Honda Exhausts: Stick with Stock?

[rh77]

So, after a year or so, I still need a new exhaust system on the '98 Integra (all needs replaced except the Cat and Header).

The concensus was to stick with stock since the engineers designed the car to operate under those conditions -- but we know better than that, right?

With the complexities of backpressure, flow, and velocity, what will attain the optimum FE at an average of 2000-3000 RPM? The setup is the LS automatic (1.8 DOHC non-VTEC), and rarely sees past 3500.

Should I:

• Reduce or enlarge the piping diameter (and if so, where in the line of flow)?
• Stock or Free-Flow Muffler?
• Other???

I've been putting this off for quite some time, because I don't want to invest in something that's going to fail and is rather permenant.

One note: I had a '96 Civic DX 1.6 SOHC manual that I placed a free-flow muffler onto. It absolutely killed the torque. During a Winter mishap, I put the stock muffler (that I saved) back on. Torque and FE were restored -- hence the concern. It seems paradoxical from the "engine is an air pump" analogy. State Inspection is coming up and I need to finally pin this down...

Any pneumatic engineers or experts out there???

RH77

[GasSavers_Ryland]

if you are going to reduce the size at all, I wouldn't go more then 1/8" smaller diamitor, because if you look at a 2" circle has an area of about 6.28318531 square inches, 1 3/4" circle has an area of 5.49778714, or nearly 8/10 of a square inche smaller, and that turns out to be alot of volume.

[rh77]

Now that I'm back in town, I may stop-by my local exhaust shop. The owner has a small operation and looks like he can fabricate mandrel bends and custom requests. Stock piping and a quiet, standard-flow muffler will be investigated for an estimate. The A-pipe has a tube within-a-tube that busted loose years ago to create an annoying buzz and rattle. Further downstream, the muffler buzzes and most pipe connectors leak.

I've been down the road of obnoxiously loud exhausts (even stock), so quiet and efficient is the goal. I'm just worried that the A-pipe is expensive (as it's been noted in the past) and might require a tack-weld on the existing collared tube to secure that loose inner tube. Back from there, it should be simple.

RH77

[brelandt]

Odd?

I own a 91 teggy LS (manual of course) with 180,000 miles and the only thing that needed attention exhaust wise was a new muffler (pervious owner changed) and the pipe rusted open where it bends back towards the rear suspension near the passenger side rocker panel. Was told that is where most Honda's go bad first.

Everything else is fine. Car was kept in Arkansas most of it's life which may explain this? Hardly see snow and saltly roads.

[rh77]

First, I'm jealous of the manual

I inherited the Teg from the original owner -- my wife. So far, it's been a good challenge to hypermile and is perfect for coasting, handling engine off steering, and retains a cold A/C charge. At 90F IAT I can get 45 mpg at 60 mpg cruise on level ground, with a 34 mpg combined average of really trying (started at 26 before GS).

Regarding the exhaust wear -- it's had a lot of short trips in its lifetime, and somewhat salty Winters in Kansas City. The A-Pipe is a common problem with this Gen -- for some reason there's an inner pipe (for resonance?) that busted loose (also the heat shields are gone as they proved to be flat out noisy). Otherwise, as of current, I've noticed a raw, unburnt-fuel smell at idle. No holes or rusty piping, just rusty connections at the spring-loaded joints. I hoped it would last longer too. Luckily the Cat is intact. I think the quality degraded in later models as well.

RH77

Originally Posted by brelandt

Odd?

I own a 91 teggy LS (manual of course) with 180,000 miles and the only thing that needed attention exhaust wise was a new muffler (pervious owner changed) and the pipe rusted open where it bends back towards the rear suspension near the passenger side rocker panel. Was told that is where most Honda's go bad first.

Everything else is fine. Car was kept in Arkansas most of it's life which may explain this? Hardly see snow and saltly roads.

[brelandt]

Kansas city! The only place I have ever been where I saw about 60 cars on the side of the road because the drivers refused to slow down during the snow! I'm from New Orleans so I was scared The whole way threw white knuckles and all but I made it without much affair. Just had my backend comeout from behind me a few times, but let off the gas when it did.

I was stationed in Omaha for 5 years. They used sand instead of salt. surprised KC doesn't as well?

I miss the mid-west. Had a lot of fun out there!

[rh77]

Originally Posted by brelandt

Kansas city! The only place I have ever been where I saw about 60 cars on the side of the road because the drivers refused to slow down during the snow! I'm from New Orleans so I was scared The whole way threw white knuckles and all but I made it without much affair. Just had my backend comeout from behind me a few times, but let off the gas when it did.

I was stationed in Omaha for 5 years. They used sand instead of salt. surprised KC doesn't as well?

I miss the mid-west. Had a lot of fun out there!

You got it -- the problem is that we generally get a layer of ice and then some snow, but after the first Winter storm, there's vehicle after vehicle in the median or off into the ditch. Omaha generally gets much more snow, and probably lower temps where salt isn't as effective.

Here we use a mix of salt and sand (not sure how they determine what to use) -- but our Winters vary greatly year-to-year. I learned to drive in the Ohio snow and try to apply that here -- and with FWD, it's been OK (especially when I had the AWD Evo -- I looked forward to bad weather )

This last snow, they must've used 100% salt as my blue car was covered in a white layer of "awaiting corrosion".

RH77

[rh77]

Originally Posted by theclencher

Double-walled pipes were used to insulate, leading to quicker cat light-off and in some cases eliminate the need for separate heat shielding.

I have no idea what's going on with this exhaust, but now it's in the stage where I can't smell raw fumes at idle. A few weeks ago it was pretty strong. It has been warmer lately -- perhaps that's a factor -- or that inner pipe is more restricting at times

...or the car isn't burning the fuel entirely and I'm smelling the actual tailpipe emissions. If so, I assume I'd get a CEL for some parameter out of whack. What's odd is that I'm currently getting about 34.5 mpg (SG) on this tank, which is abnormally good for this time of year (without the fumes). The whole system still rattles and clatters at various RPMs, but when prompted (rarely) it'll still climb to redline without a single miss or ping. I still haven't taken it in yet I've never had a non-test related CEL and there's none stored to retrieve in the SG, so I'd guess that it's running right. Perhaps the joints expand and contract with the hot and cold?

RH77