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Twin Turbo / Supercharger System

 
 
 
 
  #11  
Old 09-05-2007, 08:21 AM
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holy mother of god chris. you gotta get this things going now. i gotta see it. this is going to be something else!!
 
  #12  
Old 09-05-2007, 09:19 AM
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dude has way too much time on his hands!! I WANT TO SEE PICS!!!
 
  #13  
Old 09-05-2007, 02:44 PM
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I figured I'd better post an updated drawing of what I was talking about in the earlier post. Also note the jackshaft pulley design on the super's drive. To get a 6:1, it would take a huge crank pulley, with the jackshaft, a regular sized pulley can be used on the crank, and the overdrive ratio is compounded through offset pulley sizes on the jackshaft. For the Throttle Bodies, I'm using good ol' Chevrolet 3" TB's. They also have a mass air sensor built in to them that I plan on leaving in place. Once I get a friend of mine to make the board to read them, I'll be able to monitor air MASS that the engine is injesting. Just another cute by-product of the GM MAF/TB assembly.

As far as time on my hands....I used to have alot more, but not anymore. Which is why this hasn't come to fruition yet!
 
  #14  
Old 09-06-2007, 04:54 AM
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i wish i had the means to do a mock up of this set up
 
  #15  
Old 09-06-2007, 05:19 AM
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why not look for a sponsor?
 
  #16  
Old 09-06-2007, 08:35 AM
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The trick that I employ to build this kind of stuff is just to use what you have on hand. I don't spend the bucks to build what others are buying off the shelf. My compounds consist of a marine S3A off a John Deere marine engine I R&R'd, my BHTB3 is a $400 OEM application, the supercharger will be a take off from a lightning or cobra that has been upgraded to a whipple or turbo. All the plumbing is exhaust pipe and off the shelf tight radius stuff that I cut to the right angles. I have spent no more than a couple 3 grand on this engine in the last 4 years....I'm not the richest, and I am a family man. It can be done though without a second mortgage. Time invested?? Countless hours....and crunching numbers and searching for the right parts, but that has a benefit as well right? So don't be afraid to experiment, go outside the box, and even fail once in a while to get it right. It's really where a lot of the fun is in this hobby. It's another reason I'm a 12 valve kinda guy.

So a little more tech on this thing now that I have some time.....The trick with tuning this set-up is going to be phasing the throttle bodies. Because the super will be at 5 or 6 thousand rpm at idle, it will be breaking the positive pressure point before you even tip the throttle. As soon as you do, the ratio will ramp up the super very quickly and provide 10 to 15 pounds of boost right off idle. This will allow a pretty agressive pre-boost fuel curve because the air will be there to burn it. The by-product is alot more exhaust energy as well, which will get the turbos into spool much quicker too. So when the super is peaking it's pressure we want to start phasing the throttle bodies through adjusting the actuator (a take-off turbo wastegate actuator) with a controller that's the same as used on the turbos. The secondary turbo should also be in early spool at this point as well. Ultimately, we want supercharger pressure to be about equal to turbo pressure when we start to phase the throttle bodies. This should provide a seamless transition into turbo pressure. Once the throttle bodies have completed the intake tract switch, the super will be pumping against a closed TB, which will trip it's internal bypass and take it pressure ratio to zero, causing no parasitic load on the engine, nor create any excessive load wear on it. The important thing here is that your chosen super has a bypass, if not, you have no way of "turning it off" so to speak, short of an electric clutch drive which carries a bunch of it's own challenges. So while the super's TB is shut, the turbo's TB is wide open, leaving an un-obstructive intake tract so that they operate as normal.

So what happens at part throttle...say cruise power when you're only making 6-8 pounds of boost? Well, because the TB actuator is dynamic with manifold pressure, and adjusts in a linear fashion, The super AND the turbos may be operating in parallel with the TB's allowing both systems to feed the engine. The pressure ratios will balance and therefor not be a problem, as soon as you tip the go pedal a little more, the turbos will make more pressure than the TB actuator will allow the super to see, and consequentle cut it off from the loop by phasing the TB's completely....but talk about some instant passing power right?

So anyway, that's the way all the numbers crunch....in practice we'll see if it pans out, but it should. Just a matter of tuning the TB actuator, as well as adjusting the bellcrank that connects the two of them together.

Oh and some of you might notice double CAC's on the turbos but no CAC on the super. Firstly, cooling the outlet air from the primary before it gets to the secondary makes huge gains in efficiency for the secondary's compression stage. I don't think a CAC is really needed for the super because in reality, it's duty cycle is so short, and low in the rpm range, it just won't matter enough to try and figure out WHERE to put a 3rd cooler! I estimate the super will be contributing air to the engine for a maximum of 10-15 seconds (and more than likely a lot less) from a hard throttle stand still before it's bypassed and the turbos take over. And under normal driving, pressure ratios aren't high enough to generate alot of heat to get rid of anyway.

Chris
 

Last edited by Cummins Express; 09-06-2007 at 08:43 AM.
  #17  
Old 09-06-2007, 12:06 PM
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I see you are still alive! Let me know if you need any help fabricating this thing. Give me a call some time

James
 
  #18  
Old 09-16-2007, 11:30 AM
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Originally Posted by Cummins Express View Post


I figured I'd better post an updated drawing of what I was talking about in the earlier post. Also note the jackshaft pulley design on the super's drive. To get a 6:1, it would take a huge crank pulley, with the jackshaft, a regular sized pulley can be used on the crank, and the overdrive ratio is compounded through offset pulley sizes on the jackshaft. For the Throttle Bodies, I'm using good ol' Chevrolet 3" TB's. They also have a mass air sensor built in to them that I plan on leaving in place. Once I get a friend of mine to make the board to read them, I'll be able to monitor air MASS that the engine is injesting. Just another cute by-product of the GM MAF/TB assembly.

As far as time on my hands....I used to have alot more, but not anymore. Which is why this hasn't come to fruition yet!
the only problem with those "stock" blowers is that they need a manifold to set on, if you use a paxton or vortech "sealed" unit i think it would be easier to mount and work with even though the price wont be as low. i would think that big charger would force too much air past the small charger and over spin it causing bearing damage, a good thing is that it will actually start to scavage exhaust at higher rpm cause the small charger will begin to spin faster than the exhaust can drive it, this will start a sucking effect and "clean" the cylinders for the fresh air........i could also be way over in left field with all this too.....
 
  #19  
Old 09-19-2007, 09:34 AM
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Originally Posted by DieselfreakMI View Post
yeah...I understand where your coming from, I would stick with turbocharging and plan too..but those old detroit screamers sound cool!!...the college that Im going to has a 6v92T..so you dont consider it a supercharger unless there is fuel going threw it.
6v92,8v92.... still just a blower. just mounted on top...
a blower and supercharger have different tolerances from the rotors to the case.
i know people refer to gas engines as "blown" with a blower on top.

to me when a blower has been modified to make more power on a gas engine it then becomes a supercharger. just my awkward way of thinking.
you can go here
http://www.blowerdriveservice.com/contact.php

they are really cool when answering questions.
 
 
 
 
 
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