Twin Charger....hmmmm
 

well the seed was planted and I am having no luck moving this stage 3 so here's an idea.... Keep the stage 3 supercharger running on a Hydra or other standalone. water/methanol injection. AND a single garret gt40 series tubo... I thought I was going to use the 4088r for a large single turbo but if I am tiwn charging I can use something a little larger as there is not as much lag. It was suggested to use a 4094 as per my original intentions that were changed from the turbo setup I had wanted to do.

So after the VERY confusing statement, I ask.... Is twin charging going to be worth it?? Also, how much of the turbo am I going to be losing through the PD blower... BTW the turbo will feed the s/c.

Tom

I would expect that you will have to run the SC at much higher RPM than usual, in order that it will boost a high input pressure. It has as it were, to catch up on an already fast moving air stream and push it along some more. ;)

Worth it? You have had a guts full with the SC, and did not really sort it so is adding to the complexity involved going to drive you up the wall???????? Frankly on several counts, no IMHO. :D

I think going twin charged would be cool, but you run into a problem:

Your already pulling timing, presumably because the intake charge is HOT. twin charging would best be donw with a centrifugal supercharger and a turbo, both being run through an intercooler

if your "stuck" with the stage 3, it might be wise to cool down that intake charge and run a standalone ems. Im sure that would be key to making ANY fi system on the svx work

Thanks for the reply Trevor, I had always thought it would be useless the twin charge a PD blower, But here is my questions. The PD blower is meant to move a fix amount of air at atmospheric pressure and pressurize it internally to release a fixed ratio of more pressure into the intake. Now that being said, if the inlet side of the blower has more than atmospheric pressure(from a turbo in this case) would it create the same ratio to increase air velocity?? Or would it be more of a restriction?? I hope I am making my thoughts clear.

Tom

I've built a few twin charge setups. Even worked on one of the original Lancia Delta rally cars once. The PD blowers can be used in a twin charge arrangement you just typically need to spool down the SC a little bit with a larger pulley, to keep the rotors from exceeding their flow rate by a bit rate if a large(IE 4088R). You don't want to exceed the rotors maximum airflow with the turbo you use because you'll cause massive surge at the turbocharger inducer when the flow rate of the rotors peak.

TC setups also help the bigger turbos spool a little faster as well as the volume down low the SC draws puts a low level vacuum between the turbo and SC rotors, reducing the compression force the turbo must exert during spoolup(building pressure). Once the turbo CHRA gets up to speed this vacuum is gone however most really big(GT35 size + ) you'll notice the turbo will spool up a hundred or two RPM sooner. Plus you get the low punch of the SC.

I've never had a problem using the Lysholm's either. biggest thing is to map out the turbo's flow rate at your intended useage against the flow rate of the PD blower you'll be using. I have no idea what type and size blower Mike(lan) used in those S3 setups he built.

-Adam

BTW....still working on that Hydra EMS, just slow right now trying to get some more stuff figured out :o I've got so much money tied up in so many areas around this project car I'm going looney....

the lysholm is a 1600ax. I really need the answer to my quesiton above. If there is positive pressure on the inlet side of the PD blower, will I still see the same fixed amount of airflow as if there were not (atmospheric pressure)??

Tom

An excellent example of twin-charging in the real world. GT40 turbo, Eaton supercharger, Volvo engine in an old Opel Manta. 578 hp on pump gas.

http://www.hilmersson-racing.com/start.asp?show=ec

There are numerous videos here, including 1/4 mile runs and a dyno pull.

Bob

There's no direct mathematical formula to determine the actual flow output(as far as I've researched and worked with) as the two compressors have an infinite variable of shaft input speeds and output temps, but also how fast the turbos get up to those speeds. It has a direct correlation to the input pressure as well as the inlet air density(based on inlet temperature)..so you can see some slight fluctuations in the boost curve if you are pushing a turbo beyond it's normal efficiency range and start forcing really hot air into the screws. Hardly going to happen with a 4088R unless you're talking crazy power numbers here.

Every system is more of a trial and error in setting up and tuning but they do work, and work well once setup correctly. But overall the PD blowers don't care if the ATM is 14.7 psi or 28 psi. They just suck and compress the air. The setup just essentially creates a higher ATM than the normal 14.7 and the SC does it's work. You must intercool the crap out of the charge air pre SC as the PD blowers can really heat up the air in the upper PR levels, and adding already hot air to the mix just compounds that effect.

1200 and 1600ax are what I've used in the past with excellent results, no reason you won't have the same. I've never set up something with a 4088R and twin charge, but I've used the Turbonetics GTK550 and the Garrett 3076, 3071, and 3582 r's all with good success.

1600ax flows 1.6L of air per revolution of the female rotor(5 lobe) per positive displacement. Has a max efficient PR of about 2.0 but can carry up to 2.2 at most IIRC. Max rpm input of 1600ax I believe is about 14-15000 rpm. 14K rpm it's flowing ~ 22400 L/min worth of air. If you need the map for it let me know as I've got all the Lysholm stuff here in a file somewhere.

-Adam

I have the map as well. But you kinda hit the head of it in your post. Still a little hazy but I would just like to make a general question to put my mind at ease.

So in a perfect world with no inconsistencies, atmospheric pressure is 14.7psi right?

So right now the s/c is making 9psi at AP

If the inlet was to be pressurized by the turbo to say... 29.4 or 1 Bar, the discharge would 18psi correct?? I know this needs to be done in CFM's but psi is just easier to work with right now.

Tom

wouldnt the blower have to be able flow more than the turbo?

as far as I understand it the blower works on the basis of a pressure ratio. Thats why I am asking, if the pressure on the inlet side is doubled, will the pressure on the discharge side also be double. So if the blower is running at 2.0:1 for a pressure ratio the inlet should be doubled on the discharge. BUT what I need to know is if that if the inlet is increased, will the discharge be increased in that same manner?? Or is it more based on volume where sicksubie would be correct

Tom

For the record you are crazy......





:lol:
:lol:
:lol:

Can't do **** else with my stage 3... might as well make it worth while

Tom

got my answer... Now, Boxer6, how far out are you with the hydra??

Tom

I have not witnessed this on the buick...

SC provides decent boost down low, turbospool not only sooner, but at a MUCH faster rate... when the turbo exceded the output of the eaton nothing ill appeared to happen.... upon accel, the middle gound is real "blast" ;)... when decelerating it is shall we say a bit sluggish by comparision, but recovers quick.

I'd say use a lower psi on the blower, huge freaking turbo works.. but be sure what ever you go with spools up within 1500rpm of your blower's plateau and you should be happy. Would be cool to see this happen... if talked about doing it before, but obviously it would be difficult in my situation :lol: