Turbo Lag Solutions?

[lahondal 17]

Hi!.

 

Thinking on the turbo lag problem on long inlet pipes, for a 205 turbo 8v i will make on three or 4 months, i have an idea which could be a partial solution for the turbo lag.

 

If we put an additional throttle butterfly nearly the turbo boost outlet, between the turbo and the IC, controled by the throttle cable....

 

And we put the dump valve between the turbo and that first butterfly....

 

In this space between the two butterflys, can we keep the mayor part of the boost, while in the dump valve space the boost scapes to atmosphere?

 

So when we accelerate again, the boost which we loose only is the boost for the first region. Retaining the turbo speed and with minimal loose of boost in the inlet pipes...

 

 

What do you think? It is possibly correct?

[wicked 103 3 Cars]

*throws in some math*

 

If you're in the low rpm range at boost, you'll probably pumping 100 CFM of air. That's almost 50l/sec.

 

If I estimate the volume of the intercooler and piping, were the boost is contained, at 10l (probably too high estimate), means that the contained boost is gone within 0.2 seconds.

 

Within the 0.2 seconds the engine maybe will pick up a little faster and generate more exhaust gasses, but I doubt it will pay off the effort to build it...

 

Most lag is caused by inertia of your (big?) turbo charger itself and the energy needed to speed it up.

 

 

my 2 cents...

[lahondal 17]

So why a large induction piping cause more turbo lag? If the lag is probably generated by the inertia of the turbo (which it take a lapse of time to begin to spin).

 

With this system can we eliminate the lag produced by the induction pipes, at last? Isn´t it?

 

Past night i thought again, and it will be much more easy if we use a diesel EGR butterfly, controlled by de vacuum of the main butterfly, like the mercedes diesel which have a type of this system. All to do is put this butterfly near the turbo, and doing it close by vacuum.

[wicked 103 3 Cars]

It depends on the size of your turbo...

With a stock turbo, the turbo comes in fast and dependant on the inlet tubing volume (and volume between turbo and first valve+manifold volume) you might reduce the lag.

But for large turbo's (GT30 size) the turbo is more dominant in the lag than the induction pipes (your contained inlet boost is already gone before the turbo generates boost).

 

If it would be that easy, OEM's probably wouldn't bother with compound setups like the VW TSI's with compressor + turbo.

 

But bottom line, I would keep the induction pipes a short as possible still. Next to that, the second valve is also another obstruction in your tubing...

[Tom Fenton 1,542]

If you are really keen to get rid of lag for say competing in the car, you could run a small nitrous set up triggered by 100% throttle posn and maifold vacuum. This works in 2 ways, 1st way makes the engine pick up due to the extra oxygen and fuel, 2nd way is that you get a sudden burst of gas volume through the turbo to push it into boost.

[kyepan 291]

anti - lag..

 

found on some high end ecu's... will kill your turbo quick..

 

also check out Autospeed.com.au has loads of useful articles.

[allye 530 3 Cars]

Fit a small turbine to always keep it spinning like that crazy sports libre class car!!! (not very helpful sorry. )

[davev 1]

how about seeing if theres a variable vane turbo suitable? that way youll be just on the brink of boost at idle(no lag ever )

[wicked 103 3 Cars]

The 405 T16 has a VAT25 turbo

Edited July 14, 2011 by wicked

[rallyeash 155]

build a proper N/A engine, that'll learn it...

[lahondal 17]

I´m a easy-ingenious-cheap solutions fanatic, so anti-lag is not for me. Special valves, special turbo, sprecial management....definitively not for me.

 

Im spend many time thinking.....if we make a really large reservoir of air in the inlet track, we can improve this effect while the turbo begin to spin....and fill the time on LAG with the air reservoir....

[peter 20]

i have personaly tried my 2.0 turbo with the shortest boost pipes and small intercooler, and then change it to nearly 3" very long boost pipes and a what can only be described as redicules size intercooler and there was no noticable change in lag!

 

also your idea will not work because the dump valve will relase the boost before your throttle butterfly/valve closes.

 

it wont work, i wouldnt waste your time.

[lahondal 17]

i have personaly tried my 2.0 turbo with the shortest boost pipes and small intercooler, and then change it to nearly 3" very long boost pipes and a what can only be described as redicules size intercooler and there was no noticable change in lag!

 

also your idea will not work because the dump valve will relase the boost before your throttle butterfly/valve closes.

 

it wont work, i wouldnt waste your time.

 

....ok...so i have to begin to think in other improvements....my head is always working...

[205_sunderland 4]

i my honest opinion the issue of turbo lag is something that has now been well a truly surpassed by modern technology, Lag was always an issue due to old style bearing turbos relying on the size on them to determine what characteristics it produced.

 

The way to overcome lag is to quite simply embrace the new age roller bearing etc turbos out there, they spin like no other and can produce boost at low rpms easily due to there fast spool time and due to there amazing balance and capabilities they carry on delivering boost right up the rev range. Fit one of these fellas over your standard turbo on old style t3 fitted to cossies etc and youll be blown away by the performance.

 

Alot of people use them and the gains are un-believable, however so is the cost, this is not to say they can not be used still as alot of companys can build nice little hybrids now and create a real lovely turbo for not alot of money. As regards anti lag systems yup they work great but long term your turbo will sh!t itself due to the strain you putting on the old girl.

 

I would say save your money forget the idea and give this engine the modern advances the old girl derserve and you will unlock its true capability, even an uprated/ hybrid turbo running standard boost will increase driving power massively as it will deliver the boost alot quicker and will hold it with great ease.

 

Boost drop from piping is very minimal, just find the shortest possible route and choose pipes that are not oversized for the turbo size (2.5" for under 280bhp id say), get a nice big exhaust to let the old girl spool up as fast as possible and let the good times roll.

[Ruan 0]

Old "T" series turbos like the T2/T25/T3 are 1970s technology really, by simply placing a modern GT series turbo, GT25 or similar on the engine you can improve the response no end without even switching to Roller Bearing technology - to be honest, the bearing system isn't the limiting afctor to spool up, it's the inertia of the wheels and the tremendously more advanced design of the wheels that gives it the advantage.

 

Boost piping sizes make no difference at all if I'm honest, the outlet size of the turbo within probably 1/2" is absolutely fine, but as people have said, it makes little to no difference on the size of the piping, you're only noticing the inertia of the turbocharger...

 

I know I'm going on about Diesels here, but a GT2052V off a Volvo D5 strapped to an XUD9TE was less laggy than the stock T2 turbo they came with... Admittedly that's VNT, but that turbo is good for 170-190hp on a Diesel with the fuel in place..

[kyepan 291]

interesting

 

more indepth

 

expert

 

cheers

 

j

[wracing 19]

How about change down a gear and get on with it!!

 

Are you talking about the time it takes the turbo to respool after a gear change or the point at which the turbo spools Vs RPM.

 

Your dump valve must be as close to the throttle plate as possible to prevent flow reversion and map/setup your can properly.

 

James