Olsen Island

I've got a 2003 C4S, and am wondering about the adviseability of supercharging this. How does a supercharger effect engine life? Is this modification adviseable?

Steve Weiner-Rennsport Systems

Hi:

You'll get a lot of opinions out there so I'd simply offer mine;

Based on what I've seen, its unwise to add 4-6 lbs of boost to an engine with a 10.8:1+ compression ratio. Those kinds of cylinder pressures are not condusive to a long engine life.

There are many many differences between the Twin-Turbo engines and the N/A ones to safely accomodate forced induction,.......

Ultimately, its everyone's dime but one should be aware that that kind of power isn't "free". The manufacturers of Supercharger kits are not likely to tell you that,......

1999Porsche911

6 pounds of boost on the NA engine does not more to reduce engine life as does the 14 pounds of boost on the turbos.

Steve Weiner-Rennsport Systems

Well sir, that runs counter to what I've seen over the past 30+ years,....

1999Porsche911

Let see....my first SC'd car was in 1970 and I have done dozens since then. Never once blew an engine including 100's of drag races with times in the 9 seconds range and all street legal. I have setup 4's 6's and 8's with no problems nor any shortening of the life expectancy compared to stock turbo. Most of these were to cars without computer comtrols. The modern day computers make the setup even safer. The key is proper setup and tuning. If you just want to install an SC on your car without proper safety componants, then you are right, the life of the engine will be lessened. Try closing the bypass valve on a Turbo and improperly set the timeing you will get the same results.

You will do more damage to the lfe expectancy of an engine running high RPM's than you will running moderate amount of boosts at a lesser engine speed. The fact is that even the most moderate powered engine has cylinder pressures between 500 and 1500 psi and many engine go has high as 2500 psi. Your ultimate pressure in the cylinders can vary greatly depending on the fuel you are burning, temperature, etc. So if increasing dynamic pressure 6 - 10 psi is going to ruin an engine, I wonder what a hotter burning fuel would do to the same engine?

It all boils down to the setup. I have never seen an engine that has been ruined just because the pressure in the cykinder was increased with boost. Most compressors will lock up or explode long before an engine will. What WILLl blow the engine is not properly setting the spark to start at the appropriate time duing compression stroke, improper exhaust valve timing and excessive heat and several other simply tuning tricks.

If you follow the false belief that increased cylinder pressure will shorten the life of the engine, then I guess those who own cars in Denver should expect a much longer life out of their engines.

Of coarse, the life of any engine is decreased the harder it is driven. This is whether your power comes from internal mods, gases, blowers, or just driving a stock car at the extereme. The goal is to find the right balance for your needs.

Geoffrey

I don't think Steve is saying that supercharging is bad, only that installing a supercharger on the Porsche engines which run an 11+:1 compresion ratio requires trade offs that may not necessarily be good. I agree with Steve and my experience with laptop programmable MoTeC engine management systems used with the bolt on supercharger kits support his assertations. On a 964 engine with a supercharger installed, running 10.7:1 compression and 6psi of boost, the engine required the timing to be retarded to such a degree that the EGTs were too hot in my opinion. We're talking about 6-7 degrees BTDC at 6psi of boost. In my estimation, we are talking about an engine where the installed component has made it a knock limited engine, in other words, the engine's effeciency is such that you can't get a reasonable amount of timing into it.

I'm now trying the combination at 9:1 compression and will see if that is better.

1999Porsche911

As I stated above, it takes a complete system with appropriate mods to properly and safely run a SC. In the air cooled engine, an aftercooler is even more important than in a water cooled engine. Your knock problem could most likely be corrected by cooling the air charge and increasing the fuel level allowing you to set your timing back to a more reasonable level. You must also be sure to use a cooler spark plug than the stock ones specified. Lowering your static compression ratio will only require more boost for the same power gains with a big loss of bottom end torque.

Geoffrey

An intercooler will not allow for the timing to be advanced from 6-7 degrees to the 14-20 degrees I'd like to see. The engine needs to be designed differently to accomodate the supercharger effectively.

Steve Weiner-Rennsport Systems

A big "Amen", to that,....

1999Porsche911

Correct, cooling of the intake charge will not allow for the timing that you need, but neither will lowering the static compression in the engine by itself. It take several mods to make the system efficient and reliable. Cooling of the intake air, along with proper fuel mapping, colder plug and top fuel are a few that will allow your to get a timing of 15 or more at WOT. Done it many times to air cooled, high compression engines with excellent results. If you have carbon build up, this will also increase the heat in the cylinder.

Unless your looking for ONLY better top end power and NO bottom end power, you would never lower the static compression of an engine when boosting the intake air unless you go to some extreme boost levels above 10.

Woodster

in other words unless you want to completely rebuild your motor to accomodate the s/c,
don't do it or don't expect much performance without risking engine life??
this is the exact reason I bought a 993tt rather than s/c my 996, the cost benefit ratio
did not make sense to me. IMHO, I am not an expert just a horsepower junkie.
m.k.

Bob Rouleau

Olsen Island - the thread has digressed from your question. In your shoes I would NOT add a supercharger. Your C4S is a valuable car and adding a supercharger will seriously reduce its resale value.

Based on the recent sale of a C4S locally with a Turbo Performance Center SC kit I can accurately say that it would be cheaper to sell your car and buy a similar 996 TT. Local dealers refused to take the car as a trade in at any price!

Consider:

Cost of the SC kit and proper installation + Added depreciation of your car resulting from the modification = more than the differential between a C4S and a 996 TT of the same age and condition.

Put this another way, when you bought your car, how much would you have paid for the same car with an aftermarket super-charger?

There is also the question of warranty - Porsche will take a hard line if anything went wrong with the engine after someone added an unauthorized SC.

Rgds,

TT Surgeon

Word

Captain Tal

Well, I guess will disagree with almost all of you on this thread. I have an 04 C4S and it is currently undergoing a major performance upgrade including an Evo Supercharger. I have investigated this issue thoroughly (at least to my satisfaction) and feel certain I will not affect my engine life in any way noticiable to me. The general consensus from performance mechanics I have spoke to (Not tuners who were trying to sell me a SC) is that an engine will suffer no more than a 10% degradation in the total life expectancy of the engine. Some suggested there would be no detrimental effect under normal boost levels.

I guess the proof is in the facts. The Evo Supercharger system has experienced no engine or mechanical failures in the last three years of existence on nearly 100 intsallations and tens of thousands of miles. The Porsche 996 engine is a strong and capable engine and is more than capable of handling the compression differential of a SC. Supercharging is a proven and extremely efficient way of improving performance of your car. The Evo system is tuned appropriately conservative and is designed with engine longevity as a primary goal.

While I agree there is a likely depreciative effect on the value of your car after you install a SC, this is inconsequential to me. I intend to hold onto the car for the next 4 years and will enjoy the car without worrying if my mods will hurt my resale value. An Evo SC adds 40% more HP with very little risk. And while there is risk, I choose to accept it as a tradeoff for fun and enjoyment. It is certainly less risky than modifying a Turbo to achieve 640 HP as is commonly occurring.

agentpennypacker

If you are tracking the car (a 996), I wouldn't mess with it at all. The non-modified engines are having a hard enough time getting the oil to the right places during hard cornering, I'm not sure what adverse affects adding a SC to a wet sump system would add. Maybe on a 993???

I agree with the above - sell it for a TT.