Big decision: Supercharge the 996 C4 Cabrio or buy a 996 Turbo Coupe....

I've put the questions out on both forums (996 n/a and 996 turbo) as to which way to go. Each board says go with their car (not surprising), but I have noticed a few things. The turbo guys say their engines, clutch, etc. seem to last much longer than a regular 996 n/a car. I really am down to this: has anyone on here actually daily driven a Supercharged Carrera for several years or 10,000+ miles? If so, how did it fair for dependability and was it as fast as a stock (non X50, etc) 996 twin turbo? I am not just asking for the heck of it. Within the end of the year I'll be pulling the trigger on this. The turbo option costs a little more (22k+ vs. about 14K+) for a same year/milage car. However it has more potential for future mods and "might" be more bulletproof at taking the power. If I don't hear anyone having driven for an extended period on the Supercharger, I'll have to upgrade to the turbo. But, if I keep mine its 200+ lbs. lighter, done with mods, faster? than a stock TT, and a sleeper. Plus, it has a convertible top! Learning (one way or the other) about how the TPS or EVOMS intercooled supercharges have worked out will help. Any input (especially those who have had them/compared them) would help!! Please keep in mind I'll be keeping either car for the rest of its life (probably another 10 years/150,000+ total miles) and both options have their advantages and disadvantages. Money is available for either, but I am concerned about the costs over the long haul (an engine swap at some point is ok, but two or three isn't!) Thanks all!

Turbo, almost entirely because I'd always rather have factory engineering and factory support than being left to deal with the problems myself.

Turbo, not even a question.

I would go turbo. The N/A motor is already at 11.3 : 1 compression, boosting it will increase cylinder pressure tremendously. There really isn't any room to increase boost without decreasing engine life at this threshold, if you will. The other issue I see is the N/A trans struggling with holding the power for the long haul. There have been some who broke the trans N/A (probably abused), boosting will just increase stress. I have zero data, just a gut feel. But, from what 1999Porsche911 says, he will walk a stock TT (understandable, power to weight). He and Karlooz have boosted their N/A engines without issue for many miles and track time. PM one of them, they have first hand experience.

There is no question .....TT cab

As Tippy said, the compression is too high with the NA engine to safely supercharge. The turbo is the way to go.

Thanks all. That was the way I was leaning also. I'll miss the Cabrio top (Cabs are another 15-20 grand), but the power and solid top will be a big plus. This site is great, I really appreciate it.

You will have to spend even more money in oder to to get a stock TT to have better engine performance that an SC'd 996. If you like a convertable, SC you existing car.

Read this... http://www.6speedonline.com/forums/s...d.php?t=123442 btw that 996 is a cab, there are alot of SC installs out there and there are some with over 30K miles out there. Its well designed and its only 5-6 psi boost for 450+hp...

don't tempt me dammit

I think you know the answer deep down inside here, but if you're going to FI then definitely a factory TT 1) way more tuning upside 2) stronger motor by most accounts 3) if kept factory or even just flashed it will retain more value over time If you were looking at an SC because you're worried about turbo lag or anything like that, I'd do 997S X51 (I feel like it is faster than the spec sheet reads, and that motor SPINS, sounds great, is preferable to me over turbo, although no tuning really possible) But another poster raised a good point. If you like a cab, a turbo cab might be a lot more money

You need to compare the cost of a SC cab and Turbo Cab to be fair. Otherwise its kink of like apples and oranges.

In addition to the SC having better perfromance than the TT, drivability around town is much better because you have higher compression ratio that you do in the Turbo. No lag and the car will drive just like it does now.

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Very true points but there is nothing like the violent, wallop, sledge-hammer-to-the-back, OMG this is craziness of a turbo Just my .02 Yes, the N/A with a S/C should feel a little peppier around town than a TT but the WB of the TT car, mmmm........mmmm. Preatte

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Thanks again. That other thread was perfect, some SCs with over 60,000 miles on the blower, that'll work... Just so everyone knows, I'm content with being just a little faster than a completely stock 996TT and "in the race" against faster 997TTs or C6Z06s... If I "need" to go faster than that I'll get back on a motorcycle... For me the SC cab and Turbo coupe is apples and oranges, but the only ones I can afford! Total cost to upgrade mine 15k, to sell mine and upgrade to a turbo Coupe (for me, I'm upside down is 25k+ To go to a Turbo Cabrio is 40k+ SO, apples to apples is price. 15k one way (SC) or 25 k the other (996TT Coupe). Thanks again all, leaning back toward the SC now...

