Anti-Lag system for a street car...

Been reading about anti-lag system. Pretty tough and ingenious system. It dumps fuel into the exhaust just before the turbo to keep it spooled by retarding the timing to just as the exhaust valve starts to open @ idle in order to basically create a flame thrower. It's hard on both the turbocharger and the exhaust system. I've heard of people using compressed air before too. How would you design a street friendly anti-lag system?

My thoughts would be to take a piece of small diameter brake line and tap a hole into the exhaust manifold or turbine housing and duct it in there so it hits the turbine wheel dead on. I'd wrap the tubing around the exhaust to get it hot in order to reduce the thermal shock from hitting the superhot wheel with compressed (liquid) air. Hook it up to a switch or solenoid that attaches to the clutch pedal to turn the system on. I'd also put a belt driven air compressor on the engine and put a scuba tank or something similar wherever I needed the extra 40 lbs.

In the DSM world, they use antilag to pre-spool the turbo on the line before a drag pass. It's all done via the ECU though. Dump a lot of fuel and retard the timing to the point the exhaust valves are open when combustion occurs. Turbo-destroying fireball goodness.

If you want to shoot fire balls all you need is to add fuel and cut timing at higher rpm low load areas of your ecu maps. That assumes we are talking about turbo cars

I think it's mostly electronic, but watch a video of a NHRA Pro Mod turbo car staging. It sounds like crap, it's hard to stage, and flames are coming from the pipes. I am pretty sure that's what they're doing.

Left foot braking and keep the throttle on the mat.

It is just easier to take the existing equipment and make sure combustion takes place in the exhaust pipe and not the cylinder.

I'd ask how the rally guys do it. Their systems aren't for just off the line, but to keep the turbo spooled when the throttle is closed during the rare times they're not on the gas.

If you used one of the systems involving dumping tons of fuel into the engine and retarding the timing, I imagine it would be a nightmare on the street, like riding a 2 stroke dirt bike with jets a notch too rich. Your spark plug company of choice would become your best friend.

There's always the option of driving your turbo with a turbine. http://www.youtube.com/watch?v=11687nVdzdk

The older way was to inject CNG into the exhaust, and let if combust.

Depending on the set up, getting decent, reliable combustion in the exhaust has a lot of options.

Air injection + running rich (really rich) is probably the most straight forward. Should be some great backfires.

Couple of points- when you get great combustion in the exhaust, you are not getting in the cylinder, which is kind of required to run the enigne. Good enough will take some of the lag out.

• I hope you are planning on no catalyst. Virtually all ways to keep a turbo spooled without the normal engine operation will burn a catalyst up very quickly.

DI is easier, since you can actaully inject the fuel late enough into the exhaust stroke.

Conquest351 wrote: How would you design a street friendly anti-lag system?

More seriously...

There's several different kinds of antilag, but the common thing among them is that they kill engine power when off boost so the engine has to run closer to atmospheric in order to not die. So basically there's no engine braking, and a lot of times the engine is actually fighting you when you're trying to slow down.

Bang-bang type systems do basically ignite fuel in the exhaust manifold, so you need a $5-10k turbo to last any time at all, and you'll still nuke them on a regular basis, along with exhaust manifolds and valves. This kind of system can actually build boost faster by letting OFF the throttle... The more friendly systems just jack the idle up and cut fuel to random cylinders, so you're still running the engine under no vacuum at "off throttle" and moving air through the engine, it's just not actively burning fuel solely to turn the turbo. Dig?

Nutshell - antilag is never actually lifting off the throttle, whether by driving style or by letting the computer do it for you.

If you want to something pretty cool check out the "rocket"anti lag article over on MotoIQ.

One benefit to anti-lag is that you will get really good at changing out turbos and exhausts on your car!

Or even better you can put on one of those Hot Licks exhaust flame thrower kits.

Rally anti lag pipes air from the intake into the exhaust manifold which mixes with hot fuel vapor and ignites. Simple and effective.

Toyman01 wrote: Left foot braking and keep the throttle on the mat.

this.

The ignition-retard fuel-dumping type wrecks turbos and the rocket type is hyper-expensive, that's what I know.

Heck. Turbo dodge guys having been doing this for years, all inside the stock hardware.

Even better is the staging limiter activated by the brake pedal or cruise switch. On mine I just touch the brake and it activates. Then with a manual tranny the rev limiter is engaged until the vehicle hits 4mph. So I floor the throttle and there it sits bouncing neatly off 3300 rpm. After it hits the limit a couple times it pulls spark and dumps fuel. Nothing to it. Boost with no load on the engine. Then as soon as 4mph is hit everything is back to normal.

