Ian928

Hi all,

Again I have changed the plans for my Whipple supercharger project. The plan now is to blow into an air/air intercooler and have one throttle body on the intake of one plenum for each bank. To went excess pressure on deceleration I will use a similar system as found on WV G60's, where excess airflow from the supercharger is vented by another valve working in the opposite direction (open at idle but linked to the throttle so it closes when throttle is applied - forcing the excess air to enter the engine). I chose this setup because I wanted to use a air/air intercooler and still get good throttle response.

I have two Euro S throttle bodies at hand, and the easiest and cheapest for me is to use them. I believe they are about 80mm in diameter. But after the supercharger the air is compressed, so maybe these will be too big?

Thank you!
Ian

Imo000

Now that’s’ a different way of addressing the excessive pressure under closed throttle problem. There is the conventional way (Blow Off Valve or Bypass Valve) that will achieve the same results with a lot less hardware. Using a throttle body as a venting agent is interesting but you will have to run a reverse linked throttle cable. This might be a bit complex to achieve. I’m using a HKS Racing Bypass Valve for venting. Its’ located just before the air-to-air intercooler and it works fine.

dr bob

Pumping/compression effort through the supercharger is typically lowest when the suction-side pressure is lowest. If you can keep the rotors cool with minimum mass flow, consider putting a throttle at the inlet of the compressor to starve it for air on trailing throttle. A Vortech-type will suffer from surging if starved, but the Whipple should do fine thanks to the design of the screws/rotors.

Just a thought...

blau928

You should only put throttles in the INLET side of the Screw Compressor..... Using a Whipple with all the piping for two Air 2 Air IC's will be a very tight fit...

Why not use one of Andy K's setups...? Somebody was selling a kit on the Rennlist..

It's a lot of work to build a system... If you have 2 TB's, then they have to be after the MAF as well...

HTH,

Tony

Look at DR and his set up.

Ian928

So are you saying you use a throttle body downstream a fixed-displacement blower?

Ian928

Funny, I was thinking the same thing but didn't consider it hard enough! I even have the vacuum-activated bypass valve ready(http://www.flickr.com/photos/2196736...7594052999722/) because my initial plan was to use the two throttle bodies upstream the supercharger and use a air/water cooler (conventional way). Of course, this little valve can not vent all the air the supercharger pushes out when it's intake is not restricted, but if the intake is (almost) closed, it is of course fine.

VERY interesting thought, I will consider it!

Imo000

Sorry I didn't read the original post carefully enough to notice that you are talking about a positive displacement supercharger. My references were for a centrifugal blower.

Ian928

Yes, I know what Corky Bell says that, but I want Twin Screw, Air/Air intercooler and good throttle response. I am pretty sure you can not get good response with the volume from a big intercooler and piping downstream the throttle body? If the volume does not pose a problem, of course I will choose the easiest path! I have searched the net, but I haven't found much about it...

I will use one IC, and split the air to each bank from the IC outlet tank.

No MAF, I will use a standalone system and MAP.

And yes, it would of course have been easier(and cheaper!) to just buy a kit, but I really would like to create something for myself. I believe the building process should be equally fun as the driving...

blau928

In this case, you have options.. Depending on the size of the Whipple, and where you mount it. The IC obviously goes in the nose, and if you will use a different Electronic system and MAP, then you can put use dual TB's without issue. Good luck..

I have designed and am in process of building a Twin Screw system with dual AWIC's and additional fuel and boost control.... The new TB flows 1600 CFM.... Yes, it's also mounted before the compressor...

I know all about the building part.. I just redesigned the system, as the IC's are now more efficient than the old design...... I can appreciate the joys of building and designing a one off...

Lots of luck to you..! Please post pics when done..!

