Running a bang-bang antilag on a road car
Discussion
Hey all, I was wondering what the implications of running a bang bang anti-lag system on a road car would be, and thought "what the hell, someone on Pistonheads has probably tried it". Now, I can't try it, because I don't have a turbocharged car, but I've seen a few road cars that have it installed. I know it's rally kit really, and only truly useful when you are really pressing on a on a difficult road, so most of the street cars with it must have it only for show.
Is it illegal? I can't see how it could present a danger, but still the police might take a dim view to the excessive pops and whooshes, not the mention the occasional gout of fire from the exhaust!
How hard is it on the turbos? Rally cars can be serviced very often by companies with deep pockets, so new turbos are probably not an issue for them, but how quickly do they wear out regular road-car turbos? I expect it also increases fuel consumption considerably?
How tough is it on the exhaust system? the temperature in the system must go a lot higher than normally experienced temperatures, and the continual pressure-spikes from the explosions within the system must put stress on it, does it not blow the pipework to bits? Would a proper full sports exhaust system (Blitz, Milltek) be able to handle the stress?
Strange questions from someone with no intention or ability to test these questions, but hopefully someone can shed some light on this!
Dave
Is it illegal? I can't see how it could present a danger, but still the police might take a dim view to the excessive pops and whooshes, not the mention the occasional gout of fire from the exhaust!
How hard is it on the turbos? Rally cars can be serviced very often by companies with deep pockets, so new turbos are probably not an issue for them, but how quickly do they wear out regular road-car turbos? I expect it also increases fuel consumption considerably?
How tough is it on the exhaust system? the temperature in the system must go a lot higher than normally experienced temperatures, and the continual pressure-spikes from the explosions within the system must put stress on it, does it not blow the pipework to bits? Would a proper full sports exhaust system (Blitz, Milltek) be able to handle the stress?
Strange questions from someone with no intention or ability to test these questions, but hopefully someone can shed some light on this!
Dave
it's totally possible, but yes, not really recommended because:
1) any catalyst will be quickly destroyed, by either the raw unburnt fuel contaminating the catalyst, or more likely the raw unburnt fuel exotherming and simply melting the substrate. On the WRC the "cat" is a 100cell metal matrix device, and it is positioned at the tailpipe, (something like 3m from the engine!) and it is just there for "show" it looses all it's catalytic capabilities after a single shakedown test!!
2) turbo durability: wrc turbos use a high temperature stainless steel alloy that maintains it's mechanical strength at up to 1150 degC, a std road turbo will be scrap at about 1000degC. Turbine inlet gas temps of 1300dgC are not unusual during als operation (short period of operation means bulk turbine material temp is lower) Also the turbo bearing system needs to be VERY robust as turbine shaft speed and crucial axial thrust loads are massively transient. To withstand this a wrc turbo is pretty speciallist, typically a TR30R garret wrc turbo is approx £9k !
3) lack of engine braking during operation: depending on the throttle system and spark retard used during als operation, there can be a significant loss of engine braking, not a problem in a race/rally environment, but possibly an issue on the road
4) Exhaust system: any "packed" exhaust will literally have the stuffing blown out of it after a short period!
5) noise: as mentioned the police and your neighbours will not really appreciate the als as much as you!
6) it's quite easy to set fire to your rear bumper or even the cars underfloor plastic and underseal if the system is used and the car not allowed to cool before stopping!
Of course the "agressiveness" of the als system is tunable (by the amount of bypass air, extra fuelling and spark retard) so a more "road friendly" calibration can be used to maximise turbo shaft rpm without actually breaking too much!
Also, using a "pre-turbo" combustor (a-la scooby wrc) allows you to run an effective but much more durable als system, although thermal management is still a massive challenge at low speeds
1) any catalyst will be quickly destroyed, by either the raw unburnt fuel contaminating the catalyst, or more likely the raw unburnt fuel exotherming and simply melting the substrate. On the WRC the "cat" is a 100cell metal matrix device, and it is positioned at the tailpipe, (something like 3m from the engine!) and it is just there for "show" it looses all it's catalytic capabilities after a single shakedown test!!
