Exhaust Conundrum

[Janbur]

I discovered this weekend that one of my car's previous owners removed the muffler but kept the catalytic converter. I've been wanting to do something to improve flow, reduce turbo lag, and make my note a little louder. It has been suggested to replace the cat with a bypass pipe and keep my existing muffler. I like the note but just want it a little louder. My recent discovery changes everything though. If I remove the cat now, I'll have a straight pipe. My neighbors probably wouldn't appreciate that very much. So, the way I see it, I have two choices. The first is to go with a high-flow cat and continue to run without a muffler. The second is to ditch the cat and install a muffler. I don't know which is the best for flow, and I'm concerned that if I mess with it too much, the note will change completely. I've read that Random Technologies has a cat that flows more CFM than a muffler, so that might be an option, but if the best way to go is to remove the cat and go with a muffler, I'm afraid that I'll destroy the sound in doing so, not to mention about the illegalness of doing that. Does anyone have any advice on this?

[local600]

This is the easiest and cheapest solution:

[Randy Chase]

Seems odd to use a cat for sound quality. Makes more sense to remove the cat and add a muffler, properly tuned for the sound you want.

[Janbur]

Thanks local600. You provided quite the inspiring response.

Randy, that was my thought as well. The problem comes in choosing a muffler. The note will most definitely change if I add one. That's why a high-flow cat is appealing. My hunch is that the note won't change that much by replacing the cat with one of those. The real question is whether or not a high-flow cat with no muffler will get me equivalent or greater exhaust flow than a muffler with no cat. My goal is two-fold, increase flow while getting the note a little louder.

[Mr. Know]

You want a note that's a little louder than running no muffler at all? I'm confused...

[Janbur]

Yeah, I know it sounds dumb, but the cat that's on there, which I assume to be OEM, does a more than adequate job of acting as a silencer. I've heard other Esprits with the 910 sound louder, but they had the cat removed and used an aftermarket muffler. I guess I'm really focusing more on the flow and will assume that whatever I end up doing will result in a little louder note as well.

[carbuff]

Originally Posted by Janbur

Yeah, I know it sounds dumb, but the cat that's on there, which I assume to be OEM, does a more than adequate job of acting as a silencer. I've heard other Esprits with the 910 sound louder, but they had the cat removed and used an aftermarket muffler. I guess I'm really focusing more on the flow and will assume that whatever I end up doing will result in a little louder note as well.

I can't speak for the "note" (which IMO is subjective) but the '88 came with a 3" exhaust that was louder than any that came from the factory after that.

A simple resonator would change the sound of the exhaust without resulting in backpressure...that's what the "Neil Micklewright Exhaust" for later cars consists of. (But these are 2 1/2" systems)

We installed a cat bypass pipe and NM muffler on an S4s, then measured decibels...that setup was only a little louder than the stock exhaust on my car.

Perhaps the previous owner needed that converter in place to pass an emissions check?

[Janbur]

Atwell,

I just Googled and found your sound report on your chapter's website. Interesting indeed. I might just leave mine alone after all. :^) You can't get those Micklewrights very easily from what I hear. Only a handful were made, and they consisted of a Magnaflow resonator IIRC. That's what the fellow at LOG had that had me drooling. He was 2 cars ahead of me on the scenic drive and I heard him over my own pipes, not just loud but mean and clean. If I only knew what the model number of that Magnaflow was, I might be able to fab my own.

Brian

[carbuff]

Originally Posted by Janbur

You can't get those Micklewrights very easily from what I hear. Only a handful were made, and they consisted of a Magnaflow resonator IIRC. That's what the fellow at LOG had that had me drooling. He was 2 cars ahead of me on the scenic drive and I heard him over my own pipes, not just loud but mean and clean. If I only knew what the model number of that Magnaflow was, I might be able to fab my own.

Brian

Sanj Vatuk might know what type of Magnaflow. I'll ask. But again, YMMV since the inlet and outlet pipes are 2 1/2" not 3" in size.

EDIT: Sanj reports the muffler is a 4" x 14" round Magnaflow, p/n 14416.
MagnaFlow Performance Exhaust
The 3" version is # 14419.


PS If you were following the yellow NJ S4s, lets ask his GF how she liked the sound after 8 hrs on the highway.

If you really like the roar of an engine, buy a normally aspirated S2 Esprit. THERE'S a healthy exhaust note! Especially in the Lincoln Tunnel...

[Janbur]

Wow, thanks for the leg work Atwell. If I decide to do away with the cat and go with the Micklewright-type setup, I know exactly what I need to get now.

