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Discussion Starter #1
i am not looking for feedback how this is a waste, or dumb. personally i wouldn't do it, but myself and another couple people may be responsible for making this happen.

what info can y'all provide or conjure on a roots blown 3.8 and then sticking a centrif. s/c on it before it?

no promises that this'll go through but i should be getting the deposit very soon. lately a lot of my plans have fallen through and i don't want to be known as the guy with the big mouth.

let me repeat: i am not looking for feedback how this is a waste, or dumb.
 

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I'd like to know if this is possible.. hey someone told me a Skyline has a twin turbo engine, that true btw?
 

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Discussion Starter #3
twin turbos makes sense because each header goes to a smaller turbo. however, a roots blower on top being supercharged by a centrifugal offers little IMO.
 

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somehow you'd need a bypass system, where the roots gives low-end power and the centrifugal gives high end. To me, it sounds like it would be one of those things that looks kinda cool at a car show but has no actual feasability. Seems like a waste of a lot of money because it definitely would take a lot of custom fab work



No offense, but i think you should just stick to the roots system you guys are developing and not think about really hard expensive stuff like this....
 

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I read your post completely


It's almost impossible. You would need a switch under the roots blower that cuts off the roots at a certain RPM and opens up the flow of the centrifugal. you can't keep them both open because the roots would be making less boost, and therefore the pressure of the centrifugal would be reduced when mixed with the air from the roots. In order to make that work, you'd need some way to make the roots freewheel, or have a big friggin blow-off valve for it. the BOV would also just bleed power at high RPMs, because the roots is still sucking power but not making any. So, if some way you can construst this cutoff valve, make the roots freewheel at high RPM, and make the transition smooth, go for it. I think it would be next to impossible.
 

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Discussion Starter #7
a guy may have us make him a custom dual supercharger kit, that's what he said he wanted. it's not in our hands, unless we want to pass up money, which i'm not one to do.

we have a freewheel in the works. works on a solenoid. i'll post more late.r
 

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Discussion Starter #9
that's the plan. he doesn't post here, so i don't feel bad in mentioning he's commiting more than 5k. i want to see the deposit asap!
 

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you cant bypass either blower. both are run off the main drive belts. what you would have to do is have the roots with a small boost factor so that it makes the power down low. then put the centrifugal with a higher boost setting. that way it starts to make boost at ~3000rpms and doesnt make full boost til 3500rpms. the roots will make all the boost needed down low at maybe 5-7psi and then put the centrifugal at about 7psi to keep it up top and you will still be getting a little boost from the roots at that high of rpms.

just have the air pulled from the centrifugal, cause it will be spinning even at low rpms, it will pass into the roots blower to be compressed.
 

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it wouldn't work.

With both superchargers spinning, you'll make double the amount of boost at any RPM.

The only way I could SEE it working is that if you had a bypass as you said. You need to vent basically all the air from the roots and then switch over to the air coming from the centrifugal. However, 5-7psi being dumped is gunna be loud and blow some **** around in your engine bay.

I know you dont want to hear it, but don't waste your time. Just build a solid TT kit and be done with it. Custom unique stuff like this rarely works and takes massive amounts of money/tuning to get it to run.
 

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Discussion Starter #12
yay, he's been convinced otherwise. 1.7l autorotor. i want to see the $$$ first this time.
 

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It can work, the roots will provide the low-RPM boost
but them later, the ATI (let's say) will feed pre-pressurized
air to the roots, allowing more capability for the roots.

But actually, a properly sized ATI or a roots is plenty
on any V6, a big autorotor will do as much as what you ask.
The P1SC (ATI) is big enough to make low-end boost
on even a 5.0 if properly pullied. I've seen it. Proper sizing
is much better than trick setups like this guy wants. You do
not have the knowledge to make it work, or you would not ask
these Q's so it is best to tell the customer that or risk being
sued and if it does not work for him (and I doubt it will) you
would lose out too, and end up losing $$$ very likely, or making
an enemy or getting sued. Or all 3 :(
 

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Discussion Starter #14
don't worry anymore guys, the guy thankfully has been persuaded to get an autorotor twinscrew 1.7l.
 
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