Which supercharger to get new owner
10-08-2015, 11:43 PM
#1
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Which supercharger to get new owner
Hello Gents,
I'm a brand new owner of an awesome 928S4. I bought her 3 weeks ago. I've been a BMW guy for a long time. This is my first Porsche. I enjoy the 928S4 for it's timeless design, smoothness, as well as highway speed. I am not a racer. I would be happy with more power. My 928 feels much slower than my 335i. I am not bored of my 928S4 already. I have planned my budget accordingly. I knew I would buy a supercharger before I bought my 928S4.
My 928 is good candidate for SC.
She has 97xxx miles grey over black interior. It has been well taken care off and is in pristine shape. Everything is stock except for an exhaust with X pipe. Sounds very nice. She is an automatic. Unlike most I love the auto. She has been serviced regularly.
I have been planning this for over 10 years. I have a budget for a supercharger.
I would like to invite the experts for suggestions.
I researched on goggle.
4 options exist.
Twin turbo sounds good. Too rich for my taste.
Murf's SC
928 Motorsports SC
VCG SC
Please give me some direction. I can afford up to $10000.00 for SC.
Thank you in advance for your comments,
Erin
I'm a brand new owner of an awesome 928S4. I bought her 3 weeks ago. I've been a BMW guy for a long time. This is my first Porsche. I enjoy the 928S4 for it's timeless design, smoothness, as well as highway speed. I am not a racer. I would be happy with more power. My 928 feels much slower than my 335i. I am not bored of my 928S4 already. I have planned my budget accordingly. I knew I would buy a supercharger before I bought my 928S4.
My 928 is good candidate for SC.
She has 97xxx miles grey over black interior. It has been well taken care off and is in pristine shape. Everything is stock except for an exhaust with X pipe. Sounds very nice. She is an automatic. Unlike most I love the auto. She has been serviced regularly.
I have been planning this for over 10 years. I have a budget for a supercharger.
I would like to invite the experts for suggestions.
I researched on goggle.
4 options exist.
Twin turbo sounds good. Too rich for my taste.
Murf's SC
928 Motorsports SC
VCG SC
Please give me some direction. I can afford up to $10000.00 for SC.
Thank you in advance for your comments,
Erin
10-09-2015, 12:14 AM
#4
I would venture to guess (and I will defer to the experts) but I would seriously consider a few housekeeping/infrastructure items before SC the car. 25+ year old cars will need to ensure that certain items like WP/TB, top end refresh are absolutely done (if not recently done) first. MAF within tolerances, fuel pump upgraded, injectors upgraded. I would even consider a new engine and FI harness from SeanR before I would SC. Then you will have to Sharktune the car after the SC install. Just a few thoughts... Welcome to the tank, enjoy the time with a great car and great folks in the community.
10-09-2015, 12:30 AM
#6
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putting a blower on an engine NOT designed for higher pressures is a recipe for disaster sure you can get away with a little for a little while but it really does not work out all that well in the long run. Might as well add NOS which is cheaper AND BLOW IT UP SOONER !!!
10-09-2015, 12:33 AM
#7
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10-09-2015, 12:36 AM
#8
Race Car
Alright...Madturk is right...good advice follows. Enjoy your car. It was amazing in its day, but even supercharged there will be some tradeoffs back and forth if you continue to compare it to a modern performance coupe- and its very unlikely that it'll be able to sneeze a modern high performance coupe. Depending on how one defines that last, of course.
Last edited by SMTCapeCod; 10-09-2015 at 11:32 AM. Reason: Walking back unproductive rant
10-09-2015, 12:37 AM
#9
Now now.....
C'mon people...
It's not all that bad. The 928s4 has been proven reliable when sc'ed. It should kick azz. With that much cash you can do stage 2.
500hp sure sounds nice on S4. In my opinion the S4 deserves that hp. You might spend less and update to gts brakes.
Just know it will kill your resale value should the 928 S4 ever skyrocket as they say.
C'mon people...
It's not all that bad. The 928s4 has been proven reliable when sc'ed. It should kick azz. With that much cash you can do stage 2.
