bigbass37

Which is preferable for a S2 engine? Which gives best 0-60 time? What are the cost differences?

Yabo

as far as I had understood, is that a supercharger gives more power than a turbocharger because it doesnt blow more air with more throttle, but can give boost at anytime, no matter speed of the engine. I coudl be way off, but i figured id give my .02.

MM951

Supercharger will give best 0-60 but less power overall.

FSAEracer03

Well, it depends on what (type of) supercharger you're talking about. Generally speaking, superchargers give you more low end power while turbos give high end. To best aid a 0-60 sprint, a supercharger is generally the best bet if all the power makes it to the ground. If you're looking for more usable power though and more efficiency, a good turbo and intercooler setup will benefit you more. Furthermore, you can keep better gas mileage with a turbo more often then with a blower.

But this is all "general" information. As with so many things in the car world, specifics can easily turn these broad generalities right back in your face.

IMHO, a supercharger would be the best bet for your S2 droptop. There are good kits out there waiting for you. Supercharged motors aren't as hard to tune (once again, generality) as turbocharged engines. If you love turbo lag, and are willing to sacrifice a little more time, effort and money, look into turbo kits and/or custom kit for your existing mods. Reading what I put above can be a little misleading, let me rebalance the scales there, I think I misrepresented blowers. Centrifugal blowers can prove to be very useful as they are linear power adders. Unless the poor thing chokes (as a small turbo might) you will get both low end punch and increasing boost later on in the rev range.

Lastly, I believe that there were a few lengthy threads in the past 2 months or so debating super/turbocharging. Might be worth the time to find them!

mossy

A supercharger requires more horsepower to turn it as the compressor is driven from the crank (it is a mechanical device that turns when the engine turns), a turbocharger is driven by the exhaust gasses and therefore requires less initial energy to turn, which makes it more suitable for a smaller capacity engine (I would think that the 3.0ltr S2 engine counts as smaller capacity).
They can both generate the same amount of extra horsepower (they work in the same way), but the supercharger always has the overhead of requiring more to make it turn, so you get less in total
The great advantage of superchargers is that they do not suffer from the 'lag' associated with turbos (as a turbo requires a certain amount of exhaust gas velocity to compress the induction air), so they come into their power lower in the rev range.
If you're thinking of tuning your S2 engine with a turbo or super charger, have you considered a 968 transplant (or a 944 turbo S transplant)??? I think the cost would be comparable, and you have the added reliability of a factory developed solution.
I don't think you could seriously wind up the boost with a turbo to get more than an extra 30-50HP without doing some serious internal work (pistons and bottom end) and a 968 generates about 240hp, turboS at around 250.
Whatever you decide, ignore the purists and go for it!!!!! A 944 with good power is fun, with more power has got to be better!!!!!
Mossy

88BlueTSiQuest

Lag is always mentioned when a turbo is compared to a supercharger, but what is always left out is the fact that a turbo will reach full boost much sooner than a supercharger.

A supercharger's maximum boost is set by the pully and the engine speed. A supercharger doesn't reach full boost til redline. A turbo charger can reach full boost midway through the RPM chain. Under a quick shift condition, a supercharger's boost level will once again be directly related to engine rpm's, where-as a turbo can reach full boost nearly instantly between shifts(utilizing a blow off or by-pass valve, and a quick enough shift).


Which would be quicker from 0-60? Depends on the super/turbocharger in question, and the amount of boost, along with the compression ratio of the engine. I'd say turbo. Generally a supercharged engine doesn't have the lowered compression, therefore it's got a heck of a lot more low-end torque, and an easier time smoking the tires off the line(based on driving my GTP). Where as the lack of torque in the Conquest(turbo charged), allows me to get on it off the line, and get the turbo spooled up quickly. For brutal acceleration, you can't beat the turbo, but for smooth linear power the supercharger reigns.

MM951

Hey Jack- if you got an AIM account or anything else I can contact you off the board I got a few questions on timing the conquest..

thanks!
mike

88BlueTSiQuest

Check your PM's. It can be hard to catch me at times though.

FSAEracer03

Jack, but the world is all about trade offs (my economics teach always used to say that, sorry). True, turbo's reach their maximum boost quicker... but what you didn't mention is that they so often fall off afterwords!

Also, I agree with overall brutal acceleration being reigned by the turbo, especially anywhere above 3k rpm. But the fact stands though that the turbo isn't going to help for squat out of the hole (though neither will the supercharger if the tires spin.... going back to the specifics issue).

"Whatever you decide, ignore the purists and go for it!!!!! A 944 with good power is fun, with more power has got to be better!!!!!"

Mossy.... I couldn't have thought of a better way to put it in a million years. Owning a sports car isn't about oem part loyalty... if you can make your car perform better, don't hesitate to do so!

