In sportscar racing, why aren't superchargers used?

[chernaudi]

The stock Lister Storm had 2 of them. And they are legal under ACO/FIA/IMSA rules. And most of the tracks suit cars with a lot of torque. And that's achived through turbocharging, large engines, and supercharging, as well as diesels. I think that(similar to VW's TSI twin charger FSI engines) they would also want a turbo to balance out the loss of topend power caused by the supercharger, which I don't think is legal now. Everyone complains how the R10 has a fuel economy advantage, and how much the torque has helped with it's drivability(something that should've been know about the R8 as well), and a supercharger would help, so why not use one?

[chernaudi]

I mean, the Judd 5.0 V10 made 445 ft/lbs. My father's Ford 351 Cleveland V8 made 451 ft/lbs stock. And probably makes Panoz Elan like numbers after he modified it(the Elan was a 351 SVO derivetive, which used an aluminum Windsor block and Alu. Cleveland heads), which made 600+ hp and 540+ft/lbs. The Audi R8 and R10 both had torque in their back pockets(520+ and 811-885 respectively), and that's where the current NA sportscar engines have problems, especially in traffic. So why not used superchargers to boost low end toruqe?

[AU N EGL]

Two words: Heat and unreliable.

Supercharges produce a lot of heat, disipating that heat is difficult to do.

with all the heat comes the reliabilty factor or the lack there of for road racing.

[Notso Swift]

Modern Turbo's work over such a wide band that there is little room for superchargers.After all race cars still only work of the top half of their rev range, and if you geard a super charger up to suit it would have the same lag problems as a turbo.
Also I seem to recall that all the cars/classes you are talking about have to run a restrictor, the action of the supercharger (Positive dispalcement type) may send a shock wave back towards the restrictor and interfear with its ability to flow, don't know for sure though.

[Bob Riebe]

A turbocharger is a superchager.

A blower is a blower, the difference is how the air is forced, and the vanes driven.

[AU N EGL]

arent they close? a turbo charger is an evolution of a supercharger.

Supercharges are forced air induction that is belt driven and

turbocharges are forced air induction that is exhaust gas driven

[Bob Riebe]

Originally Posted by AU N EGL

arent they close? a turbo charger is an evolution of a supercharger.

Supercharges are forced air induction that is belt driven and

turbocharges are forced air induction that is exhaust gas driven

Years back the term "turbo supercharged" was often seen to so let buyers know their blower worked on a different system from the mech. units.

The turbo just eventually became the hype word favoured as a way to impress the ignorant, although in reality, it is much simpler than saying - exhaust driven supercharger.
Bob

[dtype38]

I thought turbo- and super- chargers were fundamentally different in that the supercharger takes away crank power at less than 100% efficiency, but the turbocharger uses waste energy from the exhaust gasses, and so can only add to the crank power. For that reason a supercharger can never be as efficient or effective as a turbocharger.... other than it doesn't suffer from low end lag.

[andy97]

Originally Posted by dtype38

I thought turbo- and super- chargers were fundamentally different in that the supercharger takes away crank power at less than 100% efficiency, but the turbocharger uses waste energy from the exhaust gasses, and so can only add to the crank power. For that reason a supercharger can never be as efficient or effective as a turbocharger.... other than it doesn't suffer from low end lag.

For the lack of lag reason I have often wondered why Superchargers were not used more in Rallying.

[Bob Riebe]

Originally Posted by dtype38

I thought turbo- and super- chargers were fundamentally different in that the supercharger takes away crank power at less than 100% efficiency, but the turbocharger uses waste energy from the exhaust gasses, and so can only add to the crank power. For that reason a supercharger can never be as efficient or effective as a turbocharger.... other than it doesn't suffer from low end lag.

Yes, the drive method differs, just as there are differing ways to manage how the air is forced into the engine.

They all differ, yet they are all superchargers, each has pros and cons.

Bob

[davyboy]

Originally Posted by andy97

For the lack of lag reason I have often wondered why Superchargers were not used more in Rallying.

The mid-1980s Lancia Delta S4 used a combination of turbocharging and supercharging to overcome lag and was probably the most effective of all the Group B cars.

[GORDON STREETER]

Knowing nothing about top fuel dragsters I often wonder why they don't use turbo's . I would think that those massive blowers must use a lot of HP !
Obviously they have been tried and can't be as good in that type of motorsport ?

[dtype38]

Hmmm... would have thought that the top fuel dragsters would happily trade a few dozen hp for the odd tenth of a second less lag :-)

Interestingly (or not as you wish) I went to a lecture by the head of Jaguar engineering about the launch of the XJR and XKR range of cars. In both instances they opted for superchargers rather than turbochargers to increase the power of their 4.0ltr (later 4.2ltr) V8. He said that they evaluated all the pros and cons of both charging systems and in terms of ease of installation, heat management, complexity and efficiency, the turbocharger won easily. But... for that bottom end grunt that Jaguars were always famous for, it had to be the supercharger. That and a certain, shall we say "exclusivity" over the average less expensive performance car ;-))

[GORDON STREETER]

I must admit that I'm impessed by the Merc SLKs that I service .

[ian_w]

In my opinion, superchargers are the work of the devil and a very poor choice for a performance engine. They need loads of power to drive them, for example the 4.2 Jag V8 mentioned needs over 80bhp to drive the supercharger - i.e its a 500hp engine delivering only 420 at the flywheel. So the fuel consumption of the engine is high and also the stresses on the whole engine are much higher than you would imagine from considering the brake hp figure.

Sure they have no lag but then again they don't really generate any boost at lowish engine speeds. The faster the engine goes the more boost it produces so the engine actually has a 'top-end' character which is the complete opposite of what most people imagine.

