Why Aren't We All Swapping To Superchargers?

[NOS4R2]

People get far too caught up in whole "turbos make more horsepower" factor. Torque is loads more fun IMO. Peak power produced is only one side of things. I think of turbos as kid of the same as a big cam. You need to use lots of revs to get the power out of them. With my blower the instant boost quickly smooths out the big (blower friendly grind) cam I also run. I can waste turbo cars out of the hole at the drags. But at the other end they start to pull me in.

most poeple shun blowers cos unless they shell out moonbeams for a kit, it's not bolt on and go.

Given the screw blower my CA is getting can support 2.2 bar, but the time an equivelent turbo has spooled up I'll be a spec on the horizon.

[Duncan]

Hey the thread title says "for motorsport". My comment stands, turbos for motorsport. Unless improperly sized a turbo will be very effective

For OEM use either tiny turbos or a supercharger are the way to go for sure. no-one likes a factory car with lag.

Aftermarket use is totally different again and depends on your goals.

[Adriano]

Having built plenty of supercharged falcon/commodores, i dont really rate them. A centrifical blower has a boost curve that goes up linearly, the more you rev it the more boost. Unfortunately that means if you want 15psi at 7500, you have to gear it then live with 10psi at 5000, which means you are close to 100rwkw behind a similarly sized tuebo setup at those revs.

Centrifugal blowers got you out of the hole, but are horribly inefficient, power hungry and once again if you want top end you need a blower the size of the slab of beer your wife drinks nightly.

[lachlanw]

face palm at how some people dont realise how closely horse power and torque are related .

[jiffo]

To me the question isn't supercharge V's turbocharge, it's what's wrong with today's motor engineers that they can't sort out a reliable high performance engine driven turbocharger.

They've been around in very large HP applications forever, but I've never seen the technology transferred to the auto industry.

This VW monstrosity could have been done so much better/easier/simpler with an engine driven turbo.

http://www.greencarcongress.com/2005/08/inside_vws_new_.html

[Birds]

On the topic of supercharger versus turbocharger efficiency, there is some misleading information here...remember that off boost a turbocharger is very restrictive to engine breathing and the engine is operating at low compression (therefore wasting combustion) for 1/3 of the rev range, where we spend most of our time driving. The only time they can be considered efficient is when they are on boost. And even then, they are considered thermodynamically inefficient despite producing lots of power. So a supercharger isn't the only one that is wasting/draining energy on the constant, and the exhaust side of things is never restricted. In fact, in the lower rev ranges it is more efficient than a turbocharger.

You need to think of the comparison as linear versus non linear power production. Both have their advantages and disadvantages.

[Kinks]

^^ agree, in the sense that turbos don't give you "free energy" by harvesting exhaust gases. you do have a penalty and that penalty is in the form of backpressure.. turbos require pressure in the exhaust manifold in order to spin and do work. that pressure pushes against the piston on its exhaust stroke and "restricts" the engine. the plus side is you are cramming a whole bunch more air in the intake side so it is a net gain. but it is not "free" power. and yes, when turbo is off boost you have a nice restriction in your exhaust. however, it's likely the restriction is less loading on the engine than a mechanical supercharger.

i think a blown engine would need just as low compression for a certain boost level, would it not?

[Birds]

That depends how much boost it is running and the type of fuel it uses. The temperatures of induction produced by superchargers are typically lower than their turbocharger counterparts, so you can get away with higher compression and no intercooler. That said, yes - from factory, supercharged engines usually do come with low compression. But keep in mind that the supercharger (atleast a roots type) is producing boost from idle onwards so you don't really feel the effects of running low compression. Therefore no feeling of lag and boost (they technically lag for the whole rev range, you just don't notice this because there isn't a big non-linear change of torque like with a turbocharger). The supercharged V6 Commodores of the 90's were as fast as their V8 counterparts off the line, due to similar low down torque, but lost out above 80km/h.

[Kinks]

But keep in mind that the supercharger (atleast a roots type) is producing boost from idle onwards so you don't really feel the effects of running low compression.

That's the big benefit - they feel like a bigger engine without the weight penalty.

[xALmoN]

doesn't seem to be any bolt on supercharger kits for the supra/skylines, especially for the NA boys, could be a route with less headaches, although not necessarily costing less.

NA-S?

That said, if there was a supercharger kit for the NA supra, i might even consider getting another supra, as a fun daily.

if only.

