I'd be careful with that intake opening hanging under the truck. Personally, I think I would put some type of screen or mesh over the opening to protect from any debris shooting up the pipe and into the air cleaner. Nothing too restrictive.......maybe just some wire mesh. I would also drill a hole to allow for water drainage if you should drive through some rain or standing water. You could put a fitting in the hole and connect a rubber drain hose to it if you want to get fancy. Just my .02.

 

 

Any other thoughts on my exhaust?It is more T than Y.Not any different than factory.Also exhaust is half inch from trans. cooler line.Any problems with heat transfer?Also any better flow air filters?

 

I personally believe you need to get a smooth transission happening from your stock 2 1/4 pipes to the 4". The sudden change with "flat-square" corners has to be causing a lot of turbulance and a "back eddy" effect in your exhaust flow, which in MHO is what is causing a performance problem. FWIW, with my headers, increased fuel, and smooth free flowing exhaust and ram air, I would bet my performance is at least as good as a stock turbo truck (everyone don't start yelling at me, but I am REALLY happy with the power my truck puts out). I have some pic of my Y pipes in my gallery.

 

F-Super Duty: Yeah, now that I see your transition, that could be some of you problem.My suggestion is that you separate the two headpipes and extend them back so that the shortest of the two is at least 24 inches long. Then weld on a two-into-one collector. Flowmaster makes some, so do Dynomax, Magnaflow and others (I'm looking at a Jegs catalog right now at some that go 2-1/4 in and 3-inch out). Run three inch to your muffler than adapt up to your 4-inch muffler (remember my earlier post abut poking the pipe into the muffler), making sure the muffler is near the end of the system with only a short 4-inch tailpipe. I think you could build that easily without a lot of major expense or hassle. This system would offer good size transitions but maintain enough velocity to keep the scavenging effect going.

 

Oh my gosh!

I guarantee that y-pipe is your problem, after seeing the pic. For a N/A truck that turns low rpms (ie...diesel), 4" is way too big. That is absolutely killing all your torque, especially being such an abrubt and wierd transition. You need to redo that whole y-pipe setup with a nice 2 1/4" or 2 1/2" (can't remember what the stock head pipe size is) to 3" 2-into-1 collector. Run each head pipe far enough back so you can get them close to parallel to each other before you have the collector. Then go 3" single exhaust with a good muffler the rest of the way. That will definitely help the scavenging and will decrease your fuel consumption and give more power.

*After rereading thread, I forgot you already have the 4" muffler. That's ok- just transition up from 3" to 4" in front of the muffler. Then 4" the rest of the way will work. It's still important, however, to only be 3" for the intermediate pipe to keep some exhaust velocity up as far down the pipe as possible. What you're trying to achieve is a balance between an increase in flow CAPABILITY while keeping that hot air moving, not stagnant and tumbling through the pipes from going too big.

 

Jim Allen,

sorry for seemingly "copying" what you said-didn't realize we were saying the same thing til I reread your post! So is it true that great minds think alike?

 

That abrupt transition with square shoulders is not a good thing.
I do agree that the transition needs work to smooth it out.

Have not looked at the Y pipe yet, but I can say that the stock system needed a lot of work in that area.

 

i agree the new y pipe is causing flow issue due to the abrupt change and the right bank tube is intersecting the left bank tubes flow
it is most likely creating a pressure instead of a drafting effect

 

Mine seemed to gain some responsiveness and seemed to pull a little harder in the powerband. However, mileage went down about 2 mpg. I'm not sure if that's because I drive it differently based on the sound the exhaust now makes, or if I'm subconciously compensating for less power by giving it more fuel. My IP is starting to go south, too. It leaks some and my exhaust doesn't smoke at full power, even with the old 2-1/4" exhaust. Other than that, it runs fine.

 

Yeah, I have to agree with several others here. The transition point of your Y-pipe is the focal point of your problem.

Not to pat myself on the back too hard, but take a look at the pictures of the y-pipe I fabricated in my gallery. Smooth transition from the smaller downpipes into the bigger pipe is key. The two 2-1/4" downpipes with transition into one 4" pipe much more cleanly side by side - the way the one in my gallery is built.

 

So is that white PVC some kind of air scoop? What are the thoughts behind that? Smoother so less air turbulence, less restriction to the walls versus the dryer vent? Using it as an air ram? Is that more air than the hole in the radiator support?

What happens to the butterfly when it gets sucked in?

 

i used 4" stove pipe, pics here:
optikal_illushun/Trucks/Smokie/Engine/Intake - Photobucket - Video and Image Hosting

 

I made a my truck into single 4inch exhaust, worked great. I just cut my factory exh. Y and flipped the right side down pipe over and welded an extension on the pipe so both were the same length. The pipes were stacked right side on top of left side. I then took a piece of 4inch exhaust tube and heated it with a torch till it was orange and hammered it to shape over the other two pipes. I then mig welded it all together. i have had no leaks at all. And its a nice smooth transition. looks good, right at home!!