Z

It really depends on the intended application. The typical car in Germany is driven differently than the typical one in the United States. If the way Porsche and Audi were building their new cars was the ultimate setup for here, anyone who thought so and wanted to go along those lines would be installing a four or six cylinder engine in place of thier V-8. I haven't heard of that happening on any wide scale here yet. More and more manufacturers, including Mercedes and Jaguar, are moving towards belt driven superchargers. There are reasons for it. As time goes on, I fully expect the trend to continue. Don't be at all surprised to see supercharged Porsches some time in the future either.

Lagavulin

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">I do like the simplicity of the centrifugal setups, and the fact that they do not make the engine run high exhaust back pressures, that is nice. I would be curious how much power it takes to run one though.</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Roughly 10% of the horsepower.

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">That exhaust is being pumped out by the engine. The restriction makes it harder for the engine to pump it out, requiring more power from it to do so.</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">A lot of people do not realize that part of the engine's power goes immediately towards pumping the exhaust out of it’s cylinders as Z has stated. Each power stroke is expending energy right off the top by pumping out exhaust out of a cylinder which is on it’s exhaust stroke.

And when a turbo is affixed which is seen as a 'blockage' of the exhaust port, it will take more power to pump the exhaust out of the cylinder than a normally aspirated engine. It is no different than exiting a building which has a revolving door; you have to exert energy to push on the door’s ‘vane’ to rotate it so that you can exit the building, versus merely walking through an open door as is the case of a normally aspirated engine.

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica"> Made from a 944 turbo intercooler? </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">That is correct; good eye!

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica"> but I think the water to air intercooler would be better for my Supercharged 560 SEC Mercedes </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">If you have the room, an air-to-air is more efficient than an air-to-water-to-air ‘aftercooler’. You don’t have to worry about plumbing, water pump, wiring for the pump, radiator, etc, versus the simple air-to-air unit. If space is tight like the 928, then you have no alternative and must go the water route.

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica"> It a book. "Forced Induction Performance Tuning", by A. Graham Bell. It's a pretty good book, but maybe not as applicable as the Corky Bell book that's been mentioned to people who just want to install a supercharger without getting too involved in a lot of stuff </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">As Z has stated, Corky’s book is straight-forward for supercharging. If one is more inclined for more in-depth subject matter and theory, then A. Graham Bell’s book supplements Corky’s book very well as one book supports the other. I think both are a ‘must have’ for a supercharger enthusiast. Uh, don't forget to read them, either!

SHRKBIT

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Hacker-Pschorr:
<strong>Its even track tested.
Exiting turn 6 at road america:
</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Er, how much "track testing" can you do without a helmet? (See the picture you posted.)

<img border="0" alt="[ouch]" title="" src="graemlins/c.gif" />

hacker-pschorr

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by SHRKBIT:
<strong> </font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Hacker-Pschorr:
<strong>Its even track tested.
Exiting turn 6 at road america:
</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Er, how much "track testing" can you do without a helmet? (See the picture you posted.)

<img border="0" alt="[ouch]" title="" src="graemlins/c.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">I had an opportunity to shoot Tim's car at Road America during the annual May PCA club event. PCA had touring during the early afternoon that Tim participated in. In case you were not aware, touring does not require a helmet. My only regret was not being in the car. Pictures are worth 1000 words so I'm glad I was able to shoot them. And for anyone one says "Touring isn't really racing" no kidding, that is why its called "touring" but if you've ever done 5 laps around Road America at even 50% of max, your car still needs to be in top shape. I should know, lost the brakes on my 944S touring one year. Boiled them over pretty good. Nothiing like going into turn 5 at 90mph, pushing on the brake pedal and feeling mush. That was fun. Everything turned out ok in case you were wondering.

BC

Those pictures can take up quite of bit of time just trying to imagine the changes from a stock S4 engine bay, especially if you have one in pieces in your garage downstairs

Who's that guy in the passenger seat? Magnum PI?

Anyway, I had a thought about all of those vacuum lines, and breathers. I think Maybe Tim or the other gentleman could chime in here:

You need crank case venting. Even better if the crank case has a bit of vacuum to it - even with supercharging, right Z?

In the summit catalog, there is a little motor that creates vacuum for the brake system on supercharged or radical cammed cars. If that was hooked to our S4 engine, then all we would need to run all the vacuum systems is that unit. The other concern would be to handle the crank case venting, and oil blow-up for the oil fill tower.

Any thoughts on this?

BC

I also like how big that red car's intercooler is. That combined with a nice 5 gallon tank in the back of the car in the spare tire well, and a aux radiator with a fan on it would keep that charge VERY cool. Add a methanol spray to the intake, maybe two valves, right before the throttle body, and you could probably run enough boost to be happy for at least a while. The 944 forum had a few threads on a 100psi pump kit.

