Non-restricted exhaust

[brackie1]

One of our club members mentioned today that I should look at a non-restricted exhaust. We were all kind of in a hurry so I didn't have time for him to explain what it is. Does anyone have any experience with this and explain what it is and how it works. I have a 77 spider.

[aevansgatech]

He probably meant removing the catalytic converter and replacing it with a "test-pipe" or straight through exhaust. Removing the catalytic converter results in a less restricted exhaust flow, but will also make the car louder, possibly smell worse/different, and won't give you much hp benefit in my opinion.

If you think your exhaust or converter are shot, then consider it, but if your exhaust is in good shape I wouldn't modify it.

[focodave]

If you want to hear what it may sound like without the cat in place, I made a video of mine with no cat, no rear muffler, and just the center resonator in place: https://youtu.be/zxc9TEcS1Eg

[So Cal Mark]

free-flow exhausts are important for power increases, I can't imagine why in your opinion they aren't worthwhile? Exhaust systems with back pressure cause reversion to enter the cylinder during overlap, sapping hp.
Would you care to offer some proof to back up your opinion?

[RRoller123]

He probably meant removing the catalytic converter and replacing it with a "test-pipe" or straight through exhaust. Removing the catalytic converter results in a less restricted exhaust flow, but will also make the car louder, possibly smell worse/different, and won't give you much hp benefit in my opinion.

If you think your exhaust or converter are shot, then consider it, but if your exhaust is in good shape I wouldn't modify it.

I put a Test Pipe in my 80FI, and noticed a great improvement in Mid-Range Torque, whereas before I would climb a long moderate hill at speed but would have to shift down to 4th or 3rd, I could absolutely now stay in 4th, and often stay in 5th. Big difference with just the pipe.

Pete

[brackie1]

My '77 spider does not have a cat and badged as such

[brackie1]

Sorry didn't get to finish my post. Since I don't have a cat does that mean I have a free flow exhaust? My exhaust is somewhat loud a lot like the video.

[Nanonevol]

If it's loud maybe you have a leak. Otherwise, if yours is a stock '77 it has a 4 into 1 exhaust manifold and you would see improvement with a 4 into 2 manifold from an earlier or later Spider.

[vandor]

+1 on upgrading to the earlier moanifold and downpipe to make the system a 4-2-1.

For the rest of the system an inexpensive alternative is the Euro-1800 exhaust, which is ~2" in diamter, vs. ~1-5/8" for the US 1800. These will work for any non-catalyst 1800 (ie it will fit all 49-state models, but not California models). The center muffler slips right onto the stock downpipe.

https://autoricambi.us/collections/exha ... erformance

https://autoricambi.us/collections/exha ... erformance

[grrrdot]

Free flow exhausts are great.
I put a 1608 in my car and was really happy. Then I went from the stock 1197cc OHV exhaust to a 2.25" with both a MagnaFlow and Borla muffler, you can see straight through both of them, I thought it was going to be really loud but its about the same volume and the power change is amazing. It used to only pull between 3-3800 RPMs now its a blast all the way up to 6K.

-G

[PhillySpider]

I want to play!

I have a 1980 FI spider. Stock.
1. Do I have a CAT, where is it, what's involved in removing it, what to replace it with.
2. Would I have a 4-1 exhaust or a 4-2-1 exhuast?
3. What does #2 even mean and which do I want.
4. If I'd want what I don't have, how to go about remedying that one?

[vandor]

If it's an FI Spider then you have a 4-2-1 system, which works well for the stock engine. To get a 2-3 HP gain you can replace the cat with a test pipe if your area allows it:

https://autoricambi.us/products/test-pipe-1980on-4-bolt

[PhillySpider]

If it's an FI Spider then you have a 4-2-1 system, which works well for the stock engine. To get a 2-3 HP gain you can replace the cat with a test pipe if your area allows it:

https://autoricambi.us/products/test-pipe-1980on-4-bolt

Here in PA i get to sport antique tags. Hence no emissions or inspections required . Looks like this is in my futrue, no welding required I'm down. Should I save the old cat for originality when these hit 6 figures LOL!

[So Cal Mark]

you'll also need a straight-through muffler to reduce backpressure

[brackie1]

Mark, since I can't find a 4-2-1 manifold right now I have decided to change mufflers. I have a '77 carb non-cat. What you recommend?