John..

This is why the Bastard will be running the stock rods and crank. Inertial loads break rods, not power loads (within reason). If anything takes a fast dump it will be piston ring lands...I have eliminated that problem altogether. Stock Reinz narrow fire ring head gaskets as well! Control detonation and you don't need an o-ring setup. Best of all, making this power will happen well below 6000 rpm, so my rods won't see huge inertial loads. Actully, the new pistons were 30 grams lighter, so I had the whole shebang balanced out. It should be a sweet deal once it is running.

Stay tuned, I should have my dyno results in about 4 to 5 weeks.

The animal is getting put in the car this weekend while my brother is in town. Slowly building up all the parts...nice clean parts I might add.

chris928

John,

I hope you're taking lots of pictures for us...

Z

Since longevity is being discussed, here are a couple of points that might be worth thinking about. During normal driving and operation, a supercharger installation isn't really affecting much of anything as far as wear or durability. Any real effects, if any, would be at full throttle, under significant boost. How long do you really think you're going to be in that situation? With 525 rwhp I'd be willing to bet that the majority would run out of nerve before the gas pedal was floored for even 15 seconds at a time. Even 10 seconds at a time would be extremely rare. Problems generally occur at high RPM. Trust me, you will not be spending much time at all at high RPM when making a significant amount of boost. The RPM range goes by very quickly. You'd be spending considerably more time at high RPM with a stock engine.

Just RPM isn't the only thing to keep in mind. Doubling the RPM will not double the wear rate. The wear rate will more than double. Wear will increase at a rate significantly faster than the increase in piston speed. At any given RPM or road speed, a supercharged engine will have the same piston speed as a stock engine of that same stroke. This isn't the case with an engine that has a longer stroke though. Since the transmission will still have the same gearing, and the engine the same RPM range, the average piston speed in a stroker motor will be higher than in a stock or supercharged engine. The RPMs will all be the same, but the pistons in the stroker motor will be traveling a longer distance in each crankshaft revolution. The pistons in the stroker motor will be traveling that longer distance faster any time the engine is turning. In other words, even at idle the pistons in a stroker motor are traveling further and faster than those in a stock or supercharged engine. Since more and faster moving parts travel means an accelerated wear rate, I wouldn't be at all surprised if a supercharged engine had greater durability than a stroker motor if both started out in the same condition. That's if the supercharger installation was properly done, and nothing blew up. There are bad supercharger installations by people who don't fully know what they're doing, just like there are bad stroker motor or stock engine rebuilds by people who don't fully know what they're doing. The results are often the same. There are several key factors that have a significant effect on preventing detonation in a supercharged engine. Tim has effectively dealt with those issues, and has never had any kind of knock or detonation problem, even though using pump gas. Just that I know of, he's got around 40 dyno pulls on it, by no means babies the car on the street, and has also had it on the track on occasion. The one exception to fully addressing those issues at this point is the fuel mixture. Right now the mixture's a little leaner than it should be, due to the fuel pump being inadequate to supply the amount of fuel needed at high RPM. That didn't become an issue until over 500rwhp, and should be addressed very shortly.

show'n'go

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Z:
<strong>At any given RPM or road speed, a supercharged engine will have the same piston speed as a stock engine of that same stroke. This isn't the case with an engine that has a longer stroke though. Since the transmission will still have the same gearing, and the engine the same RPM range, the average piston speed in a stroker motor will be higher than in a stock or supercharged engine. The RPMs will all be the same, but the pistons in the stroker motor will be traveling a longer distance in each crankshaft revolution. The pistons in the stroker motor will be traveling that longer distance faster any time the engine is turning. In other words, even at idle the pistons in a stroker motor are traveling further and faster than those in a stock or supercharged engine. </strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Makes sense to me.
Big numbers on the dyno chart, obviously some serious homework has been done on this installation.
Torque numbers like that could turn tranny gears into "corncobs"!

Brad

Tom. M

Another question for Tim,

Did you remove or de-activate the flappy?...appears as if the torque curve seems to be slightly hurt by its presence (if in fact the dip at 3500rpm is flappy induced rather than a result if ign advance).

Awesome to see the torque continue to rise with rpm!!...

Later,
Tom

Tim Murphy

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Sterling:
<strong>is Tim running the stock ignition?</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Yes, stock ingnition. Actually I have chips in the car but I'm not sure how much of a difference they make, they were in it when I bopught it.

Tim Murphy

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Tom. M:
<strong>Another question for Tim,

Did you remove or de-activate the flappy?...appears as if the torque curve seems to be slightly hurt by its presence (if in fact the dip at 3500rpm is flappy induced rather than a result if ign advance).

Awesome to see the torque continue to rise with rpm!!...