Yes, I was behind the yellow NJ S4s. That thing was the best sounding Esprit I've ever heard. The cool thing is my wife thought it was too! :^)

PS, was your car the one at the concours that said "no wing" as it's special note? If so, I was just a few cars down in the front row next to Young's yellow V8 at the Speedway.

[carbuff]

Originally Posted by Janbur

PS, was your car the one at the concours that said "no wing" as it's special note?

Yeah, not having a rear wing is my "running gag" on the TurboEsprit forum.

At LOG 26 I "borrowed" another owner's Esprit and had to cover his wing with newspaper to hide it! Can't let my adoring public down!


+++++++++++++++

Anyway, the yellow Esprit has a Cummings Test Pipe installed in lieu of the CC, and a Micklewright exhaust.

[socal450]

Hey Janbur,I am picking up a 90SE on tuesday and the exhaust is my first concern.I live in So.Cal. and they are strict on emissions,so I dont want to touch the cat,are you telling me that running a straight pipe(cat back)does not improve the sound.Thats the first thing I was going to do! Can you give me a brief description of how it will sound compared to stock,ie-just a bit louder,deeper,much louder,the same,etc...The last thing I want it to sound like is a Japanese import!! What size pipe do you reccomend(or muffler if any) Thanks......

[carbuff]

Originally Posted by socal450

I am picking up a 90SE on tuesday and the exhaust is my first concern.I live in So.Cal. and they are strict on emissions,so I dont want to touch the cat,are you telling me that running a straight pipe(cat back)does not improve the sound.What size pipe do you reccomend(or muffler if any) Thanks......

There are several options for exhausts on a 90.

First of all, some of those years had a left-exit pipe and some had a right-exit. A 90 SE would use 2 1/2" pipe.

With some modification to the lower valence you could even install a dual exhaust (hint: the late-80s Camaro used a 2 1/2" single inlet with outlets on each side, look on the Magnaflow site previously referenced)

You will get a deeper sound with a cat-back resonator rather than a straight pipe, in my observation. For some reason, stainless systems have a deeper sound than mild steel, as well. (And they last a heckuva lot longer. Buy a Flowmaster at your own peril.)

For extra dollars you could even get a late V8 look with center-exit exhaust and the metal "Cheese-Grater". Viking Motorsports (Harry Applebee) sells these kits:

http://www.vikingmotorsports.com/parts%20001.jpg
Installed pic on his home page!

You would probably need a new lower valence though.

All of the above would make the sound louder and deeper than stock, which as I mentioned, were designed quiet because of European noise regs.

[Janbur]

socal450,

Atwell certainly knows his stuff. He's a good one to listen to. Unfortunately, I never had a chance to hear what my car sounds like with stock exhaust, but I have no doubt that it would have been quite a bit quieter. The note and loudness that I have right now is really great. No ragged-out, whiny Civic sound there. Just a nice deep rumble. If I hadn't heard that yellow S4s at LOG, I would have been perfectly content. Perhaps it's a "grass is greener on the other side" type thing. I'll see about taking a video and uploading it to YouTube or something so you can get a feeling of what it's like. Not sure how good the sound quality will be, but will give it a try. Like Atwell said, though, your car will have 2 1/2" exhaust, whereas mine has 3". From what I understand, the smaller the diameter, the more defined the note will be. I've also heard that 90 degree bends in the pipe can make a big difference. I may try to get something fabbed that gives me the routing I need but without 90 degree bends to see if that theory proves true.

[Janbur]

Sorry it took so long, but I finally had the chance to slap a crude YouTube video together:

YouTube - 1988 Lotus Esprit Turbo

The audio quality kinda sucks, especially on the cackles.

[carbuff]

Originally Posted by Janbur

The audio quality kinda sucks, especially on the cackles.

Brian, Do you LIKE the "cackles"? Because that usually indicates a malfunction in the fuel bypass valve system. Your ECON light in the right side of the pod should light up between 3200 RPM and 1500 RPM on over-run.

Other than that your exhaust note sounds great. Like you said, no "ricer" tendencies with Lotus!

[Janbur]

Atwell,

Hmm, well, I dunno, I thought they were just normal cackling that occurred when the engine was holding back (that's the only time it happens). I have no lights coming on at all. One other thing that I forgot to mention is that the EPV (exhaust pressure valve) has been removed. I'm not sure if that would have anything to do with it. I can only assume that whoever did this mod also took care of the upper side of things (I briefly researched this on one of the Esprit sites).

[carbuff]

Originally Posted by Janbur

Atwell,

Hmm, well, I dunno, I thought they were just normal cackling

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