944J

my point is that, from my research, the new superchargers have near equal or better upper range than turbos, especially old turbos. (i.e. high efficiency) so you can't assume there will be any roll off at the top end that would result from the supercharger being too small or too hot to push more air at high flow rates at high rpms.

the dyno shows that its flat up to 7000RPMs:



compared to hot mod turbos by powerhaus (who made supposedely the fastest or one of the fastest street 944turbos ever) the supercharged 944T from sweden looks better at the high end:



it even comes close to a 16 valve 3.0 turbo:



(i've always thought that a supercharged 951 engine would be the way to go, porsche also published an official research paper confirming that a superchagred 944Turbo performed better.)

333pg333

Well quite possibly you're right. I haven't studied s/c's of late. Time usually brings about progress. Having said that to really tell, you would have to do some very close build comparisons to get a true idea of thier relative virtues.
To clarify, when you said that Porsche did an official research paper to say that the s/c'd Porsche would be superior to a turbo'd one or in addition to a turbo'd one?

944J

yep, I have a copy of it somewhere, porsche concluded that the supercharged 944 performed better than the turbo charged one, this was way back in the day, but I think that superchargers have improved more than turbo chargers since then, just look at the kenne bell and whipple twin screw superchargers like the ones used on this 944, although both have improved since then.

333pg333

Well if what you say is true then 99% of us should be converting to a s/c rather than all this talk of turbo mods. Certainly off the mark the s/c has always been superior, but if you're saying that they run right through to redline then what's the downside? Obviously there's some parasitic loss, but that can be taken into account for. Much like unsprung weight, just add more power and push through it. I've always loved the sound of s/c's too for obvious reasons, but I'm thinking that a race spec bb turbo is going to be pretty quick to respond to the right foot. Also I like a bit of lag otherwise I'd drive some big assed V8 I guess. lol

944J

it's possible that turbo's are cheaper? more reliable? i really don't know why people don't use them more on porsches, esp given the official porsche experiments showing their superiority over turbos...

333pg333

First I've ever heard about those reports you allude to. Be interesting if you do find them and post them or excerpts at least?

Duke

Turbochargers are much more efficient at higher rpm's.
Just think about it... the turbo is run by a part of the excessive waste gases from the engine.
That means there is no strain on the engine to run the turbo, except for a little back pressure.

The supercharger on the other side is run directly by the engine.

Sure you can design a supercharged engine with strong top end, but it will not produce the same power as if it was turbocharged running the same boost.

944J

i've posted it before, and I found it from a post on here... they used to be on my server, but now are only on my backups...

944J

this car's supercharger is far superior to 95% of all turbocharged 944's i've seen on this site... without lag. so it has better high end power and low end drivability.

edit: if you look at the dyno's i've posted... this supercharged 944 beats Powerhaus's 944 turbo by far and it is using less PSI (1bar and 1.1bar vs 1.3bar)... it has better low end and far better high end, the curve looks almost ideal. if you compare it to the 3 liter 16 valve 944 turbo from Powerhaus it is still comparable, but less of course, but remember its a turbo with a 3 liter engine and 16 valves and its still doing pretty good, just imagine if the orange supercharged car was a 3 liter engine with 16 valves.

Duke

First, the old Powerhaus dyno runs with tripple K-turbo's not exactly the best solutions by today's standards... Actually - far from it.

But anyway, we can compare these charts if you want..
I don't know what you base your post on?
Turbo: 400 hp at 1.3 bar.
SC: 355 hp at 1.1 bar
Results in:
Turbo: 174 hp per liter and bar of boost.
SC: 169 hp per liter and bar of boost
Verdict: Turbo is more efficient.

AND the turbo has a stock cam while the SC-car has a more aggressive cam and head work!
If the turbo car had the same mods and ran until 7000 rpm instead of 6000 rpm the turbo would be even further ahead of the SC-car.

And perhaps you haven't noticed but the SC-car has it's torque reading in Nm not ft/lbs.
The SC-car has 400 nm and the Turbo-car has 580 nm.
Huuge difference.

944J

well you are looking a peak numbers, and no one said that the supercharged car's cam was more aggressive, just that it's cam was matched to the supercharger. keep in mind that the cam is already matched to the turbo, so its only fair to match the cam to the supercharger in the supercharged car.

the supercharged car has a nice even torque and hp curve, which means there is less lag and less drop off at the top end...

the turbo car has a big bump right in the middle then it tapers down to 300hp at 6000rpm, at that point the supercharged car is still rising in HP.

powerhauses car is tuned to get a high peak number but the driveability is really bad... you'll need to shift a lot to keep the the RPMs between 4k and 5k and peak power is only for a few hundred rpms not very usable, whch may not be that bad, but you'll have power on demand in the supercharged car...

it would be good to look at the average HP/TQ over a limited RPM range.

to do a real comparison you'd have to turn the supercharged car up to 1.3bar of boost, remember the numbers might not be linear.

i think this just goes to show that they are about equal (174 efficiency - 169 efficiency), while the turbo gives you slightly more peak power, but less driveability and the supercharged 944 gives faster acceleration by A LOT (based on deduced logic from the dyno charts and on other rennlist members saying they smoke their 944 turbo in 0-60 speeds by just bolting on a old roots style supercharger on their 944 na.)

just imagine if they had fitted a larger displacement supercharger with more boost...

edit: by doing some math the supercharged car makes about 380-400hp at 7000rpm (which is the same difference in your numbers 174ef-169ef)

Fishey

I think the paint would be sweet on a race car...

Also, in the end the effectiveness of a Turbo or supercharger makes no difference because a larger supercharger making more boost > Smaller turbo making less boost. In every aspect of power the supercharger has the advantage. The argument of superchargers vs turbochargers is a dumb one as in the end it always ends up the same way if you want to make alot of power both can do the job but if you want a non lag engine supercharger is the only option when you start getting into the 800+ hp range.

944J

i think it is a race car... how would you drive a car that low with 20" wheels on the street?

i'm far from even an educated person on this subject, I've just read a few books and have an open mind... it does seem that the turbo makes more peak power, but what do I know?

Duke

The turbo uses a stock cam. It's not matched "to the turbo" at all. It's matched to get midrange torque - nothing else.
The SC car has a more agressive cam and probably a better flowing head - THAT is what mainly dictates the power curve. You have to stop believing that the only reason the curves looks like they do is because of a turbo or a turbocharger.

Yes, it's spelled headwork and camshaft.

Actually I don't know what you get that from. It's not tuned to get a high peak number.
Power is just a function of torque and rpm. If the turbo car had a better and more suitable turbocharger, head+cam it could make peak number at 7000 rpm if you want. And in that case the power "advatange" would be even higher.


I agree, it's the average HP of the used rpm range that dictates the acceleration. Torque by itself means nothing.
No things are seldom linear, the supercharged car would most probably have less hp per bar of pressure if the boost were turned up...

There is no point in discussing this anymore. It's rediculus to compare completely different engines and try to judge results of a SC vs Turbocharger.
I too like that flat and nice curve of the SC-car. But I wouldn't a trade a good matched turbo for it. To each his own

333pg333

Also I wonder just how if in the past we've always associated s/c with a good early boost / rpm then tapering off when some decent turbo engines were just starting to wake up, how is it that superchargers have made quantum leaps ahead to override this tendency? As far as I can tell they're still operating as they have for over 50 years. Sure materials and have improved but so have they in turbos. Physics is physics. My guess is more money and research goes into turbocharging than Supercharging?? I'm not being deliberately argumentative here, just posing my questions.
I do agree that this car in question does look like it has a nice curve though. Nicer than the paintjob anyway...