JEC_31

As far as I know (Corky Bell's books + much internet lurking), the excellent low-range response of the Whipple means than even at low RPMs you will easily be filling the intercooler and all piping nearly instantly with fully compressed air. It's not even likely that the pressure drop after the IC will be drastic enough to hurt. This means throttle response is not an issue, as soon as you crack it the boosted air will be slamming into your combustion chambers! Hopefully with plenty of atomised fuel...

Twin 80mm throttle bodies just gives you an immense volume-flow potential. Perhaps more hp than the drivetrain can withstand.

Man, Ian, every time you add something to this project the predicted end result gets bigger!

Ian928

Thank you and the same for your project!

I think I have seen some pictures of your (earlier probably) system. I think yours had similarities to the one I originally planned to build. Are you using Laminova cores in a cast manifold? Do you have some pictures of your setup maybe?

I think putting the TB before the compressor would work perfect for a engine with a relatively small volume between them and the supercharger. I am a little unsure how it turns out when the volume increases. I calculated that the volume after TB almost doubled when going to a air/air intercooler.

I have an article about a Swede putting two 3150 Autorotor superchargers on a 35 engine, and he had the TB's before the superchargers. There was no mention in the article about response though...

Ian928

This may be true, but still I have the nagging feeling that it will not be "ultimate". After all, racers prefer individual throttle bodies because of better response.

What I am not sure of, is if this method will create pressure spikes that is too high and can damage the blower. The VW G60 use a so called G-lader supercharger that may be able to withstand higher pressure without damage than the twin-screw. Switching off air supply to the twin-screw will of course not create pressure waves in the intake, but slamming close a throttle plate at full airflow may very well create a pressure pulse travelling back to the supercharger even if another path is opened for the air to vent...

blau928

Ian,

Thanks for the kind words of encouragement.

I am now using 6 Laminova 392mm cores, 3 for each bank of cylinders. The compressor is in the "V" of the engine, and now blows "upwards." (Old design blew down.) The air then turns right and left then goes through the IC and into the intake runner blocks. (The new injector blocks have been reconfigured to hold 2 injectors per cylinder, 1 for LH, and 1 for HKS AIC.) The charge then goes into the cylinders. Short, simple, and should be effective. (TBD)

Depending on compressor size, and piping size and length, your volume should not be that much more... In addition, you can mount the bypass valve before the Air 2 Air IC, and have the air recirc to the inlet side of the compressor and after the TB to put minimal stress on the compressor.

I have had many lengthy discussions with Opcon (Laminova) engineers, and their research supports many others in the arena. I used their knowledge and tips as parameters in my design. Heat was the enemy in + pressure applications, so I maximized heat removal.. The cooling system for the IC's require about 5 gallons (US) to keep the efficiency up.. Often very much overlooked in AWIC systems.... as well as flow of water through the IC core.. Each core needs 40L/min to be at 90% efficiency..... therefore lots of coolant, and a big pump....

I am using an Opcon MX 422....

Also keep in mind that distance of the TB from the compressor also influences throttle tesponse, as well as the length and volume of system from the TB to the Intake port..

I used the following logic... If heat is caused by compression of the air, which is mainly from the compressor, but also increased by bending pipes, then shortest path after the IC to the intake port would minimize this.

Interesting about the bi compressor engine... I think it's very interesting, as the heat is less compared to the airflow... I have some ideas for a V8 with 2 compressors as well....!

Clearance was also a BIG issue on the 928.. I refuse to cut the bonnet open to fit the compressor system.........

I will post pixx when done.. I can email you jpegs of some parts, and maybe a sketch later. Until all the CAD is done, I will not be machining anything else, as the system will be built as an assembley in CAD to ensure fitment, then the remaining parts will be milled.. The IC's are already done as well as the cooling modifications.. I have also had to make a new radiator, as the old one was a bit too big for comfort.. (I'm using laminova oil coolers as well.....)

Funny you are from Norway.. A very good friend of mine had the record for pike fishing in Trondheim..

Regards

Tony

I CANNOT wait to see this!