gofastlvr

I have put about 75 hrs on my Vortechs on 500 EFI's w no problem at all. I have ran with guys with whipples and ProChargers. I can assure you, if installed correctly, you won't be disappointed.

GPM

I have seven seasons on my Procharger Efi with no problems,
they All need good fuel systems and proper tuning to live.

Whipple Charged

A centrifugal is not more efficient, simply not true. If you compare size vs. size, the positive displacement always has a much broader curve so if you wanted to plot a usable rpm range for blower efficiency, the twin screw would be far higher. Centrifugals have one major advantage though, but this also leads to other issues, they get to push through a throttle body while twin-screws suck through. It's easier to push. When your pulling throught the throttle blades, there's some slight loss. If everything is right, it's less than .1%, but in some cases, especially cars, this can be an issue. But we supply our own TB's for this reason, we give it the maximum amount of air available.

The reason many go to a screw or roots now is the throttle response and torque. Although some say it's similar, it's clearly not, and the bigger the power, the bigger the difference. Example, on the 496, at 3000rpm, there is nearly 150lbs of torque difference. Boost for boost, they'll make close to the same power, when you have AF and timnig the same, but PC does zero to the PCM, and your depending on the factory computer to have the same calibration, even though there's well over 100 different calibrations now. The fuel and spark tables are all different. Then you get into codes, PC, if you stay in boost for longer than 30 seconds, you set the MAP HI code, which goes into a default map based off of TPS, this doesn't work, runs bad, detonates, breaks pistons and gaskets. Now your rebuilding motor. Some have tried a bypass loop around the MAP sensor so it doesn't see full boost, but this puts you in a lower load cell, which gives less fuel and more spark, which is dangerous. Some make it, and this can be based off your driving habits, maybe it's overly rich, could be early programming which is safe and cautious, maybe your propping and boat doesn't put much load on it, etc.

Dustin

bcarpman

I always hate discussions where neither side wants to take the time to dig out the data It's been a long time since I've done any work with these, so I have to admit, I'm not really willing to do the digging. Dustin?

Compressor efficiency is definately not a simple topic. For instance, conventional roots blowers can be very efficient at very low boost levels (~2-4psi), but who runs them there???

Yes, you are correct, if you look at the boost (efficiency??) over the torque curve, the whipple does look good, but it really depends on the application. I have a limited perspective on boat torque curves, but to date, I haven't been in a single boat where the torque below 3500rpm mattered all that much (the area where a whipple will produce more boost than a centrifugal). I've never seen an any data to indicate a whipple will have anywhere near the efficiency up top, especially at higher boost levels.

You are correct about the tradeoff between before vs. after throttle. Any time the compressor is further up the air path, there will be some throttle response loss. I have never felt it was at all significant in a car. I'll have to rely on others as to whether it is objectional in a boat.

I still think that most (including manufacturers) stick with roots type blowers because they look cool, as well as my statement that trying to package everything in the V compromises airflow and intake tunning, as well as intercooler efficiency more than one would think. Yes, you can always just "turn up the boost" but EVERYTHING works better when you can make the same power at lower boost.