2) turbo durability: wrc turbos use a high temperature stainless steel alloy that maintains it's mechanical strength at up to 1150 degC, a std road turbo will be scrap at about 1000degC. Turbine inlet gas temps of 1300dgC are not unusual during als operation (short period of operation means bulk turbine material temp is lower) Also the turbo bearing system needs to be VERY robust as turbine shaft speed and crucial axial thrust loads are massively transient. To withstand this a wrc turbo is pretty speciallist, typically a TR30R garret wrc turbo is approx £9k !
3) lack of engine braking during operation: depending on the throttle system and spark retard used during als operation, there can be a significant loss of engine braking, not a problem in a race/rally environment, but possibly an issue on the road
4) Exhaust system: any "packed" exhaust will literally have the stuffing blown out of it after a short period!
5) noise: as mentioned the police and your neighbours will not really appreciate the als as much as you!
6) it's quite easy to set fire to your rear bumper or even the cars underfloor plastic and underseal if the system is used and the car not allowed to cool before stopping!
Of course the "agressiveness" of the als system is tunable (by the amount of bypass air, extra fuelling and spark retard) so a more "road friendly" calibration can be used to maximise turbo shaft rpm without actually breaking too much!
Also, using a "pre-turbo" combustor (a-la scooby wrc) allows you to run an effective but much more durable als system, although thermal management is still a massive challenge at low speeds
Ok, so its not got a turbo but my TVR pops and bangs on the over-run, its like having a tail gunner in the back. Its never done any harm to the cats or the exhaust. So im my normally aspirated experience detonating fuel in the exhaust headers hasnt caused any problems. Quite common with TVRs, never heard anyone mention cat or pipe problems with it. Mines on its original cat and exhaust and its 13 years old now.
No idea what the impact would be on a turbo.
No idea what the impact would be on a turbo.
Thanks Max Torque, this is the kind of spoddy, tech heavy nerdism I was hoping for! 
9 grand on a turbo, bloody hell, that is pricey. I imagine the road cars you see it on probably have the factory standard exhaust system kept at home for MOT time, because clearly switching ALS on with a regular road exhaust would be a recipe for big bills or even a fire under the car!
9 grand on a turbo, bloody hell, that is pricey. I imagine the road cars you see it on probably have the factory standard exhaust system kept at home for MOT time, because clearly switching ALS on with a regular road exhaust would be a recipe for big bills or even a fire under the car!
Mr MXT said:
If rally cars drive between stages on the public road, surely any tech on them (inc anti lag) must be road legal? 
without wishing to get into the "road legalness" of WRC cars (which btw is massively shady... lol) the cars run in "road" mode between stages, als is only activated in "stage" mode, so it is not operational for transition mileage!!bigdods said:
Ok, so its not got a turbo but my TVR pops and bangs on the over-run, its like having a tail gunner in the back. Its never done any harm to the cats or the exhaust. So im my normally aspirated experience detonating fuel in the exhaust headers hasnt caused any problems. Quite common with TVRs, never heard anyone mention cat or pipe problems with it. Mines on its original cat and exhaust and its 13 years old now.
No idea what the impact would be on a turbo.
A friend has an Astra VXR and that gives some good pops and bangs on lift off after high revs, but it's nothing on what a proper ALS does. Even a loud back-pop is nothing on an ALS bang, complete with fire bursting forth from the exhaust tip!No idea what the impact would be on a turbo.
This is not the most aggressive or forceful ALS and you can imagine the pressure and heat this must generate
http://www.youtube.com/watch?v=eFVSsuonOtY
Was really common in NI for a while on subarus, evos and all sorts.
I did see someone near get shot by the police though who must have thought someone was shooting at them and pulled their guns. Im pretty sure whoever it was got a stern talking to and a dry cleaning bill for trousers x3!
I did see someone near get shot by the police though who must have thought someone was shooting at them and pulled their guns. Im pretty sure whoever it was got a stern talking to and a dry cleaning bill for trousers x3!
Mastodon2 said:
Thanks Max Torque, this is the kind of spoddy, tech heavy nerdism I was hoping for!
9 grand on a turbo, bloody hell, that is pricey. I imagine the road cars you see it on probably have the factory standard exhaust system kept at home for MOT time, because clearly switching ALS on with a regular road exhaust would be a recipe for big bills or even a fire under the car!
me? Nerdy? lol, k, maybe a little bit! lol9 grand on a turbo, bloody hell, that is pricey. I imagine the road cars you see it on probably have the factory standard exhaust system kept at home for MOT time, because clearly switching ALS on with a regular road exhaust would be a recipe for big bills or even a fire under the car!
