cut the muffler off!!!!

[shift1313]

NA vehicles need backpressure. If you have gutted cats and no muffler you have little to no back pressure. you will notice better flow at lower rpms but when the rpms get higher you have less scavenging effect so you actually get a collection built up at the back of the exhaust valve rather than the negative pulse you need.

as far as your fuel gauge goes, no ford truck i have ever owned has been linear. It takes alot longer to go from full to 1/2 than 1/2 to E. its partially the design of the float, partially the shape of the tank.

as far as the mpg thing its no sweat off my back. i think the general consensus was that low mpg means poor performance and something is typically wrong. with these trucks its usually something emissions related or possibly the igntions system. it looks as though you have all the tune up stuff taken care of.

i know with my bronco i got better mileage once i deleted all of my emissions equipment and made a carb spacer for it. My truck went through a few of those check valves below the carb so i finally had enough and did away with everything and the mpg difference was night and day. also the gas station you go to makes a big difference. Ive driven 3.5 hrs on the highway on a full tank of bad gas, and the same trip with good gas only took a 1/2 tank.

 

[Broncobill78]

im doin good now. i can really tell the difference with the exhaust cut off, i have way more power for some reason. i go faster

Let me start off by saying that everything that I say, I say with a smile. I'm not looking to *slam* anyone, but some things simply need to be said so I say them with a smile and the best of intentions.

I'm *quite* sure that if the truck is going faster it's because you're really getting off on the open exhaust and that right foot has gotten just a bit heavier since you *modified* your truck. Yeah, sure, back in the late 70's you could restore some power to the engine by stripping the emissions hardware & losing the *old-style* cats. EXHAUSTIVE testing by almost *every* magazine published has repeatedly shown that removing the mufflers results in NO power gain and occasionally results in a power loss. Same deal with the cats. That one's not even open for debate. With the current (well, as far as 92' can be considered the last Bronco's and as "current" as they get) trucks and the engine controls it's the same deal, hack up the exhaust *without* doing some extensive repinning & rewiring of the sensors and you're just going to lose power. A 92' is NOT a 75' and what worked really great on a 75' will do nothing for a 92', you'll lose power, milage and drivability. But hey, if it *sounds* good to you then I guess everything's cool /emoticons/[email protected] 2x" width="20" height="20" />

Without running it on a chassis dyno before & after each mod there's really no evidence for any sort of improvement and I have to go with the countless technical articles that argue against doing this. Sure tearing off the exhaust makes it louder. I don't think anybody's disputing *that* fact, unfortunately that's ALL it does. In every other *measurable* way the performance suffers. It might have accomplished something with a late 70's/early 80's truck but not with a 92'. Are you *honestly* asking me to believe that the truck is THREE times faster than it was just because you gutted the exhaust and reduced the efficiency of the engine controls in the process ?

It's your truck, tear it up all you want but if you're going to start claiming that you've accomplished some HUGE leap in performance by doing so then provide some evidence. Find us something, *anything* from a respected source that suggests this is a good idea and I'm sure a lot more people will be interested. Things *used* to work the way you're talking about but with the advent of high-flow/effeciency converters and moderm engine controls all that changed.

 

[Redneck86]

Yea man i gotta agree, my 86 had the 351 with a 4bbl and smog equipment. I took all the emissions off and plugged every thing when i got it that got me some power. Then i had open headers on it for awhile, sounded bada$$ but gets old really fast...thats ungodly loud not to mention it started ****** people off. It had pretty good top end like that but no low end, i got some good low end with dual Flows. But my buddys 90 runnin outta the cat was a dog compared to my 86 with open headers.

 

[shift1313]

after reading what broncobill said i feel i should add something to my last post. when i said i removed the emissions equipment from my truck and it ran better and got better mileage, this is only because half of it was broken, leaking air/fuel etc. My truck got to the point where it just wasnt feasible to replace all the emissions equipment for me. my 89 FI truck ive kept everything stock with the only exception being the cat. it was clogged pretty bad so i gutted it when i made my cat back system. had i known it was bad i would have replaced it but that was a weekend job and i didnt have a cat.

i wouldnt want people to go pulling all the emissions equipment and hope to get better mileage. My truck wouldnt yield any better mileage than a good running stock truck.

 

[Redneck86]

Well where i am at i dont have to run emissions equimpment. Im guessing i got more power from less accesory drag with the smog pump gone, plus not goin though a cycle that was goes though everything. On my truck it was pretty easy to take off, theres no computer or sensors on it to mess up so i just took the brakets off and plugged everything up. I also took the A/C off when it broke, thats when i noticed alot better milage.

