JMFabrication O2 dump results
OK. I have read through this entire thread and I am still trying to determine if this is a thumbs up for the JMFab O2 dump or a thumbs up for using any O2 dump. I have always figured that any O2 dump would add power due to elminating restriction but these numbers are pretty impressive. I previously had the MAP O2 dump on an older EVO and I really loved it although I never knew how much power it added. I now see that JMFab as well as Toxic Fab both have O2 dumps. For this build, I wanted to try something just a bit different and was looking to purchase the Comp Gate 40 set from MAP. I am hoping to take advantage of the O2 dump set up at the same time hold boost alot better.
http://www.maperformance.com/map-com...-cg40-o2h.html
http://www.maperformance.com/map-com...-cg40-o2h.html
I have actually never seen any dyno results with this set up. I know of only one person that currently has this set up but he is only running a moderate build with the stock EVO8 turbo. I stand by my belief in what the part is capable of doing and willing to take the plunge to try it out. I just do not see it being a bad purchase.
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Joined: Jan 2004
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That's how we redid Mikey's on his Black setup. It takes almost all the boost spike out since you can run both top and side ports at the same time. We'll be testing JohnnyTSI's on the 19th as well.
Aaron
Aaron
I'm going to do a 2" dumptube with a stepped section to 2.25"
Using a larger diameter dump tube will help as well as reducing the bend radius on the turbine discharge...and smoothing the transition from the turbine outlet into the o2 housing...
I think it would behoove us to port the turbocharger out to nearly 3" from the turbine wheel to match the o2 housing... then you have a smooth transition from the turbine wheel into the o2 housing... somewhat UNLIKE what some of the manufacturers have been doing. It may only make a few more horsepower, but I figure it would be worth it.
Using a larger diameter dump tube will help as well as reducing the bend radius on the turbine discharge...and smoothing the transition from the turbine outlet into the o2 housing...
I think it would behoove us to port the turbocharger out to nearly 3" from the turbine wheel to match the o2 housing... then you have a smooth transition from the turbine wheel into the o2 housing... somewhat UNLIKE what some of the manufacturers have been doing. It may only make a few more horsepower, but I figure it would be worth it.
http://i874.photobucket.com/albums/a...t/DSCN1000.jpg
I don't know if you could actually get it up to 3" (or 2.875" ID anyway). I had mine punched out pretty well and I think I got it to around 2.55"-2.60". I simply tapered the flange at like 7* (14* included) which got it to ~2.7" and then a small section of a 7.5* (15* included) cone got it the rest of the way there in another 1/2". You can see it here.
http://i874.photobucket.com/albums/a...t/DSCN1000.jpg
http://i874.photobucket.com/albums/a...t/DSCN1000.jpg
The turbine discharge gets as large as it can.
Then you port through the flange (1/2" thick) and then you blend it into the 3" downpipe flange.
03white, it doesn't look like your ported your flange. I would give myself an additional .020"- .040" from the flange being bigger than the turbine discharge...and then taper the flange into the tube.
You are right, I didn't port it. I machined a cone directly into the flange so I didn't need to port anything. 
The cone angle was just a 15 degree cone, about the maximum angle you can get away with and not cause airflow seperation in the boundary layer.
1/2" flange at 15* only buys you 0.13" larger diameter. I beleive the flange outlet was roughly 2.65", up 0.15" from the 2.5" discharge.
The TD05H 1.93" turbine wheel exducer means you up have to transition up 0.945" for 16g tube or 0.972" for 18g. To do this with a 15 degree cone angle, you need ~3.75" of cone length to make it happen. There is about 2" of cone length in the housing, to transistion the rest in less then about 1.5" just means you are getting flow seperation and not taking full advantage of the difffuser for pressure recovery.
The cone angle was just a 15 degree cone, about the maximum angle you can get away with and not cause airflow seperation in the boundary layer.1/2" flange at 15* only buys you 0.13" larger diameter. I beleive the flange outlet was roughly 2.65", up 0.15" from the 2.5" discharge.
The TD05H 1.93" turbine wheel exducer means you up have to transition up 0.945" for 16g tube or 0.972" for 18g. To do this with a 15 degree cone angle, you need ~3.75" of cone length to make it happen. There is about 2" of cone length in the housing, to transistion the rest in less then about 1.5" just means you are getting flow seperation and not taking full advantage of the difffuser for pressure recovery.
Last edited by 03whitegsr; Nov 1, 2011 at 01:15 PM.
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