Why do drag cars use SC instread of TC?
Discussion
I know it has probably been asked before, but i can't find it with a search.
The reason i ask is that superchargers are parasitic (Top fuel dragsters require more power than a conventional hemi can produce just to spin the SC they use) whereas Turbo's are using a "free" resource, ie spent exhaust gases for propulsion, ergo surely turbo's are better and (going by the accepted wisdom of road cars) produce significantly more power for a given boost.
Greg
The reason i ask is that superchargers are parasitic (Top fuel dragsters require more power than a conventional hemi can produce just to spin the SC they use) whereas Turbo's are using a "free" resource, ie spent exhaust gases for propulsion, ergo surely turbo's are better and (going by the accepted wisdom of road cars) produce significantly more power for a given boost.
Greg
o.versteer said:
Complete guess here but wouldn't the obvious answer be that superchargers have no lag? You'd think that was important in drag racing, as they only have 400 yards to do their stuff in, no? I have no idea but that'd be my guess.
I'd say he's hit the nail on the head there.
Depends on the detail of the application - turbos work better for the flat fours used by some street and funnycar competitors, and they spin them up before launching, but for a big V8 top fueller that's only going to stay in one piece for a few hundred revolutions in total that's not an option.
cronk-flakes said:
o.versteer said:
Complete guess here but wouldn't the obvious answer be that superchargers have no lag? You'd think that was important in drag racing, as they only have 400 yards to do their stuff in, no? I have no idea but that'd be my guess.
I'd say he's hit the nail on the head there.
I wouldn't, drag cars are revving the nuts off the car on the start line and a turbo would instantly be in boost, i am happy to be proven wrong though.
I think its more of a rules thing.
In other classes, people are moving over to turbo setups now.
Oh, and if you have ever read that list of facts about top fuel dragsters, especially the one about the spark plugs being destroyed, its true!
See here:
www.mez.co.uk/santapod.html
In other classes, people are moving over to turbo setups now.
Oh, and if you have ever read that list of facts about top fuel dragsters, especially the one about the spark plugs being destroyed, its true!
See here:
www.mez.co.uk/santapod.html
Edited by eliot on Wednesday 25th April 19:45
Primarily because sc gives absolute instant grunt, is very easily maintained and packaged.
BUT, you will see the likes of Redvictor et all using turbos, which tend to make the power further up the strip and make the life of the tyres at launch a tad easier.
Slinky, hodgy or Redvictor will no doubt be along shortly to explain in better detail.....
F
BUT, you will see the likes of Redvictor et all using turbos, which tend to make the power further up the strip and make the life of the tyres at launch a tad easier.
Slinky, hodgy or Redvictor will no doubt be along shortly to explain in better detail.....
F
Hi
Umm the answer is mostly historical actually...
Top Fuel engines were mostly based on the 426 Hemi...firstly Iron blocks then Ally blocks...
Dont forget this was in the sixties and seventies....in those days when these engines were being developed for top fuel...there were no turbos...the turbo technology for car engines was not really available....there were some huge old fashioned turbos on trucks...but not cars...high performace turbos are a fairly recent thing...long after most of the engine development and rules were set for top fuel.....
All the best Brett
Ancient ex top fuel mechanic
Umm the answer is mostly historical actually...
Top Fuel engines were mostly based on the 426 Hemi...firstly Iron blocks then Ally blocks...
Dont forget this was in the sixties and seventies....in those days when these engines were being developed for top fuel...there were no turbos...the turbo technology for car engines was not really available....there were some huge old fashioned turbos on trucks...but not cars...high performace turbos are a fairly recent thing...long after most of the engine development and rules were set for top fuel.....
All the best Brett
Ancient ex top fuel mechanic
Turbos have been tried in the past on Nitro engines. Gordie Bonin ran a turbocharged / Nitro setup in one of his funny cars in the late 1970's. Heat seemed to be the main problem.
What you have to remember is that the fastest, quickest and most powerful internal combustion Otto cycle engines on the planet are actually almost agricultural in nature. 8000 hp and 330 mph in 4.4 seconds is no place for highly complicated stuff sat on jewellers bearings and the like. Big and Chunky is generally the way with Nitro engines. They were once described to me as being like a bonfire, the more fuel you can chuck at them, the more you will get out. Shove loads in, burn as much of it as you can on the way and then (the tricky bit) harness that power into some meaningfull acceleration. Get it right, and it's better than sex!
The Street Eliminator guys are getting some really great results out of turbo setups, and Andy (Redvictor) will hopefully be along soon to explain this far better than I ever could.
HTH
JC
Edited because it isnt called CCSE anymore!
