SureShot

Kind of-
They both both boost relative to ambient temperature & pressure.
The higher the altitude the less absolute boost pressure.

In typical automotive applications, turbos have more headroom so boost can be dialed up at altitude.
You only need an adjustable controller for the waste gate.

Superchargers can be (but rarely are) setup with more headroom.
Then variable boost controls would have to be added.
This would be expensive in automotive applications.

My dad worked on P38 turbos to prevent them from scattering at high altitude.
Ground testing didn’t reveal how fast they were turning to make absolute boost at high altitudes.
I worked around Wright R3350’s* that had a shaft driven SC with variable boost controls.

-Bill

*Wright R3350: State of the art early in the early 50's, 18 cylinder radial.
3350 Cu In, 3,350 HP, supercharged, water injection, 3 power recovery turbines geared to the shaft.
(And the little Renesis makes 2.9 HP/Cu In.)

dos

Lol, you mixed up Colorado and Ohio!! The Rocky mountains of Ohio

Harry)I expected the rocky mountains to be a little rockier than this
Lloyd) Me too. That John Denver's fulla ****, man

MazdaManiac

iTrader: (3)

Only if you have a purely mechanical wastegate control. Very few people with aftermarket turbo systems are without an electronic boost controller.
No matter what my altitude becomes, my absolute manifold pressure at maximum boost remains the same.

Doing that with a supercharger like the Pettit is not possible.

SureShot

That sure dates me.
I'm thinking waste gate springs & manual boost controllers.
I forgot electronic boost controllers use MAP sensors.

True - Of course with a huge budget anything is possible.
IIRC the R3350 compressor wheel was about 16" in diameter and boost was controlled with a bypass throttle.

-Bill

MazdaManiac

iTrader: (3)

^^ Very dated, but terribly interesting. Thanks for that!

These days, the bypass limits boost by dumping it - there isn't enough finesse to control it.
Not to mention that you immediately run into the efficiency wall on a positive displacement unit if you "over-spin" it that way.

rx8spiritR

could it be your exhaust problem? wanna sell it to me?

DOMINION

Yup Turbo baby! yeah!

StewC625

Of course from Iowa to Texas, the highest elevation you'll reach is about 1000 feet above sea level.

I have not had my RX-8 out to Colorado but have driven there numerous times, most recently last summer in my Honda Odyssey.

ALL air-breathing vehicles suffer reduced performance at acceleration, and I-70 is definitely one of those really high spots up by the Eisenhower tunnel and points west. The amount of grade isn't helping you at all either - about 7% on that last six miles up to the tunnel.

Still, something is amiss in your engine - yes, some loss of acceleration is inevitable, but solveable by carrying more RPMS and climbing in 4th or even 3rd gear - traffic normally slows to 50 mph or so going up there. But if you're saying it would not even pull in 3rd gear, you've got a big problem ...

Stew

cptpain

i guess the natural lack of torque theory that our motors have doesnt play into this........

but yes, somethings amiss on your motor