ok i never really did understand the method or reasoning behind using 2 positive displacement or roots style superchargers. i believe one of the Aston Martin Vantages uses a twin supercharger setup and i have also seen a new challenger using 2 twin screw kenne bells.

i really have no idea why this kind of setup is used of if there are advantages to this method. i dont really think its just for looks and novelty if Aston Martin used it on the v8 vantage but you never know.

heres the double twin screw challenger
http://www.autoblog.com/2009/01/05/1-000-hp-twin-supercharged-dodge-challenger-by-rdp-motorsport/


please discuss thank you

 

That is a "bit" over the top in most cases, perhaps hood clearance? I know Mike Sitar of toohighPSI fame did it because he couldn't get the required CFM for a 5L with an M90, but that is working the JY too. I mean shit they make a 3.3L twin screw and if that isn't enough you can get a 14-71 which is almost as big as the engine it's on. Wonder if the nitrous is actually hooked up and used at all...

 

Like this lol
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For the power he said he is making I don't see why he would need 2 blowers. The wow factor is definitely there and so is the this thing must suck to drive on the street because I can't see shit around my blowers factor.

 

No matter how outdated and how much power those blowers (don't) make, they still make me smile every time one starts up.

Now don't go off and tell me how much they do make, we aren't talking top fuel here, we are talking street cars......

 

I'd bet money that thing would make more power if you took one of the superchargers off. Wouldn't be surprised if one of them was just a hollow case with no rotors inside.

 

Jerry Magnusom was one of the very first guys to use a pair of small Eaton superchargers and make some power. He did this by designing his own supercharger case that fit two sets of rotors in a "Pyramid" shape. Each supercharger was at a 45 degree angle.

Here are some pics of an old unit from the H.A.M.B. website:

http://www.jalopyjournal.com/forum/showthread.php?t=152117

He did this deal 25 years ago. (1984)

Now Mike Sitar used two units but mounted them individually. Dual capacity but not as
much "WOW" factor as Jerry's deal.

As was said, they only made a few smaller superchargers (like the roots 4-71) in the old days. The Eaton units were maxed out at 90 cubic inches of volume per revolution.
Jerry made a very cool street rod intake with his deal but it was expensive. Bob Roese who used to be the "track Guy" for Vortech Superchargers) now is Jerry's right hand man. .

Tom Vaught

 

so im guessing this setup is used to flow more CFM easier? maybe like moving up from a 76mm to a 80mm with same psi but better flow rate?

wouldnt there be twice the parasitic loss using 2 superchargers?

 

About 2 blowers in series, if they both displace the same amount per revolution and they both turn at the same RPM, isn't one of them not doing anything?

 

You're on the right track... for clarity, you're not going to move more cfm through the engine unless you do something to change the engine itself, (heads, cam, intake, etc.,) but if two superchargers happen to be more efficient than one supercharger, you may produce equal boost with less heat generated. Remember, heat tries to make air expand; if it can't, the pressure rises. So what you may see is an increase in mass flow, a reduction in intake temp, and more power at the same psi. This can happen when people increase the size of their turbo, as in your analogy.

It's quite possible.

 

so there is some benefit to using twin superchargers? like in the case of the 93-2000 aston martin V8 vantage
http://en.wikipedia.org/wiki/Aston_Martin_Virage where its 5.3 v8 pumps out 600 hp 555 tq

but would the benefit outweigh the twin parasitic loss? or maybe there are ways around this?

 

The Eaton 122 cubic Inch per revolution will barely make 500 hp.

Some of the larger screw stuff from Whipple or Lysholm as well as the TV (Twisted Vane Eaton stuff will move 2.3L per revolution. 3.3L/ 3.4" 4.0L and 5.0L screw stuff is available.

Basically it has to do with the capacity of the unit and PACKAGE. A TALL unit like a 2.3L screw might not have fit but TWO smaller units did fit on the Aston Martin. There is ALWAYS that PACKAGE DEAL.

Tom Vaught

 

See Tom's post above.

