Where to cut

[BrianX128]

Exhaust on dad's idi is all but rusted off in several spots. We're just going to rig something 3" back as I have a ton of 3" pipe laying around from a buddies exhaust system he didn't need and gave me that we can at worst make a side exit in front of passenger tire and depending on muffler might be able to get past the tire if we buy a bend or two.

That being said we can't decide where to cut. My dad seems to think if we cut 1" away from the factory Y it's more beneficial than leaving feet of the non rotted exhaust that straightens out before putting the 2.5>3 adapter. I am of the opinion that this won't make a difference if the "restriction" is 1" or 1 foot. Is it common to make a different Y piece? I know years ago on here I read that people were buying a completely new piece from dynomax even on the non turbo's I believe, but there is no chance the nuts are coming off the studs on the manifolds on his truck.

If it were me, I'd either leave whatever amount from where it "runs straight" that I can get an adapter on to run the new exhaust back from to do the least work possible, or..

Just cut the down pipes from each manifold and run duals and get rid of the Y pipe. I'm sure it will be ugly and will need an odd bend. His truck does struggle with EGT's compared to mine, but mine has the banks power pack na exhaust with the non existent "stinger" system that just seems like smoother bends but the same basic route.

 

[ROCK HARVEY]

I’m sure there is a flow difference between a 1” long restriction and a 2 foot restricted section, but if it were me I’d do it the easy way anyway. If you do a custom y pipe or a true dual exhaust, just make sure you leave enough room to pull the transmission without having to remove the whole exhaust system (lesson learned the hard way)

 

[hacked89]

It’s an NA IDI, If I understand you correctly, the 2.5” doesn’t matter just run whatever is easier to accomplish what you want.

On my bronco I used a new Y you just mentioned and then 2.5” turned down by the passenger door.

 

[BrianX128]

Yeah, basically we're just trying to do anything we can to see if we can get the EGT's down while we re-do this. I'm pretty sure cutting the clogged and bent factory muffler off will probably make more of a difference than half of what we are considering doing. If it were me alone I'd just straight pipe it from the last good piece a foot from the Y, maybe run a wire brush into the Y and see if I can clean the area up a bit.

He's now found a thread where someone left the factory Y in place, and cut a slot in the drivers side pipe right before it crosses over to the passenger side and put a tee in essentially making an H pipe. I'm not sure it will ever make a difference. His truck has always just been "tired" feeling compared to my IDI's. He then got the perception the bigger exhaust on my crew cab is the difference. I'm sure the "power pack" banks system on these non turbo's they did don't hurt, but... In reality it's because I turned the pump up, pump was already from a turbo truck with only 60k miles that got wrecked, and my truck only has 140k original "easy" miles. His has 300k, injection parts all a mystery, and can't turn the pump up when it's melting itself up a hill floored empty.

I'll probably stick to my guns of suggesting to just straight pipe it and try it from wherever he wants to hack off the old exhaust. If he wants to lay under it with a sawzaw and try and cut the driver side manifold pipe and somehow jam a tee and run duals that's his fun lol

 

[hacked89]

If he’s running a turbo pump on an NA engine another contributing factor of his higher EGTs

 

[IDIBRONCO]

If he’s running a turbo pump on an NA engine another contributing factor of his higher EGTs

Brian has the Turbo pump.
Brian, I'd just do it the easiest way you can since you're just hacking it together. I'd tell him that if he wants to do it some way other than the easiest, then I'd sit back and enjoy watching. I'm sure that you're right and the muffler is the biggest restriction. There's only so much power that you can get out of a N/A IDI.

 

[BrianX128]

Yeah, I guess this was nothing more than verifying my sanity.

Comparing apples to oranges sometimes even though two trucks have the same engine. I've tried explaining that to him but he'll cherry pick 1 factor and ignore 5 others. My pump is cranked up because of my bigger exhaust and the fact that the engine takes it well. My truck is also a 5 speed with 4.10s and 2wd. His is an auto, 3.55s, 4wd, and kinda clapped out even though the truck is "nice". Mine is also often empty even though it's heavier than his. His almost always has stuff in it [hauling wood, gravel, etc]. Just not the same.

I should make him drive it with the od off once. Sometimes I swear the computer thinks it can handle od when it shouldn't. 3k rpms is a lot better than 2.2k with 1100egt and not accelerating.

 

[XOLATEM]

I tried to save some hard-earned cash on the exhaust on a late-eighties Ranger...about two-three years ago....I thought that I was pulling a slick one...

The tailpipe was a pre-bent that I had scored offa craigslist oh--about ten years or so ago and I had adapted it on and ran it until it rotted from the back of the after-muffler pipe and it rode in the bed for a few years...

