Running 1/4mile right off the collector and no air filter.

[lewd lude lover]

So Im just wondering how the engine would react if you suddenly took off the cat (or decat) and removed the air filter for a run at the pod or something.

It strikes me that you see plenty of massive money builds running open intakes so I'm not so worried about sucking in anything bad (bee's, dust etc) for the short time your running.

I wonder, would you need to give the car a few short drives about the showground, start stopping the engine, so the ECU had a feel for the new values being presented? They take an average over the past few drive cycles dont they? Or does it not matter when you running open circuit in VTEC?


And how might it affect your time? It would be one of the louder Honda's there thats for sure

The exhaust would be held tight on its bracket, you might want to use a steel tie and hook up the flexi section maybe? I cant remember off the top of my head how and where the braces are...


I think I will bring a jack and some spanners next pod meet and give it a try.


Or even just take off the manifold all together though that involves more messing about i think..

just a thought, what do you think?

[bristol_bb4]

I think the lack of exhaust may even just cause more of a problem than free some power, perfect for forced induction aplications as the exhaust need no back pressure where as n/a needs it. Removing the filter would help though for sure!

[mercutio]

yeah the exhaust has a lot to do with how much power the engine makes as a good exhaust will help scavenge gases from the cylinder and the backpressure has a lot to do with this i cant remember it all as it was ages ago when i read up on tuned lengths and stuff

[lewd lude lover]

''tuned lengths''


I see, that makes sense. So the same would go for superchargers etc then? im just thinking of the big V8's with the small pipes.


it would sound awesome

[A1ex]

We have a dyno day in a couple weeks. Why not try a run with a filter and a run without the filter & see what the difference is?

You'll have some comparable values then

[NafemanNathan]

Yeah, without an exhaust and therefore no back pressure, on an N/A engine you'd loose a shed load of torque. Also, if you're talking about doing it on a standard ECU, it'd need a number of reasonably lengthy drives at all different speeds and rev ranges before it "tunes" itself to the new setup.

Also, when you say "remove the air filter" are you meaning everything up to the TB? As without a proper tune you'll rev faster, but again you'll loose torque (and that's without taking the removed exhaust into account).

If you're considering doing any of this on your lude, then the only thing you would possibly see a gain from would be just to remove the filter from the box, but leave the rest in place. That said, your ECU would still need a number of drives at all different speeds, and the resistance lost from removing the air filter would be negligible (especially if said filter is that of the likes a K&N filter), and so it's not really worth the freak risk of your engine drawing something inside it really shouldn't

[Lude-dude]

I dunno, if noise is not an issue maybe undo the cat and have the gases blowing staight out the manifold?