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calculating boost with a twincharge setup

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Old Nov 24, 2008 | 02:17 PM
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Default calculating boost with a twincharge setup

I'm trying to find the formula to calculate boost in a twincharged setup. I'll probably run a turbo into a roots type supercharger, but still researching s/c into turbo with bypass valve. Also any do's & dont's will help.
Thanks

Last edited by 1jettech; Nov 24, 2008 at 05:00 PM.
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Old Nov 24, 2008 | 05:04 PM
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why?
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Old Nov 24, 2008 | 06:53 PM
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Originally Posted by 1jettech
...dont's will help.
Well there's no shortage of those.
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Old Nov 24, 2008 | 07:06 PM
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I'm trying to calculate the total boost of the system and need the formula.
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Old Nov 24, 2008 | 07:13 PM
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Originally Posted by 1jettech
I'm trying to calculate the total boost of the system and need the formula.
Ok, for starters, it would help to know where you are referencing the wastegate and what will it be set at.
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Old Nov 24, 2008 | 09:33 PM
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The wastegate will be on the turbo manifold and refrenced from the intake manifold. I'm dont know what i will set the wastegate as of yet. I would like to know a specific formula for compounding boost. eg.t3/4 turbo fed into 1.2 liter per rev. roots type s/c. thanks
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Old Nov 24, 2008 | 10:01 PM
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Originally Posted by 1jettech
The wastegate will be on the turbo manifold and refrenced from the intake manifold. I'm dont know what i will set the wastegate as of yet. I would like to know a specific formula for compounding boost. eg.t3/4 turbo fed into 1.2 liter per rev. roots type s/c. thanks
Well, if the wastegate is referenced to the plenum, then it will make whatever boost you set the wastegate or whatever boost the SC makes on its own, whichever is higher.
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Old Nov 24, 2008 | 10:05 PM
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Boost does not even come close to mattering in this situation... Boost is actually a measure of restriction. You need to know what kind of air flow this setup will produce.

I know this setup works, BUT it is VERY pricey, NOT easy, and from a true performance standpoint it's kind of a waist of time... from a "damn thats cool" it might be worth it though.

The "boost" pressure will generally be limited by the supercharger. The boost pressure before the blower will likely be MUCH higher than overall boost that the manifold sees. So the real question is, what section of the setup are you trying to measure boost from?

It's not going to be easy to match a turbo to the blower... all you are doing with the turbo is increasing the blower's efficiency, but you are limiting the turbo's air flow potential for maximum potential... look at the twin charged cobra setups... you are basically just making the stock blower X times more efficient...producing the massive HP. but building a setup from scratch is a waste of time when you could just buy a properly matched turbo or blower for your setup.
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Old Nov 25, 2008 | 01:25 AM
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Thanks Adam that answered a couple closet Q's I had about a turbo into a blower
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Old Nov 25, 2008 | 01:28 AM
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Originally Posted by engineermike
Well, if the wastegate is referenced to the plenum, then it will make whatever boost you set the wastegate or whatever boost the SC makes on its own, whichever is higher.
Thats what id do!

Chris.
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Old Nov 25, 2008 | 01:31 AM
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Originally Posted by 1jettech
I'm trying to find the formula to calculate boost in a twincharged setup. I'll probably run a turbo into a roots type supercharger, but still researching s/c into turbo with bypass valve. Also any do's & dont's will help.
Thanks
what car is this for?? i hear the ford guys run these to some success...also the mini guys like them, but you have to make sure the intake temps into the SC are as low as you can get, ie BIG FMIC.

be intresting to see a Twin Charge setup on a LS engine. although you might want to take a look at what this guy is doing to reduce spool time of a BIG turbo....

https://ls1tech.com/forums/forced-in...-sts-kits.html

(look at post 12)

Chris.

Last edited by chuntington101; Nov 25, 2008 at 01:38 AM.
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Old Nov 25, 2008 | 12:18 PM
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so you want something like the Hellion Hellrasier kit (for those who dont know its a TT Termi that keeps the stock eaton and Hellion claims its capable of 1400 to the tire and 49PSI!)

good luck
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