500hp sure sounds nice on S4. In my opinion the S4 deserves that hp. You might spend less and update to gts brakes.
Just know it will kill your resale value should the 928 S4 ever skyrocket as they say.
10-09-2015, 12:41 AM
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Hi Erin, Clearly Tuomo and I are advocates for Twin Turbocharging, your old BMW had it and it suits the 928 very well. Talk to John at Kuhn Performance, he can guide you through the whys and wherefors. Yes it will be more expensive than a simple blower kit, but it will also be better.
10-09-2015, 12:44 AM
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10-09-2015, 01:08 AM
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BMW 335 is 306hp, 928s4 is 316hp in stock trim. Granted the shorter gearing (and more of them) in the BMW will make it feel faster off the line, but from a rolling start upwards they should be pretty even.
Sounds like your S4 hasn't had the age-related issues fixed, and is thus down on power (e.g. knock sensors or hall sensor (cam angle) not working). Have you had it connected to the correct diagnostic computer to read the fault codes and run the diagnostic tests? A fault in either of those sensors will cost you almost 30hp, and thats assuming other stuff like cam timing is correct.
Once its working, by all means supercharge it, but supercharging a motor with issues is a recipe for burning money and possibly busting an engine.
First tho', I'd fix any issues with: vacuum system including HVAC (if the flap inside the intake isn't working you're down on torque in the mid-range), fuel system (injectors clean, pump volumes/pressure checked), intake seals/gaskets, Mass AirFlow sensor, throttle cable adjustment, and the knock sensors, hall sender, and throttle position switch (failure to read Wide Open Throttle is common on 25+ year old TPS').
After that, your S4 should be making factory power and feel a lot zippier. If thats still too slow, then SC it
Sounds like your S4 hasn't had the age-related issues fixed, and is thus down on power (e.g. knock sensors or hall sensor (cam angle) not working). Have you had it connected to the correct diagnostic computer to read the fault codes and run the diagnostic tests? A fault in either of those sensors will cost you almost 30hp, and thats assuming other stuff like cam timing is correct.
Once its working, by all means supercharge it, but supercharging a motor with issues is a recipe for burning money and possibly busting an engine.
First tho', I'd fix any issues with: vacuum system including HVAC (if the flap inside the intake isn't working you're down on torque in the mid-range), fuel system (injectors clean, pump volumes/pressure checked), intake seals/gaskets, Mass AirFlow sensor, throttle cable adjustment, and the knock sensors, hall sender, and throttle position switch (failure to read Wide Open Throttle is common on 25+ year old TPS').
After that, your S4 should be making factory power and feel a lot zippier. If thats still too slow, then SC it
10-09-2015, 06:18 AM
#15
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Erin,
Welcome to the list- this resource is probably one of the best of its kind with a tremendous knowledge base and an infinite number of opinions as you have no doubt realised already.
Some folks are ardent supporters of boosting these motors, others fervently against it. The initial attempts at marketing such conversions started around 15 years or so ago with varying degrees of success [i.e. misery]. But now they are comparatively well sorted, each with its own specific positives and as some would argue, weaknesses.
Expecting to bolt 40% more power straight on to a reasonably tuned motor is optimistic to say the least but to be fair, it has been done quite a number of times now. As you might expect we tend to hear about the successes but whether we read of the failures is something that intrigues me.
If you are hell bent on doing this then my personal recommendation would be to get a benchmark dyno reading from a reputable shop, preferably done back to back with a known good example to give you some idea of where your example fits in the scheme of things. Trying to boost a sad S4 is a complete waste of time and dangerous for the motor. The sad fact is most 928's are in a pretty poor state when sold unless you purchase from a real enthusiast and even then there are no guarantees.
An often overlooked aspect of this upgrade path is what needs to be done to support power adders. Stock rubber is arguably inadequate for the stock setup and when driving the S4 after driving the GTS the S4 brakes feel "inadequate"- not really the case but just feels that way.
When aquiring a 928S4 I advise folks to allow $2k for unknowns if it is a good one and much more for unknown provenence. The scope of things that may need attention is big and expensive. On top of that, my experience with the S4 is that you should also be prepared to do custom tuning with the likes of a sharktuner kit [about $1k] as one size does not really fit all- some will argue differently.
