Might have scuffed mine a little bit on a fast compression on the moors and now it's falling off.
First car I've ever had one on. Do I actually need it?
You may find engine cooling compromised if its not there. Noise will increase too
My Alfa used to regularly hit the deck on compressions.
Does a few things, even on normal cars. It helps channel air around the engine bay, it helps keep junk out of the bay and it helps improve fuel economy. You can do without it with very little effect, but it's not ideal. Not got them on any of my cars after snow/ice fun but I'd put them back on if they were cheap enough. Unfortunately they're usually stupidly expensive.
You may find engine cooling compromised if its not there. Noise will increase too
I would have to disagree 2wass. They only have one purpose, to improve underbody drag, but enclosing the engine bay mostly reduces the exits for hot air. It may increase wind noise slightly at speed, but doubtful thats noticable.
What is much worse is leaving it hanging down like I see on so many cars, flapping away. That certainly will increase drag and make noise.
usually just screwed/bolted one, just see if it's ripped off at the bolt holes. If not it can slide into part of the chassis before being bolted and secured. It protects the engine and as said above may aid engine cooling although I don't believe it channels any air on the cars I've had... it's just collect a lot of crap on the engine side
I had a car without one, during a particularly wet winter, driving a lot on somewhat uneven country roads.. Every time I went through any amount of standing water (ie very frequently) the engine would almost cut out and struggle badly for a good 10 or 20 seconds. After a big one it was touch and go whether or not my momentum would be enough to keep the engine turning long enough.
They do have a cooling function, usually forces air through the rad into the engine bay then out the rear if the engine bay.
Mine fell off (my driving over some rough ground may have had something to do with this) 6 months ago. All fine so far!
Replace with a nice alloy sumpguard as soon as possible.
Then you can really have a go at those compressions !
Don't they provide a degree of protection? Are you planning on scuffing it again?
Zip ties are your friend...