[Shotimes] Power adder discussion

[Kevin & Cheryl Airth]

Jonathan:
 I will give it a shot but there are a multitude of answers out there? Terms
can cause confusion also. All turbochargers are superchargers but not all
superchargers are turbochargers!

> Why do diesels only seem to have Turbo power adders?

Most over the road trucks use turbos but not all. The famous Detroit Diesel
had/has a mechanical supercharger and this was adapted to drag racing use
early on. These are the big blowers on the top fuel cars. But turbo's
increase the thermal efficiency of the engine and give better fuel economy.
They don't consume any power from the engine but extract addition power from
waste exhaust heat and flow. All mechanical superchargers cost HP to run.
Just like any engine driven accessory. Water pump, alternator, PS pump or
supercharger. Top fuel racers have claimed it takes 250 HP or more just to
drive the blower at top speed!

> Why do imports and small cars seem to only come with turbo chargers and
not
> super chargers?

The problem with small displacement engines is the drag a supercharger puts
on the engine. Plus now packaging becomes a real problem. Some how the
supercharger has to be spun and have tubing to the intake of the engine.
Just look at all the plumbing on the few supercharged SHO's out there! A 18
wheel truck has plenty of room under the hood for just about anything but
not the small 4 cylinder cars or our 6 cylinder SHO's. Very tough. Now the
transverse mounted straight 4 cylinder engine has room in the correct spot
for a tubo or supercharger. So now you have some room you can use. Plus a
turbo runs on exhaust flow and not a mechanical drive. Usually easier to
plumb. Fuel economy is normally not a factor but HP is!


> Why do most people add a supercharger and not a turbo to N/A car?

For the street you want instant power. The supercharger is running from idle
on up providing boost at low RPM's. Turbo's can match and exceed the
mechanical supercharger but require more engineering to work well. The turbo
has a spool up time before your making power so in a street encounter you
might NOT have time to wait for the turbo to spool up! Now this can be fixed
too like Mazda did with the dual turbo RX7. They used two different sized
Turbo's. A small one to get you making power as soon as possible and a
larger unit to add the hammer on top. But this is a very complicated and
expensive set up. I don't know of any current production cars using this
setup now? The driving experience is different also. The supercharger just
has all the power right here right now. It's very addictive and fun!! The
turbo is almost sneaky. I have a good bit of experience with the SVO
Mustangs. At launch the car seems pretty normal but at about 2K rpm's the
back end started to move around and I could hear the tires squealing!! The
power as the rpm's build is almost scary!! I have a video of a SVO that runs
the quarter in 9.35/144 mph. The car is so close to stock it's crazy!

 I think the big issue is what kits are available from the aftermarket. I
want a turbo on my SHO but would gladly take a supercharger if it was cheap
enough! Of course putting cheap and superchargeing together is just not
possible!!!
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> Jonathan Zane