Exige 380 exhaust onto a 350

Exige 380 exhaust onto a 350

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Discussion

Leggy

946 posts

187 months

Saturday 15th April 2017
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Am I one of the few that doesn't mind the stock V6 Exige exhaust?
Technically apart from the sound are any of the after market exhausts better?
Jim supplied one for my previous Elise SC and it made a noticeable difference in pick up.

Jesus

12,663 posts

154 months

Saturday 22nd April 2017
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I don't mind the sound, but it looks so bloody awful.

Wayoftheflower

950 posts

200 months

Monday 24th April 2017
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Wayoftheflower said:
321freeflow said:
{ yawn } But hang on a bit and I'll show you some from the UK.
Hanging on a bit, more.
Don't leave me hanging! I'm intrigued as to whether it's a colossal stuff up by Lotus, or something else.

321freeflow

281 posts

186 months

Tuesday 25th April 2017
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Wayoftheflower said:
Don't leave me hanging! I'm intrigued as to whether it's a colossal stuff up by Lotus, or something else.
Sorry! I'm a very busy man - plus we're moving into a new-build unit - it's hectic.

I doubt very much if Lotus could tell one end of an exhaust from the other. Their systems are built by another firm - and my opinion of that outfit is well-known.

As for the "colossal stuff up": boost drop when changing to a larger inlet/exhaust is well understood by tuners dealing with forced induction motors. Looking at the big-bore downpipes and system on the 380/400 installs, maybe they just went for the NOISE.
With that size of bore on a 350bhp motor, you lose control of the sound (as well as boost-drop!).
Appreciation of exhaust sound is subjective anyway. I don't like the "gargly" note of the 3" bore - but it has its fans. There's little you can do about large power increases on the 2GR if you retain those awful log manifolds with their integral "pre-cats" - and Lotus HAVE to keep them for emissions certification world-wide. Those UTC's (Ultra Thin Catalyser) in the pre-cat manifolds are a fragile ceramic substrate and they're showing the strain with several engine failures that I know of. Let's face it 350bhp from a 3.5Ltr supercharged V6 is PATHETIC.

I can't discuss the dyno graphs any further. I will show you precisely what happens with 2.75" Vs. 3" when we finish this move.

You talk about "back-pressure" - if it was a simple case of fitting a 3" exhaust then EVERY car would have one. Gas-speed is absolutely critical to performance and exhaust bore is an important part of the mix. I need to get on - will post more later.

Wayoftheflower

950 posts

200 months

Tuesday 25th April 2017
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Can we leave the slagging off of Lotus/Toyota designers? It does smack a little of wanting to drum up business.

I would be gob-smacked at Lotus forgoing another 40bhp and getting a saving on exhaust pipe sizes into the bargain though.

I've not had a problem with the supplier you hint at, their facility seemed good to me when I visited a couple of years ago, they were transitioning from short aftermarket runs to more serious volume with the non-Lotus OEM business they had. They demo'd some lovely titanium work as well. However they are a business and Lotus are renound for not paying well so I'm not surprised at low cost welding to get margin. Valved exhaust have pretty serious leakage around the pivot of the butterfly anyway.

How do you "lose control of sound" The frequency response of a pipe is far more dependent on its length than diameter.

I do agree with you those integrated cast iron manifolds with close coupled cats must be phenomenally restrictive designed as they are for an NA engine with ~6500rpm limiter. There's probably a 20% power increase locked up in them. But that's what Lotus' engine supplier have and until they get a new one or the money to homologate their own system they're stuck with it.

I await with interest the 2.75 v 3" pipe data. What's the mechanisms for the boost loss, excessive valve overlap or change in scavenging?

Edited by Wayoftheflower on Tuesday 25th April 21:49

jayemm89

2,985 posts

95 months

Tuesday 25th April 2017
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I would like to know at what power levels you think a 3" Exhaust becomes necessary Jim

321freeflow

281 posts

186 months

Wednesday 26th April 2017
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Wayoftheflower said:
Can we leave the slagging off of Lotus/Toyota designers? It does smack a little of wanting to drum up business.

