ok...im looking to open up the exhaust on my f250 5.4 sd.

ive heard various things like "opening the exhaust drops low end torque" and such...

ok, here are my plans.....

a gibson swept side exhaust
http://www.stylinconcepts.com/part.a.../categoryid/28

and this performance y-pipe
http://cgi.ebay.com/ebaymotors/00-04...QQcmdZViewItem

along with a high flow cat.

will that give me gains in hp and torque, or losses in one or both categories?

i would have posted in the exhaust forum...but there doesnt seem to be too much activity in that area....

 

The y pipe looks like a joke - as if the couldn't weld the joint, so they slapped some sheetmetal on it. That 'y' doesn't remove any of the other points of restriction in the stock intermediate. IMHO you'd do better to have someone custom fab your 'y' for you. Taking any restriction nearer the cats to where the new Gibson exhaust set up is going.


Leave the cats... they're not as bad as people like to claim. Remember our thread about flow versus velocity - you want velocity, not necessarily high flow volume which will kill your torque. The stock cats assist with that.


As far as the Gibson side swept... the setup is good for torque, but nothing spectacular.

-Kerry

 

so what would you suggest?

(no sarcasm...i know it may have sounded like it....)
i want to do this right the first time and i would appreciate some imput

 

also...would the stock y help in this too? greater velocity i mean...

what if i went with gibson stainless headers and the swept side exhaust?

 

Just hack off some of the y-pipe and run 3 inch straight pipe from it with mandrel bends at the rear and finish it with a nice 4 inch tip. Price is right and you have a nice rumble, it will help your performance slightly.

 

Hacking the pipe and running straight pipes will give you horse power.... at 5500 rpm - slightly. Not what we are dealing with.

You didn't sound sarcastic in the least, but I thought we had already discuss much of this when you first asked the exhaust question a few weeks ago.

The stock 'y' is a bad set up (see this thread). The factory has put several restrictions in that actually slow things down. Which is what we are trying to avoid. Why not run true duals? Simply put, you need both sides operating together to give you the torque production you are looking for. When an exhaust pulse runs through the 'y', a vacuum is created that helps draw the air into the cylinder. The speed of the incoming air is part of the torque equation that we didn't get into.

Just remember that speed of the intake air and exhaust, when balanced and tuned to the cam(s), will give you the best torque production.

I did suggest that you find some one to custom fabricate the 'y' for you earlier in the thread. Other exhaust manufacturers actually make y's as well. It's really up to you, though... just my suggestion.

-Kerry

 

kspilkinton... just wanted to say thanks for all the help.

i know we'd already discussed it, but between that and now ive read some other things that have confused me a bit...

i think im just going to leave the factory y there....
are there really any noticeable gains to be had in replacing it?

what, of these three, would produce the best results?

1. gibson swept side alone
2. gibson swept side and headers
3. gibson swept side and high flow cat

 

You could also do something like this:
It's a Magnaflow 5"x11"x24" dual-in/dual-out 2.5" muffler with the internal crossover. We cut out the terrible OE "Y",and made it dual 2.5" all the way back,and turned it out the side.
JL
http://members.tccoa.com/jl1997bird/...fflerfront.jpg
http://members.tccoa.com/jl1997bird/f150mufflerrear.jpg
http://members.tccoa.com/jl1997bird/f150sideexit1.jpg
http://members.tccoa.com/jl1997bird/f150sideexit2.jpg

 

That looks nice! Any gains?? I have a 2000 F150 H-D that is stock but has the muffler cut out and just a y-pipe in there now. It sounds REALLY nice actually. Converters are still in place though. I'll have to get a video clip.

 

It gained better sound quality,and I'm sure removing the terrible OE "Y" helped a bit in power output.
JL

 

It'll save you money for now, but if you're gonna be under it, might as well do the whole thing, IMO. Performance wise, it's one of those things that no one has wasted a dyno run over, I'm sure. Every little bit will help, though. After cutting mine out and doing my custom setup, I really don't know what helped more - the catback or the loss of the 'y' pipe. I've had 3 different exhaust setups, btw, since I've owned it... the last one being the best by far.

I did have a single 2 1/2" out without a muffler before (tight on funds and needed a fix for the lack of a tail pipe) using the stock 'y', the placebo effect may have come into play, but the truck was just as loud before as it is now.

When I cut that y out, I was suprised. I have pics in my gallery and have posted them more than once in threads about the exhaust. That 'y' looked like Ford didn't give much thought into performance at all. It was simply the passenger side pipe with a hole not big enough for the driver side pipe to freely flow into. That's why I am a believer that removing the stock piece can only help.

I haven't installed my headers, yet - haven't decided if I'm doing headwork or not - just be one more piece I'd have to remove. I can only say that, again, the stock pieces don't really lend themselves to hi performance apps. They simply do their job. Mind you that most of the aftermarket headers are not tuned (I believe Bassani builds tuned ones), but the principle behind the mandrel bends and flow velocity supports the fact the headers enhance torque. Once again, nobody has posted a dyno run after simply installing headers, though. Headers by themselves don't offer enough gain to do so. Manufacturers claim numbers, but I have yet to see a dyno.

High flow cats, that goes against what you are trying to do - keep the power at lower rpms. High flow is something you worry about if you are building a drag car or have added a power adder, such as a turbo or supercharger. High flow cats promote top end horse power unless your are pushing more air into the cylinder through the power adder. The stock size of the factory car internally is 2 1/4", that diameter promotes torque production. That's why I oppose replacing the stock cats with anything other than stock size, unless you have a power adder.

Since you're trying to promote your low end, I'd say go with the headers and your Gibson side swept, but remove the stock 'y' for a custom. Keeping it would seem to be counterproductive.

Pretty much what I did with the Bassani supercharged Harley kit. The muffler has the internal cross over for the scavenging/balancing effect. The pics for that are in the same gallery before you see the factory 'y.' As far as applying these two ideas to a Superduty... it's all up to you. It would be purely custom.

-Kerry

 

wow.....thanks man

that quelled all my questions in one fell swoop

thanks again man for taking the time to type that up

 

The more you stick around... the more you see I tend to have a lot to say.

-Kerry

 

Yes, Kerry can be long winded at times, but that's a good thing since he post lots of valuable info.
Thanks Kerry