Turbo BS Thread

I took my O2 sensors out and they looked fine so I just swapped sides to see if my rich/lean swaps banks... And heard a pop on my oil line while I was in there, it wasn't a "nothing to worry about" pop. So a trip to O'Reilly's and $50 later I have a new supply line lol

 

I still don't know what's up with boost, but it only builds to ~5 psi till it shifts, and you can tell that it goes 70-80 much quicker than 50-60, sucker just wants to go fast I guess.
Also camera didn't quite come on as fast as the pedal went down... Gravity
https://youtu.be/JoJi9Pumygg

 

What is the wastegate spring psi?

 

Pretty sure I have a 7.5 and 1.5... been a minute since it was opened up lol that probably hit 7-8 in the video... I know I'm losing that stuff somewhere

 

Time to pull the wastegate apart and inspect it. As well as all vacuum hoses and sources. BOV.

 

Yeah I have been thinking about making a port pre IC to source my bov anyway cuz I get a little flutter because there is less pressure on the manifold and it doesn't open fast enough I guess. I took the WG off today because I don't think my fire ring was seated quite properly, I have always had a little leak through it even after valve lapping compound TLC. But I couldn't feel anything at idle today so maybe it's better than it was anyway

 

The BOV must have a source that is post throttle valve. As that source offers vacuum and boost. So unless your intercooler is post TB, you won't be able to do that and have it function properly.

 

Oh then nevermind I guess I'll keep it where it is lol maybe I meant I would move my bov pre IC... That seems more like what I meant I went through a lot yesterday haha

 

Has anyone thought to or seen anyone mist water into the exhaust pre turbo? I was thinking today that cooler exhaust is more dense plus it would create steam to a degree which is used commercially to spin turbines sooo... In theory it would be a relatively cheap and easy way to help spool a turbo I thought, but wanted to see what other people thought

 

The increase of density would lower the pressure going into the turbine. You'd lose power. I'm assuming the water is absorbing all the heat of the exhaust in order to turn to steam and heat up.


Unless you assume the steam is already the same temp of the exhaust gas before being injected.

 

No I was thinking creating a more dense flow even at a lower velocity would create a more efficient turbine spin like how diesel is lower velocity but much more dense, or in an extreme example hydroelectric dam vs windmill. Plus the additional mass of water. I do understand that in bullets, if you double the mass and maintain velocity you double energy, while doubling velocity and maintaining mass increases energy four fold so I guess it makes more sense to keep it as fast as possible

 

Water turning to steam expands exponentially. I think it could work if the blades didn’t crack or something catastrophic.

 

Steam would be a minimum of 212° F and likely much hotter by the time it made it to the blades so I doubt it would crack the blades but it could cool off the up pipe in the spot across from the spray in at or near freezing temps rapidly enough to crack it I suppose.

 

Water does expand a lot when it changes to steam. It also takes a huge amount more energy to heat up than air.

Just trying to say the energy required to do a phase transformation of water to steam and also heat up the steam is going to just cool down your exhaust.
Assume water is already steam. Steam has roughly a 2 to 1 specific heat ratio with water and air. Every time you add cooler water it is just going to cool down your exhaust going into your turbine.

Say you have 30lbs of air flowing thru your motor. Inject water. Water is going to cool your exhaust. Lower exhaust temp means lower pressure going into your turbine.
You are lowering the power you are putting to the turbo.

When you inject water/meth into your intake your exhaust drops a few hundred degrees. You add more wastegate and timing to get the temps back up. Water absorbs energy that's why it is injected on the cold side.

Could inject some fuel and air. Get some afterburner going on.

 

Oh. Lemme find something from yesteryear. Gimme a lil bit.

 

Found it quicker than I thought.

https://motoiq.com/external-combustion-rocket-anti-lag-system-jdm-spec-c-impreza-sti/

 

Good link. I remember that one.
I want to say that is a take of a pulse jet engine.
That would blow up my truck.

 

This conversation is an interesting one, very tricky, and got me thinking:

Injecting steam would require energy, as you would need to overcome the exhaust pressure present at the injection site, and already being steam, the energy required to push steam into the exhaust with volume enough to increase turbo output; would require substantial pumping energy, and you might as well just pump high volume high pressure air; or might as well impart that energy directly on the turbo shaft with a motor; any way you slice it, where does this pumping energy come from.

On the other hand, pump water spray into the hot exhaust, and by turning to steam, yes it absorbs heat, but the water also expands as pointed out by others. This expansion might increase the volume and velocity going past the impeller; only if the steam volume increase is greater than the reduction from cooling the air temperature. The nice thing here is injecting water would take the same pressure as injecting steam, but needs very little volume. It is sort of a huge leverage, regarding the energy needed to inject water, and have it turn to steam in the pipes. But would it produce more turbo power? Would the expansion of water into steam exceed the loss from cooler air temperatures?

I was not certain at first. But in a simple terms, I think I agree with @MadTaco461 in most regard.

To me, it boils down to energy at the turbo, and heat is energy. Here that heat can be extremely hot air, or less hot steam and air, but even with the water phase change, the amount of energy at the turbo has not changed. We have not reduced the amount of energy leaving the engine, and we have not increased the energy by injecting water (with a very small exception). Injecting water will transform some heat energy into a cooler denser, moister air, but this transformation makes no difference to the available energy, so there is no reason to think there would be more energy imposed on the turbo (nor less); for the effort. (turbo fin design being better or worse for denser air, not considered)

That very small energy being added, is the energy required to pump the water in, but this is at such small volume, that it must be very little energy that is added.

Now lets go one step further, and go back to injecting steam. If we were to boil water Post Turbo, and inject that preturbo, then we would truly be using waste heat to inject more energy into the turbo. Not sure it is worth the effort, as turbo design allows for getting whatever boost you need, without the complication of adding a Boiler, but it at least is easy to see here that we are adding energy preturbo, no matter how the temperature compares to the exhaust temperature we pump into.

Therefore, making steam does not make power, steam is simply a nice medium, to move energy from a boiler to something else (that performs work). If making steam created energy, then somehow we would kick off a boiler, and then let the fire go out and use the steam to make more steam (perpetual motion).

Sorry for the length, hope some enjoy.

 

So a chambered muffler but fill the chambers with water... When it starts boiling it will eventually build enough pressure to overcome the exhaust gasses preturbo eliminating the need for a pump... However without a regulator you may build boost at idle until your reservoir runs dry lol. Having the steam inlet upwards at a 45° would probably also lessen the pressure required for entry and could possibly even create a Venturi effect

 

I do suppose that even a down stream heat source would slow exiting exhaust down though creating more back pressure... No such thing as a free lunch