yasuro

well if you won't read the article, no skin off my nose. i linked to some facts about SCs to support my "ridiculas" assertion.

you can be happy with your faith-based belief in SCs and i'll stick to my view which is supported by facts and physics.

Mfletch

I understand that, in theory, you will experience a parasitic loss from any supercharger, just like you would from turning on your AC compressor. In actuality, I would take what 99 and Redridge say as gospel....they both have SCs on their 996s.

Tippy

Welcome to Rennlist, gotta have thick skin here.

yasuro

well, the debate of parasitic power loss in superchargers has been around since the first production supercharged car, which i believe was a mercedes sometime in the '20s, so i don't expect the issue to be resolved here.

actually, i wouldn't be surprised if the debate has been going on since francis roots patented forced induction sometime in the 1860s according to wikipedia.

1999Porsche911

I only care about the fact that what you stated is not true and never has been with a centrifuge compressor. Don't care about anything else the article says. Show me a car that loses power at any engine speed after installing a centrifuge compressor and I'll show you an incompetent installer.

redridge

I think we all understand that the SC has parasitic power loss... its inline with the serpentine belt, thats the nature of the beast. The evo kits power loss is 25hp from the total power... OK so instead of 500hp on the 3.6 engine your getting only 475hp... How is that a loss?
Lets be realistic, $$$ wise I dont think the SC and the turbo is the same price at all . A good turbo will be at least $10K+ over a SC... Thats a full blown moton suspension, control arms, sways... the works. Ever see the prices on modding a TT... like 2x-3x more than a carreras' price.
If you want a fast cab... theres only 2 ways to do. A turbo or a SC. Like the OP says, a cab turbo is $25K more and a SC cab is $15k (though with a group buy and installation $12K)

yasuro

w=f*d (work=force * distance). so if you increase (f) with all things being the same, you increase the work. work for an engine is measured in horsepower. the increase in force required to turn the engine comes from the added mass of turning the SC (if this wasn't so, lighter fly wheels wouldn't help. lowering mass in all engine components wouldn't help). so early in the RPM (and further on) there is less horsepower produced at the wheels for a given air and fuel in the engine.

this is why with equivalent PSI and air and fuel, a SC engine produces less (net) HP than a TC engine (again, all things being equal).

of course any forced induction will produce more HP (net) than a non forced induction engine. i'm claiming in the brief time that an SC is not spinning at full RPM (around 9k for most) there can be a net loss of HP at the wheels because energy (work) is being spent spinning the TC before the TC is producing optimum forced air into the engine.

it's similar to turbo-lag. except there is a parasitic effect (because the crank or belt is being driven by the engine and not by exhaust gas) and the period in which it lasts is much shorter than in turbos.

so i can't "show" you an engine that produces less HP (net) than non-forced induction.

but if you look here: http://i62.photobucket.com/albums/h90/slc92/dyno011.jpg

it shows a dyno measurement (before and after).

you can see that between 2500-3000 RPM the non-forced induction engine produces more HP and torque than the same engine after getting fitted with a Vortech SC. all things being equal there is a very brief period of parasitic power loss (but it's only for 500RPM).

i'm sure that isn't enough proof for you or you'll argue the SC wasn't installed correctly, etc. but you'll find all SC engines have a similar result (but smaller RPM band of loss if using a smaller SC) of around 2-500 RPM of parasitic power loss due to the engine working to spin the SC before the SC gives enough air to the engine for a net power gain.

ultimately under equal PSI (on the engine and fuel mix), TCs don't give the 0-60 times of SCs (because turbo-lag is longer than the time it takes for the engine to spin to 3000 RPM), but TCs do have higher top speeds because the PSI is given to the engine with less penalty. again, all things being equal.

but you and others are correct, the ROI on TC vs. SC makes the math easy. SC gives more bang for the buck, apparently.

Benjamin Choi

yasuro quit the mumbo jumbo.

i had an s2000 with a comptech sc... never once ever in the 15K miles i logged on it did i ever feel like i had less power than sans sc.

no lag, all power, all reliable for $6K installed. was great stuff.

yasuro

but you would have had a lower top speed (and perhaps slower 1/4 mile time) than if you had a TC with the same boost (assuming it costs $6k as well). it all depends on what you want. but isn't that the reason why we all do different mods?

i don't claim a TC is better or worse than SC. it depends on what you want, that's what drives the mods we perform for a given amount of money.

Benjamin Choi

yas, but i'm referring specifically to my supercharged setup, not turbo charged to which you were debating with the others in earlier posts in this very thread.

the comptech sc added 80HP to the wheels. and it was felt. all of it.

bmartini

uhhhh didn't read anything except the title so this might be a BIG enzo....

but, a 996TT has an air cooled block and the heads are water cooled. thats why they are much better cars. supercharge your water cooled aluminum 996 and it won't last very long....

redridge

I see you have a new engine in your 99 (for sale)... was it ever SC?

Jackel

Thanks everyone. I have to wait for some money coming in and bills going bye-bye, but this will happen. I am concerned about the engine difference (my biggest concern actually) as I'm planning on keeping the car, for good, either way. So, how it holds up over the next 10yrs/120,000 miles is critical. However, I also saw some had as much as 60,000 miles on an SC without an engine blowing up. I've heard a turbo engine is $20,000 vs. $10,000 for a n/a 996 engine. Between those two costs I could still replace my engine twice for the cost of one turbo engine (including the cost to "upgrade" to a TT coupe). Please correct me if my math is way off. Plus, it sounds like the SC is quicker on the power and holds its own vs a stock TT, especially at lower speeds (where I drive it most the time) like 0-60. I really appreciate the input, I'll be talking to Orin at Eurosports Ltd here in the next few days (a very reputable installer

Jackel

BTW, since it will probably be the end of summer by the time I do the mods (later if I trade in to a TT), I will post/repost my results, costs, findings, etc for all. I did hear you Raisedina911! I appreciate what eveyone here on rennlist is doing... great people, great site!

1999Porsche911

What do you mean "all thngs being equal"? All things ARE NOT equal. A stock TT will always produce less power than an otherwise stock 996 that is running a centrifuge compressor when both cars run the same amount of boost. It doesn't matter whether they run 3 psi or 7 psi. It doesn't matter what the engine speed is. The 996 will always have an effectively larger displacement and will therefore perform better than the TT when boost is equal.

As for your dyno, if in fact that was a centrifuge compressor, there was an install problem, or god forgive me for thinking this......but, maybe the dyno wasn't accurate?