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You know as well as anybody WHY that is. How much additional boost is needed to overcome the HP absorbed by spinning the rotors/screws/gearbox(centrifugal) as opposed to how the restriction caused by turbo(s) can actually be helpful to their setup.

I am biased toward turbos, though as they just seem so much more efficient: Just riding along not using any power at all until needed and then WHEN needed/wanted, they come in gradually which is easier on drivetrain parts down-stream.

There's a reason why more and more of the new upper-level automobiles AND pickups are turbocharged.

Just got a BMW 750Li for the wife. 4.4L twin-turbo V8. I've never experienced a car that is that QUIET be that FAST. Very, very impressive.
 

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Discussion Starter · #3 ·
You know as well as anybody WHY that is. How much additional boost is needed to overcome the HP absorbed by spinning the rotors/screws/gearbox(centrifugal) as opposed to how the restriction caused by turbo(s) can actually be helpful to their setup.

I am biased toward turbos, though as they just seem so much more efficient: Just riding along not using any power at all until needed and then WHEN needed/wanted, they come in gradually which is easier on drivetrain parts down-stream.

There's a reason why more and more of the new upper-level automobiles AND pickups are turbocharged.

Just got a BMW 750Li for the wife. 4.4L twin-turbo V8. I've never experienced a car that is that QUIET be that FAST. Very, very impressive.
The screws are VERY efficient too though. Even with the parasitic losses.
Until recently the turbo pro-mods were just a tick off of the performance of the screws. I don't think it was that they couldnt make as much or more power, it was just combination-power application, getting the power to the ground without blowing the tires away . But seems they are getting it figured out.
 

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Without a doubt, screw-type is next up - especially since they have added the bypass valves to almost fully cancel out the parasitic loss when not needed. At boost, they are still requiring raw HP from the snout to make the power. Yes, exhaust restriction grows in the turbo system as well, but still....no power is being robbed from the crank.

I've had one Whippled pickup several years ago. Other than that, I'm on my third Buick GN (restored and sold the first two - keeping this one) and now the BMW, so my love for turbines and compressors continues to grow.
 

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Discussion Starter · #6 · (Edited)
are you suggesting these are nhra legal pro-mods????
No, they run in Pro-extreme or Pro boost. Less weight, larger engines, and larger turbos
Extreme Outlaw Pro Mod Rules

Troy coughlin won the championship in NHRA his first yr out with his NHRA legal promod. in 2012 @ 2700lb and boost limited to 47psi
 

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47psi. Wow. That's 3.24 bar!
 

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No, they run in Pro-extreme or Pro boost. Less weight, larger engines, and larger turbos
Extreme Outlaw Pro Mod Rules

Troy coughlin won the championship in NHRA his first yr out with his NHRA legal promod. in 2012 @ 2700lb and boost limited to 47psi
troy is tough. so is ricky smith and mark castellana. but none of them run quite as quick as these two. not too far off, but no .46's. nhra promod is a great class with all the different combinations. there are always ways to go outside the rules and go faster...
 

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Getting a turbo to 60 ft. is the key, they are starting to figure it out.
Would love to see the incremental time on that run for both cars. The turbo did what they do best, hauled the mail on the second half of the track. It must have been hard losing with a 5.47:)st
 

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It would be interesting to see a comparison between turbos and screws where the organization wasn't tryin to make them competive against each other ! Going by that video of the fastest side by side pass they have them pretty close but holy %$#* that turbo sure does mile an hour !
GD
 

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It would be interesting to see a comparison between turbos and screws where the organization wasn't tryin to make them competive against each other ! Going by that video of the fastest side by side pass they have them pretty close but holy %$#* that turbo sure does mile an hour !
GD
This organization lets you run what you brung. No rules except no nitro and has to be non center steering with doors. Turn em loose and watch some bad a$$ racing. From the video the screw blower car got out front and ran out of gear, the turbo car drove by him like he was sitting still, WHAT A RACE:thumb:
 

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Being as quick or quicker is one thing. Being as consistent is whole other ball game.
Bingo. I don't think there's any debate on turbo's making the power, they're just not predictable or controllable enough quite yet, but they are getting better.
 

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Is their a rule of how much overdrive the screw blowers can run?
Sfi limits input rpm to 26400 rpm. I talked with Roger @ PSI he said they are turned close to 40000 rpm cycled like 4 times for 5 minutes each cycle for the SFI cert. The discharge temp is still good... Problem is getting enough pulley on it to do that.
 

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Ain't Right Racin
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Being as quick or quicker is one thing. Being as consistent is whole other ball game.
Info's deal is looking like it is.
 

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Bingo. I don't think there's any debate on turbo's making the power, they're just not predictable or controllable enough quite yet, but they are getting better.
In the last 3 races every lap, test and tune, qualifying and eliminations have been within .2ish sec. Extremes of DA included.

Unfortunately .1 of that range is below the index. :|err

The car guys I would imagine managing all of that power to the track is difficult.
 

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steelcomp was here
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In the last 3 races every lap, test and tune, qualifying and eliminations have been within .2ish sec. Extremes of DA included.

Unfortunately .1 of that range is below the index. :|err

The car guys I would imagine managing all of that power to the track is difficult.
You certainly have it easier than the car guys since you really don't have the traction issue they do but you're also not pushing your engine or boat any where near as hard as you could. Turbos IMO are right at home in open cockpit jets once through the learning curve. The lag off the line is actually beneficial and you can dial in your HP as needed with more than enough on reserve to cover any track or weather conditions. If I was going to build a QE boat from scratch right now it would have either a TT Ford Coyote or LSX.
 
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