Say, could you dump water-meth in the header and keep it spooled on steam?

I just finished installing an antilag system that I will use for autocrossing the svo. It is essentially a "bang bang" style, but it should be able to bypass a lot more air than rally cars were able to due to their rule set(no air bypass hardware, they jacked open the throttle), I will run less aggressive timing, and I installed two 1" electric solenoids ducted around the throttle plate. so hopefully it won't kill my turbo and exhaust manifold. The rally guys run like 60 degrees retarded timing, I will be way less than that. Should keep the turbo on the boil though. ;)

My plan is to use a frame rail to increase my vacuum storage capacity, maybe let the power brakes last the whole autocross course.

The newer egr antilag is cool, but requires pwm valve, computer to know turbo speed and pressures in order to work.

Antilag creates big egt. I am using a stock cast manifold on my engine and Holset turbo off my pickup. I think it will be ok for autocrossing. Well I hope (this is my hundred mile a day daily driver after all). If it doesn't work I expect it to at least go out in a fantastic blaze of glory!!! :)

ronholm wrote: Heck. Turbo dodge guys having been doing this for years, all inside the stock hardware. Even better is the staging limiter activated by the brake pedal or cruise switch. On mine I just touch the brake and it activates. Then with a manual tranny the rev limiter is engaged until the vehicle hits 4mph. So I floor the throttle and there it sits bouncing neatly off 3300 rpm. After it hits the limit a couple times it pulls spark and dumps fuel. Nothing to it. Boost with no load on the engine. Then as soon as 4mph is hit everything is back to normal.

This is not antilag. Antilag keeps the turbo spooled while having the engine create very little torque so it doesn't push through the brakes, all while the throttle is closed.

http://www.motoiq.com/magazine_articles/id/2771/external-combustion-rocket-anti-lag-system-jdm-spec-c-impreza-sti.aspx

Think pulse jet and you will have no idea how this thing works much like me.

On our really laggy 2.3 Mustang we use a few things to get to a very basic anti lag that isnt predictable but seems to work. Agressive N/A silder cam about 3 degrees retarded, rich idle, and, advanced timing hold it at 3800rpm for a few seconds and anti-laggy things start to happen.

Of all the reasonably priced turbos on the market/at the junkyard HX35s tend to be fairly tolerant of the exhaust side being on fire. Ebay/Chinese T3/T4 hybrids are not but you all ready knew that.

Shameless plug: The MS3 recently added anti-lag code for the "extra fuel, air dump" sort of strategies. It's not in the regular manual, but the MS3-Pro manual covers how it works in detail.

But for a street car? If your state laws allow driving it on the street, I'd favor a more elaborate version of the compressed gas method: A 50 hp shot of nitrous. Less exhaust heat and responds instantly.

Here's a crazy idea: Helicopter turbines.

Description

Video

Basically, the premise is that you use a small gas turbine with its own fuel supply and cooling system to produce a set level of boost that's independent of engine revs. Not only do you have zero lag, but you have full boost at every engine speed. Of course, the example in the link is a bit extreme, but perhaps an RC helicopter turbine with an automatic startup/shutdown could work.

Thoughts?

Really there is no such thing as a "street friendly" anti lag system because anti lag is supposed to be for cars that spend 95% of the time under boost and 5% of the time not, as opposed to street driving which is 1% of the time under boost.

Something I alluded to in my earlier posts, and I'll finish up on now: Key is tuning the engine so that it basically never runs under vacuum, keep air moving and the turbo spinning. This is impractical for use on the street... unless you're drive by wire with DI.

Many/most DI engines have the throttle wide open most of the time and control engine power with fuel, thanks to stratified charge. They're closer to spark ignited Diesels than traditional gasoline engines. Point is, modern engines already run under no vacuum most of the time, which is part of why turbo response on modern cars is so much better than it used to be... they already HAVE a soft form of antilag.

This is also probably why you see cars (ahem BMW) with fake engine sounds piped in. A lot of the engine sounds that we find pleasing are INTAKE sounds. You don't get pleasing intake sounds (in the driver-feedback sense) when the intake is WOT all the time, so they have to muffle out the real sounds and provide pleasing ones.

Knurled, you present a good point with the factory turbocharged cars. They haven't been around too long, but after a while I bet we start seeing datalogs popping up showing something very similar to what you've described.

I invented a no-lag device for my 1997 Volvo T5. It worked great but I couldn't afford to patent it or get the turbo manufacturers to bite. Here is the link to the provisional patent file and test data.

http://sdrv.ms/X6hoCW

geekspeak