Big roots blower on LSx
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Joined: Dec 2004
Posts: 841
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From: Baltimore, MD.
Originally Posted by technical
Not really. Injector/carbs sit over the blower.
And at that point, all you'd really need is a set of butterflies on top of the blower for throttlebody duty.
But it still doesn't make up for the 6-71 et al's tremendous lack of efficiency.
'Dreamin'
Originally Posted by JustDreamin
See, that's the problem. The 6-71's and such have flow capacity over the Magnacharger (which is too small for serious motors, along with the Eatons). But the screw type compressors (and the centrifugals too) are light years ahead in terms of efficiency. I'd bet the old roots type blower is only in the 40% to 50% efficiency range (my guess, anybody have any numbers?). Compare that to a good turbo which is in the 70% to 80% range (depending upon compressor and where in the operating range you're in). I doubt the Magna is at the same level of a good turbo, but I'm expecting its better than the 6-71. And the lower the efficiency the hotter the air entering the engine (and the more power it takes to spin the blower at the same boost level).
As far as the sheetmetal intake, I think it'd be alot easier to hog that manifold out of a solid chunk of alum on a good cnc mill than to do a completely fabricated manifold. Especially since the intake is dry (no coolant to worry about and no fuel to puddle). Would be a pretty good sized billet to start with however, and the machine time wouldn't be all that cheap if you have to pay for it (depends upon your connections).
'Dreamin'
As far as the sheetmetal intake, I think it'd be alot easier to hog that manifold out of a solid chunk of alum on a good cnc mill than to do a completely fabricated manifold. Especially since the intake is dry (no coolant to worry about and no fuel to puddle). Would be a pretty good sized billet to start with however, and the machine time wouldn't be all that cheap if you have to pay for it (depends upon your connections).
'Dreamin'
I would say on a limited production run, it would be cheaper to build a sheet metal intake (I would think)......a solid block of aluminum is not cheap.....now on mass production scale, CNC milled aluminum casting would be the best......
Originally Posted by technical
Not really. Injector/carbs sit over the blower.
....though I said put the injectors in the ports so they spray into the head/back of the valve.........THOUGH.....fuel through the blower cools it so...... The problem that would arrise with not running carbs or injector on top of the blower is that the roots-type blowers are incredibly inefficient, and the fuel helps to cool, and seal the blower rotors. I am currently working on the tooling to create a blower to accept a 6-71 blower to go on a LS1, but it will likely run a mecahnaical fuel injection system, run an injector hat much like the one pictured above, and will most definitely NOT be meant for a street application. Creating my own manifold will alow me to dial in the proper blower setback, to maximize equal flow into all cylinders, and won't require near as much injector or compression stagger. Has anybody figured out what this is going into yet?
Originally Posted by Sandmann120
The problem that would arrise with not running carbs or injector on top of the blower is that the roots-type blowers are incredibly inefficient, and the fuel helps to cool, and seal the blower rotors. I am currently working on the tooling to create a blower to accept a 6-71 blower to go on a LS1, but it will likely run a mecahnaical fuel injection system, run an injector hat much like the one pictured above, and will most definitely NOT be meant for a street application.
Originally Posted by Sandmann120
Has anybody figured out what this is going into yet?
Thread Starter
Joined: Mar 2003
Posts: 10,615
Likes: 1,883
From: Little Austin
For the street a pair of supercharger 600s will do the trick. A 6-71 is really just a touch too big. I am thinking that a Weiand 256 would do the trick nicely. Sure the roots are not as efficient as a twin crew or a turbo, but the WOW factor is definitely there. Besides that, it will make more power than most people will know what to do with anyways.
Check out the latest Weiand baby 142 kit for Vortec cylinder heads:
http://www.holley.com/data/Products/...ower_Curve.pdf
Check out the fuel curve. That is with an out of the box 700 cfm supercharger carb.
Andrew
Check out the latest Weiand baby 142 kit for Vortec cylinder heads:
http://www.holley.com/data/Products/...ower_Curve.pdf
Check out the fuel curve. That is with an out of the box 700 cfm supercharger carb.
Andrew
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