Cayenne Turbo boost levels

[Adam]

I've been reading European reviews on the new Cayenne and I've come across similar power and performance claims, but Motor magazine seems to have mis-quoted the amount of maximum boost the Cayenne runs.

It reads "... the Cayenne turbo runs a whopping 1.6 bar at maximum boost..." and by my maths, isn't that somewhere in the region of 23psi?

Even hardcore Pelican HP-Junkies like Mike, Juan, Merv and Rarlyl8 are too frightened to turn up the wick that far.

Perhaps these journalists aren't hacks afterall and the Cayenne is massively force-fed, but can anyone say for sure?

[osidak]

Running a chip in my VW TDI I see 30psi boost before it settles back down to 18-19psi. I know of a few people that have changed turbos and run different maps that sustain 30-35psi boost in their TDI's.

Maybe the pepperwagon does get 1.6 bar but I doubt that is sustained.

[930fan]

The actual figure is 0.6 bar or 8.7psi. See Car and Driver Jan 2003 issue for a preview test of the car.

Journos always screw this up. When the 996 turbo first came out, some were saying it boosted to 1.8bar instead of 0.8bar.

[pwd72s]

Will this get me to the club for tee off time???

[Mike the mechanic]

The 1.6 bar rating has to be atmospheric, so minus the 1 bar atmospheric pressure, leaves you with 0.6 bar. 1.6 bar in a big V8 would make over 1000hp!!! Although my Tdi makes 1.6 bar at about 140hp!!!

[Adam]

Thanks, Guys.

I was really starting to marvel at the advances Porsche would have had to make with this motor. I mean, they'd need 4:1 compression, water/ethanol injection, refridgerated intercoolers etc etc to make it streetable on 23psi!

I guess some over-zealous motoring journalists just get a little too excited.

[WydRyd]

Damn! The Journalist isn't the ONLY one that got excited then. What an anti-climax

[beepbeep]

I was really starting to marvel at the advances Porsche would have had to make with this motor. I mean, they'd need 4:1 compression, water/ethanol injection, refridgerated intercoolers etc etc to make it streetable on 23psi!

Not necessarily, i've run 1.2 bar on my 2L 9.1:1 CR SAAB, and i know people who run more. Cossie-guys frequently boost over 1.8 bar...

It's just that our aircooled heads are poor when it comes to turbocharging...they are big, promote detonation and must run pretty cool. On the top of that, there is no knock-detection circuit, so everything needs to have substantial margin.

New engines have watercooled heads (= more EGT), 4-valves (= more flow), electronic knock detection and can typically stand up to more boost.

Also, more boost doesn't necessarily means more power...you can run more boost with delayed ignition timing but it won't make more power, just heat ;-)

It's totally different picture when it comes to diesel engines beacuse they work with surplus of air, doesn't knock in traditional sense and are built sturdier...