Z

http://www.vortechsuperchargers.com/...137&cat_key=24

I don't know why so many people automatically think cast pistons are such a weak point. At 2.1 horsepower per cubic inch, the Ecotec 2.0 liter turbo engine is the highest specific output engine that GM has ever offered. Stock specs are 260hp at only 5300 RPM, with a stock 20psi of boost, and a 9.2:1 compression ratio. A number of changes were made to the 2.4 liter Ecotec engine when the turbo was added, including reducing the stroke, and reducing the bore to give an increase in cylinder strength. It uses cast pistons.

Chrysler's 2.4 liter turbo engine is rated at 300hp with a 6,500 RPM redline. When they added the turbo, they also made a number of changes to the original naturally aspirated engine that they started with, but it also uses cast pistons.

If forged pistons alone were the complete solution, you wouldn't see so many broken forged pistons. Those sure don't seem to be too hard to find though. If anyone's got forged pistons and is sure that they're failure proof, I'm very sure I could show you otherwise if you'd let me try to see if I could break them.

Kevin,

If you aren't running lean due to the inability of the fuel pump that you have to deliver sufficient fuel at an adequate pressure, the Boost-a- Pump won't do anything for you. If you are running lean due to the inability of the fuel pump you have to deliver sufficient fuel at an adequate pressure, get a bigger/stronger fuel pump.

The only time you'd need to upgrade your ignition system would be if it wasn't up to the task of firing the spark plugs, and you were getting missfiring as a result. If it's in good condition, your stock ignition system is more than capable of working just fine under any boost and power level you're ever going to get to, unless you significantly modify both your engine and method of boost. You'll max out that supercharger before you max out that stock ignition system if it's in good condition.

Kevin Michael

Z , thanks for clarifying and your advice. There are alot of misconceptions, I think, about our cars.

Erik, I am running a bosch copper plug one range colder.

toofast928

Hacker awesome numbers!

Tony

Tony

X2


as for those 2.4L Chrysler Turbos, Watch out for those PT Cruisers ,some of the tweeked ones can seriously haul *** and will leave a stock S4 behind.

Z....
You going to SITM?

V2Rocket

The PT Turbo and the Ecotec use cast pistons, but don't you think that casting techniques have changed in the last 20-30 years? The new pistons were designed to make up for shortcomings previous ones did. Although the 928 pistons are strong enough for alot of boost, turning it up to Ecotec levels would mak you shoot a rod out the oilpan (or other catastrophic failure)

SharkSkin

Really impressive work, Erik! Definitely gives hope to those with unfounded feelings of inadequacy due to having half the valves/cams of later cars.

killav

This is always hard to quantify. If you are a lead foot, not as long. If you like the status of being "huffed" and can drive like a sane person and resist the temptation of thrust, it will last longer. Either way, you'd go broke stuffing 96 octane in it all the time.

Aj928

With all $tuff we do to our 928's...the price of mixing race fuel with premium unleaded is not so bad and does lower the chance of detonation. However, my 928 is not a daily gas-guzzling driver.

Sounds like 8psi w/intercooler is the max set up on a stock 32V motor.

hacker-pschorr

Murphy is running 17psi with stock (dished) pistons. Everything else is 100% stock except for the fueling system to up the pressure.

Even though he is running a lower compression ratio for extra boost. His pistons have less material than a stock piston would.

BC

Where is this info coming from? 8psi max? Please, lets try and keep our personal issues of concern and worry about grenading an "Expensive" engine to ourselves (also unfounded). TESTING and A LOT of miles under boost on m928 motors has proven that the 8psi number is not true.

*With proper fueling* while there is more "heat" in the combustion process, and more power being taken by bearings and clutches and synchros, there is no reason that the 928 engine can take 50% more then that safely. Now letting the 530rwhp that 12psi should do in an S4 hit your clutch from 5k rpm is a separate matter.

Z

Engine failure began the instant the starter motor was first turned inside the Porsche assembly plant. A lot of things will influence the rate of how quickly the failure continues to progress from that point on.

I don't even know what I'm doing tomorrow yet.

Even with a less than ideal setup, more than 8psi has worked fine on a stock 32v, even without an intercooler. On the otherhand, even some normally aspirated setups people have had resulted in damaged engines. It's not as easy as saying X-psi of boost or less is completely safe, and anything more isn't.

This is not intended as a slam towards anyone, as I've heard a lot of similar statements to some that have been made here for years, but it might get some people to think about a few things. Lets say that someone had a fireplace in their house that exploded because they modified it, and all the windows blew out. Everyone pretty much agrees that getting your windows blown out by an explosion is no fun. Some people might have the opinion that the windows were too weak, and that the homeowner needed stronger plexiglass windows to make them strong enough to withstand the explosion. Some might have the opinion that newer windows, like those used in newer houses, might not have broken, because glass is made differently than it was back when the original windows were made. Of course if the windows were made strong enough to survive the explosion, the walls or ceiling would have blown out instead, but hey, the windows wouldn't have. I may be in the minority here, but it seems to me that knowing how the fireplace works, and taking the proper steps to keep it from exploding in the first place might have been a reasonable solution.

So Erik, when is the 400+rwhp attempt?

hacker-pschorr

Well, just spent the last 5 hours at Murf's house going over some details. Not sure what the next step is. Most likely the 81 will just be driven very hard while I put my 944S back on the road. Then I'll work on the 4.7 liter engine to drop into the 81.

So now the fun begins - EuroS cams, intake.......who knows.

Actually - my #1 priority with the 81 is finding out why the heat doesn't work.

BC

Yes, this is very important in Green Bay in May.

hacker-pschorr

Well, both ends of that red vacuum line are not going anywhere. So that means the valve is open.......still no heat.

Something else is stuck - time to pull the center console.

SwayBar

Ouch!