Relocating the Turbo on a 951?
11-09-2011, 11:57 AM
#31
Yet is is totaly true, With 931 Porsche had turbo car, but the turbos were unreilable. Heat was the main problem. Remember this was in the early days of street car turbocharging and things were different then. Any for reliability reason Porsche chose to move the turbo to the cooler side of the engine. They also water and oil cooled the turbo. There is also a turbo water pump designed to cool the turbo on engine shut down. Due to heat issues on the 931 Porsche worked extra hard to make the 951 turbo last. As drive ability... That has proven to be adequate over the years. Back in the early 80's 220 hp was more than 911 of its day and darn near super car performance. All the while the car got 25 mph on the hwy and could run over 100 miles with cats in place. I remembe their was an early 944 turbo run on the street for something like 200k miles in a publicity stunt to show longevity of the system.
Now technology has moved on and it may very well be possible to put the turbo in a hoter enviroment and make it last. There are high power race motors that have right side turbos. These are few however and the ones that I know of often put the turbo in the passenger foot wheel after some major cutting.
The turbo placement in the 951 met the goals of porsche back in the early 80's. Remember the entire 944 family was designed to to price point and performance point. It was never designed to be the flag ship of Porsche. That design ethos left the 944 only adequate in a number of areas.
These days you can chose all the right side turbo placement you want, but packaging in the tight engine bay become and issue. Most fined it much easier and simpler to work off the basic left side placement of the turbo and just live with draw backs of the extra exhaust pumbing.
Now technology has moved on and it may very well be possible to put the turbo in a hoter enviroment and make it last. There are high power race motors that have right side turbos. These are few however and the ones that I know of often put the turbo in the passenger foot wheel after some major cutting.
The turbo placement in the 951 met the goals of porsche back in the early 80's. Remember the entire 944 family was designed to to price point and performance point. It was never designed to be the flag ship of Porsche. That design ethos left the 944 only adequate in a number of areas.
These days you can chose all the right side turbo placement you want, but packaging in the tight engine bay become and issue. Most fined it much easier and simpler to work off the basic left side placement of the turbo and just live with draw backs of the extra exhaust pumbing.
I thought the reason for the 924 Turbo's always going bad was because the oil wasn't that great. Also it wasn't watercooled at all. All the 80's turbo cars had these kinds of issues also people would love to give the car a little throttle right before shutting it off. Never understood that. I think if there would have been enough room Porsche would have put that turbo on the passenger side/hot side of the engine. The 924 didn't have sufficient air flowing around it. I think this is a cool idea, getting rid of all the extra piping that either leaks or cracks overtime. If we didn't have people constantly trying to improve these cars then they would all vanish from the streets(I would hate to see the day). Keep the ideas flowing.
11-09-2011, 01:36 PM
#32
Sure it does, especially on a car that already has a factory turbo option. The #1 reason why the remote systems are popular on Camaro's and pick-up trucks is ease of installation and cost. Nobody is going that route because it's the preferred location for the turbo's.
Taking a car that's already turbocharged from the factory and moving the turbo 10 feet away from the engine is a horrible idea. Designing a turbo system from scratch on a car that never had a factory option, it's a case of "better than nothing". Eliminating custom exhaust manifolds greatly reduces the cost and fabricating involved with turbocharging a car. That doesn't apply to a 944 since there is already a factory turbo manifold.
Taking a car that's already turbocharged from the factory and moving the turbo 10 feet away from the engine is a horrible idea. Designing a turbo system from scratch on a car that never had a factory option, it's a case of "better than nothing". Eliminating custom exhaust manifolds greatly reduces the cost and fabricating involved with turbocharging a car. That doesn't apply to a 944 since there is already a factory turbo manifold.
I highly doubt you would notice a difference relocating the turbo on the 951 to the right side.
Who has the Kelly Moss 968? Maybe he could chime in on anything he's noticed with that set-up.
11-09-2011, 03:19 PM
#33
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People seem to be pretty happy with their kits, performance wise. I've also seen 928s doing it that way (I am not saying that a remote mounted turbo should be considered for a 944). If having the turbo so far away was such a detrement to performance, people would have thrown it out the window long ago. I'm not saying it's better, or that it overcomes the obvious downsides to amounts of plumbing, and effects on spool or longevity, either.
If you were not implying it's a good idea on a 951, why bring it up or comment on how great they are in a thread about relocating the turbo on a 944?
Gee...I wonder why they decided to go back to the 2-valve turbo setup for the limited production 968 Turbo???
The long list of reasons why the 944/968 were killed does not include how unsuccessful the engines was or the car in general.
One of the biggest factors that sealed the fate of the 944 & 928 was increasing regulations starting in 1996 that proved to be cost prohibitive for these aging platforms.
The 944 almost single handily saved the company from bankruptcy when it was introduced....yup...total failure.
Porsche was losing money hand over fist in the late 80's / early 90's, even the 911. Porsche studied (and even visited) Japanese auto plants to learn how to streamline their production.
Since the 911 was not going anywhere, the re-tooling for "new" 944/928's just wasn't feasible and the Boxster prototype was filling the covers of every car magazine.
The answer was simple and the front engine cars were no more.
11-09-2011, 04:51 PM
#35
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They went with the 2 valve turbo motor due to fitment and because it was available at the time. I already said that the sole reason the turbo is under the intake is due to packaging. Knowing now that the 968 was the last version of a 944 chassis, they probably did not want to invest in creating a turbo 16 valve for it. Not only that, but the 968 turbos were extremely limited (can you really even call it a production run?). R&D was nil with the 8 valve turbo swap compared to trying their hand at a 16 valve turbo plant, and it shows that Porsche did not want to invest that kind of money in a dieing platform.
Add to these new standards / regulations, slow sales from trying to charge $50k+ for a 4-cylinder sports car during a time when sports cars in general were not selling every well.....all added up to the demise of the 944 (and most of the same reasons the 928).
Most publications noted the 968 was too little too late and low on power (wishing the 89+ turbo power-plant were retained). Again, to reiterate from the above, the turbo motor wasn't axed because of how unsuccessful it was during it's production run.
11-09-2011, 06:10 PM
#36
11-09-2011, 07:38 PM
#40
11-09-2011, 07:54 PM
#41
Three Wheelin'
+1 I have just bought a LHD '94 968 6 spd as a parts car because it was imported into NZ secondhand and it can't be registered for normal road use. it doesn't meet frontal impact regulations, which all cars from 1990 or newer must.
11-09-2011, 08:18 PM
#42
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inefficiency has to do with turbo size and placement. a 951 spools at 3k rpm correct? my stealth turbo spools at 2250...small turbos place right after the exhaust manifold.
the 951 turbo was moved from passenger side to driver side to make it more reliable. also remember when the 931 was introduced turbo technology was still young, the 951 was designed 6yrs after the 931. 6yrs for a car is a long time
the 951 turbo was moved from passenger side to driver side to make it more reliable. also remember when the 931 was introduced turbo technology was still young, the 951 was designed 6yrs after the 931. 6yrs for a car is a long time
11-09-2011, 10:17 PM
#44
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I don't have any numbers to support this claim, but I would imagine that putting the turbo on the right side would have resulted in a quicker spool time. It would also have the benefit of shorter compressed-air piping with less bends, which is important as cooler air flows with more resistance compared to hot air.
A majority of manufactures today place the turbo directly on the manifold when packaging allows. Today's CFD programs have come a long way compared to the punch-cards Porsche would have used in the 80's, so the modern placement can't be too far off base.