Forced Induction Exhaust Setups & Discussion

You can do the AEM X gauge I believe it's called if you don't already have a wideband. They plug into the OBD2 port, and will inject a signal into the CAN data stream allowing you to log the AFR without having to buy the pro features.

 

I know few guys with bungs on both banks seem to have issues with their afr sensors shitting the bed. I have mine just past the merge and have had no problems. I suspect the sensors get cooked when they are more upstream.

 

What are you using the truck for?

If I had a boosted X-Runner for track (high rpm all the time) I would try the 2.5" y-pipe.
For most, 2.25" (what I use) is a good size as it keeps exhaust velocity up at lower rpm without choking flow at higher rpm.

After the merge I run 3".
2.5" will have impact on high rpm flow.

 

Why I use finned bungs!

 

That attention to detail is why your y-pipe has the reputation it does!

 

Thats why I am checking with all of your guys. I would have you build me a Y but being in CA I am trying to keep it as close to CA legal as I can so the cats stay.

 

ok that makes sense the 2.5" was an idea but wasn't sure it was needed or not. So from cats into merge keep at the 2.25" then run 3" back? I am sure crank wise it will be close to 400hp when all said and done. Also trying to future proof it some.

It won't be a track truck, Its a off road rig/daily truck to some degree.

Sounds like keeping the Y at 2.25" is the way to go.

 

Much appreciated!

 

So you are welding factory cats to the JBA headers?
Then also keeping stock rear cats?

If so I would use 2" od tubing until aft of last cat. Then transition to 2.25" to merge collector.

You want to minimize dimensional differences such as going small big small big on tube size. It makes the exhaust have to speed up, slow down, speed up, etc. Not efficient.

Look up Bernoulli's principle.

@nudavinci64 pm me if you want my # so we can chat about this.

 

Ill wrap up and we can chat. I figure yes ill be keeping all cats as needed here in CA.

 

Here's my 4 banger

URD s/c stage one (~8.5lbs boost)
MAPECU3
5th injector
LCE header
URD midpipe
Stock catback
LCE lightweight steel flywheel
SPEC stage 2+ clutch
5.29 gears
295/70/17s

https://m.youtube.com/watch?v=pjTkBEwr_Ag

 

Yup! That’s what I got. But it would be interesting to see comparison dyno graphs between a 2.25 and 2.5. And show the high and low rpm flow differences

 

Absolutely!

What we would be looking for is velocity rate as a larger diameter would decrease velocity.

 

Has anyone used the catless afe y pipe? It has 2.5" runners and a 3" merge collector. Wondering if it hangs low, or has interference issues with skid plate. My DT pipe bomb is falling apart and want to upgrade with less restrictions. JFR is obviously the most desired but not in budget at this time.

 

Will be installing URD headers and catless Y pipe. Any tips on running a cat in the cat-back? I currently have a home built 3 in cat back with 2 vibrant resonators and a cheap Thrush muffler. Been dreaming of a side exit through the fender in front of the passenger side rear tire. I think I will have to swap a res for a cat to squeeze it all in.
Suggestions/ experience on 3"in/3" out catalytic converters.

 

I use Magnaflow 59959 3" metal spun cats.

 

I believe the AFE headers use Magnaflows. I think they suffer the high temps of boosted applications. Is the temp drop by the time the gasses reach the cat back section diminished enough to make these last? I will probably install with V-bands so I can swap out ever 20k mi. when the elements begin to fail.
How many miles have you ran the magnaflow?

 

I run them post y-pipe.
I have seen one fail out of probably 20 installed.
I cant vouch for everyone but I have only seen the one failure.

Cats require a break in procedure to seat the substrate to the case.

 

A break in? Tell me more, please. A sequence of heat cycles?
I assume the failures I experienced, both cats in the twisted steel headers, were from the increased heat of boost. Do you think the location of the aftermarket cats makes that big of a difference? I ask since you are running further down stream.
Are there any other rules of thumb that I should follow? Like, depending on how I orientate my set up, is it plain stupid to install a cat between a resonator and Muffler?

Also, If I am at 3" from the Y pipe collector back, how critical are bends? If I can get a side exit through the fender to work, it will be with a couple extra bends. Assuming I will never be over 400HP. Hoping that if I am a bit oversized I can be a little more creative with getting around the frame and out. I have only found some first gens that were able to get the fender exit. I may be pushing it...

 

A quick youtube search can explain the process better but basically you have the main material (ceramic or metal spun) substrate but it needs a seal between the cat material and the metal casing.
Breaking it in (dont quote me on this) is like running at idle then maybe a bit higher rpm in neutral, then let the cat completely cool.
Then it's broken in!
There is basically a one time expandable media between the cat substrate and case.so you need to heat it to allow it to "seat" then cool to allow it to set.