Air-tank or compressor to fix turbo-lag

Hello,
I was just reading up on turbos and I read about turbo-lag. Would it be possible to mount an electric compressor, that will have a storage tank. Meanwhile, it will pump its compressed air into the engine before the turbo spools up. I realize that you could simply lower the injection quantity to reduce smoke, but then you would lose power. Would it be possible for this to work? I know its a crazy idea but I think it might work.

Thanks,
Greg

1. Ok first how are you going to keep it from back flowing in the intake system? Assuming you do get a tank large enough(This would be about the size of most upright shop compressors and take about 1/2 hour to pump up) to supply the volume needed to out flow the amount of air consumed by a 1.9 liter engine @ say below 2000 rpm(the area where we have the most lag). It seems to me that the turbo would just surge and go into overspeed probably resulting in a blown turbo.

2. On our cars turbo spoolup is to the tune of 250 milliseconds which is practically nothing talk about. So if it aint broke don't fix it.

Locosmotion said:

2. On our cars turbo spoolup is to the tune of 250 milliseconds which is practically nothing talk about. So if it aint broke don't fix it.

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You said that I would need a large enough tank which would be very hard. Well if the spoolup is 250ms then how much air could it use in that time? How many liters of air will it eat in 250ms? I know that this isn't a lot of lag but I like to use everything up to 100% of its use.

As for the back flow to the intake I could use a check valve.

madman, have you ever driven a car that really has turbo lag? TDIs don't have nothing compared to many others. Go take an old 300SD for a spin....now THAT is lag! The TDI is virtually lag-less.

And in 250ms your TDI moves a LOT of air!

oilhammer said:

madman, have you ever driven a car that really has turbo lag? TDIs don't have nothing compared to many others. Go take an old 300SD for a spin....now THAT is lag! The TDI is virtually lag-less.

And in 250ms your TDI moves a LOT of air!

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Well with larger injectors and a rc it will smoke, so the compressor will stop the smoke, it would be perfect. Also how much is a LOT of air. How many liters/sec?

I think that you guys are convincing me to drop this idea . Darn, I was looking forward to hours of work for not too much gain.

Thanks,


P.S. I have an RC question but do not want to start another thread. It should be short.

What is the difference between the RC2 and the RC2 Euro? Why don't they just make more stages? 1 2 , (3 instead of euro2) , etc..

The Euro may have to do with EGR duty cycles, but I am not sure.

If you want less smoke you'll need a bigger turbo (more air) which will mean more lag. Little turbo+big engine=no lag. Big turbo+little engine=major lag. So, the 1.9L TDI with its tiny turbo has hardly any lag, but the older 1.6L VW turbodiesels with a [relatively] large turbo on the smaller engine had very noticeable lag.

Of course the 1.6L/1.9L comparison really applies to the early TDI as they still used a conventional wastegated turbo. The later TDI uses a VNT, although it is still tiny, it works differently and helps to minimize lag.

The V10 TDI uses twin electric-assisted turbos, though, so if you really want something cool try cramming one of those bad boys under your hood!!!

oilhammer said:

The V10 TDI uses twin electric-assisted turbos, though, so if you really want something cool try cramming one of those bad boys under your hood!!!

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Just out of curiousty how much fabrication would be needed to fit one of those under the hood, or would it be possible to electronically assist my little turbo? Sounds like a fun mod . Anyways, I know this doesn't really matter anymore but how many liters of air will the engine eat in 250ms?

Thanks

Our motor is 1896cc or 1.9L so 1 revolution of the crankshaft @ sea level atmospheric pressure (not even on boost) will eat 1896cc/revolution of air so times that number by 2000 RPM the revolutions divide off and you are left with 3792000cc/min or 133.91 cubic feet per minute divide by 60 and you get 2.23 cf/second divide that by 4 to get the amount of air used in 250ms nets you .56cf and thats at 0 psi so if you wanted boost that volume of air needed would increase. That is alot of air to be supplied by a tank. Considering that you would need this to happen every time you shift gears or punch the throttle when you are off boost the jumbo tank would probably last you a block or so... With a check valve you are still blocking the flow of air from the turbo charger to the engine. When the turbo is spooling there is still air flow when that air is stopped by the check valve the pressure will build behind the check valve and the turbo will surge.
Ok so take your hairdryer while its on and put your hand over the business end of it and listen to the motor speed up because of the fan cavitating. Thats what will happen to your turbo if you do what your suggesting.