A turbo engine may have a fraction of a seconds lag and perhaps not really start boosting until 2000/2500 rpm but once it reaches that speed it can normally generate at least 1 bar of boost compared to say 0.2-0.3 bar from a supercharger. The turbo also doesn't need any power to drive it, as it extracts energy from the waste exhaust gases so the overall efficiency of the engine is much higher.

If any of you have driven both supercharged and turbo cars of similar power then you will know that there is no contest - the turbo absolutely spanks the supercharger on performance and thats without even considering the hideous whine you get from a supercharger.

So to answer the original question, superchargers are not used in sports car racing because the engine is very inefficient for the amount of power generated. As fuel economy is a major factor in most sports car racing then they simply can't compete against NA or turbo engine.

As you may have guessed I'm not a big fan of superchargers!! Rant over now.

[davyboy]

What about compound charging as in the case of the Delta S4 ? Clearly they used the supercharger to overcome lag at low revs, but then the turbo kicked in for boost further up. How does compound charging work and, given the incredible effectiveness of the S4, arguably the fastest Group B car, why others never tried it ?

[Speedblood]

Originally Posted by GORDON STREETER

Knowing nothing about top fuel dragsters I often wonder why they don't use turbo's . I would think that those massive blowers must use a lot of HP !
Obviously they have been tried and can't be as good in that type of motorsport ?

Sorry I'm going off topic!

I think it has been tried but I believe it was awfully difficult to get a turbo to work efficently. I think superchargers on Nitro Cars take nearly 700-800 HP away. Nothing has been proven though because it is awfully difficult to measure teh power of a Nitro burning car.
A good example of the the advantages of a supercharger in drag racing is between a Top Methanol Dragster and an "A/FUEL" dragster. The top methanol dragster runs on Methanol with a Supercharger and the "A/Fuel" dragster runs on Nitro Methane but has no supercharger and is "direct drive". They run in the same class and you can see the benefits of a supercharger at the start of a run. The supercharged cars always tend to have better starts and up to 1/2 track they are usually ahead. The "A/fuel" dragsters then tend to catch up because of the power advantages with nitro. Most of the time though the acceleration advantages of a supercharger win. (BTW thats here in Europe, I don't know what it's like in the USA or Austrailia.
Sorry that was a bit pointless but I thought I'd clear that up!

I think because superchargers are all about acceleration it is ideal for drag racing. Turbo lag would be a problem because it could cause slower starts and because Top fuel/funny car etc races last seconds Turbo lag would probably count against them.

Anyway back to topic, I think that superchargers are not suited to long distance races because of the stress on them and the power required to spin the belt isn't ideal.

I do like superchargers but this probably isn't there area.

If any of this is wrong please correct me!

[Notso Swift]

Of course the other way to look at it is they did use supercharges for long distance racing... from about 1929 we have the MB kompressors and the Brikin blower Bentley's... it may be telling that niether finished and a NA Bentley won the race.

[Chris Y]

Originally Posted by davyboy

What about compound charging as in the case of the Delta S4 ? Clearly they used the supercharger to overcome lag at low revs, but then the turbo kicked in for boost further up. How does compound charging work and, given the incredible effectiveness of the S4, arguably the fastest Group B car, why others never tried it ?

I would guess that rally cars spend a lot more time at low revs. It's possible that sports cars really don't need the extra boost at low revs, particularly with the extra losses associated with the supercharger, combined with the problems involved with packaging a super and a turbo, and all the hosing, etc.

Also, perhaps more modern turbo systems have less lag, and therefore don't see the need for the Delta's system.

[xc4pot]

[quote=thats without even considering the hideous whine you get from a supercharger.[/quote]

ok i think the whine is so much nicer, i wish my car sounded like this, it would make small childern cry

http://videos.streetfire.net/search/...5e001ff2e1.htm

[AU N EGL]

Originally Posted by xc4pot

ok i think the whine is so much nicer, i wish my car sounded like this, it would make small childern cry

http://videos.streetfire.net/search/...5e001ff2e1.htm

Kenny Bells are grear super chargers for Drag racing.

[monaroCountry]

I would go with the supercharger, instant response wow.

[R59]

Originally Posted by Speedblood

Sorry I'm going off topic!

I think it has been tried but I believe it was awfully difficult to get a turbo to work efficently. I think superchargers on Nitro Cars take nearly 700-800 HP away. Nothing has been proven though because it is awfully difficult to measure teh power of a Nitro burning car.

I wouldn't say that this bit is off topic.....

It has been quoted elsewhere on here (ten-tenths) that the supercharger on a top fuel 500ci Hemi takes so much power to turn, that a standard 5.7L Hemi wouldn't be able to turn it.

Power outputs have been measured on dyno's - last time I was with Smax Smith (former FIA European Top Fuel Champion) he quoted figures of circa 6600bhp for a nitro engine.

Back to the thread....

Superchargers would give you the advantage of grunt out of the corner, but you'd run out of puff down the straight. They have the disadvantage (roots or screw type) that they sap power due to being tighter than a ducks.... otherwise, they won't pump air! And when the belt breaks - the engine stops - it can't breathe!

A turbocharger has the issue of lag out of corners, but once it kicks in, it's banzai time! If it fails, you can limp to the pits at least!

A compound system does give good results. The Lancia S4 was one heck of an example of this, though how much the "change of fire extinguisher" after each stange had in it's success, I don't know.

Personally, I'd just go for more cubic inches!! There is no substitute you know!

[AU N EGL]

Originally Posted by racing59

Personally, I'd just go for more cubic inches!! There is no substitute you know!

No replacement for displacement

[Notso Swift]

Actually, there is no substitute for cubic dollars