This thread is blossoming into a very interesting talk about the benefits of the two all-time power adders; I like it!

87Porsche951

Damn it would be nice to have a kit for our cars to have a turbo & supercharger. we would have boost at all RPM's. now a 16V DOHC Turbo/Supercharged 2.8L Inline 4 would be a bad@ss motor.

One could only dream. I did see a oldsmobile in hotrod mag a few years ago that had two blowers on top.

930 under Restoration

If you want a quick, easy and somewhat cheap power addition, go with a supercharger. A supercharger is driven from a belt off the crank and can use as much as 30% of an engine's power to turn it. A turbo conversion will cost cosiderably more but is more efficient as it uses 0 power from the engine and just wasted exhaust gas to turn the compressor to create energy. "Turbo lag" is a very old term from a very young technology that can be all but totally negated with a properly sized turbo or twin sequential turbos so "lag" is now a virtual non issue but people still like to refer to it.

As far as the best for an S2 engine...................there is no magic with an S2 engine or any other combustion 4 cycle engine, for that matter. Typically a supercharger wont add a whole lot of extra temperature to the intake air like a turbo will so detonation is not as much of a problem. But the supercharger will be limited in the amount of boost it can produce by it's design at a given rpm that is dictated by the engine rpm. A turbo is also limited in kinda the same way by it's exhaust wheel and compressor wheel size but can be overcome.

If you want 0-60 times, a guy with a turbo who is good with rpm control and clutch control can be as fast or faster than the same guy with a supercharger.

If you just want easy power, go with a supercharger.

If you want more power and to learn to be a better overall driver and to learn how to really tune your engine, go the more difficult route with a turbo.

From a practical standpoint, keep the S2 as a fun cruiser and buy a 951 to cure your need for speed. It will cost you a minimum of 4 grand to supercharge(and possibly damage your S2) whereas you could find a beater 951 for 5 grand to play with.

Hans

To get enough wasted gas, sometimes the cam has to be changed to open the outlet a little sooner. (That sometimes may be more often than you think). So sometimes the addition of a turbo will cost efficiency in the low RPM range when there is insufficient boost to compensate for the loss of power caused by early opening of the outlet valve. Whichever way you go, have fun.
TakeCare

88BlueTSiQuest

That's usually negated by properly sizing the exhaust and intake wheels on the turbo. I'm thinking in terms of the N/A, as I don't know the max rev's of S, but given the fairly low rev's of the standard N/A a turbo can add power through all of the mid to upper rpm range. Even though the turbo can be at full boost very early on in the RPM range, doesn't mean the engine will consume that airflow as you will still be limited by the actual CFM's the engine can digest. So if the engine is capable of 450cfm's at 6500rpms, just make sure your turbo is capable of putting that out efficiently, and you'll be fine all the way to redline.

Once again the trade off. For the turbo to efficiently operate at that level, the 'lag' may be totally undesirable in the lower rpm range. Since you are starting with a High Compression engine, the lag can be somewhat combated when building up the engine. Lower the compression to 9:1 or 8.5:1, add some high lift/duration cams, 3 angle valve job with p&p work to the head, larger injectors, RRFPR, convert to a MAF sensor, smooth intake piping, a good external wastegate, equal length header feeding the turbo exhaust wheel, and a large diameter mandrel bent exhaust. Add a large efficient intercooler, and an electronic boost controller(these have circuitry to help eliminate lag). Set the boost level to 7 to 10psi(maybe higher depending on knock, you can always add a water injection kit) and you can have a serious power monster on your hands with the right turbo.

The price is what will hurt you here. You could wrap up an easy 7 grand on the above setup, and it doesn't even tell you whether the stock drive train will handle the power increase(LSD tranny could be in your future, if the car isn't already equiped). Where-as simply bolting on a supercharger could be under 3 grand. This is why the 'purists' always say to just buy a 951, and why other's mention the 3.0l.

I think that looking back at the old Callaway 944 conversion though, would show you the serious power potential you can have. As the Callaway 944 had more power than the 951, so if you started with an S engine to begin with, you can be well into the upper 300 range for horsepower. This is just all in theory of course.

87Porsche951

I know Callaway 944 made more HP than factory 944 Turbo but if i remember correctly the factory 944 Turbo made more TQ!

loonyjuice

Couple of things worth mentioing, I think.

Surely if you want brutal acceleration, less weight is more important than any power increase? More power has a detrimental effect on the rest of the car's components, whereas less weight has the opposite effect.

What's to stop a supercharger boosting as high as it likes mid-rpm, and then the dump-valve vented any surplus pressure?

If a car produces 300bhp via whatever means, turbo or super-charged, then by saying that it takes 60bhp off the engine to run the super charger is no different to saying the water-pump, alternator or drive train all take power off the engine. However, the fact is, the engine still has a maximum power output of 300bhp, does it not?