3FE exhaust mods, any noticeable power gains? (1 Viewer)

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J

Jiggy

Joined
Mar 20, 2004
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I've seen a few people on here with pretty heavy exhaust mods on the 3FE, just wondered if they felt it was worth it in the end. Noticeable power gains? Mileage?

I'm ready to cut my cats off and put on the MAF header if it'll give me a worthwhile advantage, just want to know before I take the plunge.

Let me know what you've done and what it did for ya!

-Thanks!

-Jared
 
I gutted my two cats and did not feel a thing. On a side note, the rig sound more tin(ny) now.
 
Nothing real radical, but I put a cat back dual system on my 92, 2.25" pipe w/ dual inlet/outlet flowmaster that acts as the crossover. The system is run in the same place as the original system except I turned both pipes out behind the ps rear wheel.

Besides sounding better, I immediately noticed more pep in the rig. The duals also improved my fuel economy as I get a consistent 14 mpg now as opposed to about 12.5 before the conversion. I can now squeeze 16 mpg on highway trips at 65 mph and below.

What has impressed me the most is that the rig runs noticeably cooler when stressed or run harder than normal. It still heats up to normal temp range, but biggest difference I have recognized is I use to be able to see the temp gauge move/creep up a bit when running it harder than normal up over grades, pulling the trailers, or during times when you are just on it harder. Now, the temp gauge does not even flinch. :D

Got it done with a great exhaust man and $375. I did make sure the cats were flowing good first or I would have had to spend a bit more. Overall I am very satisfied with the mod and it comes with a bonus; it will eventually pay itself back in the gain in fuel economy. Can pm you some pics if interested....
 
I'm not 100% on what you mean by pretty heavy exhaust mods, getting an exhaust done is pretty common for all vehicles.

IMO, skip the headers unless you have your engine out. The consensus is that they are more of a pain than they are worth (leaks, hard to fit, etc.). If you can get away with taking out your cats, then do it. Also anything else you can do to open up the exhaust (larger exhaust, dual exhaust, better muffler, etc.) will help greatly.

Best bet is to get a trusted exhaust shop to do dual 2" or single 2 1/2"-2 3/4" with high flow muffler(s) and gut your cats. The single 2 3/4" is what I am running now, cats come out next week to be gutted.
 
I have a really great exhaust shop near me, and they'll "customize" my cats for me if I'd like. I think I'll ask them about the dual 2" and single dual in/out flowmaster. Thanks for the info!

-Jared
 
If you are going to do the whole exhaust, headers may provide a noticeable improvement over the stock manifolds. I had headers on a 60 series 2f until the smog police caught up with me here in cali. Freeway hills that I could run in 5th with the headers were 4th gear hills after going back to the logs. Don't expect miracles though... it's still a 3FE...
 
I'll check them out, but yeah, I was intending to go from the engine back if possible.

Has anyone had any problems with the enging popping codes due to the cat removal?

-Jared
 
exhaust mods

I have both my cats removed and a 40series flowmaster. I did not notice much increase in noise when doing either. I do get better mpg than most, from what other people tell me as least. I just recently cut off my tail pipe right after the muffler. And yes its alot louder inside and out. I noticed the most benefit when running at high speeds. Usually I can only get up to 90 unless its a big downhill,...but the other day I got it upto 95mph on a flat. Like most have said, don't expect too much just keep the pedal to the floor!:grinpimp: 3FE POWA!!!!
 
Gutting will be taking place next week. 2.5" from the manifolds, solid pipe pushed thru the cats and welded in place, and a dual-into-dual flowmaster 50 series with the low resonance.

Is dual 2.5" too big? I don't want to burn up my valves.

Thanks!

-Jared
 
With these, you can't go too big. But you're not gonna fit 2.5" over the frame across the drive shaft, nor are you gonna be able to fit dual 2.5 out the back over the rear axle. You can fit dual 2.25" all the way to the muffler, then you could go 2.75" or maybe 3" out the back
 
Sounds good, I'll tell them to go as big as possible. I'll be dropping it off monday and heading to the bahamas on tuesday, so I won't see it till at least wednesday the 26th, but I'm hoping for some kind of improvement.

I'm still debating having them rip the head off and getting the valves reground. I think that might help me notice more gains, maybe get it ground down a few thousandths.

Any more advice as to what I can do to get a bit more out of it? Wanting to get the OME lift and bull bars/sliders, but with the current power levels I can't see that happening.

-Jared
 
Alrighty then!

Had to go dual 2" from the manifold, did keep the pipe-thru-the-cat trick tho, and kept the 2" dual up to the flowmaster, and right out the back.

Removed the muffler from the spec location, removed the heat shield, removed the spare tire carrier and placed the new muffler in the spare tire space. The dual tips exit in the center, about 1"-2" on either side of the tow hitch holes which keeps the exhaust pipes between the frame rails from the cats back. The pipes only drop 1.5"-2" below the bumper to minimize dragging.

So far I'm very happy. I've noticed some fair power gains all over the RPM band. The sound is really raspy but tho unlike a V8, still really cool. Still planning on getting the head re-done. How much do you think I could safely shave it before I'd start seeing detonation with regular gas? I was thinking betwen .03"-.05" would put me pretty close to max on regular gas, but I invite comments!

Also, any chance I can enlarge the intake valves? If so, what's the biggest I can go? And what else should I get done?

Thanks!

-Jared
 
Didn't notice any huge gains until I fiddled with the timing, and now it's a different vehicle. I hit 100 mph on flat ground with a headwind and still had more pedal left in it, and I couldn't believe it! Mileage is dramatically better, takeoff and top end are both dramatically improved. It's like having a different engine in it, and I'm now happy.

Thanks!

-Jared
 
The 3FE has two marks on the flywheel to set the timing. One mark looks like two BB's (as they are commonly called) the second is a single BB timing mark. The two BB's is TDC, the single is 7º BTDC.

The way to advance the timing is to use a advancable timing light. Advance the dail to your desired setting (Ex. 9º) BTDC.

Don't forget the pins in the diagnostic box in the engine bay.
 
To expand on jklubens post, it was really hard for me to see the timing marks through all of the wires. I had to tape the timing light on and jamb it down as close to the "timing hole" as possible, then stand in front of the LC and eyeball the timing marks as I turned the dist. HTH
 
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