sizing a supercharger?
 

how do you size a supercharger to an engine? I notice that the whipple 1600 ax displaces 1.6ltr, which roughly half the size of our 3.3 ltr motor. Would you want to use a supercharger of the same displacement?

Re: sizing a supercharger?
 

Supercharger manufacturers make 3d plots of supercharger output. The whipple twin screw supercharger is a positive displacement blower meaning that for every turn of the input shaft a set amount of air is intermeshed between the rotors and forced through the blower. In the 1600 ax the set amount of air is 1.6 liters. The input shaft of the blower is spun by a belt connected to the crank pulley. The size of the pulley on the input shaft of the blower is sized as a ratio of the size of the crank pulley to spin the supercharger at the speed you want in order to force the correct ammount of air through. The size of the supercharger you need is a function of how fast you will be spinning it, how much air you want to force through it (how much horsepower you want), and the size of the engine which as a ratio to the amount of air you are forcing through the supercharger determines how much boost you are running (pressure in the intake). You're actually after a quantity of air not an amount of boost but as you force a quantity of air unfortunately the pressure goes up and makes life hard on us. If you look at the magnuson products website you can find their 3d plot of supercharger performance for each model. Their plots are fairly simple to read because they sell a lot of supercharger head units to people who make their own systems. From the plot you can see there is an input shaft speed and boost area where the supercharger is most efficient. You want to size your supercharger to produce the amount of power you want when run in that efficient range.

I don't think whipple even provides plots of their supercharger performance because they don't really sell bare head units to the common installer. You have to go directly to lysolm who has the intellectual property rights and does the manufacturing. Whipple superchargers are actually lysholm superchargers. Because they could care less about you buying a supercharger their plots are not very easy for you to read. The ideas are generally the same though and the information is excellent. Because twin screw superchargers are much more efficient at higher boost levels the output you will get from a twin screw compared to a similarly sized roots will be much higher. You'll won't get any nice little cfm graphs to go plug into your turbo calculator though. The lysholm engineers don't know what a cfm is and could care less about selling their products to someone who doesn't know how to do the math themselves. They aren't much into psi either. You'll see #'s like 1 2 3 on their plots which are ratios of atmospheric pressure.

Re: sizing a supercharger?
 

To put it easy. The engine consumes about 1600cc of air per revolution. So a blower that pumps 1600cc per rev, will only supply the engines needs, at a drive ratio of 1 to 1. If the blower is driven at twice engine speed it will pump 3200cc per rev, to supply 14 lbs of boost, less this, that, and a bit of the other. :)

Harvey.;)

Thank you Harvey he was a little confusing

Sorry :) I didn't mean to be confusing. You'd have to actually look at the plots to understand what I was saying though. If he's actually interested in sizing a supercharger he'd want to do that.

Longass...
 

I really appreciate what you are doing to the EG33 as mods. In my opinion you should be really nominated as the SVXer of the year 2004. your engine mods are really impressive in terms of making the impossible being made possible. comparing it to the bodykit, a bodykit can be easily made, any handy guy can get fiberglass or carbon fiber and do it, whereas it requires a real genius to tune up an engine correctly...
the thing is that most of us are not really deepened with mechanics and ECU readings and stuff... not all people know that but they know when they see a body kit that it is made either in fiberglass or carbon, and molds are used to do it... but mechanics is a vast world, most people know around 20% of it (like i do, i know a lot of stuff but not deep enough to understand a 100% the mods you did on the EG33)...
so the bottom line, we are eager to reach this 100% knowledge about your mods, if you can really resume them along with pictures in a thread in an english description rather mechanical english one....(like in the movies when the boss doesn't understand the achievement of his employee he says:"... does somebody speaks english around here?...) it would be helpful for us and beneficial to you... (people will then understand the mods you did and as a basis demands for it will grow = $$$ to u :D :D )

Re: Re: sizing a supercharger?
 

ok, so. The enine under normal condition uses 1.6ltr of air to function, and with this model supercharger we are forcefeeding it twice the volume of air per revolution?

Re: Re: Re: sizing a supercharger?
 

Yes, if the blower is driven at twice crankshaft speed.

1:1 = 0 boost
1.5:1 =7lbs boost
2:1 =14lbs boost
Harvey. ;)

Re: Re: Re: sizing a supercharger?
 

That was just an example he was giving. I don't have either the supercharger performance plots or the completed math in front of me so I can't give you any simple to understand #'s. The actual math is pretty complicated compared to thowing out a couple #'s like that so without the results it's hard for me to make it simple for you. I have a couple of pulleys on hand for when we first start the car up. Both are pretty aggressive, I think one was about a 1.6 ratio and the other a 1.8 ratio. It's been a good while since I did the math so don't take those ratios are gold.

As I remember the math I used to decide on our drive ratio began with factory peak power and the ve at that rpm to determine air ingested and the power derived from it. From there I think I threw in the power level desired compared to peak power to get a multiplier for the air ingested to produce an amount of air injested that would produce around the power output desired. Then I did something like determine the ratio of atmospheric pressure that amount of air forced into the engine would produce. (somewhere around here a power correction for predicted ignition advance decreases was done) Then looked up in lysholms perfromance chart what input shaft speed would drive that amount of air. Then took that as ratio of max rpms as our peak power will now be at max rpms. My math was more ellegant and correct than this but just throwing out most of the variables used and roughly how so you can get a vague idea of how it is done if that's what you are looking for.

If you are looking for the final result, to give the simplest answer possible..........It's plenty big and will produce lots of power efficiently.

No No He just shaved off the 5o'clock shadow so to speak.(slight realignment that made it All clear)