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The key is to find a good installer... or if your good, you can DIY, yes its been done before as a DIY.

I talked with the PCA guys. A few have use local tuners here (eurosport and 3R racing) here in Denver, Colorado so I'll have them do everything (I suck as a mechanic). I was wondering, any thoughts on upgraded clutch or lightweight flywheel for this application? any other mods I should do to it for the SC'd car? Thanks again all!

I've had my SC (EVOMS) for about 3 years now, and have put about 24K miles on it, which includes about 20 track days. Absolutely no issues with it, and I have the stock clutch and flywheel. And it's a cab, also. I love the combination!

Jackel, I am very interested in what you decide. I am a cab owner( and lover) I believe I get your dilema of apples and oranges. My dream would be to have a TT Cab, but it is way too spendy for me. I chose the cab over an older TT. The idea of near or equal TT power for approx. 15K is very intreging and is not out of the realm of possibility for me. An SC seems to give the biggest bang for the buck. please keep us posted (literally) Does anyone know if there are any issues with an SC in a TIP?

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Oh, so you're in Denver? (Why don't you add it to your profile?) Well, no wonder you're looking for some boost, duh. In that case (why didn't you say you're a mile high!) I'd say an s/c is almost a no-brainer if you like your ride and just want more power. In the Audi/VW V6 world, larger fuel injectors are included for s/c.

the performance characteristics of superchargers and turbo chargers are markedly different. the biggest negative about superchargers, imho, is that they tend to be parasitic at certain engine RPMs. it's possible to actually lose horsepower until the benefits of compressed air into the cylinder starts to take hold. the ideal, that i've seen in other cars, is a 2 stage blower. a small supercharger is used (small to minimize power loss at low RPMs out of the engine) to blow air onto the turbo. this gives the benefit of removing nearly all turbo lag and, so rumor has it, gives a flatter torque curve and improved response through more of the RPM band. this is a trick that i've heard is used most often by the "fast and the furious" crowd. it's also, i'd imagine, extremely expensive.

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There is never a time, whether on boost or off boost, that a centrifuge compressor on a 996 will ever produce less power or performance than stock. Never.

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If you plan to do 1/4 mile stuff, I would upgrade to a beefier clutch... If you dont plan on dumping the clutch much, then the stockers are fine... TRG lwf is supposed to be chatterless and heard good things about them. When my clutch goes, Im gonna put this setup on. As for the brakes, they will be fine, on the track I would change the pads and put a gt3rs brake ducts to help cool them. Oh and another thing, I would go with a shop that done this install already.

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I have had 4 boosted vehicles: '69 Camaro coupe (Vortech centrifugal), '69 Camaro convertible (B&M roots), '02 Lightning (Eaton roots), '87 911 C3.2 (single turbo). The 2-'69's made more power with the S/C's over stock in the low RPM range. I put the S/C's on both of them so I know the baseline. You dont have to have boost to make power, the S/C will push air into it which in turn makes more power. As far as a S/C forcing a turbo (you will probably starve the turbo inlet), I have never heard of, but a turbo supplying a S/C has been done from the factory on Detroit Diesel engines for a very long time.

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i would disagree. what drives a SC? a belt or chain from the crank. so, if you add more "work" to the crank, it'll add to the overall work for the engine. so i would think this would affect HP at the wheels.

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that's interesting. here's a link to the disadvantages of SCs. http://auto.howstuffworks.com/supercharger6.htm also on the same page you'll see VWs work on the SC/TC combo.

