Which makes more power:

-3" downpipe with stock o2 housing

or

-o2 dump with stock downpipe

or

-3" downpipe with o2 dump


I just don't see the need for a bigger downpipe once you dump the wastegate. I was curious if anyone has done dyno testing with these parts.

 

3" downpipe with a stock style O2 housing like megan racing one.

 

^x2---->

 

I actually have an O2 dump now and I just bought a megan racing O2 housing yesterday. I had the dump for over a year. Just dont like it anymore not to mention its melting my radiator...

 

Your third option will make the most power out of what you have listed. You should have a forth option as, 3" downpipe with aftermarket o2 hosuing". Some argue that a recirculating o2 housing makes equal if not more power than a dump.

 

The idea of a turbo is to have pressure on the manifold side and the least amount of backpressure on the downpipe side to get the most efficiency out of it. I just don't see how a recirculated o2 housing could be the same or better than the wastegate being dumped. Even on the stock turbo there is a lot of exhaust air/pressure being dumped back into the exhaust stream.

 

I just don't see the need for a bigger downpipe once you dump the wastegate. I was curious if anyone has done dyno testing with these parts.[/quote]Larger diameter downpipe should create less exhaust backpressure than a smaller diameter downpipe. Yes, or no?

 

^ yes you are correct. The larger the downpipe and exhaust line the less back pressure. I personally have not done any testing on my 02 dump but I think Robert lost 3psi of Back pressure by dumping his wastegate. Also if you take my car for example. I'm making 40 more hp then my Friend dan with the exact setup. The only difference is he is recuirculated on a Red and I dump on my Red. Both are at 30psi. DUMP FTMFW The dump does gain horsepower. I don't care what anyone has to say. If you want to run a recirculated 02 housing then don't whine when people are making more power than you!

3" downpipe with a 2.25 wastegate dump will make way more power than your other two choices!

Mikey

 

Mikey: Itīs not really a fair comparison that you make. Your O2 dump is the best looking design for a stock frame turbo that I have seen. However, your setup is not commercially available. It is a one off. If I could get one just like it then I would. You yourself admit that the other available dump options are somewhat compromised in comparison to your setup. I just donīt like broad generalizations.

 

^ you are correct. A dump is a dump and the concept is the same though. The quality may be different than what I have and the results may be a bit different but If done properly a dump is the way to go. I think Shearer is the best dump on the market. It is the only one that allows the wastegate flapper to fully open, eliminating the potential for boost creep... This is what I have heard from others and I use the same flange as them. It is the best flange on the market. I have 0 boost creep and performs well. I will be making a modification to my 02 housing in the next few weeks to test a few other things. Mine may become for sale soon too. Just all depends on what I decide to do next...

Mikey

 

Letīs say that R/T Ernie were to set his mind to designing and fabricating a 3.5"-4" DP that wasnīt dumped. Letīs say that the manifold is either a tubular setup flanged for an external gate or the stock manifold with the antilag ports opened up and fed into a remote gate. This way the dump tube wouldnīt be stealing space away from the DP itself. Maybe a larger than 3" DP could be fitted.

 

^ It can be fitted a 3.5" can fit with the internal wastegate. Hell you could do a 4-5"downpipe and eliminate the internal wastegate all together and build a tubular manifold with two 38mm tial wastegates. I don't know about you, but I'm not going to pay 1500 for 20hp on the stock turbo. If I wanted to break records then yes, maybe I would but it is just not practical to go that far. I will be going a step further but not that extreme.

To build that setup:
Twin Scroll tubular manifold - 1,000
2 tial 38mm wastegates - 400
new downpipe 200-500 depending on what you actually do.
Machine work 100

Total: 1,700+...

Also to run this type of setup the A/C would have to be removed. It is hard to put a 3" 02 housing in with the A/C. The radial bend has to be very tight. That is why we removed my A/C...

Mikey

 

The bigger integral downpipe would be better than a smaller diameter downpipe with a dump, at least until the wastegate lifts off its seat. The dump tube only comes into play when the WG opens. When the WG is shut then the dump tube is not flowing at all, and when the WG is closed there is no merge reversion on the integral DP.

 

As a practical matter, you are right Mikey. My idea is way too expensive for the minimal power returns that you might get. I still like the R/T Ernie dump design the best.

 

^ it is dope. Eric is an awesome guy!

Mikey