Edit: As somone pointed out it should be 1896 cc per every 2 revs of the crank. I was tired and I would rather be driving a 2 stroke diesel anyways

Oh, RC2 and RC2 euro well there is a price difference for one thing. I understand the standard RC2 just gives you enhanced maps more boost,fuel,timing etc... rc2 euro gives it the enhanced maps as well as the "euro" personality so your boost pressures and sensors can run farther out of tolerance without setting a CEL. I have RC3 and I can run with my N75 (boost control solenoid) completly disconnected and not get a CEL. Jeff also said something about the non-euro chips being a 0-4000RPM tune whereas the euro chips are a 0-5000RPM tune. That being said I have driven both and I still don't know which I prefer. I guess I would have to see the differences in a car with the same mods before I could tell you for sure. FYI Jeff does EGR delete on non-euro tunings as well.

Locosmotion said:

With a check valve you are still blocking the flow of air from the turbo charger to the engine. When the turbo is spooling there is still air flow when that air is stopped by the check valve the pressure will build behind the check valve and the turbo will surge.
Ok so take your hairdryer while its on and put your hand over the business end of it and listen to the motor speed up because of the fan cavitating. Thats what will happen to your turbo if you do what your suggesting.

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The check valve I was talking about would be in the path from the compressor. It would not block the turbo. It would be like taking a hair dryer and connecting a long tube to it. Then adding another tube from the side into the tube.

Like this:
| |
| |
| |
| |
| | <==air-flow (only this direction)
-_-_-_-check-valve_-_-_-_-_-_-_ Compressor
| |
| | /\
| | || air-flow(only this direction)
| | ||
check-valve
| |
| |
| |
Turbo

Like my drawing . Its crude but it gets the point across.

Got ya...um go for it maybe it would be a hit for the drag strip air gets cooler when you decompress it too. Maybe you could do away with the turbo and run the car off the tank for a 13 second pass at the strip.

Locosmotion said:

Got ya...um go for it maybe it would be a hit for the drag strip air gets cooler when you decompress it too. Maybe you could do away with the turbo and run the car off the tank for a 13 second pass at the strip.

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I'm not racing this car. Just trying to add more air to prevent the smoke from WOT and turbo-lag. I guess you could say its a small correction tool. Not really performance boost, just not losing performance.

If this idea is so crazy, would electronically assisting this little turbo help anything out? Or is that too crazy also.

Thanks again,
Greg

No not crazy...we need good new ideas we seem to be running out of mods to do.

I for one have a crazy idea of putting a external wastegate where the EGR used to be for completely stable boost control. I just haven't done it so I don't know how well it will work.

So should I spend more time with my old compressor idea or with the electric assist idea? I'm thinking the electric assist.

Thanks for the extremely fast posts. This felt more like a chat room rather than a forum .

madman91 said:

Well with larger injectors and a rc it will smoke...

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Not if you go with a chip and program reccomended by Jeff.

If you want to loose any lag, why don't you do what the big turbo guys do? They purge nitrous into the turbo housing to spin the blades before you give it gas. Not too mention you'll burn cleaner and eliminate any smoke you had. It might seem like overkill, but so does the idea. It would be an easier way of doin it instead of the air tank. Figured I'd throw it out there for consideration.

V10 TDI uses electric actuation of the vanes, but the turbos are NOT electrically assisted.

Seems to me all you need to do is add a supercharger à la TDI.

Edit: I meant to say, "...all you need to do is add a supercharger à la TSI."

you could maybe make it like a turbo supercharger engine like the tsi engine. you have the turbo so just add a supercharger. how reliable is that going to be? not very......

Locosmotion said:

Our motor is 1896cc or 1.9L so 1 revolution of the crankshaft @ sea level atmospheric pressure (not even on boost) will eat 1896cc/revolution of air.

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Actually, that's 1896cc per 2 crank revolutions.

As for US vs. Euro tune... any chiptuner only "tweaks" the stock ECU program. The majority of the ECU code is unchanged. The Euro RC tunes start with a stock Euro file for an engine which uses larger injectors. So basically the whole software is expecting more fuel then you would get with stock injectors/stock tune on a 90hp engine. Therefore, the euro is a great match for those of us with larger injectors, since the stock code is already expecting larger injectors.

In chiptuning, the more you deviate from the stock tune, the harder it gets to keep it stable, drivable, reliable, etc. Starting with a more powerful stock file lets you push that envelope a little more.

tdipower4me said:

you could maybe make it like a turbo supercharger engine like the tsi engine. you have the turbo so just add a supercharger. how reliable is that going to be? not very......

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And a remote (electrical) compressor, reservoir, plumbing, check valves (without even discussing if such a beast would work) and control system would be any better reliability-wise?

madman91 said:

Well with larger injectors and a rc it will smoke...

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jackbombay said:

Not if you go with a chip and program reccomended by Jeff.