The questions you should ask yourself Jackel is what are your goals. In the near term the SC is the solution if you must have a Cab at the same price point. However the SC is an investment that is lost forever as resale of modified cars are usually pennies on the dollars ie 10%. Thus financially it would make more sense to sell your car and buy a used Turbo as it will retain more of its value. The cost to install a SC and the value of your car is about the same as a Turbo. I also feel there is more potential in a Turbo as far as future upgrades compared to your current cab. In my opinon its better to get the turbo. Power wise a SC will feel better off the line, but at the top end the turbo will catch up. Simple mods such as ECU upgrade will give an extra 40-50 HP on a turbo so there is no real HP advantage to a SC.

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No doubt that S/Cs have parasitic drag (I am a huge turbo lover now since my new car), my point was that when you put a S/C on (even with retarded timing), the car will have a little more grunt on low end due to the S/C helping the air into the motor. +1

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Sorry, regardless of what the article says (haven't read it nor do I intend to) there is no loss of power or performance at any time, or at any engine rpm with a centrifuge compressor on the 996. That's just a fact. More power than stock at 1000 rpm and more power than stock at 7000 rpm. There is little parasitic drag at low rpm. On boost or off boost, you will never have less power than you did before your 996 was supercharged. Therefore, your statement "..... it's possible to actually lose horsepower until the benefits of compressed air into the cylinder starts to take hold" remains a ridiculas one.

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I believe he means supercharger vs. a turbo. Turbos have very little effect on the engine except for back pressure vs. the parasitic torque/hp loss through spinning a supercharger. I read in Hot Rod magazine that a Top Fuel dragster's supercharger takes something like 300-500 hp of parasitic drag to spin at the engine's redline.

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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.

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.

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Welcome to Rennlist, gotta have thick skin here.

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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.

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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.

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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)

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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.

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.

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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.

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.

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....

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

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

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!

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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?

I am not a combustion, compression, lag, psi, displacement, induction, etc etc expert. What I take from the dyno chart is that at about 4500 rpms, you get a noticabe kick in both power and torque that I have to think would be felt and it continues up to when you should be shifting. Compared to othe mods such as headers, cats, mufflers, chips, intakes, etc., the SC seems to give a much bigger power upgrade. I personally am not excited about spending 7-10k for a 20 hp gain when a SC can give you 2-3 times the power for a few grand more. I also agree that after an SC installation, if the origingal engine lasts for 40k additional miles, that is fine for me because I am a weekend warrior who likes to have a few blast off sessions over each weekend. 40k miles is probably 5-7 years. It all depends on what your program is.

forgive me for being PRACTICAL AND REALISTIC but if porsche could supercharge the water cooled 3.4 properly they would have done it. but VW -ahhhemmm, i mean porsche couldn't do it. once again, the block which is air cooled on the TTs is done so for a reason. i've done more than a few R&Rs (see my past posts) and in my experience, you are looking at a whole of computer issues, your dash lighting up like a christmas tree, and some shiity *** resale. scrap up the cash, get a TT, and enjoy life. no offense, but the 3.4 is **** in my opinion. worth the (used car) money for the speed and flash but it ain't quality. just my $.02.....

I would take your oppinion seriously if you had more experience with Porsches - Jeeeeeeze you have had some nice cars(my favorite was the 84 cab - ours was red and was an upgrade from a '74 911s) What about in a 3.6l? What about tiptonic?

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well, with your criterion, it seems an SC is the way to go.

I just talked with the speed shop. Great guy. Seemed to say the same things as most on this site have. It sounds like its back to the "speed=money" as always! If I SC I should have a quicker initial acceleration at any speed and when the stock TT goes on boost it will catch up a little and be pretty much up to the drivers at that point. Sounds good to me. Besides, if I'm itching to blow 15 grand on this, I can only imagine what will happen after I buy the Turbo! Money isn't limitless for me and there is an upper limit for a street daily driver for me. If I need sub 11 1/4 mile times, I'll have to get a bike again (Wife is hoping I avoid that, and this upgrade may help) Thanks again all. I'll keep trolling rennlist and keep an open mind to both options. Both are great cars, no doubt the TT is sturdier, that's why its so much more $$$.

when are you making this move? if immediately then I'd say do what you feel is right, but if you can hold out, TTs have been falling off a cliff lately, enjoy the summer cruising in the cab, wait it out until winter and I'll bet the pricing gap will narrow quite a bit