Edited September 6, 2010 by xALmoN

[Birds]

Would be such a waste when there is already a forced induction model of that car available for cheaper.

The only cars I would ever aftermarket turbocharge/supercharge are cars that never came with it from factory. It almost ALWAYS ends up costing more than the factory version. Tthe only exception I can think of is a VL turbo because those factory cars holding their value in a way that defies the laws of depreciation.

[xALmoN]

I was thinking along the lines of doing something different, but then i thought, if there were after market kits for supercharging a supra, then it wouldnt be too different would it?

[rotarytt]

you can't make the same power. theres a point where the supercharger has peaked the turbo will keep going.

they won't fit in a lot of engine bays.

Twin charging is awesome if you can be bothered tuning with many hiccups.

the only advantage is in an engine such as an ls1. where turbo chargers melt the damned thing.

torque sucks you hit your peak then get overtaken.

it's only for initial take off.

I'd like to hear from someone who went from turbo to supercharger on the same engine.

[Birds]

If you're setting up a car for street acceleration, roots superchargers are pretty good...by the time you run out of torque you've already passed the speed limit on most roads.

Bottom line, they both have advantages/disadvantages...but OP was referring to motorsport. In which case, track based motorsport tends to favour the turbocharger and drag racing favours the supercharger. Not because one is necessarily better than the other, but because one is generally better suited to that application.

[VB-]

if you really want an argument stop calling it lag and start talking about boost threshold

this is like the 2nd time i've seen someone on here who actually made note of the difference, good work

face palm at how some people dont realise how closely horse power and torque are related .

now i'm really starting to like you

^^ agree, in the sense that turbos don't give you "free energy" by harvesting exhaust gases. you do have a penalty and that penalty is in the form of backpressure.. turbos require pressure in the exhaust manifold in order to spin and do work. that pressure pushes against the piston on its exhaust stroke and "restricts" the engine.

its more commonly reffered to as 'pumping losses' and turbos still have the same issue, those its less noticeable then with a supercharger

i think a blown engine would need just as low compression for a certain boost level, would it not?

not necesarily. superchargers have one big advantage of being able to run large diamter extractors to an open exhaust , as opposed to a turbo manifold+turbo combo, extractors and open pipes get more heat out of the cylender easier (thats the theory anyway lol)

[Peter89]

On the topic of supercharger versus turbocharger efficiency, there is some misleading information here...remember that off boost a turbocharger is very restrictive to engine breathing and the engine is operating at low compression (therefore wasting combustion) for 1/3 of the rev range, where we spend most of our time driving. The only time they can be considered efficient is when they are on boost. And even then, they are considered thermodynamically inefficient despite producing lots of power. So a supercharger isn't the only one that is wasting/draining energy on the constant, and the exhaust side of things is never restricted. In fact, in the lower rev ranges it is more efficient than a turbocharger.

You need to think of the comparison as linear versus non linear power production. Both have their advantages and disadvantages.

but overall, turbo is more efficient.

vast majority of the worlds trucking fleets run, turbo diesels. there's now even more small cars with turbo diesels for that extra efficiency.

Edited September 7, 2010 by Peter89

[Galois]

bmw has said for years that turbochargers are the way of the future. for all applications where the extra force required to pump the air through the turbine is less than what is required for the supercharger, the turbo will be more efficient at generating power (fuel wise at least).

the mercedes mclaren slr needs 120 hp to power its supercharger!!! thats more than my lil bros camry makes hahaha

on the racing front, remember the most powerful f1 engines ever were the 1.5L turbo ones, producing 1500hp!!! pretty epic huh

[Rolls]

face palm at how some people dont realise how closely horse power and torque are related .

So close in fact they are 100% directly related lol. Horse power is proportional to torque x revs.

[rotarytt]

also a supercharger can only spin at 1/3 the speed a turbo can.

they should be rebuilt every 100k whether damaged or not. cost more, yet less complicated too install. if there's room.

can drain upto 20% of the engines overall power to run.

yet add around 30-75% say 50% for most.

http://www.ehow.com/facts_5752326_turbo-vs...onsumption.html

I honestly don't like the whine of large ones often hear it over a noisy v8.

roots last longer yet aren't as efficient as a twin screw.

centrifugal is great on a standard car if you want low boost.

for some reason i want to put one on a n/a 4 cylinder.

[Birds]

but overall, turbo is more efficient.

vast majority of the worlds trucking fleets run, turbo diesels. there's now even more small cars with turbo diesels for that extra efficiency.

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.