Rootski

iTrader: (1)

Hey guys. Sorry to clutter up the board with another thread but I didn't see a suitable one to hijack.

I'll assume everyone knows how a turbo works: exhaust gases spin a turbine that spins a compressor that forces air into the engine. Turbo lag occurs when the exhaust gases aren't powerful enough to spin the turbo as fast as desired, and the car becomes sluggish while boost pressure builds. So my idea is to have an injector inline with the exhaust manifold, coaxial with the exhaust flow and in close proximity to the turbine pointed directly at its vanes. This injector would be connected to a small compressed air tank, pressurized to about 50psi or so (and with appropriate safety valves, like a nitrous bottle). During turbo lag, this injector could be activated to fire a stream of air into the turbine and help spin up the turbo.

Or, it could go on the other end of the system and be part of the intake manifold, between the turbo and the engine, and fire compressed air into the manifold to create a temporary overboost.

So, let's have it. What's wrong with my idea?

lennon

wat happens to your 02 reading?? It will be a mess....

benh

The first thing I could think of that this will not work is; when the compressor spin, it heat up, you inject a cold stream of compress air into it, in time the housing and blades will crack.

Rootski

iTrader: (1)

I guess it would read lean as hell, but you'd know what's causing it. I didn't think of thermal shock, that could be a problem.

dillsrotary

it actually works very very well (this is widely used in drag racing), many just use nitrous instead of an air compresser

chickenwafer

iTrader: (9)

Instead of reinventing the wheel, you can just use a proven method, like nitrous oxide injection, that will end up being cheaper, and the whole system will also weight less. Besides, I don't think we're at the point yet with giant turbines that people are noticing much "turbo lag" because most have full boost before 3500rpm, when things are just starting to get fun.

Also just remembered; a lot of car and motorcycle manufactures use a sort of air injection system to combact emissions. They inject small amonts of air into the exhaust system to burn up unburned hydrocarbons. If you injected air in your exhaust manifold between the housings and the turbo, you could potentially ignite unburned hydrocarbons in your exhaust manifold, causing a backfire- in your exhaust manifold. Depending on how bad it is, the weakest part will break, especially if it happens enough, and it will either be your manifold the turbine housing.

mysql101

yeah... as long as you're in the correct gear, it's fairly difficult to get any "lag"

eviltwinkie

a properly designed system, with a proper driver...hath no lag...

BigRed

lol^

Rootski

iTrader: (1)

Okay, so there's not much point and could make it backfire. What about overboosting by adding air to the incoming charge

rotorocks

Our engines are lag proof... lol

MazdaManiac

iTrader: (3)

^^ Pretty much.
There is SO much exhaust pressure that it takes almost nothing to spin a turbo.

BTW - lag isn't just low pressure - it is inertia. Inertia of the rotation assembly, inertia of the soon-to-be compressed air and inertia of the exhaust gas.
Dragging around a 50 lb can of compressed air isn't going to buy you anything.

ricky356

get a supercharger......

R.

chickenwafer

iTrader: (9)

Or you could figure out how to read a turbine and compressor map and islands and then properly size a turbocharger for your applications and expeirence virtually no lag and a tenth the parasitic loose of a supercharger

eviltwinkie

Heh...I like my snails and stupidchargers like I like my women...

Able to blow like no ones business...and LOOSE!

Wait...nix that...I'll just take the blow part please...

Heh....

BaronVonBigmeat

So basically you want to use an air tank as a buffer, between the turbo and engine. I'm not sure how to go about the calculations, but I suspect that the air tank would have to be way too big to be effective, at least at 50 PSI. You'd probably drain it in a fraction of a second or something. In order to keep a smaller tank, you'd have to crank the pressure up--way up--which probably presents problems with efficiency.

eviltwinkie

I had that idea waaay back in the day...and ultimately the answer is...

Its a non-issue...if you have lag...its not been properly designed...period...

No sense in trying to fix the issue with more complications...the "fix" is to properly design the system...

rotarygod

The other idea is to tune an ecu to do what Haltech has had the ability to do with their antilag feature. When activated it runs retarded timing and rich so that fuel is burned in the turbo. You can get boost in neutral this way! Of course it is damn hard on the turbo but that's the sacrifice. It's really only used by drag racers.

r0tor

iTrader: (1)

there is a difference between virtually and absolutely

chickenwafer

iTrader: (9)

Of course there's a difference. I'm not going say you'll never have any lag, becasue you might be in 6th gear and floor it and get no boost for a while, but the same will actually happen with a supercharger as well, since you're motor isn't spinning it fast enough at that point as well.

I say virtually because under most circustances and in most senarios you won't experience any lag, or you will be smart enough to downshift.

eviltwinkie

Variable Geometry Turbines! Haaa....

Seriously...they should just use the rotary to spin up a generator and slap direct drive electric motors at each wheel...

"How much power do I have under the hood? Try 1.21 JiggaWatts SON!"

Maybe its time to build a tube frame car...

rotarygod

That may be true with a worthless centrifugal supercharger but a positive displacement supercharger would make boost.

rotorocks

Ha ha, I tried that. It's true, i was able to hit 10psi from in neutral, but it was so pig rich, that it stunk horribly and the tank lasted me like 70 miles. Needless to say, that tune was deleted without any regret.