But a newer engine theres no need to take it off, they dont really rob power like they did on older engines and itll f*ck the computer up and run really bad becuase it thinks theres a problem. On an older engine though i see no point in keeping it if you dont have to, it robs power and uses up more gas to work.

To prove this my 86 can get about 12mpg if i baby it with all the smog equimpment off, a bone stock 95 gets about 13 gunnin it everywhere.

 

[bko4x4er]

well geezz guys, i really do think it runs alot better and seems like it has a little bit more pep in it. you guys arent here to know so i guess think what you want. you may be right, and you may be wrong but this is just my opinion about my truck.

compared to how it was running before and how it is now. it is alot of difference

 

[BroncoJoe19]

well geezz guys, i really do think it runs alot better and seems like it has a little bit more pep in it. you guys arent here to know so i guess think what you want. you may be right, and you may be wrong but this is just my opinion about my truck.compared to how it was running before and how it is now. it is alot of difference

You see the problem is that you named the thread... I cut off my muffler!

You seemed to give more credit to the hacking off of the muffler of why your truck runs better, than what really caused yor truck to run better AND get better gas milage.

YOu replaced an O2 sensor that was BAD. A bad O2 sensor could have dramatic impact on your gas mileage.

You also gave it a tuneup...

<snip>

remember saying i did a complete tune up

dist. cap

wires

plugs

air filter

ignition coil

o2 sensor

oil change

exhaust

and i now get around 9-11 mpg

<snip>

So if your truck really ran like $hit, and now it is running normally, you can really see an improvement.

Just take it from the sense of the responses in this thread, any improvement in performance was NOT a result of hacking off the muffler.

So other than the muffler job... good job on replacing your O2 sensor, and giveing her a tuneup.

joe

 

[Redneck86]

Yea man i agree now that i see that, a good tune up helps alot new or old engines. And a bad O2 sensor not only gives you bad mpg, it can also mess with the computer and make it seem gutless...it uses it to help deicied in the fuel/air mixture. And im not here to bash on you man, but now that i think about it i dont see how cuttin the muffler off did anything but make it louder. Since the cats are still there it wouldnt mess with the O2 sensor. The only *real* exhuast upgrade ive ever seen make a noticable power gain, was goin from stock single pipe to true duals. Cuttin the muffler prolly didn do much if anything, i bet what your feelin is your tune up. Again no offence meant man just sayin what i think.

 

[Broncobill78]

Well, once again I think I ignited a brush fire that I really didn't intend to. I could probably avoid this sort of thing If I sat down to read posts at 6pm instead of 4am, but it is what it is. /emoticons/[email protected] 2x" width="20" height="20" />

Regardless, I think Joe pretty much nailed it with the insight that the tune-up and O2 sensor probably had a lot to do with it. Considering the engine's milage there's really no telling how long it had been since either had been done and *both* could/would have had a dramatic impact on how the truck ran & pulled. In hindsight it's easy to see how he could have not understood just *which* modification had caused the increase in power since it sounds like everything was done at once. It's a good reminder to change *one* thing at a time so you can keep track of how your changes effect the truck.

Sometimes a good slap in the head is the best medicine /emoticons/[email protected] 2x" width="20" height="20" />

At the end of the day if he's thinking it runs better and he's a happier truck owner for it then more power to ya. It's hard to argue with the man on the spot.

 

[bidibronco]

Am I the only one who doesn't want my truck to be obnoxiosly (spelling?) loud? Just thought I would throw that out there?

 

[bko4x4er]

Am I the only one who doesn't want my truck to be obnoxiosly (spelling?) loud? Just thought I would throw that out there?

hey man it sounds good. it almost sounds like a straight pipe. its deep and loud. no poping or backfiring either.

 

[Redneck86]

I would put a hanger or something to hold that pipe in place. That pipe moving around will cause it spring an exhuast leak, then it wont sound good at all.

 

[swampthing]

im with broncobill if he likes it more power to him..my personal opinion is it sounds like the truck is underwater when running thats why i personally dont run them...and bidi i dont like my truck obnoxiously loud but i like it to have a nice rumble deep tone to it that i can hear at idle and gets louder at full throttle

 

[bidibronco]

I had strait pipes and I enjoy listening to the conversation my boy is giving me so I added some length and put in some cherry bombs. Not the best muffler but cheap and much better.