Compound Boost?

For those of you that ain't in the know.

When you see a Wieand 8-71 blower that is a derivitave or the 8V-71 detroilt V8. That mean it has 8 Cylinders @ 71 CID per cylinder. 3-53, 4-53, 6v-53, 3-71, 6v-71, 8v-71, 12v-71, 6v-92 8v-92, 12v-92, 16v-92, 12v-149, 16v-149,
 
yep. up to the 12v-92
 
bigike said:
Ok compound boost.

Lets talk about large engines 12,000 cubic inch diesels.

In a compound boost set up you would have a blower to start the engine and run it up to temp. Once you've reached operating temp (because as TREY knows Heat spools the turbo). When the turbo comes on the blower goes into bypass. When a blower isn't in bypass it is in boost, when it's in boost it's creating heat.

Single Turbo is the way to go. I bet that mustang would pull 1000 hp on the turbos. I wont want to be around when the blower lets go from over spolling. If you've got a 10 pound blower with 20 pound turbos pushing into it. You are creating a restriction. Create a restriction and you create heat.............................

Now how bout a 8.3L Whipple. Thats an Idea!
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Check out the site the 5.0L and the 8.3L, they have the same peak flow. The 8.3 has a lower RPM range though so to keep from over spinning it I would have to do a 1.83:1 pulley ratio instead of the 5.0L 3.0:1. That is why I think the 5.0L would work better for me. It's RPM range would better allow me to vary the boost with pulley changes. I really think that 8.3L is designed for Marine use though I very well could be wrong. Waiting for Dustin Whipple's response.......

Yes the Mustang's can produce 1000HP (even 1600HP) on turbo's only the tradeoff is lost power down low. The compound system doesn't loose down low power and the supercharger spools the turbo's quicker. The supercharger with 8psi gives the turbo's the feeling that there is a 50% larger engine there.

The supercharger is no more of a restriction to the turbo's than the engine is to the supercharger. A Supercharger producing 10psi and the turbo's producing 20psi (1.68 * 2.36 *14.7 - 14.7) gives you a manifold pressure of 43psi! and you have the first 10psi without waiting!
 
pokeytemplar said:
Check out the site the 5.0L and the 8.3L, they have the same peak flow. The 8.3 has a lower RPM range though so to keep from over spinning it I would have to do a 1.83:1 pulley ratio instead of the 5.0L 3.0:1. That is why I think the 5.0L would work better for me. It's RPM range would better allow me to vary the boost with pulley changes. I really think that 8.3L is designed for Marine use though I very well could be wrong. Waiting for Dustin Whipple's response.......

Yes the Mustang's can produce 1000HP (even 1600HP) on turbo's only the tradeoff is lost power down low. The compound system doesn't loose down low power and the supercharger spools the turbo's quicker. The supercharger with 8psi gives the turbo's the feeling that there is a 50% larger engine there.

The supercharger is no more of a restriction to the turbo's than the engine is to the supercharger. A Supercharger producing 10psi and the turbo's producing 20psi (1.68 * 2.36 *14.7 - 14.7) gives you a manifold pressure of 43psi! and you have the first 10psi without waiting!
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Series and parallel dont work here............. ;) you might have 15 psi or what ever above the blower but below would be a different story.
 
Sorry to disagree BigIke. Here is another article that explains it better. Roots and Twin screw are positive displacement blowers (as you already know). They take x amount of material per revolution. So if the turbo is producing 14.7psi the supercharger is still moving the same amount of air it is just twice as dense. The manifold will now see this compound of air pressure. Same way compound turbos work on diesels. That is how the diesel guys are able to get those insane boost levels.
 
i love 149s 8-20 cylinders i have spent alot of time with them but since the government gave grants out for people to upgrade detroit is just fading. no matter how bad you treat them they just keep going, change adroped valve in 2hrs. you just cant get better than that.

So explain why you couldnt just put compound turbos on a gas engine?
 
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Well we don't have intercoolers and I just don't see the benifit of compounding the Roe, it becomes inefficient at 10 or 12 pounds as it is...................

On compound turbos your using the small turbo to spool the big one. With the roe youd be trying to push more air into a smaller space
 
I think the intercooler problem will be taken care of soon. Look at the mustang build: 8lbs with the roots blower the rest provided by the turbos. All of the piping required for compound turbo's would be daunting. A quad turbo system would be really cool and could be packaged rather well. A Roe with a large single turbo would be tremendously cheaper. Especially if you have already invested in the Roe.

The Roe will move the same volume of air every revolution. The turbos will only increase the density of the air going through it. There is a lot of space in the air. I would intercool between each stage of compression to greatly increase efficiency just like Hellion did.
 
The Roe will move the same volume of air every revolution. The turbos will only increase the density of the air going through it. There is a lot of space in the air. I would intercool between each stage of compression to greatly increase efficiency just like Hellion did.
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That is how I would do it Robert.
 
Yep those Ram's have plenty of space under the hood for everything. IF I wanted to compound boost I would have to use twins just to get everything to fit (in a Durango).

Personally I am leaning towards the twin screw. I am building a mostly daily driver so I am more interested in average power over peak power. I find the notion of being able to "lug" the engine along at 2000rpm (or less?) and still having 1000ft/lbs of TQ on tap instantly very appealing. I also have to be honest with myself that I don't have ten's of thousands of dollars to spend on my build or its maintenance. An engine will last considerably longer running at 2000rpm than at 5000+rpm as we all know.

The correct TS could produce in excess of 1500hp with my build. Instead of adjusting a wastegate controller I would be swapping pulleys. A pump gas pulley producing no more than 16-18psi and a race pulley producing 26+psi.

Don't get me wrong I love turbos but since most driving on the street is at part throttle your spooling turbos for nothing (kind of ties back into the other thread). However, the TS opens it's bypass valve in these situations and uses only a couple of crank HP.
 
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blackviper said:
It doesn't end does it? It's a sickness or are we all just mad?
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Nope. We have to admit we do have an awsome platform to begin with. and we see so much room under the hood we get the urge to fill it:D So I would have to say your right we are all mad or Goofy:marchmellow:
 
its being done by some guys over on compitition diesel, blower for idle (eliminates turbo lag) plus a compound turbos for the higher boost, its a simple and easy solution, even easier since gassers wont run the boost of the diesels
 
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