supercharger philosophy
#16
Re: Re: supercharger philosophy
Originally posted by gbyron
Sure weight is important. Sure balance is important. If you remove your factory seats, and install aftermarket ones (or just have one lightweight seat for racing) you've done more "damage" to that balance (~120#stock seats v. ~30#race seats). Yes, that weight is closer to the center of gravity, but if you run the numbers, it would be little different than say, an extra 40# nearer the front of the car. Let alone removing all the interior trim which, egads!, everyone who races one (hardcore where the fine line of balance really matters) does. They really "trash" that fine balance. Oh, BTW- have you ever heard of adjustable suspension and corner balancing? The 928 has adjustable suspension, which allows you to mitigate little imbalances.
Greg
Sure weight is important. Sure balance is important. If you remove your factory seats, and install aftermarket ones (or just have one lightweight seat for racing) you've done more "damage" to that balance (~120#stock seats v. ~30#race seats). Yes, that weight is closer to the center of gravity, but if you run the numbers, it would be little different than say, an extra 40# nearer the front of the car. Let alone removing all the interior trim which, egads!, everyone who races one (hardcore where the fine line of balance really matters) does. They really "trash" that fine balance. Oh, BTW- have you ever heard of adjustable suspension and corner balancing? The 928 has adjustable suspension, which allows you to mitigate little imbalances.
Greg
I was even thinking of doing the water radiator for the intercooler system in the rear, but I am concerned about the efficiency associated with the indirectness of whatever air flow the unit would get.
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Actually Brendan, the water radiator isn't that important of a component and one could make a good argument to eliminate it. Whenever you are not on boost the intercooler acts as the water radiator to cool the water in the intercooler system. Unless you are on the track, you are in boost for a VERY short time.
#18
Originally posted by Tim Murphy
Actually Brendan, the water radiator isn't that important of a component and one could make a good argument to eliminate it. Whenever you are not on boost the intercooler acts as the water radiator to cool the water in the intercooler system. Unless you are on the track, you are in boost for a VERY short time.
Actually Brendan, the water radiator isn't that important of a component and one could make a good argument to eliminate it. Whenever you are not on boost the intercooler acts as the water radiator to cool the water in the intercooler system. Unless you are on the track, you are in boost for a VERY short time.
Come to think of it, the way I drive normally I may be on boost more then others.
I suppose it couldn't hurt right?
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Ok, don't make myself or Normy do a weight and balance calculation on the 928.
Are your seats full fwd..or full aft? full tank or half tank...normal oil level or are you running a bit low? Is your high intensity washer tank full? How about that soda pop bottle wedged up under your seat? Extra tools you carry? How much does your wife weigh in the right seat
The non-stock amp you have in the trunk after you removed the 1.75lbs factory amp from datum point -32.5?
Guys, what im trying to say here is that your splitting hairs on the "perfect balance" thing so don't let it get in the way of progress no matter who is trying.
I can guarantee that in every day use most of your cars aren't at the quoted "50/50" balance. Mine isn't.
More obvious and of issue, how many of you REALLY drive at the level where this(2,7,15lbs) even begins to becomes apparent! I dont.
I can think of 4-5 people on this board where they do take note of such things and rightfully so.
Forward guys!
Are your seats full fwd..or full aft? full tank or half tank...normal oil level or are you running a bit low? Is your high intensity washer tank full? How about that soda pop bottle wedged up under your seat? Extra tools you carry? How much does your wife weigh in the right seat
The non-stock amp you have in the trunk after you removed the 1.75lbs factory amp from datum point -32.5?
Guys, what im trying to say here is that your splitting hairs on the "perfect balance" thing so don't let it get in the way of progress no matter who is trying.
I can guarantee that in every day use most of your cars aren't at the quoted "50/50" balance. Mine isn't.
More obvious and of issue, how many of you REALLY drive at the level where this(2,7,15lbs) even begins to becomes apparent! I dont.
I can think of 4-5 people on this board where they do take note of such things and rightfully so.
Forward guys!
Last edited by Tony; 03-25-2004 at 01:10 AM.
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Tony, you forgot about us Wisconsin boys. The beer and cheese we are always carrying is at least 40lbs.