Without doubt there is scope to do more with the 928S4 stock motor but Porsche did not leave an awful lot on the table as has been well proven [I believe]. If you have a need to be more competitive performance wise then by all means have a go but personally, if I felt I needed 500 bhp I would be more inclined to go for a 996 TT as bang for the buck it is the cheapest route and an equally fine machine in its own right-but that is me. Oops- I forgot- I have already done that with my 520 bhp Cayenne Turbo S- thus I get the best of both worlds. I like the Cayenne very much- it is very rapid, handles like most sports cars, is sublimely comfortable and has been very reliable in the 3 years I have owned it- but - I still prefer to drive my 928GTS with my 90 S4 motor in it during the weekends. I find the handling mods more than compensate for the [by todays stds] modest power output and driving these cars just feels magic- something special that money simply cannot buy at this price point.
I may put modest boost on my motor one of these days or I may try to upgrade it to full GTS spec motor.
As Hilton states, a well sorted 928 goes reasonably well and in reality does not need to go any faster than 170 mph for all practical purposes, but it would be nice if got there quicker.
Finally, there are other alternatives to consider like a stroker motor but not at the price point you mention.
Good luck with your choices
Rgds
Fred
Welcome to the list- this resource is probably one of the best of its kind with a tremendous knowledge base and an infinite number of opinions as you have no doubt realised already.
Some folks are ardent supporters of boosting these motors, others fervently against it. The initial attempts at marketing such conversions started around 15 years or so ago with varying degrees of success [i.e. misery]. But now they are comparatively well sorted, each with its own specific positives and as some would argue, weaknesses.
Expecting to bolt 40% more power straight on to a reasonably tuned motor is optimistic to say the least but to be fair, it has been done quite a number of times now. As you might expect we tend to hear about the successes but whether we read of the failures is something that intrigues me.
If you are hell bent on doing this then my personal recommendation would be to get a benchmark dyno reading from a reputable shop, preferably done back to back with a known good example to give you some idea of where your example fits in the scheme of things. Trying to boost a sad S4 is a complete waste of time and dangerous for the motor. The sad fact is most 928's are in a pretty poor state when sold unless you purchase from a real enthusiast and even then there are no guarantees.
An often overlooked aspect of this upgrade path is what needs to be done to support power adders. Stock rubber is arguably inadequate for the stock setup and when driving the S4 after driving the GTS the S4 brakes feel "inadequate"- not really the case but just feels that way.
When aquiring a 928S4 I advise folks to allow $2k for unknowns if it is a good one and much more for unknown provenence. The scope of things that may need attention is big and expensive. On top of that, my experience with the S4 is that you should also be prepared to do custom tuning with the likes of a sharktuner kit [about $1k] as one size does not really fit all- some will argue differently.
Without doubt there is scope to do more with the 928S4 stock motor but Porsche did not leave an awful lot on the table as has been well proven [I believe]. If you have a need to be more competitive performance wise then by all means have a go but personally, if I felt I needed 500 bhp I would be more inclined to go for a 996 TT as bang for the buck it is the cheapest route and an equally fine machine in its own right-but that is me. Oops- I forgot- I have already done that with my 520 bhp Cayenne Turbo S- thus I get the best of both worlds. I like the Cayenne very much- it is very rapid, handles like most sports cars, is sublimely comfortable and has been very reliable in the 3 years I have owned it- but - I still prefer to drive my 928GTS with my 90 S4 motor in it during the weekends. I find the handling mods more than compensate for the [by todays stds] modest power output and driving these cars just feels magic- something special that money simply cannot buy at this price point.
I may put modest boost on my motor one of these days or I may try to upgrade it to full GTS spec motor.
As Hilton states, a well sorted 928 goes reasonably well and in reality does not need to go any faster than 170 mph for all practical purposes, but it would be nice if got there quicker.
Finally, there are other alternatives to consider like a stroker motor but not at the price point you mention.
Good luck with your choices
Rgds
Fred