What you have to remember is that the fastest, quickest and most powerful internal combustion Otto cycle engines on the planet are actually almost agricultural in nature. 8000 hp and 330 mph in 4.4 seconds is no place for highly complicated stuff sat on jewellers bearings and the like. Big and Chunky is generally the way with Nitro engines. They were once described to me as being like a bonfire, the more fuel you can chuck at them, the more you will get out. Shove loads in, burn as much of it as you can on the way and then (the tricky bit) harness that power into some meaningfull acceleration. Get it right, and it's better than sex!
The Street Eliminator guys are getting some really great results out of turbo setups, and Andy (Redvictor) will hopefully be along soon to explain this far better than I ever could.
HTH
JC
Edited because it isnt called CCSE anymore!
Edited by Jon C on Thursday 26th April 00:26
In theory, turbos can produce more power, which is why you're starting to see them making a splash in some classes -- Street Eliminator being the obvious one. But they're not without problems. For a start, there's lag, which can be minimized by various techniques. As others have said, though, you're launching at high revs, and plan to keep it that way for the duration of the run anyway, so all you need is to be able to reduce the lag enough to go from hitting the transbrake up to launch RPM and get the turbos spooled up before the tree runs.
In top fuel (and indeed, all of the other pro classes[1]), turbos are banned in the rules. But even if they weren't, there are problems with using a turbo with nitromethane. Nitro burns very slowly, to the point where it's still burning when you take it from the exhaust and feel it into the turbo. You really want to try and cool it down before sticking it back in the combustion chamber, which isn't easy. That said, it is possible, and Bob Norwood built a turbocharged nitro burning engine a few years ago, and got respectable (albeit not earth shattering) performance out of it. I haven't heard anything about it of late, so I don't know if he developed it any further.
[1] That's why Jöran had to run his 6-second Trans Am in Super Pro last year -- it's not eligible to run in Pro Mod.
In top fuel (and indeed, all of the other pro classes[1]), turbos are banned in the rules. But even if they weren't, there are problems with using a turbo with nitromethane. Nitro burns very slowly, to the point where it's still burning when you take it from the exhaust and feel it into the turbo. You really want to try and cool it down before sticking it back in the combustion chamber, which isn't easy. That said, it is possible, and Bob Norwood built a turbocharged nitro burning engine a few years ago, and got respectable (albeit not earth shattering) performance out of it. I haven't heard anything about it of late, so I don't know if he developed it any further.
[1] That's why Jöran had to run his 6-second Trans Am in Super Pro last year -- it's not eligible to run in Pro Mod.
Furyous said:
Primarily because sc gives absolute instant grunt, is very easily maintained and packaged.
BUT, you will see the likes of Redvictor et all using turbos, which tend to make the power further up the strip and make the life of the tyres at launch a tad easier.
Slinky, hodgy or Redvictor will no doubt be along shortly to explain in better detail.....
F
He may not agree with you about the life of the tyres BUT, you will see the likes of Redvictor et all using turbos, which tend to make the power further up the strip and make the life of the tyres at launch a tad easier.
Slinky, hodgy or Redvictor will no doubt be along shortly to explain in better detail.....
F
Brett928S2 said:
Hi
Umm the answer is mostly historical actually...
Top Fuel engines were mostly based on the 426 Hemi...firstly Iron blocks then Ally blocks...
Dont forget this was in the sixties and seventies....in those days when these engines were being developed for top fuel...there were no turbos...the turbo technology for car engines was not really available....there were some huge old fashioned turbos on trucks...but not cars...high performace turbos are a fairly recent thing...long after most of the engine development and rules were set for top fuel.....
All the best Brett
Ancient ex top fuel mechanic
Umm the answer is mostly historical actually...
Top Fuel engines were mostly based on the 426 Hemi...firstly Iron blocks then Ally blocks...
Dont forget this was in the sixties and seventies....in those days when these engines were being developed for top fuel...there were no turbos...the turbo technology for car engines was not really available....there were some huge old fashioned turbos on trucks...but not cars...high performace turbos are a fairly recent thing...long after most of the engine development and rules were set for top fuel.....
All the best Brett
Ancient ex top fuel mechanic
...and didnt the superchargers come from WW2 aircraft engines, therefore were (relatively) readily vailable
williamp said:
...and didnt the superchargers come from WW2 aircraft engines, therefore were (relatively) readily vailable
That may or may not have had an influence, but the traditional GMC n-71 supercharger (with the 14-71 currently being the commonly used one) was originally developed for large 2 stroke diesel engines where it was not intended to increase manifold pressure (i.e. build boost) but to assist cylinder filling directly.
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