Engine bay floor pan

[streeties]

Evening all, Hopefully this is in the right spot.. 

I'm in the process of re-building a GBS zero with a 1.8L Mazda engine and have it stripped down to the bare frame. I'd like to try and add a removable floor pan to the engine bay / any open areas on the bottom of the car. The reasons for this are twofold, firstly and most importantly it's to try and keep any road debris, mud, water, etc out of the engine bay. Secondly, and I'm likely being optimistic here, I'm thinking that closing the bottom of the engine bay would prevent air from passing through the nosecone and then out under the car which would if anything add lift. Whether this actually adds lift to a car that sits 100mm off the floor and is relatively "thin" width-wise is questionable but, my understanding is that in most track / racing applications, adding air underneath the car is a big no-no hence the use of bonnet radiator vents and rear diffusers. 

I was wondering if anyone else has done / considered this and what effect it had if any? 

If I were to do this, I'd likely weld on small tabs with captive nuts around the inside of the engine bay, 3/4mm up from the bottom of the frame. I'd then cut a piece of 3mm ally composite panel which would be held in place using the captive nuts and some U strip around the outside to seal everything up and stop any rattles. This should give me a nearly perfectly flat bottom to the car with no extra air being forced under the car from the bottom of the engine bay. My main concern with this is that in closing the bottom of the engine bay, I might be effectively closing out the only air vent for the engine compartment and in turn limiting the amount of airflow over the radiator and the amount of cooling it can deliver. I could, and likely will add bonnet louvers to help vent some of the air but this wouldn't come close to the same surface area of the nosecone opening.

Any thoughts or ideas would be much appreciated. 

Thanks in advance, 

Sam

Edited May 31, 2023 by streeties
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[nelmo]

As you say, I've never heard anyone complain of lift on a GBS - the old RHs with clamshell wings had that but not a Zero.

However, LOTS of people have over-heating issues and bonnet louvres help but closing in the engine bay is not a great idea IMO. The Zero bay is already half-closed in, with the side panels extending to the inner chassis rails, so it's not a huge expanse left uncovered. The engine sump accounts for another large chunk of the inner section - I get very little debris into the bay.

[streeties]

Thanks Nelmo. 

I assumed heating would be a more important issue than the tiny amount of lift that might be reduced. Plus, if Caterham aren't filling in the floor area then they must not think it's any issue. 

[Darrell]

I would suggest closing in the engine bay would add to a higher temp in the engine bay and possibly lead to problems.

I agree with Nelmo, I also get very little debris in the engine bay