Twin Turbo 928 fixed and back out there terrorizing the streets!
#661
Nordschleife Master
Thread Starter
New downpipes being fabricated
Here are some photos of the turbine downpipes. These are only the main turbine circuit. The wastegate circuit that is much more difficult is still work in progress. The punch line is that these are going to just flat out flow. The old more restrictive pipes had less than 0.5 psi of back pressure at 700 rwhp, so these should accommodate what the compressor can push thru and what the engine can burn.
#663
Nordschleife Master
Thread Starter
#667
Is cutting the housing a normal thing ? No, right?
#668
Nordschleife Master
Thread Starter
He is.
Fitting these turbos under the 928 V8's wings requires a lot of surgery. The earlier smaller turbos had the compressor cover cut and rewelded to a different shape. These bigger turbos require at minimum cutting and welding the turbine housing for a wastegate circuit. There's no alternative way to route the wastegate circuit while meeting the clearance spec.
Fitting these turbos under the 928 V8's wings requires a lot of surgery. The earlier smaller turbos had the compressor cover cut and rewelded to a different shape. These bigger turbos require at minimum cutting and welding the turbine housing for a wastegate circuit. There's no alternative way to route the wastegate circuit while meeting the clearance spec.
#669
Man of many SIGs
Rennlist Member
Rennlist Member
#670
Nordschleife Master
Thread Starter
The design intent is similar to the housing in Fabio's photo. That housing would likely not fit in this spot, the space constraints make everything a custom job.
The wastegate priority ended up working very well, the flow path is close to ideal:
The fire-breathing bastards staring at you below. V-band clamp flanges are pretty:
The wastegate location is designed to be easily serviceable and tunable. The spring can be changed without much work at all. The wastegate is also placed high enough such that it is comfortably above the lowest point of the chassis:
Here's how it all fits on the driver side, installed on the car:
The wastegate priority ended up working very well, the flow path is close to ideal:
The fire-breathing bastards staring at you below. V-band clamp flanges are pretty:
The wastegate location is designed to be easily serviceable and tunable. The spring can be changed without much work at all. The wastegate is also placed high enough such that it is comfortably above the lowest point of the chassis:
Here's how it all fits on the driver side, installed on the car:
Last edited by ptuomov; 10-15-2013 at 09:43 PM.
#671
Does Taxachussetts have speed bumps? That's where speed bumps hit when you go over them somewhat quickly but not quickly enough and not too slowly.
#673
Nordschleife Master
Thread Starter
MA has top income tax rate that is almost exactly 1/2 of CA's. Also, we're not bankrupt here. So much for Taxachusetts.
There aren't many speed bumps here. People have a healthy disrespect for the traffic laws in MA, people driving with MA plates in the North-East are called "Massholes". Massholes would just run over the speed bumps and launch their beaters to a nice jump. I lived in East Cambridge for five years and they had one of those "jumps" on 3rd street close to our loft apartment. Evel Knievel show for free, every day.
Although there are not many speed bumps, there are obstacles that someone might casually mischaracterize as "potholes." These in reality are giant holes on streets that would fit a tank, but if you hit one of them potholes you have bigger problems than your wastegate. I once took a right turn in heavy rain hit one of those pretty hard, the left front tire popped off the rim. (The wastegate on the Saab 93 was just fine.)