Exhaust for mileage

[aldive]

One area where I feel there is room for improvement in the mileage department ( and HP ) is the exhaust system.

What do you guys think is the optimal exhaust for the SOHC? Headers, cats, mufflers, piping, etc.?

 

[spindlecone]

Best bang for the buck is an offroad Random tech Y -pipe

 

[RickOTR]

If it where possible I think an H pipe would give some good improvement. Been thinking about headers but not sure what performance gainss I would see. JBA?

 

[spindlecone]

If it where possible I think an H pipe would give some good improvement. Been thinking about headers but not sure what performance gainss I would see. JBA?

About 2-3 H.P. gain on a N/A SOHC engine, not worth 4-500 bux IMO

 

[davidmmm69]

Best bang for the buck is an offroad Random tech Y -pipe

what is the stuff wrappped on your pipe.

 

[spindlecone]

what is the stuff wrappped on your pipe.

Header wrap,Helps keep heat away from the tranny pan and starter

 

[CDW6212R]

The factory SOHC headers look wonderful, for a stock manifold. The wrapping is worth some power also.

I'd suggest building better cat pipes. There is room for improvement in the bends(they are too tight), and the cats I'll bet are restrictive internally. If you have ever seen inside of a catalytic converter; imagine the exhaust having to turn sharply on the outlet side of the "brick," and squeeze into a small 2.25" protruding pipe.

The inlet and outlet of a cat should smoothly open up to the exact surface dimensions of the "brick" and then gently adapt back down to a 2.25" pipe. Buy a couple of larger universal cats. Cut off both ends and weld on two adapters that would be used for changing collector sizes. Find them at places which sell header building parts. Good luck,

 

[aldive]

Anyone who has replaced stock cats with performance cats .... what gains did you achieve? Please post pictures of the set up.

Thanks ....

 

[CDW6212R]

The restrictions are about the same in all cats. The performance cats usually just have a larger brick in them, and less elaborate heat shielding.

More gains there could be had by rebuilding the oulet side of the cat, any cat. The inlet side isn't as important, but i'll do them both, when I get to doing my V8 cats.

No one has altered the inlets or outlets, everyone thinks that they are magic boxes, or evil devices. Look past common knowedge, and assumptions, and make the magic. Good luck,

 

[Katmandu]

Anyone who has replaced stock cats with performance cats .... what gains did you achieve? Please post pictures of the set up.

Thanks ....

What about those that just eliminated the Cat(s) altogether ??

How much does that help in the MPG department ??

 

[aldive]

What about those that just eliminated the Cat(s) altogether ??

How much does that help in the MPG department ??

Thats not an option for me.

 

[CDW6212R]

I don't believe in the emissions magic of catalytic converters, or EGR systems, etc, but I don't fight their use. The drawbacks are not so bad that I want to deal with legalities. You can remain legal, and achieve close to the results of not having them.

 

[Rx4phun]

couldnt you just hollow out a cat and leave it on for appearance? Would it really through off your emissions that much? (cause you to fail)

 

[aldive]

couldnt you just hollow out a cat and leave it on for appearance? Would it really through off your emissions that much? (cause you to fail)

... and not to say anything about the air you breath.

 

[CDW6212R]

It is very common to delete rear cats from exhausts which have pairs in series. The V8 Explorers have four, with O2 sensors on each side of the front cats.

I have read tests which showed exhaust output with cats to be as bad as the same exhaust without the cats. The chemicals which catalytic converters convert the measured gases into, are as bad for the atmosphere as those which are tested for. Some info to chew on. Regards,

 

[aldive]

I have read tests which showed exhaust output with cats to be as bad as the same exhaust without the cats. The chemicals which catalytic converters convert the measured gases into, are as bad for the atmosphere as those which are tested for. Some info to chew on. Regards,

Care to share the source of your information?

 

[CDW6212R]

I'd love to have a photographic memory, and give it. That was probably almost twenty years ago, and I don't remember the chemical that is increased by using cats. The scientific community is too fast to condemn common products, and create new industries.

We all know now that the R134 freon is no better than the old R12, but the laws will not change, and the prices will not go back down. I believe that it is the same with cats, just like air pumps. Fortunately, the manufacturers were able to get rid of air pumps. I doubt that catalytic converters will be allowed to ever be removed. Regards,

 

[Turdle]

Hydrocarbon emissions are dramatically reduced with a cat. The by product from the conversion ( burn ) is a higher level of nitric oxide. That is what I read, but don't ask my source ( don't remember).

 

[CDW6212R]

That's close as I recall. The point I was making is that, the new chemical produced is not tested for for emissions, and it is equally bad for the environment. Regards,

 

[Afboy143]

interesting point CDW. However, Im sure cat's do SOMETHING better than without them or Im sure states wouldnt require them and every car come equipt with them....

Aldive,
All the research ive done for the sohc exhaust system makes me come to the following results( this is what I summed up)

For our SOHC engines, it requires backpressure for torque. So say if you do a Y pipe (like spindle said)off the cats into a single IN single OUT muffler with a 2.25" or 2.5" pipe, that would be ideal for lower end power.

In the middle, there is a dual in/dual out muffler which will restrict some but won't flow as freely as tru duals. This gives the medium between both worlds.

If you did say a X or H pipe off the cats with true dual mufflers that will decrease lower end power but increase higher end power. I honestly havent read anything about what kind of MPG gain is in each of this, all I read was the MPG gain was higher with aftermarket than with stock exhaust systems. I am interested to see which exhaust system yeilds higher MPG. I WOULD GUESS the free flowing,true dual, wide open exhaust would yield higher mpg gains over the more restrictive exhaust but thats just my opinion. Again, all this info is what I have come to a conclusion with after doing all my homework on these forums on exhaust