won't be able to rev your engine above about 4650 rpm without risking damage! That would be an obvious sign you need a bigger supercharger.

In the case of the 2.5 we really have choice of either the M62 or the M90. Both will work and both will fit. The same is true with the 3.0 and the 2.0 could use either an M45 or an M62.

To be continued, it's time to go to work at my real job.