Exhaust pipe shape

Here are 2 pics from my exhaust system. Basically you have the V8 and a twin-turbo setup, next are the catalytic converter and the racing mufflers.

I noticed that there is a kink in the U-shape of the custom made muffler pipe. Do you think this affects the exhaust gas flow and the performance to the extent I should change the exhaust ?

P.S the setup is in a 2001 Lotus Esprit V8. (My other car is a Ferrari 360 Modena thats why I post here !! Hehe)
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Uh yeah, that is totally not good. If anything you should put an x-pipe merge in there.

 

Actually, I bought the car with this setup last week.
I went to a well known muffler place in my neighborhood to discuss about putting test pipes in the place of the cats with V-band exhaust clamps, so I can install and remove the test pipes whenever I want.
Once he saw the setup, he didn't like it.
He told me to build an exhaust with an x-pipe as you suggested to help the scavenging of gases.
Do you think I will see a difference (more power/ better sound) ?
I originally didn't want a new muffler, in your opinion is it worth fixing this muffler ?

 

Yes.

The x-pipe will help smooth out the exhaust note, and you'll pick up a little bit of power. You do not want the pipes to completely merge, just enough to expose pulses from one side to the other. Be sure to do a before and after dyno so you can see the results.

Here is a pic of a race exhaust I had made for my 348.

Keep us posted.

 

I would also chat with the Lotus owners as much work already done here..... absolutely agree with E ref that sumo too... see what your baseline is and what you’re going to solve/improve for your cash.

Does it feel like you have a lag/power issue?

At one point US cars cane with the Lotus sports exhaust system, but there are lots of mods. Another benefit is weight saving - the stock is not light!


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Ernie has already told you of the solution, and as cut and welds go, a fairly easy and straightforward one.

 

Do you think it's worth fixing ? Or go with new system ? (exhaust guy wants to sell new system !! Hehe)

I think it is fixable..

The only thing left to do merge just a little bit the 2 pipes to create x-pipe, and install V-band clamps to be able to remove and install test pipes !!

All agreed ?

P.S. the other scenario is to build from scratch an exhaust with test pipes and leave this system with the Cats just in case I need to put it back from MOT inspection !!

 

And one more relevant question, shouldn't the X-pipe go before the actual muffler, or is it ok to put it after the silencer as it would be in my setup ??

I read somewhere that you want the x-pipe as close to the engine as possible so that you get maximum scavanging effect.

If that's the case, then I will need to put the silencers after the x-pipe

 

I would put the mufflers/resonators after the x-pipe. Another thing you may want to do is replace the stock catalytic converters with high flow metal core catalytic converters. I'm running 200 cell metal core cats on my 348. The cats can be a big area of exhaust flow restriction. I assume your Lotus is turbo, and turbos need LOTS of exhaust flow to make proper power.

So my vote is a completely new system.

Again, be sure to get a dyno test done before you take the current system off, and then again after you put the new system in.

 

Totally agree.

 

One more thing.

After you put in the new exhaust system have you car custom tuned on the dyno to take full advantage of the modifications.

 

I did my research and posted on Lotus forums too (no response there, I guess people are not that active with Lotus cars nowadays) and I came to the following conclusion : I want to do decat , and have a muffler that runs without any kinks or bents (such as in my car).
Furthermore, I came to the conclusion that x-pipe works well with NA engines that will indeed create scavenging effect and they help in creating low torque and making the car more civilized for daily low speed town driving... For race cars, all applications are straight pipes...
The same I believe applies for turbo engines, where the exhaust gases are slowed down (the turbo steals their kinetic energy) so there is little point in x-pipe... do you agree ??
What exactly is the difference between decat pipe and silenced decat ?? does it have absorption materials around the straight pipe ?
I wanted decat test pipes, but I am also thinking about silenced decat pipes both for visual (it looks like a normal catalyst) and sound (to reduce a little the sound)

 

On a turbo engine you want to reduce backpressure as much as possible, in this case post-turbine. X-pipe will not help you. Removing cats will, exhaust without cheated bends will.

I would toss what you have and start over as it's cheated going into the mufflers as well.

 

In the UK (apologies if not much help) a couple of LOTUS indies did custom manifolds too. I believe these claimed to offer better flow and heat resistance/longevity. You may want to research those as you may find useful performance gains.

I wouldn’t be averse to contacting Hethel either. You might find they are happy to help. Surprised the UK LOC hasn’t quite a bit on this. If I can dig out any of the info I had when looking at turbo charging I’ll post.


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http://users.ox.ac.uk/~ohare/exhaust.htm

This site may be of interest...


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I was looking under my Lotus today and I am very tempted to simply put 2 pipes right after the turbos with 2 exhaust tips... The distance is so short, and I bet this would give the best power results... Not sure if I will be able to tolerate the sound though...
I looked up at 2 UK Lotus parts suppliers (one starts with SJ.. and the other with PN..) and they offer either the original Lotus V8 Sports Exhaust or a kit with test pipes that go after the cats and convert the car to center exhaust exit...

I am considering following options :

1) simply replace cats and muffler with test pipes with exhaust tips : Best power, maybe too loud, probably fireworks (which I like)
2) replace cats with decat pipes and find sports muffler , either custom or original Lotus part : Good power, good balance, maybe fireworks
3) replace cats with silenced decat pipes and find side exit test pipes : Same power as (1), loud but not excessively, probably fireworks

What do you guys think of option 3 Image Unavailable, Please Login

 

That looks like Quicksilver? I would look at bore sizes - think there was something about stock in 30s moving out to mid 40s?

Would have thought you could have something in even mild steel made v cheap as a test.

As before/others, get it dyno’d before you change and do a DB check.


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While there is a gain in the low-mid ranges with an X-pipe, race engines are not used down there and the weight does not pay for itself.