#22
Burning Brakes
Anyone who wishes to believe that supercharging the 928 has been completely perfected are only fooling themselves. Once that fact has been acknowledged, it is clear that the exchange of information, along with the pioneering efforts of the select few who are utilizing their time, talent, and money should be welcome by anyone who is truly interested in the development and perfection of such a system.
Personally, it is my belief that the Big Three, Jager, Cap'n Carl, Delta P, FAST, Tim Murphy, Andy, John (working on the turbo), along with racers like Mark A., and Mark K. are ALL positively contributing to the 928 community.
Cheers to you all (and anyone else I have inadvertently forgotten to mention)...
Rennlist...a place for 928 enthusiasts to share knowledge in a mature environment.
Personally, it is my belief that the Big Three, Jager, Cap'n Carl, Delta P, FAST, Tim Murphy, Andy, John (working on the turbo), along with racers like Mark A., and Mark K. are ALL positively contributing to the 928 community.
Cheers to you all (and anyone else I have inadvertently forgotten to mention)...
Rennlist...a place for 928 enthusiasts to share knowledge in a mature environment.
#25
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Originally posted by ViribusUnits
I know how to get the 50/50 ballance back!
Add the superchargers weight in tools to the hatch area!
I know how to get the 50/50 ballance back!
Add the superchargers weight in tools to the hatch area!
Tim. I notice that, even at at idle, the blower "preheats" the air going into the intercooler, even when it is not providing boost. This dynamic is probably less significant when the car is moving than when is sitting still.
Anyway, turning the pump on, even at idle causes a noticable drop in temp on the top of the intercooler. I really like the H2O to air intercooler for a lot of reasons, not the least of which the Dyno run can be made to more approximate driving conditions rather than the heat soak that actually happens. I know, I know, it is brief enough to not matter. Tell that to an engine whose air to air intercooler is not functional if the car is not moving.
#26
I looked at the pictures there on the DeltaP web site for the '87+ cars. Wow! This supercharger stuff is really starting to get confusing. The "Stage II kit with customer equipped plumbing" picture is Blown Beast's car, and is his avatar here on the board. Just the other day he posted in another thread that he made his own system, and that if it would have been available at the time he would have bought Tim Murphy's kit.
The picture of the "Stage I kit with customer equipped blower and plumbing" picture is same car as in the "Stage III kit with intercooler" picture, and is also the same car pictured on the FAST web site. The same car is also pictured yet again on the projekt928 web site. Hey Tim, you sure that guy's not a customer of yours too?
There on the Projekt928 site above the picture of the car it states "The VORTECH centrifugal supercharger is a custom designed T-Trim unit built to our specifications based upon advice from Jim Middlebrook, founder and CEO of VORTECH engineering" but I know the supercharger on that car was bought from FAST as part of their kit.
The dyno chart on the FAST web site is one from Tim Murphy's car, which doesn't exist in that configuration anymore. Actually none of the cars pictured on the FAST site exist in the configurations shown there anymore.
DeltaP talks about the air-air intercoolers being superior, but every intercooled car on the web site is air-water intercooled.
DeltaP talks about their stuff being aluminum and also suggests Corky Bell's book which states "A 3 square inch aluminum bar will stretch the same as a 1 square inch steel bar under the same tension or compression load. This quickly uses up all of aluminum's advantage of light weight. Therefore, when selecting a material for a tension or compression link, always use steel." DeltaP also correctly states that steel is a rare material on the 928, and they use aluminum pulleys and bracketry. Some of the places Porsche did chose to use steel on the 928 are the pulleys and some of the accessory bracketry though.
Why does this stuff remind me of Abbot and Costello doing "Who's on First?" My head hurts!
The comments about affecting the perfect 50/50 weight distribution by using one type of component over another did make me laugh though. First of all, the 928 doesn't have perfect 50/50 weight distribution to start with. I also had to wonder if people are stopping for gas every 20 miles. I mean that weight reduction in the back from the one gallon you used up would change that apparently so very critical weight distribution.
The picture of the "Stage I kit with customer equipped blower and plumbing" picture is same car as in the "Stage III kit with intercooler" picture, and is also the same car pictured on the FAST web site. The same car is also pictured yet again on the projekt928 web site. Hey Tim, you sure that guy's not a customer of yours too?
There on the Projekt928 site above the picture of the car it states "The VORTECH centrifugal supercharger is a custom designed T-Trim unit built to our specifications based upon advice from Jim Middlebrook, founder and CEO of VORTECH engineering" but I know the supercharger on that car was bought from FAST as part of their kit.
