BC

Great comments Greg. With Tim's Kit, I was actually going to route (more weight, I know) the water lines to a larger water tank situated in the rear spare tire well, or even in the larger rear space inside the rear fenders. This way we are moving more weight to the rear, regaining the balance you mentioned. It IS extremely difficult to get as much weight out of the front of a 928 as the rear. Many have found that out. But if you run as much to the rear as you can with any system, then I think it would be an improvement.

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.

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.

BC

Thanks Tim. I was hoping for that extra heat transfer from a small radiator with some cool air running through it. I WAS planning on puting the car through some DE or large AX in San Diego....

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?

Tony

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!

hacker-pschorr

Tony, you forgot about us Wisconsin boys. The beer and cheese we are always carrying is at least 40lbs.

Randy V

Yeah, those cheese curds can be mighty weighty!

Mmmm, cheese curds...

Th Dude

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.

bcdavis

Sometimes mature...



Hey, where is that bouncing boobie avatar?

Hahaha!

ViribusUnits

I know how to get the 50/50 ballance back!

Add the superchargers weight in tools to the hatch area!

Gretch

Or just do what I did and install a big honkin' fire extinguisher in the back seat..........



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.

SteveM928

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.

hacker-pschorr

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.

SteveM928

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!

Old & New

SteveM, very insightful & funny.

deltaP, you got some splainin' to do ...or maybe just crawl back under that rock.

Gretch

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.