it seem's that the big motor builder's are moving away from supercharger's and using turbo's now .
Why are the turbo's better ?
and what make's them keep the engine's alive longer between rebuild's ?

thank's
mike

It's not the blowers or turbos it's the valve train making the reliability better dual over head cams no push rods

Nowhere near the parasitic loss... & IMO for a gearhead turbos are easier to acquire and maintain. Turbos always get lumped into the "tuner" and duct-tape crowd... but its like anything else, if you get someone that understands how to setup either system you'll have a monster. Now that car and diesel guys have played with it the tuning has come a long way. Also the adjustability of boost controllers. Most guys run 10lbs max on a boat... guys in cars pushing 30lbs on the street...

Edit : Having said that... I run 8-10lbs on a Whipple in the resin bucket. Super happy with Dustin and his CS in the few talks we've had when I needed help. That goes along way.

I'm not sure this is really happenning.

Valve train does not live longer unless it has more mild camshafts. Mercury's 1100 and 1350 live longer because of DOHC. SC or Turbo will live basically the same time.

To say one is better than another is very subjective. Turbo's do have less power consumption, but they are by no means "free" like most assume. They have very high back pressures in the exhaust, which causes the exhaust to leak back into the combustion chamber, as well as slow the exhaust valve opening and slow the exhausted air exiting the combustion. This is by no means "free".

Both have pros and cons so it comes down to the application, the setup and equipment to decide on what is "better" in that given application.

It's exactly free, turbo efficiency (overall system efficiency) is always higher when appropriately sized. Don't make me go all formula SAE and bust out the equations. Controlling them has what has always been more difficult.

There are certainly other tails, heat, appropriate impeller for exhaust pulse, etc. Superchargers are just easier to bolt on and go, that's why they are more popular.

Saying that a 15% (or less) exhaust efficiency is even close to the 100+ (or LOTS more) horsepower it can take to spin a supercharger is irresponsible.

Plus turbo's kill the exhaust ear candy, that's a big negative for some.

Completely agree on the valve-train portion though.

I think your refering to peak AE and yes, some are "higher" than superchargers. But, back pressure and high inlet temps are not "free". Also, OEM marine turbo applications use water cooled housings, which lowers there overall efficiency so one must consider this into the equation or debate.

A 4.0L twin screw, on a 540ci BB Chevrolet engine with decent parts, making 1000hp on 91-octane, 7.5psi takes less than 60hp. I would certainly not call that significant and I'm not even going to comment on your irresponsible comment. If a turbo was "free", the turbo would make 1060hp (60 more) with identical boost on an identical engine. The simple fact is that it will not.

If were discussing 30psi applications, then we can talk about significant power consumptions.

Almost all SAE studies fail to include twin-screw compressors nor later generation roots superchargers. I know of multiple studies coming out, which is leading one of the big 3 to change all there current turbo applications to positive displacement superchargers.

Not that anyone would believe me but I have to side with Whipple here - nothing is free

The exhaust manifold pressure takes it's toll and robs effeciency just by the simple fact you have to push it out now, there is little scavenging if any with short runner turbo manifolds.

Which robs more on a low boost engine ??? but neither is "free" there is always something given up to get something.

Can I Get a bucket of free power

Dustin & HabanaJoe couldn't have said it better.

I can provide you with a bucket of free power but the bucket to carry it in, well that's going to be pretty pricey!