I have a secondhand TR30R on my track car, and even that was £6k..........
On a lot of the more "max power" als "show /road" cars (no offence meant lol) the Popping and banging is more for show, and actually doesnt do a lot! A bit of flame out the exhaust, a few bangs, easy to do, looks impressive to the backwards cap brigade, but to actually put significant kinetic energy into the turbo system is quite hard to do without wrecking it!
(hence the develpment of the "combustor" ALS, and before it was banned (by the FIA), large air tanks being fixed in boots and behind bumpers to store a large mass of pressurised air during a braking event, ready to be used on the next accel (basically the systems kept the intake restrictor choked at max flow 100% of the time) and hence artificialy boost engine power by about 100bhp for 7 to 10 secs after each big brake event.....) (and of course the use (still legal) of over expanded "hypercooled" aftercooling systems)
I've run a wrc engine on a dyno, with such a system and seen over 600Nm at less than 1000rpm!!
I have anti lag on my track car but I've only ever turned it on once just to try it out as it not really necessary. The noise it makes is just silly, like someones firing an semi automatic shotgun behind you, it kills turbos. When you turn it on you get a full screen warning on the laptop stating that it will severly effect operational life of the turbo.
They didn't ban the "combustor" part of the system, but by putting a maximum volume limit on the intake system between the turbo compressor outlet and the engines throttle they effectively prevented the "loop hole" that was the "air storage" systems. They had to ban them really, because they made a bit of a mockery of the "inlet restrictor" rules, as we were running engines that had over 400bhp, when the regs should have meant about 300 !!!
As usual, someone makes the rules, then the engineers work out how to circumvent them ;-)
(actualy, there were some safety issues as well, as a few teams had some, er, incidents with "exploding" air tanks as well)
The combuster system effctively puts a gas turbine style combustion chamber in front of the turbine inlet. Hot exhaust gases, carrying vapourised unburnt fuel (engine is run massively rich on a low throttle angle, so injected fuel just vapourises in chamber and carried thought to combustor unburnt) then meets a stream of "fresh air" that is bypassed around the engine. The system then "lights off" and is controlled and runs in a closed loop turbo speed control mode, keeping the turbo spinning at max rpm ALL the time! (If you watch footage of the cars on the stage start, you will see the crew engaging "stage" mode and hear the engine rpm increase and then a jet engine spooling up noise that is the system starting, then a sort of "darth vader with asthma" kinda noise with the ocasional bang as the ignition controls engine rpm)
The "cleverness" of the system is mainly in 2 places; the design of a combustor system that stays lit over the massively varriable exhaust mass flow/temperature conditions of an ic piston engine, and in the control electronics and air control valving to keep from overspeeding the turbo etc.
As usual, someone makes the rules, then the engineers work out how to circumvent them ;-)
(actualy, there were some safety issues as well, as a few teams had some, er, incidents with "exploding" air tanks as well)
The combuster system effctively puts a gas turbine style combustion chamber in front of the turbine inlet. Hot exhaust gases, carrying vapourised unburnt fuel (engine is run massively rich on a low throttle angle, so injected fuel just vapourises in chamber and carried thought to combustor unburnt) then meets a stream of "fresh air" that is bypassed around the engine. The system then "lights off" and is controlled and runs in a closed loop turbo speed control mode, keeping the turbo spinning at max rpm ALL the time! (If you watch footage of the cars on the stage start, you will see the crew engaging "stage" mode and hear the engine rpm increase and then a jet engine spooling up noise that is the system starting, then a sort of "darth vader with asthma" kinda noise with the ocasional bang as the ignition controls engine rpm)
The "cleverness" of the system is mainly in 2 places; the design of a combustor system that stays lit over the massively varriable exhaust mass flow/temperature conditions of an ic piston engine, and in the control electronics and air control valving to keep from overspeeding the turbo etc.
Edited by anonymous-user on Saturday 20th November 23:43
Max_Torque said:
Mr MXT said:
If rally cars drive between stages on the public road, surely any tech on them (inc anti lag) must be road legal?
without wishing to get into the "road legalness" of WRC cars (which btw is massively shady... lol) the cars run in "road" mode between stages, als is only activated in "stage" mode, so it is not operational for transition mileage!!Gassing Station | General Gassing [Archive] | Top of Page | What's New | My Stuff