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Exhaust-less?
PSpirine - 30/7/10 at 08:38 PM

As the plan is still hopefully to use a turbocharged engine (TBC) in my locost build, I was wondering what the IVA outlook is on having a car with no silencer.

I've worked on a couple of turbo (jap) cars that basically had an exhaust downpipe, approx 3" diameter and only long enough to expel outside the nearest point of bodywork (so we're talking less than 2 foot long here), and the turbo did a bloody good job of silencing the engine to the point that it was quieter than some NA's running with free-flowing cans...

Even my 1.9td wasn't very loud when the exhaust fell off on the motorway!


Is it a problem for Mr. SVA man, other than the db noise limit which hopefully will be containable?

Davey D - 30/7/10 at 08:44 PM

you will need a cat fitted unless your engine is old enough to not need one, and you can prove the age

speedyxjs - 31/7/10 at 08:11 AM

Your engine may not run very well without sufficient back pressure.

Benzine - 31/7/10 at 09:26 AM

quote:
Originally posted by speedyxjs
Your engine may not run very well without sufficient back pressure.


84(l< P12355l_l123

smart51 - 31/7/10 at 09:31 AM

quote:
Originally posted by speedyxjs
Your engine may not run very well without sufficient back pressure.


F1 engines seem to manage.

I know a guy with a turbo diesel kit car (I know!) without a silencer. It is surprisingly quiet. My cappuccino came with a tiny after market straight through silencer and it was about the same level of loudness as the kit car. I believe IVA requires you to have a silencer. You could either try to persuade the inspector that the tubo satisfied this requirement or you could fit the smallest one you can find.

Strontium Dog - 31/7/10 at 11:46 AM

You don't need back pressure to run your engine but you might need some to prevent your turbo from over spooling! A very good waist gate to a screamer pipe might do it though!

Mr. IVA man won't like the screamer though I suspect

PSpirine - 1/8/10 at 08:44 PM

Re back pressure, turbo engines don't need any back pressure from the exhaust system, the turbo itself creates all the backpressure into the exhaust manifold and back to the cylinders!

Didn't realise IVA *required* a silencer to be present.. technically the turbocharger is arguably a silencer (a device which reduces the loudness of the exhaust/engine noise?)

The wastegate is a problem indeed, but running it with an underspecced turbo for the IVA should work (won't spool up to full boost till quite high up the rev range so hopefully not too much will be going out the waste). Having said that even if you had a full silenced exhaust system and had an external waste gate it would still cause the same problem!

pdm - 1/8/10 at 08:47 PM

Try daz-davies at 22b.com - he's got similar thing on his subaru, under Projects.