I finally got tired of people knowing who was coming down the road...and decided to graft it back on...

I went to a buddy's shop that did custom exhaust and got some pipe and a few scraps...I put the pre-bent pipe up there, cut off the rot, welded it to the stub out of the back of the muffler in a driveway with a mirror to see over the top and when I was good with that, set about cutting, flattening, and shaping some patches on the muffler itself and some other places...

When I got done I had a lot more burns in my shirt and I had used up a good amount of .030 flux-core wire.

But...the exhaust was sealed up good and never sounded better...up to that point...

So...I am going about my business and driving to work a few days later and all of a sudden....BBBBLLAAAAAHHHH.......and a scraping sound shot up through the floor....son....ova....biscuit-eater....was trying to get caught up and around my rear axle....

The durn MUFFLER blew its whole back out...

dammitt....after all of that....

I bought a 'muffler-and-tailpipe-kit' from rock auto and it took me half the time to install it than all of the welding and crafting I had done earlier...

But I would not change a thing if I had to do it all over...

I am kinda just 'like' that....

On to the next big adventure...

Somewhere...in all of this...there is some kind of life-lesson here...but durn if I know what it might be....

 

[XOLATEM]

He then got the perception the bigger exhaust on my crew cab is the difference.

Hmm...sounds like this theory needs to be proven....with a before-and-after dragstrip test...

Meaning no disrespect to your Dad...who is clearly your Elder and was your Mentor when you were just stable enough to get into everything and test his patience...

Sometimes we grow up and learn various things that surpass a lot of what our Folks can comprehend or teach us...it is just the way it is....

I have gotten to the stage where...if I know I am right...and I get tired of someone trying to sell me on what I clearly know is wrong...I offer to bet them on it...and...if you're ballsy enough...make it a bet for $100....

That'll shut 'em up....

When I first met The Girl...and we had been seeing each other for a while...an issue came up that She was 'dead sure' of...and we bet for a C-note.

Sorry to say...but She lost...and I was able to put before Her a noted authority to back my position up....so...She knew She was dead meat on that one...

She never forgot that lesson...we kept a chalk board with our tally...bets won and lost...the amounts wagered never got past 10 or 20 bucks...most were for a buck or two...or five...

But She never won enough bets to knock down that initial 100...

Now...sometimes I will bet on a gut instinct...or a 'wish-it-were-so' and I will lose miserably...but on those I am not foolish enough to risk my initial triumph...and I don't have enough of a poker face to get Her to bite on something that I am c@(k sure of....

So...how about...if you want to prove to your Dad that you might have learned a thing or two....offer to bet him on it...with a performance test..?

 

[u2slow]

The durn MUFFLER blew its whole back out...

dammitt....after all of that....

I can relate to that one well - on our Jeep tho.

I was so displeased with the krinkly jobber pipe, I returned it. Found another used one as the OEM is mandrel-bent and somewhat 'stainless'. $40 rockauto muffler with 12" of chainlink fence pipe and I was back to "good as new".


As for the OP, I would leave as much of the original pipe there as is structurally sound. I agree, 1" or 12" of the smaller pipe won't make any real difference.

 

[BrianX128]

Went for a drive today with nothing more than about 6ft of 3" pipe after a 2.5 to 3" adapter added about 8" from the factory Y pipe and his egts were down about 100* on any sort of incline while accelerating. He's gonna get an 18" straight through resonator style muffler

 

[BrianX128]

Everything is permanently done now. I have to say these straight through mufflers are useless. We got an 18" long one and I think it's technically more of a resonator [but probably keeps the cops from a ticket if you are loud and can point at it]. That being said it does absolutely nothing when the truck is really working. I guess you could say at cruising rpms it removed the drone and turned it into a deep faint humming, but if you are at 2700 hammer down it still sounds like a machine gun.

 

[IDIBRONCO]

[but probably keeps the cops from a ticket if you are loud and can point at it].

Right there is the important part.

 

[XOLATEM]

you could say at cruising rpms it removed the drone and turned it into a deep faint humming, but if you are at 2700 hammer down it still sounds like a machine gun.

I have a similar situation on my truck...it has two mufflers and the separate pipes come together in a 'U' (not a 'Y') and into a much larger pipe that goes out in a more-or-less normal fashion after the rear wheel...

When I went to check out the truck before I bought it...it was plain that someone had put some money in a custom exhaust on it...and I was going to be glad I didn't have to mess with it...

But lordy-lordy when I drove it and slapped the 'loud' pedal...that sucker 'Rat-a-tat-tatted' so ******-illy that I was wondering how much attention I was going to get...

I bought the truck anyway...it was pre-ordained that I should have, use, and love that truck...

And the rest is history...