What do you guys think?

I've heard that Twin-screws are more efficient, and make more power down low while maintaining good power above. But I've also heard that all that power down low isn't good for the engine, that it could hurt it.

I've heard that Centrifugals take a while to "spool up" since they are basically belt-driven turbos and that the high-revs neccessary for any real power is also bad for the engine: But they make more overall power than any other blower, and are the most efficient at doing so.


Can anybody help me out? Which is better for street/occasional track use? I don't want to destroy my engine in the process, though.

 

If you are putting it in a camaro, you will have a problem with trying to fit the Twin-screw on top of the motor due to the overhang. I have a Centrifugal on my car and you are right that you make your power up high due to it being run off the rpm of the motor. The best is a turbo. You use the un-used power of the exhaust to create power that can be used and if it is done right you make max boost at about 3500 rpm or so and it is there til you let off.

 

Twin screw FTW if you go lots of cash and time to make it fit...

My turbo is a LOT of fun though....

 

Simple version: twin screw is good for low boost/low end torque. Centrifugal makes better high end power. A V-8 F-body does not need more low end torque, so a positive displacment blower would be very counterproductive. The TS makes HUGE amount os heat at high boost and fabbing an intercooler for a twin screw is much more dificult than a centrifugl. And so on. I wouldn't consider any positive displacement blower on a street or street/strip V-8 F-body.

Rich

 

Thanks. To all of you guys...but I needed somebody to say this ^
It just means more when somebody else is saying it to you, you know?

Now I just have to decide...Vortech, or Procharger...

 

Tell this to the 4.6L cobra guys

To back up some of what Rich is saying, you will need a heat exchanger the blower... available from the twin screw manufacturer like kenne Bell. They run hot and genrate alot of heat.

Its tough to get one to fit though in an fbody like also mentioned.

A properly sized TS will make power all the way to redline no problem... same peak power as centrifugal, but alot more low end then centrifugal. It would make for a great street/strip vehicle, but you'll need a serious tire to use all the tq.

 

I dont know how long ago you dealt with screw chargers, but the 2.2L and up screw charger are pushed to 21psi consistently on daily driven 4.6L cobras. These are no longer a "low boost" charger. You are laughed at by the mustang community if you run 15psi or less with a screw.

I agree with them making alot of heat, but thats not an issue anymore with production kits like Kenne Bell. Perhaps back when you were dealing with it the heat exchanger aspect wasnt that worked out. They do get heat soaked on multiple WOT runs without cool down, but its not like they just die... you end losing some hp from the higher IAT's, but its not the end of the world.

A centrifugal would be much easy to launch with its linear boost progression.

I am not trying to argue with you here Rich, but some of your points are no longer issues by whats actually happening out there in the Mustang world... and has been happing for the pas 5 years.

 

i know that even centrifugals run hot... here at the shop we work with a lot of procharged cars, and the cooling system for f bodies really blows

(no pun intended)

 

Rich I think you should also leave open the fact that a 700+rwhp street car, regardless of efficiency or driveability, is going to be seen as a success by most people.

Whether they should be used on the street or not, for some reason people like to be able to break the tires loose when they stomp it in 4th gear.

 

Thats fair, but remember... BTW, if it takes alcohol to run into the 9's with a screwcharger.... you guys must not have had the right charger for your combo. Its common for the KB cobras to run mid 10's @ 135mph in a 3800+lb car... complete street car.

Some good reading on how far screwchargers have come:

http://www.kennebell.net/index.htm
http://www.kennebell.net/media/artic...hargedSled.pdf
http://www.kennebell.net/media/artic...crousSpeed.pdf

Jon

 

i have seen one LT1 with a weiand roots style blower that fit UNDER the hood. otherwise, i think you would have to cut the cowl just as if you did a single plane conversion, not entirely sure though.

 

http://videos.streetfire.net/video/4...950f6f5c8c.htm
there ya go, weiand blower under stock hood.

 

www.svtperformance.com

Good reading on a Ford forum

BTW, glad it didnt need alcohol to run 9's... racefuel sounds better

 

All I really want to know, is...will a Twin Screw hurt the engine(bone stock)?
It's not an f-body btw...not any car at all, actually - I'm asking for a future use...

 

Great blower for low boost, only, IMHO.

rich