From the power currently being made, I think an 800 hp S4 with slight Engine mods is not far off. Maybe more....

If the S4 engine is bored (not stroked, for this idea), and very solid pistons and rods are used to build it up, you have an 800hp bottom end (you have obviously reduced the compression to 8.5 or 9.0 if you have an aftermarket efi). The heads don't need much - maybe some smoothing, and a nice Supercharger cam set from <a href="http://www.928developments.com" target="_blank">www.928developments.com</a>

You are obviously past the 6-8k threshhold on the SC route when you go into the engine. But sleeving is what makes your life easier. Sleeve that block, and you can use any piston you want, custom made to your specs. The rods can get pricey, but maybe you could use an off the shelf chevy rod.

Make sure you have a 7500 rpm redline, and the blower makdes only small boost until 3k, and you won't break much in the drive train either.

Thoughts?

BC

BTW - personally, I am putting in a DTA on my 89S4 5spd. This is a foundation for future work. It is my belief that only the Computer system is holding these men back.

I also wanted to mention that the Graham A. Bell book, I think, mentions EXHAUST sizes for certain HP levels. I think that some serious gains could be made on those two Cars if a proper throttle body and header/exhaust diameter customization can be sought.

Z

Nope, it's not Tom Selleck, but I can see how you could mistake him for that strikingly handsome guy in the car.

Some is good, but you don't want too much.

You wouldn't need the vacuum from that pump for the car's normal vacuum systems, and that pump more than likely wouldn't have the capacity to effectively deal with the blowby gasses.

The intercooler on the red one is probably overkill for most situations if you ask me. That car is intended to be running a lot more boost in the future though. It's already been increased 5psi since last weekend.

There have been some pretty interesting things discussed up there in Green Bay, but some of them are definitely a lot more than slight engine mods.

That's one of the nice things about supercharging. You don't neeed the high redline to make big power. Building that high redline stuff gets expensive, and is where stuff is more likely to break.

There's definitely more power in both of them in regards to the exhaust. The red one still has the completely stock exhaust system on it, including the factory cats and rear muffler. Tim's just has an "X" pipe cat bypass, and a couple of resonators in place of the stock rear muffler.

BC

So with your idea that the vac pump that I mentioned is not so good, then with respect to rerouting all vac and crank case lines - what is a best case scenario? If you could do ANYTHING with the whole system, what could be done?

I asl thie because I no longer will have a MAF, and the elbow below it has a bunch of crankn case vent lines. If I get rid of those lines, what would be the best way to get good, solid vac, and also make sure I get no oil into the intake?

Lagavulin

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">I ask this because I no longer will have a MAF,.. </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Brendan, that's a pretty ambitious move. What are your thoughts regarding your proposed plan?

I ask because the stock unit does a pretty good job by itself. Of course there are some who successfully supplement it with various devices, but they did not replace the whole thing.

Is there another 928 that has already done this mod from which you can correspond and compare notes with?

Regardless, best of luck with your plans.

Lagavulin

Double post...

BC

The DTA will have a MAP sensor. It will use inputs from MAP, Throttle position, Coolant Temp, and air temp to figure values.

The INjection will be sequential (100%), and the ignition will be Coil Near Plug.

As I go along, and get everything ready to install, I will post more. I do not wish to steal this thread.

Carlos

Turbo vs blower, On big hp v8's like in George's Mustang I've heard numbers as high as 400 hp to drive the blower vs 100 hp or less to drive the turbo. For the street, the ruduced effiecinecy of the blower pays off in throtle response & reduced heat. Size the turbos however you want, they still wont produce the instant response of a blower but at equal amounts of boost, the turbo will always have more power.

hacker-pschorr

I'm by no means an expert on this topic, just curious. Why are the most powerful engines in racing supercharged? I'm talking about Top Fuel Dragsters. Maybe the type of fuel would fry the turbo's? They must have tried multiple turbo's on these engine's in testing one time or another. Or does anybody know does the NHRA have a ban on turbo technology on these cars?

Tony

Ive been reading a book recently on SCing (not Corkys) and there is an image and a caption of a blower made for top fuel dragsters where they were breaking it in/testing using a pretty good size V8 to turn it..once the blower hits its stride, the V8 wasnt powerful enough to keep turning it at speed!

Gives you even more respect for the Top fuel motors and the power they put out as well as the fact that they rebuild the darn things under a tent canopy by the trailer...
IMHO..Thats the one of the best things about watching NHRA is when they pan to the pits and they show these guys swarming, like worker bees, around the engine, getting it ready for the next run!
<img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" />