The dyno chart on the FAST web site is one from Tim Murphy's car, which doesn't exist in that configuration anymore. Actually none of the cars pictured on the FAST site exist in the configurations shown there anymore.
DeltaP talks about the air-air intercoolers being superior, but every intercooled car on the web site is air-water intercooled.
DeltaP talks about their stuff being aluminum and also suggests Corky Bell's book which states "A 3 square inch aluminum bar will stretch the same as a 1 square inch steel bar under the same tension or compression load. This quickly uses up all of aluminum's advantage of light weight. Therefore, when selecting a material for a tension or compression link, always use steel." DeltaP also correctly states that steel is a rare material on the 928, and they use aluminum pulleys and bracketry. Some of the places Porsche did chose to use steel on the 928 are the pulleys and some of the accessory bracketry though.
Why does this stuff remind me of Abbot and Costello doing "Who's on First?" My head hurts!
The comments about affecting the perfect 50/50 weight distribution by using one type of component over another did make me laugh though. First of all, the 928 doesn't have perfect 50/50 weight distribution to start with. I also had to wonder if people are stopping for gas every 20 miles. I mean that weight reduction in the back from the one gallon you used up would change that apparently so very critical weight distribution.
#27
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The more I read about the 50/50 of the 928 being so fragile, I'm getting very scared my car will be dangerous to drive this spring. My girlfriend and I both lost a bunch of weight since the last time I drove the car.
What should I do? I can put some weight under the seat, or should I start eating more? I'm so confused.
What should I do? I can put some weight under the seat, or should I start eating more? I'm so confused.
#28
Hacker-Pschorr,
I wouldn't worry too much about the weight you lost. I'm thinking that any change of the balance during operation would be more unpredictable in it's effect of the car. Just make sure when you drive it to keep both hands on the steering wheel and in the same position, and don't turn your head. God help you if you have a 5-speed and have to reach for the shifter to change gears though!
I wouldn't worry too much about the weight you lost. I'm thinking that any change of the balance during operation would be more unpredictable in it's effect of the car. Just make sure when you drive it to keep both hands on the steering wheel and in the same position, and don't turn your head. God help you if you have a 5-speed and have to reach for the shifter to change gears though!
#30
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Hacker, maybe you car is actually safer now...........
Yeah, Tim's success and the demand for Andy's version has renewed the enthusiasum of some heretofore slower-to-get-a-commercial-product-completed folks.
Some of the chest pounding sounds like "the-older-I-get-the-better-I-was".
The proof is in the pudding. Talking about beng in the SC kit business is easy, DOING it is all together another thing. I would have SC'd my car sooner had I believed there was a good chance I could acquire the complete components, knowledge and intent to back up the product under the same commercial conditions I purchase other (expensive) upgrades for my car.
The truth is there were too many horror stories around about these experiments that went wrong for a whole host of reasons.
I am a business owner, in my 50's and well enough off to pay for the stuff I want. I make business judgements with that background.
Last fall, Tim Murphy looked like a good business decision, in hind sight, I was right. As far as I am concerned the technical merits of each solution can be argued until the cows come home, I was looking for a commercial grade solution, and (at the time I bought my kit) no one had one except Tim.
Andy is getting close, but I think Tim stands alone in this important regard.
Yeah, Tim's success and the demand for Andy's version has renewed the enthusiasum of some heretofore slower-to-get-a-commercial-product-completed folks.
Some of the chest pounding sounds like "the-older-I-get-the-better-I-was".
The proof is in the pudding. Talking about beng in the SC kit business is easy, DOING it is all together another thing. I would have SC'd my car sooner had I believed there was a good chance I could acquire the complete components, knowledge and intent to back up the product under the same commercial conditions I purchase other (expensive) upgrades for my car.
The truth is there were too many horror stories around about these experiments that went wrong for a whole host of reasons.
I am a business owner, in my 50's and well enough off to pay for the stuff I want. I make business judgements with that background.
Last fall, Tim Murphy looked like a good business decision, in hind sight, I was right. As far as I am concerned the technical merits of each solution can be argued until the cows come home, I was looking for a commercial grade solution, and (at the time I bought my kit) no one had one except Tim.
Andy is getting close, but I think Tim stands alone in this important regard.