Why Aren't We All Swapping To Superchargers?

[Galois]

i have a mate with a ford ranger, 2.5L 4 pot turbo diesel. when he took me for a spin in it the turbo was spooling up as we slowly reversed across the flat grass in his front yard lol. Those things spool up so quickly, that's the purpose as diesels don't like to rev

Edited September 9, 2010 by Galois

[jiffo]

No can't agree.

Typical automotive discussion, way too much generalisation.

Modern large truck diesels have a beautiful flat torque curve from around 900 to 2200rpm, all due to big turbocharging boost.

OLD fashioned diesels didn't rev too well, but even an Rd28 will still be pulling strong at 5000rpm, not too shabby for a diesel.

As for this one.............

[Kinks]

^^ that is awesome

[Birds]

No can't agree.

Typical automotive discussion, way too much generalisation.

Modern large truck diesels have a beautiful flat torque curve from around 900 to 2200rpm, all due to big turbocharging boost.

OLD fashioned diesels didn't rev too well, but even an Rd28 will still be pulling strong at 5000rpm, not too shabby for a diesel.

As for this one.............

lol, generalizations are the only way to talk about a general topic like this. Your specific examples suck and he is right: diesels don't like to rev. They are typically long stroke and high compression, which is why turbochargers are employed to make the most of what they can rev to. The RD28 is not your average diesel engine, it has a much shorter stroke than most diesel engines (actually shorter than it's bore is wide), hence it revs out to 5000 and the power band is more midrange oriented. It lacks the low down torque that most diesels have. Further evidence of this is peak torque at 2400rpm...again, higher than most diesels. And surprise surprise, peak torque is 178nm...which is shithouse for a 2.8 diesel because it is designed more like a petrol engine that runs on diesel. Yet, in contrast, the 3 litre petrol engines of the same time revved out and produced peak power past 5000rpm. So no, they don't like to rev out in comparison to most engines.

Modern truck diesels have a flat curve because they've got a massive stroke and the torque doesn't die off because the turbocharger draws it out.

[Peter89]

That's cause turbos work better with diesels. They don't rev high (as per a longer stroke than petrol engines) and this would severely limited boost in a supercharger application. Turbo lag is also much less noticeable on a turbo diesel because they are high compression engines - in fact, the turbocharger is solely there to extend the useable range of the diesel engine in the middle and upper RPM (they run out of steam very quickly), rather than to produce more torque/power all round.

It's all about application. There's no "one is better than the other". One will always be better for your application than the other..."which one" depends on your application. Vehicle manufacturers around the world still have a divide about it, there's no general consensus that one is better than the other, which is why twin charging exists.

my point was design efficiency. by using exhaust gas pressure, turbos are using some of the wasted energy from the engine. sure it does increase back pressure but compared to the loss of a supercharger, turbo is more efficient.

though, im not a mechanical or thermal engineer, so i cant do the math to prove it.

[STATUS]

We see alot of supercharged domestic cars and i can tell you now most of them (vortech style) are laggy dyno queens, the twin screw are the only way to go.

i should post some boost curves from vortech, kenne bell and harop chargers vs turbos... you will be surprised.

My thoughts on supercharging fall into two groups, dyno queen or useful I prefer to use a whipple (twin screw) style setup as boost is more turbo like ie comes in and stays constant whereas your vortech style charges increase boost with rpm so peak power and boost is always @ peak rpm... great for dynos, crap for daily livability.

The whipple will hit target boost quickly and offer FAR GREATER area inder the curve, much like a turbo setup.

Here is a comparison boost curve vortech vs turbo

Here is vortech versus whipple supercharger.

Twin screw --->

Vortech --->

[Rolls]

i should post some boost curves from vortech, kenne bell and harop chargers vs turbos... you will be surprised.

I am definitely interested if they are the same motor with supercharger vs turbo for similar power outputs.

[STATUS]

I am definitely interested if they are the same motor with supercharger vs turbo for similar power outputs.

similar outputs (520 vs 560rwkw) ^^ different chargers (these were the only two graphs on my comp which where close in peak power)

[STATUS]

vortech vs whipple

[mad082]

interesting trent. obviously different applications so can't accurately compare, but for arguments sake it's good. look at the torque. the twin screw made 200nm more at 50kmh less (1000rpm), but at 2500rpm the twin screw is making double the torque. that thing would be an absolute pig in the wet..... or the damp, or even if it looked like rainging, LOL.

[Peter89]

how about a comparison with super vs turbo chargers on smaller engines? r25/6 or sr20 since that's what the majority here have.

there's a vid floating around with a s15 running a turbo and super setup, making around 300kw. (if i recalled correctly)

Edited September 13, 2010 by Peter89

[STATUS]

how about a comparison with super vs turbo chargers on smaller engines? r25/6 or sr20 since that's what the majority here have.

there's a vid floating around with a s15 running a turbo and super setup, making around 300kw. (if i recalled correctly)

look in the forced induction section under twin charged i posted a few results in there, we have a rb30 with a gt3540 and supercharger that comes in... sick setup and is all home built see build thread here

http://forums.justcommodores.com.au/vn-vp-...ukes-vn-43.html

[xALmoN]

sounds like its gonna be expensive, twin charging something.

[STATUS]

sounds like its gonna be expensive, twin charging something.

less than 1000 odd bucks in the above case.

[Birds]

look in the forced induction section under twin charged i posted a few results in there, we have a rb30 with a gt3540 and supercharger that comes in... sick setup and is all home built see build thread here (ended up @ 400rwkw 23psi @ 2000ish)

http://forums.justcommodores.com.au/vn-vp-...ukes-vn-43.html

At 2000ish RPM? Fark me...no lag there!

[Rolls]

At 2000ish RPM? Fark me...no lag there!

Whipple superchargers usually have full boost by 1200rpm, don't even need any throttle.

Edited September 13, 2010 by Rolls

[Birds]

Yeah I knew they boosted from low, I was just surprised by the amount of power the thing is putting out at 2000rpm particularly with a turbo bolted on. As is the purpose of twin charging I guess...

[xALmoN]

Hmmm...

Something different.

[STATUS]

Whipple superchargers usually have full boost by 1200rpm, don't even need any throttle.

yup, if you look at the post above you will see the whipple is making 6 -odd psi down there

[Rolls]

yup, if you look at the post above you will see the whipple is making 6 -odd psi down there

I think if someone made a Whipple supercharger kit for a skyline that didn't require $5k of fabrication for custom manifolds and relocating power steering etc and wasn't ridiculously loud there would be a definite market for it.

I know there is someone on here that has supercharged his RB25DE but he has had lots of issues with the bypass valve and making the car quieter than a 747 on full noise. If these problems could be ironed out I think a lot of people would use them.

Would make the engine drive like a big capacity v8 which all the RB30 guys seem to love.

Edited September 14, 2010 by Rolls