The twins may or may not be more efficient; to determine that would likely require testing on a case-by-case basis.

I'm not sure why Aston Martin went with the twins. If I had to guess though, I'd think there was some novelty in being able to say "twin supercharged." Probably helped sell a few cars for a (relatively,) unknown marque.

 

I guarantee you that the total volume of 2 blowers that will fit under the hood of a vehicle will be considerably larger than the volume of one blower that just barely fits.

I can think of plenty of engine bays that will easily swallow twin 2.3 W140ax's, that would never have a hope in hell of fitting a Whipple 4 or 5 liter blower.

With a low hoodline like that V8 Vantage, there was no single blower that would have squeezed under that hood and had the volume to produce 600hp.

 

Just another comment, Aston Martin was owned by Ford until the last few years.

They were looking at doing a HIGH Horsepower engine for several years.

I have some photos somewhere at work of a Centrifugal Supercharged system I designed for the Aston Martin that was capable of 800+ horsepower and FIT (not under the hood but in front of the engine). There is a "hole" in the front of the engine bay on the passenger side.

THINK STEVE MORRIS REVERSE F-3 TYPE BRACKETS BUT WITH A SMALLER SUPERCHARGER MADE BY A TURBO COMPANY.

We did some initial dyno work on the engine but later dropped the project for other work when it was apparent that Aston Martin would be sold.

Tom Vaught

ps We also built a V-12 engine with 4 turbochargers (one for every 3 cylinders).

 

Rotrex supercharger? I think I've seen pictures with holset cast into the compressor cover of them.

 

no not rotrex but roots style like eatons and whipple screw types.

i know why 2 rotrex centrifugal superchargers are used. they flow very small amounts and need 2 units to get a decent amount of hp out of them.

 

Although it wasn't utilized in the above example another possible advantage of dual superchargers would be belt surface area. Two 112s could make 800Hp no problem with a standard 6 rib belt. With a typical sized crank pulley they would have somewhere between a 3.5 and 4" pulley providing plenty of "grab". This elliminates the need for a larger 8 rib or 10 rib system that consumes more space. This of course falls into the packaging catagory Boost Engineer brought up.

 

The supercharger in my Aston Martin story was made by Bord Warner Turbo Engineering.

It was very similar to a Vortech "T" Trim reverse rotation supercharger like used on the modular Ford Engines. It utilized a special gearset that was supposed to be extremely quiet vs the normal Vortech or Paxton units. Durability and NVH issues with the gearset is what killed the project. No, it was not a pair of rotrex units but I have tested those units. They have a very high "step-up ratio" (about 10 to 1) but the average unit will not make very much real horsepower, as the larger the compressor wheel that you use the more potential slippage you have with the roller design that they use in their units. A photo is in this link:

http://hotrod.automotive.com/81380/hrdp-0512-rotrex-supercharger/index.html

You will notice that the drive shaft in the center of the unit is quite small with minimal surface area. If the shaft sees a high load (trying to drive a large lbs/min compressor wheel) the shaft may slip. If it slips very much the surface is damaged and the the unit will slip more and more over time.

The Rotrex unit has it's place in boosting but a 800 hp Aston Martin was not the case for
this story.

Tom Vaught

 

^^^ Yes spinning two superchargers would be twice the parasitic loss in power. I have seen where top fuel funny cars like John Force useing The Blower Shop Superchargers take 800 to 900 crank HP to spin the blower on a 5000 HP motor. My tunner did a compound setup on an 03 cobra running a 76mm turbo through the eaton supercharger, the car made more power with just the turbo than the compound setup becuase you can only move so much air through the supercharger before it starts backing up the turbo, a 2.3 L blower case with rotors will only move 2.3 L of air no matter how much you try to force through it. With the compound setup it made 672rwhp, he took the blower off and replaced it with one with no rotors in it and the turbo put down 786 rwhp thats 114rwhp more than the compound setup.

 

I've never seen the inside of one, that's pretty interesting. Thanks for the link.