........and besides that, I like the song of the S/C! Music for the senses!!

 

Again I hear "heat buildup in that small a car." AM I missing something?? The turbo is under the hood, not in the interior. If you are referring to the engine, what does the size have to do with it? It's a matter of whether or not cooling is sufficient for the given engine, not what size the engine is. In fact, turbos have been used for ages primarily to give more power to smaller engines.

 

^^Agreed. The cooler the engine the better it runs. A supercharger puts in more hot air than a turbo does. Thats the reason that a s/c has 50% effeciency. The effeciency is refering to the temp of the air going in at __ psi. Turbos have an effeciency percentage of 70%+. In theory for a s/c, if you are boosting 10 psi your engine is really only using 5 psi.

 

on the efficiencies of the various tech. Those are 15-20 year old numbers. Todays SCs (yes, even the crappy roots) can get TEs of 65% up to the low 80s (new 4 rotor design from Eaton). The sweet spot of the M45 is a bit over 70%, I think. (These numbers are higher than what you're used to seeing from a 6-71 or the like due to a lot of work on the air intake and exit, and the twisting of the rotors.) Turbos are even better, with some apps hitting the high 80%s in TE. Also, a roots SC has a worse TE than a twin screw that has worse than a centripital (Think Vortex or the Rotrex that's currently getting play), but they all have different characteristic curves (Efficiency plots) because they work slightly differently.

Matt

 

Agreed on working different, thats a giving. I am aware of the different varieties of s/c. I havent seen or worked with any turbos that have effeciencies of 80%, 77% yes, but not 80%. What is the housing and compressor wheel size for the 80% turbos you speak of? Ball bearing? Water cooled, oil-cooled or both?

 

theres at least 2 over 80% (one GT22 makes it over 80, the GT35R makes it over 79, but doesn't cross the 80% line) , several in the high 79s, and lots and lots in the mid 70s.... The peaks are lower than I expected though... But I only checked one manufacturer.

Here's the map for the new TVS Eaton....


Matt

 

Double post...

 

C15 family ~71%
C30 family up to 76%

Matt

 

sorry to sound like a noob but, what design are these (roots, twinscrew, etc.) Also, if you want turbos with high eff. then check the ones that go on 18 wheelers.

 

Dr. I love it. Glad to have a conversation with individuals that bring facts to the table. Now, I have actually acquired information. Thanks.

 

Once in a while I work on a turbocharged ,supercharged, 20 cylinder, two stroke engine, with pistons the size of coffee cans that happens to be a diesel! Redlines @ 900rpm's, OK this is not Mini sized and there are no facts on the debate table but veery intervesting

 

After the turbo model has been out a 2 or more years, I'm sure I will get one.

 

data driven decisions are the only way to go! (just imagine if our gov made more of them!)

And the Rotrex is a mechanically driven impellor design, so it's not surprising it has turbo like numbers. I'd guess Vortech, Paxton and the like are all about the same, and fighting it out over drive technology.

Matt

 

You shouldn't forget though that race was between YOU and THE OTHER GUY, which makes times somewhat irrelevant as the drivers' skill can't be taken into account. :impatient
Really, the only way to even evaluate the difference is to race against your own TIME in different cars. (besides it's safer then racing other cars on the same road at the same time). Also, you need to drive both cars for a similar amount of time so your familiarity with the car would be comparable.

Don't we all have the experience of improving our time on a familiar road but an unfamiliar car every other run? I have a twisty road (~30mi of fun) I drive almost every day, when I got my MCS I drove it 42 days every night (~3am)... first week average was 58min, last 10 days or so - 47min every time.
So, if I drive an unfamiliar car (car A) at a similar time as the car that I know well (car B) - I should assume that objectively car A is much faster then car B.

It's amazing, people forget about the "human factor" alltogether... Same way at some fights people try to judge which "style" is better - jiujitsu or wrestling or kung fu or something else - while it's never styles fighting, it's only people fighting...

Back to the topic though -
Mine is S/C, and that because r56 just came out. I'd rather have them iron out all the little issues of the first production year

 

turbo/SC comparissons will run for ever,and having the numbers is of little use ,what is important is how the car drives.
I am running an opcon compressor and it works very very well, some things can be added to a SC which are not possible of the turbo, such as injecting fuel pre charger which I am doing.
both turbo and SC have their place,and their advantages .
(At 12 psi the opcon outperforms the Eaton at 18 psi in all respects, for those that like numbers )

 

Have the best of both the vw golf GT has a 1.4 litre engine and supercharger and a turbo depending on the speed of the engine ,so at slow speeds its the supercharger and at high speeds its the turbo and it has 164bhp.
It will be also fitted to the audi A3 insted of the 1.6FSI.

 

lots and lots and lots were after the carb. No reason you can't run a wet charge through a turbo..... I just don't know that you'd want to do it now. Most of the apps that did it didn't have much of a choice because of when the were built...

matt

 

I've read over and over in this forum that the supercharger needs a power source and the turbo does not. With a little common sense everyone should
know that is not true. Nowhere in the universe do we get something from nothing. Anyway, is does take energy to drive the turbo - restricting the
flow of the exhaust. Fortunately with the extra air and fuel being pushed
into the engine the overall is a gain. Just like the supercharger. The real difference is the turbo need to spin up, needs exhaust pressure to operate, thus works only when the RPMs are up. The supercharger has a direct drive
to the motor so it works at low RPMs. (The turbo is much more efficient at high RPMs than the supercharger). So, supercharger: good for low end torque and loses efficiency at high RPMs. Turbo is not good for low end
torque but works very efficient at high RPMs. Which do you want?

There are some engines that have the best of both world because they
have both - a supercharger for low RPMs which has a clutch that turns
the supercharger off at a preset RPM -then when the turbo becomes
efficient it take over. More money but can be a very good solution.

There is no easy line that one is better than another. They both have
positive and negative characteristics.