SOON2BEVO,


Thanks for bringing the link about the 2.5 vs 3", I personally never saw that test but your information is good enough.

My question for eveyone is: why people keep buying 3" exhaust then. The theory of gasses applies the same way, wether you put a 2.5 restristing opening on the begining(o2 hosuing) or at the middle (downpipe) or at the end(muffler) you will always have a restricting 2.5" opening right?

I am not trying to be smart here or outsmart no none, I am saying if a 2.5" works the same why people wants to buy the Invidia and Works 3" o2 housings"?
and why we keep buying 3"exhaust ?
I know why I am buying mine, I am convinced or at least I think it will flow better but that is just me saying it.

Carlos

 

I dont want anyone to take this the wrong way, but no way in hell would I put a part on my Evo from e-bay. I could care less if someone says it makes about the same power etc. I used to have an SS autochrome header on my 97 Eclipse and that thing was a piece of junk. WORKS products are top notch and if I ever buy another Evo they will be the only ones touching it once again.

PS...If it matters, I raced a few Evo's with similar mods to mine (different tuners) and each one of them went home with their tail between their legs.

 

this is actually incorrect. a restriction further down the line where both the pressure and velocity of the fluid is lower with affect the flow less.

 

All I can see from the test is that the 2.5 was not a restriction compared to the 3" 02 housing. Im under the impression we need 3" exhaust (downpipe/catback) because as the exhaust gases travel down the exhaust they expand. I thought I remember hearing that...

 

I know exactly what you mean and I understand that concept, there is more gas velocity at the inmediate exit of the turbo more than at the tip of the muffler. The issue here is that 3" o2 housing is less restrictive than a 2.5" outlet 02 housing.


Carlos

 

Carlos, thanks again for the reply to my PM.

I'm also anxiously awaiting the results of Buschur's test. I actually sent Nick from Buschur a PM about pricing on the Buschur O2 parts, and he suggested that I hold off until the results of the testing are back. Now THAT'S customer service. Good thread...

 

No problem Bernardo, I am dynoing my car this week anyway. I will post results.


Carlos

 

Before all testing is done I will chime in and say that I think the divorce needs to be there to control how the gases exit the turbine wheel. I agree with everyone that who cares about the wastegate because for the most part it is not open.
Having the big open housing has to be causing turbulance in the O2 housing itself and I think the divorce will help control this flow as it leaves the wheel. I would be shocked if the Works makes any more power then the Invidia and wouldn't be suprised if the Invidia looks better through the entire range then the Works.

Prove me right... David!

 

Im gonna stay strong with my Ebay :-)

 

That's what I had and took off a Buschur ported and coated for it. I was however interested in the invidia before I sold the car.

 

Well, this is the catch, I was looking at my stock turbo during the removal and I observed that this turbo already has a separating wall on the hotside of about at least 1 to 1.5".


Unlike turbos like the WRX turbo the Evo turbo comes with a dividing wall already built in the hotside housing consequently in my opinion the Works o2 hosuing shouldn't need to have any extra continuing dividing wall, that is just my .2c

If you ever seen a WRX turbo you will see that there is no dividing wall in fact the waste gate opens directly in front of a wall. This wall is from the from the downpipe.

To make a fair comparison at this point it will be like me saying that at least the stock Evo Turbo already has a dividing wall while other turbos not only don't have a dividing wall but they also have a wall directly in front of the waste opening wich negatively affect the flow and perhaps the boost.

My own conclusion is that I don't see the need of a dividing wall on the Works O2 housing due to the fact that the hotside comes with one already.

Just my .2c

Carlos

 

It could also be that the cost of tooling for the divided wall costs more to produce...
It's much easier and cheaper to make one without it, higher ROI.

 

In fact the opposite is true. As the gases head down the exhaust they cool, become more dense (ie. contract) and lose velocity. Hence the benefits in keeping the gases hot = faster flow = better spool etc etc.

 

uhm... you're using some shotty comparison with lots of contradictions. contract would accelerate air. cold means slower. cold means denser. expand means slower and expand means colder. you can't just use "some general rules". there's specific rules for specific processes.

it's not quite that hot menas faster flow and better spool. it's temperature DIFFERENCE makes faster spool through greater energy transfer. going from 10000 C to 9000 C is not as good as going from 9000 C to 500 C.

the temp differential across the turbine is what makes power. that said everything after the turbine should be cold as you can get it.

 

Regarding the speed of gases as they move through the exhaust system; with a constant flow rate and cross sectional area, an increase in density will decrease the velocity. This would be the case in an exhaust system as the heat from the system would exit into the surrounding air and into the exhaust system itself. Therefore the velocity would decrease as the air cools down. But this really isn't on topic, but oh well.
The reason for the increased power from a O2 housing is the fact that it decreases the PRESSURE after the turbine which decreases the PRESSURE before the turbine (pressure in the exhaust manifold) by a factor equal to the expansion ratio of a turbine. (e.g. if you decrease the pressure from an O2 housing by 5 psi and you have a turbine with an expansion ratio of 2 you will decrease the pressure before the turbine by 10 psi.) Decreased pressure on the exhaust side of the engine will allow the engine to run a lower pressure difference between the intake and exhaust sides of the motor which will increase efficiency and power. Theoretically, the sudde change in area from the turbine and wastegate outlet to the Works O2 housing should decrease the power because the sudden increase in cross-sectional area will increase the pressure after the turbine which will be multiplied into pressure before the turbine. The separation of the flow of the turbine and the wastegate outlet should maintain a more streamlined flow which would decrease the pressure created by the exhausted gases. But none of this will matter after they test them.......but that's my addition fo the conversation.