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When you program it to not smoke you are just reducing the amount of fuel injected. This is like, your running and your legs go to fast (too much fuel) .. So instead of making the body catch up (more air) you are slowing down the legs. (the fuel)

clove911 said:

If you want to loose any lag, why don't you do what the big turbo guys do? They purge nitrous into the turbo housing to spin the blades before you give it gas. Not too mention you'll burn cleaner and eliminate any smoke you had. It might seem like overkill, but so does the idea. It would be an easier way of doin it instead of the air tank. Figured I'd throw it out there for consideration.

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How much would a setup like that cost? I think that I would rather work on another mod like .. well I don't know yet .

I think you need some spacers for between your pedal and the stop on the floor. It will help clear up the smoke problem, will cost you very little, and help your fuel economy too.

I concur on the nitrous, its the only remotely practical approach to your issue. Although converting your car to a 1.8T is another good option. Or maybe you could just one of those turbonators off ebay. Small electric fan in the intake? Isnt that what your after.

You could put the V10 TDI engine in there if you could drive from the back seat and widen your car by a couple of feet.

A properly tuned car will not smoke much at all. More boost = less smoke. You don't necessarily have to turn down the fueling.

I am becoming more and more convinced that a lot of these "lag" problems people talk about are really in the vacuum control system and or the actuator adjustment. The VNT spins up the turbo instantaneously when it's actuated.

Why not simply supply your own vacuum source to the vnt actuator? You could spin it up to boost say 3 psi at idle then there wont be any lag at all.

In fact I am probably going to run a vacuum line into the cab and tee off the vacuum line to the actuator, and hook up a gage to check things out. Maybe hook a mity vac to close the vanes a little at idle, fool around with it, tinker if you will. A little manual boost actuation will be fun.

Doesn't the VNT already do just that? A wee bit of boost even at idle? If you take one of the charge air hoses off at idle, there is quite a large volume of air being blown out. Of course I guess this doesn't really equate to positive pressure since the engine is gulping it down at about the same rate.

I do know that when my "ex" business partner installed a TT downpipe and mufflerless 2.5" exhaust on his NB, the turbo spooled up MUCH quicker and the car had a quite noticeable performance gain. This was with RC3 and some pretty fat Kerma injectors. It'll still smoke like a tire fire when you really jump on it, but it'll also plant your head to the headrest in the first three gears The last two gears the stock clutch gives up its grip

you don´t need a big plenum tank but longer intake runner.........for the turbo lag you can put a ANTI-LAG tdi system it´s safe for engine because this extra energy has been made direct inthe turbine sections and not in engine. You must have a special racing exhaust manifold which have a ejector nozzle port.....

certainly you can use this system like "anti smoke" because extra oxygen will clear the black exhaust smoke and rapidly increase the energy for turbine......thus also the engine power down to 2000rpm at high modified engines.

KERMA said:

I am becoming more and more convinced that a lot of these "lag" problems people talk about are really in the vacuum control system and or the actuator adjustment. The VNT spins up the turbo instantaneously when it's actuated.

Why not simply supply your own vacuum source to the vnt actuator? You could spin it up to boost say 3 psi at idle then there wont be any lag at all.

In fact I am probably going to run a vacuum line into the cab and tee off the vacuum line to the actuator, and hook up a gage to check things out. Maybe hook a mity vac to close the vanes a little at idle, fool around with it, tinker if you will. A little manual boost actuation will be fun.

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VNT turbo has a bolt accent only if you turn this bolt you can closer shut the vanes and help raising the pressure in turbine section but be aware too much closer vanes will be destructive......

too much effort but very little reward for what really isn't a problem. Some people see "lag" when in fact they're just trying to push the car too low down in the rev range and thre sluggishness is mistaken for lag as the turbo isn't working so well....

I would sooner get a good tuning up session done to remove what little lag there is. Even on my hybrid turbo there's little to no real lag. if you get the revs/gear/throttle right, it just goes - no spooling up to wait for etc.

KERMA said:

I am becoming more and more convinced that a lot of these "lag" problems people talk about are really in the vacuum control system and or the actuator adjustment. The VNT spins up the turbo instantaneously when it's actuated.

Why not simply supply your own vacuum source to the vnt actuator? You could spin it up to boost say 3 psi at idle then there wont be any lag at all.

In fact I am probably going to run a vacuum line into the cab and tee off the vacuum line to the actuator, and hook up a gage to check things out. Maybe hook a mity vac to close the vanes a little at idle, fool around with it, tinker if you will. A little manual boost actuation will be fun.

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I agree with Kerma's first statement. Faulty parts or not within specs.

I've done the mityvac in the car thing. You can supply your own boost or cut all boost out. Its amazing at how much or little boost is needed,,, to smoke or not smoke. Plus the car exhaust sounds different at different boost levels. Let us know what you find out Kerma.