Later,
Tom</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">I had all kinds of plans when I went to the dyno, including overriding the flappy to keep it open through the run. I only made 2 pulls on the dyno. The fuel pressure was dropping off when I hit 5200 rpm so I quit there until I can address that problem before I start messing with anything else. Too bad about the fuel though, in all my previous dyno pulls the hp continued to rise until I hit 6k rpm. If I had the fuel I think I would have hit 560+ and then with some other tricks/experiments I had up my sleave I might have seen the 600 mark.

Z

Not as likely as you might think. Kind of a benefit of the centrifugal superchargers are that they don't make that big torque way down low in the RPM range. That's where transmissions generally break from the big torque and sticky tires. If you spend any time at the drag strip, you'll see that transmissions usually blow up on the starting line, or when the RPMs go too high and things come apart. The big torque down low makes for a good launch if you've got the traction for it, but the transmission suffers. That's where a greater amount of inertia needs to be overcome, adding to the strain on the transmission. If you don't have the big sticky tires, the big low end torque isn't as much of a problem. Of course you won't have any traction without them, you'll have big wheelspin, and won't be able to use that torque there anyway.

Tim is running the stock ignition and stock fuel injection stuff. It's got bigger injectors and fuel pressure modification though.

The flappy is hooked up and working. Disabling in the open position for a test before hurt low end power to some degree. The typical dip is more than likely due to both the flappy and the ignition timing changing there. He was talking about maybe experimenting with the ignition timing there using a piggy-back computer to see about maybe reducing some of the dip a little bit.

Fastest928

Tim,
Numbers look great! And, correct me if I am wrong, but all on an original bone stock S4 engine to boot!

How many miles on the setup so far?

Maybe it is time for Marcus H to put some boost into his forged internals engine and have some fun too!

Great Job!
Marc

Chris Lockhart

OH--MY--GOD!!!!!!!!!!!!!!!! Not only am I green with envy, but I'm drooling all over the place, and I think I just soiled myself!!!!!!!!! This my friends, is KILLER power. Anyone feel like donating to the "Bigun needs a supercharger badly" fund????? Tim, as soon as the finances are in line, I WILL be calling you again. <img border="0" title="" alt="[Wink]" src="wink.gif" />

Tim Murphy

Tony

"700 rwhp" <img border="0" title="" alt="[Eek!]" src="eek.gif" />

I know its not on a dyno sheet but you gotta admit guys/gals, this is some pretty exciting stuff going on in "928 land" these days..pictures, information exchange, comradery...etc etc .

&lt;in a lousy Caribbean accent&gt;
"It is all good Mon. "

Some day, there will be a few vipers, Z06's, GT2s etc in many states that will be wondering what the heck just blew them away or stuck with them!
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />

John..

I have always claimed the 928 was possible of SERIOUS modifications! My car way probably one of the first to wear some well hung mods in 1983. To those who think the only way to make big power in a 928 is with a Chevy engine (you guys know who you are)...well READ ON!

Here is 500+ of boosted 928 power with dyno sheets to back it up. No bull****, just fact! Don't even talk about cost vs. a Chevy swap...the blower route will win hands down. Straight line vs a Z06...no contest I know what my $$$ would be on. Add suspension mods and you have a Z06 killer. Like I said before any engine can be made much more powerful and the 928 V8 is NO exception to that rule.

Tim,

If you push it much more, you might want to consider going with a forged piston... I'd hate to see you grenade that beast! I was going to shoot for 10 psig with my stock 81 internals, but once I found some block damage I opted to go with a forged piston from JE. I'll be at 14 psi by the middle of July (I hope). I measured the compression right at 8:1, but I don't have the 4 valve heads....it is all about working with what you have. Your power level on stock internals is most impressive.

NICE WORK!

Tim Murphy

PeteS

I was just playing around with a drag racing simulation program. It allows you to input a number of variables, including things like vehicle weight, weight distribution, drag coefficient, frontal area, transmission type and gearing, tire type and size, track conditions, weather, and things of that nature. In other words it seems pretty complete in what it factors in to come up with the information it does. Well, since one of the things it allows you to input for the vehicle is the power curve over the RPM range from a dyno sheet, I just had to see what it would say for Tim's car and the dyno chart posted above.

I used the S4 data, with a probably too heavy total weight of 3800lbs for car with driver, "typical" track and weather conditions, high performance street tires in a size that's pretty typical for a 928, and a good driver. It comes up with a quarter mile performance of 11.175 seconds @ 122.6 mph. The 0-60mph time is shown as 3.359 seconds, 0-100mph as 7.145 seconds, and it shows tire spin to some extent for about 100 feet, and up to 50mph, when going down the strip like that. <img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" />