Exhaust tube size

[]-[owler]

j/c, what would the effects of a flapper setup similar to the throttle body do to the torque(so as you depressed the gas, it opened more)? it would restrict as needed wouldn't it? as long as it flowed enough fully closed for the engine to run.

[FestYboy]

Dear god I want to beat that person to death with a physics book.

not too hard i hope, some of what he's saying is correct (some).

[Team Lightning]

When the catcon on my 3.9 Dakota plugged up, it would come off the line like it's butt was on fire (a definite improvement from normal). At approx 2000 rpm it would fall flat on it's face. Replacing the catcon (under warranty) solved the rpm issue. Also lost the great low end torque.
Jerry

[oxbrain]

http://www.uucmotorwerks.com/html_pr...torquemyth.htm

Dear god I want to beat that person to death with a physics book.

[MONSOON]

Congratulations lancerevo! You are todays winner!

[Banana Bonanza]

Each to their own, on a stock B3, I'd go 1 5/8 and just try to make turns as smooth and non-restrictive as possible. Frankly big diameter exhaust is only useful if you are running high rpms and trying to get last ounce of power out of the thing such as racing. The head has to be ported and fuel system set up for high flow. For daily driver its just not needed. Same thing with people using huge carburetors, pointless unless the engine can use that much flow, most stock engines cant, especially at normal speeds. Best thing on a stock B3 would be to make sure it has clean cat and try to make turns around gas tank in back as smooth and free flowing as possible. I know my exhaust back there has kink from when I hit big rock and knocked muffler off. I unbent it but still a restriction there that needs to be gotten rid of. I notice power decreasing rapidly at higher rpm.

The whole setup has to be looked at as a system. A change in one component requires changes all around to compensate.

[lancerevo]

yeah, so... Better late than never

[ejp2fast]

isnt this thread almost a year old?

....little late on that reply.......

[NovaSS]

isnt this thread almost a year old?

[lancerevo]

if it does not need the backpressure then why does it matter what size pipes and muffler you put on it? I am not trying to argue, I am trying to learn. I put a bigger exhaust and cherry bombs on my car and the low end torque was gone along with what little passing ability these cars have, not to mention my gas milage dropped off. Once I put it back to stock exhaust the cars pep was back and so was my gas milage. If it is not back pressure that causes this then what is it?

The reason that you lost power with bigger exhaust is because the engine is making lots of hot gasses, to the back of the muffler. When over sizing the exhaust piping, the exhaust gasses have to push harder on the cold air in the piping. Cold air is heavier to push than hot. Go to this site and read it and, you will understand.

http://www.uucmotorwerks.com/html_product/sue462/backpressuretorquemyth.htm

[Fordverde]

ok, so bottom line. 2" from the exhaust manifold+cat+regular muffler(I dont like too much noise) is the right way??

[skeeters_keeper]

LOL, i'd like to see that!!

[funky technician]

^funky, thats what I did, have you seen my latest "skeeter update thread"? i have a custom 2 1/8" DP + exhaust, only thing to disrupt flow is a cat (nececary for inspection).

I'm actually quite jelous of that down pipe as a matter of fact LOL I had a buddy try to build me a 2" one while I'm in the middle east and I just got an e-mail back from my girlfriend saying he did a brutal job and tried to make a 90 degree out of a streight pipe.................I can just imagine how it looks......even she said it looks pritty bad, so I guess I'll be takin that off when I get home LOL, I'll take some pics first if its really brutal and we'll have a good laugh

[getnpsi]

Agreeing with multiple people with different arguments is messy, but its the case here. I would just set aside the funds to upgrade the system for the larger engine and leave it stock until i was ready for the swap. if you are just itching for change, just go 2". that is the size of plenty of 1.8 liter engines out there and they fun fine just like that. you will be happier in the long run not having to buy things twice.

[FestYboy]

also with too large a primary (or in our case, down pipe) the scavenging effect can be TOO great and actually suck out some fuel charge before it's used. effectively reducing the engine's displacement.