[Born_Fast]

Hi everyone,

I recently ordered Larini headers and a 200 cell sport cat for my Elise SC.
I already got a Larini clubsport muffler and those other parts are supposed to complete my exhaust system.

To avoid error codes I got myself an air sensor restrictor (spacer), but will that do the job or are other modifications needed to run this complete exhaust system without troubles?

In another thread I read that headers and a sport cat will make the engine run lean without an aftermarket engine tune. Can anyone please confirm if that is true?

And if I really require a different tune, then which one is recommended to get?

What other problems might I run into when changing the complete exhaust?

Thanks for all your inputs as I plan to "do this once and do it right".

 

[sturgeongeneral]

From what I understand the gains in power will be minimal without a supporting tune. It will sound better, but a tune will optimize any gains.

 

[ERP]

What to consider when installing a sport cat - That it will fail with track use

On the street it will be fine. I used a sport cat and rear O2 spacer with no issues, until I completed a few track days. Talk to BOE if you want to get a new tune.

 

[Born_Fast]

Sure I expect that any gains in hp require a new tune. Ideally I would want to remap my ECU when also opting for a better supercharger, but for the moment I'd prefer to only change my complete exhaust (if that alone will work).

But what does "failure with trackuse" mean? Does a sport cat regularly throw codes during spirited driving sessions, which can simply be deleted afterwards? Or are there any other drawbacks I will have to deal with?

 

[Gunpilot]

It means you will fry the sport cat.

Talk to Phil at BOE for your tune.

 

[Born_Fast]

So the "sport" in sport cat means it won't survive any sportive driving??? :facepalm

Does a new tune help with that issue or is the tune only good for some more hp?

 

[Gunpilot]

Sportive street driving yes, track abuse no!

 

[Born_Fast]

Sportive street driving yes, track abuse no!

Does that mean a regular (more restrictive) stock cat is better for track use than a 200 cell sport cat?

 

[holmz]

Sportive street driving yes, track abuse no!

How is that?
Too lean or too rich?
The penalty for no CAT can be high...

 

[Gunpilot]

No cat is better for track use. Your engine is a pump, the cat restricts your exhaust flow, in some cases increases fuel efficiency because your engine works harder to pump out the exhaust. The less restrictive it is the more efficient.

A sport cat has a smaller element and increases your flow a little bit. It may or may not pass emissions.

I'm no specialist, but I would say prolonged heat and external forces would contribute to premature failure.

There is no requirement for a cat on a track. Penalty? When was the last time you got pulled over and was asked to remove your diffuser?

 

[tomrev]

The problem is with continued WOT running ,as on track, cat gets too hot, and fails / melts / catches on fire. Pretty hard to run that hard for that long on the street, unless you are truly a social misfit.

 

[Born_Fast]

The problem is with continued WOT running ,as on track, cat gets too hot, and fails / melts / catches on fire. Pretty hard to run that hard for that long on the street, unless you are truly a social misfit.

Thanks for these answers! Due to strict noise regulations on many tracks around here I doubt that i could race my car with a straight through decat pipe. There are technical inspections (including noise measurement) before the start of every race.
...And on our streets the regulations are even stricter, so a decat pipe is not really an option for me. But how likely is it that a stock cat or sport cat will fail or even burst into flames during 2-3 track sessions per year?

 

[tomrev]

Running a cat-delete on the street is pretty common, I believe,as you still have your muffler. Cat-less will increase the volume some, but is not a deal breaker. Depends on what exhaust muff you choose to go with. I have a dedicated racer, so my Elise is for the street, and I can't say from my own experience how quickly a tracked cat will fail, but factors like a richer tune, for a SC, will cause the cat to work harder, run much hotter than factory designed for, and the confined area of our car's exhaust area all work against a cat surviving longterm on track days. Track sound meter's are almost always set up to read on the outside of the track, along main straight. Racer's design the exhaust exit aim with this in mind, to point away from the reading meter.
I had a pretty wild Lotus Seven years ago, with a Supertrap muffler; Running a track day at Waterford, in metro Detroit, it still wouldn't pass, and I was pulled in, along with the Caterham I was dicing with after 2 laps. All we could do was sail around at 10/ 10th's, till a portion of the back straight, then both slipped her in neutral, coasted for a few seconds past the sound check, then resumed battle. My pipe was on the wrong side of the car, but was a street car, so wasn't going to change.

 

[invictusmaneo]

The problem is with continued WOT running ,as on track, cat gets too hot, and fails / melts / catches on fire. Pretty hard to run that hard for that long on the street, unless you are truly a social misfit.

Not entirely...not really common on Eliges, but a friend of mine with a Stillen supercharged 370Z managed to melt one of his sport cats into a molten ball (ceramic core sport cats last a little longer than metallic in general), clog a muffler, and wreck one cylinder bank requiring a new motor...no track days...so it can happen.

A good tune will mitigate issues, but prolonged track use will wreck cats one way or another. You could have an exhaust shop v-band the Cat and build you a V-band straight pipe so you can swap it out street and track to save you from wrecking a 300 dollar cat every few track days.

 

[Born_Fast]

The hardtop on my Elise came from a Lotus that suddenly bursted into flames during fast highway driving. The owner left the hardtop at home on that day and therefore it was the only part that survived the fire. The specific source of the fire was never identified, but he said the flames came at first from the engine bay.

That other Elise had an aftermarket supercharger installed and most certainly also a different tune. Could it be that these components caused the cat to overheat and this heat lit up some other parts?

I have a similar upgrade route in mind for my Elise, by first installing headers and a sport cat, then a different tune and later on an intercooled supercharger. However I definitely want to minimize the risk for my car to find its end in the same way as that other poor Elise.

 

[holmz]

Running a cat-delete on the street is pretty common,
...

Yes, but still illegal. If one is in Missouri maybe it is not an issue, but the fines cans be very high elsewhere.

The other kitty killer is that many people run "a conservative" tune... assuming the really rich is conservative.

The V-Band recommendation was good.

 

[evansp60]

For sound at the track remove the cat and put in a resonator.
This will muffle some of the sound but not fry when driven hard.

You'll still need a cat for etest.