How do Porsche manage the difficulties of turbocharging a boxer engine..? ie Un-equal length or overly long headers are not ideal.

I know that both engine designs share the same origins (axis powers WWII), just interested in how they've developed separately since.

 

Not a problem with the firing order of a flat six, feed a turbo on a short manifold off each bank, nice even pulses to work with, short plumbing.

 

Thanks JB,

Where does the turbo usually sit on a porka then and do they use a TMIC..?

 

Quote here, but I can't find pictures, cutaway of the engine, intercoolers and turbos would be nice.

"The 911 Turbo engine is based directly on the 3.6-liter engine from the GT1 racecar that won the 24 Hours of Le Mans in 1998. (The engine is not a turbocharged version of the 3.6-liter unit used in the 2004 911 Carrera models.) To accommodate the high boost pressure produced by its dual turbochargers, the engine features a 9.4-to-1-compression ratio, compared to 11.3-to-1 for the 911 Carrera models. Intake air enters through louvers in the engine lid, flows into a joint air filter housing
and then into the turbochargers. The turbos compress the air to a maximum of 11.76 psi (0.8 bar over atmosphere). From the turbos, the intake air flows through dual intercoolers (one mounted in each rear fender) and then into the induction system.

Like all current Porsche engines, the 911 Turbo features double overhead camshafts and four valves per cylinder. The new-generation 911 Turbo introduced a new version of the Porsche VarioCam® valve timing system. Called VarioCam Plus, the new system provides continuously adjustable intake valve timing. The system helps boost low-end and mid-range torque. Dual valve springs ensure reliable,
high-performance operation. Sequential multi-port fuel injection features separate fuel mixture control for each cylinder bank, and a coil-on-plug (“distributorless”) ignition system provides quick response and reliable operation. The ME 7.8 engine control module incorporates the E-Gas electronic throttle. In place of a conventional throttle cable setup, E-Gas electronically transmits pedal position to the engine control unit. The new system provides even sharper throttle response and ensures low emissions.

The 911 Turbo also offers an optional X50 engine enhancement performance package that increases horsepower to 444 (SAE) @ 5,700 rpm and sustains 457 lb.-ft of peak torque from 3,500 to 4,500 rpm. The new package includes modifications to the turbocharger, air intake cooler, electronic control unit,
exhaust system, as well as a strengthened transmission. The X50 package is only available as an option from the Porsche factory."

 

And they are a £100K.
The older pre '89 Tubo's were a lot simpler and crude in delivery, especially single turbo lagg.
There were two hill climbers, one with 500 bhp estimated and weighing about 1000Kg.

So fast to see, but a special for the hills.(though registered and taxed/MoT'd)
The max exhaust tube length would be about 350mm and the euro cars had equal length pipes, the USA manifolds were very different due to having a cat (of sorts).
Graham.

 

This do?

 

Excellent, hadn't realised the later cars had twin turbos..! Suppose it makes sense with opposing head engines. Although I though that most TT/C applications suffered from a mid range fall in torque (between boosts). I suppose latest engine management systems can eliminate this as there seems to be a few new TT/C cars on the market..! (BMW 535d)

Cheers guys,

Jason

 

 

Thats true of sequential turbocharging (i.e. where a small turbo provides early spool up and low lag and a bigger turbo takes over as revs climb to give big boost) but the Porkers use parallel turbocharging, i.e. you've basically got 2 x 1.8 3 cylinder turbo motors on a single crankshaft.

 

That makes sense. Cheers.