I would be gob-smacked at Lotus forgoing another 40bhp and getting a saving on exhaust pipe sizes into the bargain though.

I've not had a problem with the supplier you hint at, their facility seemed good to me when I visited a couple of years ago, they were transitioning from short aftermarket runs to more serious volume with the non-Lotus OEM business they had. They demo'd some lovely titanium work as well. However they are a business and Lotus are renound for not paying well so I'm not surprised at low cost welding to get margin. Valved exhaust have pretty serious leakage around the pivot of the butterfly anyway.

How do you "lose control of sound" The frequency response of a pipe is far more dependent on its length than diameter.

I do agree with you those integrated cast iron manifolds with close coupled cats must be phenomenally restrictive designed as they are for an NA engine with ~6500rpm limiter. There's probably a 20% power increase locked up in them. But that's what Lotus' engine supplier have and until they get a new one or the money to homologate their own system they're stuck with it.

I await with interest the 2.75 v 3" pipe data. What's the mechanisms for the boost loss, excessive valve overlap or change in scavenging?

Edited by Wayoftheflower on Tuesday 25th April 21:49
I don't have to "drum up business" - but I do enjoy taking a pop at certain firms. They deserve it.

Production savings on a difference in pipe size of 0.25" isn't worth bothering about.

You're "gob-smacked"? I was sitting in the office of ***************** when Lotus phoned - they were "gob-smacked" too! Still makes me smile when I think about the timing of it all. Sitting there looking at those graphs. I have TOLD you what the cause of the power loss was.

If you're claiming that Janspeed build the optional Titanium exhausts fitted to the 380/400, I would suggest you're mistaken.

Noise-control is what it's all about these days for the trackday enthusiasts. You can witter all day about pipe lengths/frequency etc etc - my opinions are totally empirically based. For instance I know absolutely if I fit a 2.5" bore exhaust on a 1.6Ltr Elise S, the noise is horrendous as well as the dronnnnnne. Janspeed know all about dronnnnnne - e.g. Stg2 and Stg3 systems.
An engineer based in Norfolk sticking up for the Lotus exhaust supplier Janspeed scratchchin

Power: There's plenty race teams looking at over 500bhp on this motor. A race team in the Far East tell me they have 550bhp with the 2.75" exhaust - but they don't have to fit a catalyser. I would suggest the limit on this bore would be approx. 600bhp. Cooling is the MAIN issue when you're up at those outputs though.

I've answered the OP's request, so I'll leave this thread now.





Wayoftheflower

950 posts

200 months

Wednesday 26th April 2017
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321freeflow said:
I've answered the OP's request, so I'll leave this thread now.
Shame, I thought I might learn something new and interesting, and after twenty years in the business that's still what gets me up in the morning. But judging by the lack of data, coherent explanation for the physics at play and attempted mic-drop exit I'll remain deeply skeptical of your original statement.

Based in lovely Norfolk, paid to travel the world solving problems, I'm a lucky boy wink



321freeflow

281 posts

186 months

Thursday 24th August 2017
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Wayoftheflower said:
I've not had a problem with the supplier you hint at. They demo'd some lovely titanium work as well. However they are a business and Lotus are renound for not paying well so I'm not surprised at low cost welding to get margin. Valved exhaust have pretty serious leakage around the pivot of the butterfly anyway.

Edited by Wayoftheflower on Tuesday 25th April 21:49
Broken Titanium exhaust on a 380 - https://www.thelotusforums.com/forums/topic/85856-...

Long way to send it for a repair (hint, not Salisbury UK!) - anyway, it's not possible to repair that.



Wayoftheflower

950 posts

200 months

Sunday 3rd September 2017
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321freeflow said:
Broken Titanium exhaust on a 380 - https://www.thelotusforums.com/forums/topic/85856-...

Long way to send it for a repair (hint, not Salisbury UK!) - anyway, it's not possible to repair that.
Sad state of affairs indeed. Sadder still those dyno runs for the "380" on the same page.

mickv

83 posts

56 months

Monday 4th September 2017
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Wayoftheflower said:
Sad state of affairs indeed. Sadder still those dyno runs for the "380" on the same page.
Which are being investigated by Lotus due to them being abnormal.