Thread: Is modifying a series exhaust worthwhile

Thanks everyone, I have it fairly planned out in my head now.

One thing that has me stumped is the 'Muffler Question'. There are many different names out there (hot dog, glasspack, straight-through, absorption etc etc) but I am having a hard time actually defining and differentiating from them.

Do most modern cars these days run a straight through muffler that would flow better than the chamber-type the stock series runs?

Are "hot dogs" straight through, and packed with fibreglass or something similar? I am hoping a wreckers yard may get me something a bit better than the stock series muffler.

Thanks again,

Sam

I thought I should clear this thread up for future reference, from my position.

I took the 2a to an exhaust shop and gave old mate the least amount of direction possible. "I want a 2.25 inch system, extractors are in the back, go nuts (essentially)".

Here are some visuals of the system all fitted up.

How the extractors look


Where they connect up to the new system. They dump well below the gearbox crossmember, but they did the diligent thing for a 4wd and bent it nicely up above the chassis rail


From there it comes up back and inside the rail:


Where it connects through a tight bend to a resonator and then over the diff:


It then turns into the Muffler:


Where it then dumps behind the rear drivers wheel:


So far, my conclusions are thus:

-I haven't had the time, inclination or dough to put it onto a dyno, but I am quite sure power and torque has increased significantly throughout the rev range. How I gauge this is the fact that I can keep the car easily in 4th gear up hills I had previously had to drop back to 3rd instead of gathering momentum and putting the foot down a fair bit.

-acceleration has increased a little bit, but nothing major.

-the system I have is SUPER quiet. The resonator and large muffler combo keeps the 2.25 VERY quiet. The adage "silence means restriction" has me a little worried that the muffler choice is not the best. Honestly, I miss poking my head out the window and hearing that great chug, but it is no more. After a little while, I will look into splicing in a straight through/perforated type muffler that may run (and sound) a little better.

-I'm not sure about efficiency yet. I may be more rapid, but not neccesarily more efficient. I will have to do a full tank of mixed driving before I have any idea.

-If you want a better running 2.25 and dont mind spending a couple of dollars, it is definately worth it.

Sam

the adage that silence is slow is wrong.

you can make an effecient system that is quite. It just costs more than doing a straight out pipe set with no muffling.

When you remove the standard exhaust manifold to put the extractors in will the inlet manifold operate ok without any modification? Aren't the two original manifolds sort of joined below the carby?

Hi Kodez.

Yes.

One issue with the extractors/headers is that they do not use the 'heater box' feature that can serve to warm the fuel by the two manifolds coming in contact together. I haven't had any problems without this, and have read that it only comes into play in cold climates. There are some empty bolt holes, but it doesn't matter.

Sam

Sam,if you can live without it for a month I'd send the dizzy to the UK for a rebuild,that one thing makes the world of difference and with the Zenith wind the fuel screw all the way in and see if it stops,if it doesn't it needs rebuilding also. Pat

Originally Posted by PAT303

Sam,if you can live without it for a month I'd send the dizzy to the UK for a rebuild,that one thing makes the world of difference and with the Zenith wind the fuel screw all the way in and see if it stops,if it doesn't it needs rebuilding also. Pat

Why send it to the UK ?

There are some very good dizzy builders here.

BTW, what's the bottom end of the dizzy the same as ? BMC A series and Ford 4 cyl ?

If so, Performance Ignitions (Scorcher) in Melbourne can build a new Bosch based dizzy with either points or electronic and all service parts are off the shelf Bosch.

My fuel screw definitely works when wound in, I seem to have a constant running battle with finding the right idle/mixture setting, esp with changing hot and cold days.

I was considering for a little while installing elec ignition with a higher output coil, but I am starting to think a fresh dizzy would give better gains. The motor is running really well and feels like it could pull a 5th gear on the freeway, but I am just wanting to modernise the old motor a little bit and get it running nice and efficiently.

My last big day on the road (mixed driving, but mostly highway) gave 13l/100km. I'm pretty happy with that.

Sam