85gijunk4x4

Been looking to upgrade my exhaust (or add an exhaust, really) on my 86 22r. What if have now, as do all my trucks is a pipe that's rusted off right after the cat flange.

The pipe I'm looking at is 1-1/2 I.D, and I think the truck comes with 2-1/4 or so from the factory?

I was wondering if 1-1/2 inch is too small and will restrict exhaust gasses to much and choke me out. Since I'm only running about 2 feet of exhaust now I'd like to see an increase in power with added pressure in the exhaust.

Its only going to be 3 feet of pipe, about 2 feet of muffler (which I'm planning on just hollowing out and having a "dummy muffler")

so factory 2-1/4 or whatever, and right behind the cat about a combined total of a 10" length of 1-1/2.

to get technical here, as my mind is wondering, my exhaust now is free flowing, so i'm gaining high end power, yet losing low end. If I take that free flowing exhaust, and choke it down some with a length of 1-1/2 I'll sacrifice some high end yet gain some low end. Making my exhaust flow the best at mid range rpm, which I seem to run at the most.

The pipe i'll be using is actually off of a ford 9n tractor, wich I got for the right price. They way I look at it the ford 9n engine is a inline 4cylinder at about 120 C.I. and it uses the 1-1/2 pipe all the way through no problem. It is however governed at 2k revs, so if I hollow out the muffler that should make up for the added revs considering the muffler itself looks very restrictive

toyquad

for a engine to make power, it needs some back pressure.

for more power you would want to increase the exhuast size, not make it smaller.

the engine will "breathe" better with a bigger exhuast.

85gijunk4x4

though there is some truth to that statement, I think some might be false.

larger pipes can create power, but also take away power...same as small pipes can create, yet take away power.

The larger exhaust pipe size will increase flow at higher rpm ranges, but at lower rpms, there's not enough exhaust gas to fill that whole pipe, so you start to make turbulence which actually causes more restriction to the exhaust flow, as exhaust is just "chilling" in there and getting in the way.

Same thing will small pipes, they increase the flow at low rpms and get more exhaust gas out then larger pipes (as the flow isn't "turbulating" and coming straight out), but at higher rpms they are just restrictive and too small to flow the larger volume of gasses.

Its hard to explain, and I feel I didn't do a good job, but bottom line is that if the pipe is too big, the exhaust wont come straight out, but it will flow all around the inside of the pipe causing more pressure in the pipe, then a smaller pipe where exhaust gets forced straight out.

but on the other hand, a smaller pipe can flow exhaust straight out, but at higher revs its just plain too small to flow out the amount the engine produces and starts to choke things down.

...does this make any sense? I feel like I did a terrible job explaining.

Btw, correct me if I'm wrong. I've just always been under the impression that's how it works

timothy47129

Here is my stock size exhaust system I put on mine I believe my stock size was 1 3/4 it only cost me 34 bucks 10 for new use muffler at junk yard 18 for new tailpipe at orilley auto and 6 bucks for a 2 foot piece of 1 3/4 pipe. Of course I prob saved 50 bucks welding it myself but it could have all been clamped together

85gijunk4x4

another point, theres no ideal exhaust size to an engine. The size of the pipe depends on what rpm's its running at. The common rule of thumb is to pick a size according to what rpm range the torque curve, or power curve happens at.

no sense in building an exhaust to work great with high rpms if the vehicle in question has a low end torque curve

85gijunk4x4

Nice! How do you like it compared to what you used to have? (is it installed yet?)

And what did you have before you made that?

travis_h

Well from how I see it the bigger exhaust is better for more high rpm's more horsepower. the smaller exhaust is better for more low rpm's more torque, but even then 11/2" seems too small. Your tractor in good to 2k where your gonna at least double that. Your only gonna flow as good as your most restrictive point.

timothy47129

The above post is on the right track too large will let the exhaust cool too much and hurt exhaust scavenging which is the ability to keep the exhaust moving on its way out and to help pull the exhaust out of the cylinders.but too small with too much back pressure will hurt that also

85gijunk4x4

good point!

My question is though, i'll only be using about 10" of the 1-1/2. the rest will be the stock pipe, but only up to the cat.

if I had a truck with 2-3 feet of 2" and about 10" of 1-1/2 pipe, wouldn't it average out to somewhere around a truck that has a 2" pipe all the way back? Or am I just dreaming

travis_h

If you dump a 5 gallon bucket of water into a funnel slow it flows slow out because the funnel has a small hole. Now if you take that same bucket and dump it as fast as you can the water still flows the same out the funnel and will overflow the top too because try as you may the funnel only flow as much as it will allow. Same for the exhaust it's only gonna flow as good as the most restricted part of the system

85gijunk4x4

now I get it

now all I need to do is find somebody with a 22r that has a 1-1/2 pipe and get their opinion on it

timothy47129

I was running 2" into a flow tech raptor with no cat and it had a good rumble at idle but over 1/2 throttle it sounded real raspy and pissed off.When I switched it didn't make any difference in power.or not much difference in sound.it was still raspy without the cat.so I welded a resonator in the stock cat location and now it's just right.quiet at idle ,and I can run it to 4500rpm with no rasp.and I can hear my open element air filter over the exhaust now lol here's a bad pic of the resonator. I got it new at junkyard too off a Nissan sentra just had to adapt it down from 2" to 1 3-4

timothy47129

Here you go not the same as i used to size mine on my built 350 but pretty much the same.You can see on the chart why im only running dual 2 1/2 pipes on the old built chevy350 / 350hp
I have an idea though you could always run dual 1 1/2" pipes and be good for up to 150hp and everyone would be happy with your choice of 1 1/2. lol.The factory exhaust joins 2 pipes into a collector before the cat.It would be easy to just cut the collector and run 2 pipes back for a dual exhaust 4 cylinder.