Corrado engine bay undertray

[KipVR 1]

I'm currently thinking of developing an undertray to help airflow through the engine bay. I did a few tests measuring air pressures inside the bay a couple of years ago and there is too much low pressure at the front of it, resulting in the air not flowing through the bay cleanly. Instead, air swells up into the front of the engine bay creating turbulence, a bit like the way it swells up onto the back of a car, especially Volvo estates etc which have a big negative pressure area as they are so upright.

 

What I think is needed is to have roughly equal (slightly bigger exit as hot air = larger volume) inlets (via the rads) and outlets, which maintains a fast air flow rate through the engine bay and maintains even pressures. Resulting in air passing under the car cleanly (and faster helping down force :wink: ) and it follows a nice path through the engine bay with the hot air from the exhausts hopefully being the last bit in the airflow before it exits underneath the car, but maybe not so good in traffic when it just wants to rise, but on the same note at least the fans will force the air out of the back of the bay.

 

It'll also keep the bay a lot cleaner :D

 

Are there any already in existence?

 

Has anyone had any experiences with one? I seem to remember someone bringing it up here before but nothing seems to have come of it. If i make one it'll only be laser cut aluminium, no fancy carbon/kevlar or anything. Just cheap and cheerfull.

[davidwort 0]

there was a complete undertray for both the mk2 and mk3 golf diesels, fitment to the inner wings and subframe should be similar, only the front fixing might need something making up for the Corrado.

[boost monkey 0]

as david, plenty of people have fabbed up a sump guard / undertray for the mk2 (vortex mainly i think) which is pretty much the same front end as the C IIRC?

[KipVR 1]

cheers david and monkey, I'm thinking Mk3 diesel is more similar than mk 2 isn't it?

[boost monkey 0]

p.s. I need to see your engineering pics to support this - preferably colourful swirlies :nuts:

[KipVR 1]

Ha ha, I may just do that! I'm that anal.

[Lufbramatt 0]

defo good idea :)

 

they also put one on mk3/4 deisel passats, ive been trying to get hold of one for ages tho!

 

theres some interesting reading about undertrays, some guys on the ecomodder forum got some pretty impressive fuel savings on a mk1 prius from a simple front undertray that was flush with the bottom of the front bumper and went back about a foot or so- so in our world that means more speed fora given fuel consumption! hehe

[boost monkey 0]

ffs, people who mod prius' to get higher mpg need to be shot OR walk everywhere! :lol:

 

aero mods like making the floorpan flatter do actually make a car a fair bir more economical. All race cars have them for good reason!

[coolrado 0]

ffs, people who drive prius' need to be shot!

corrected it for you :lol:

[boost monkey 0]

:lol: nice one :grin:

 

Kip, I think you should pioneer this floorpan idea and then send me a prototype...for testing purposes of course...ahem...

[KipVR 1]

Hey don't you need to do a final year project??? :smug:

[boost monkey 0]

Why yes... :norty: I am thinking something more along the lines of intake flow, although this wouldn't be a million miles off! ;)

[radness 0]

I'd like to see one of these made. Would be interested if the right price.

[Yandards 0]

Been thinking about this on and off for the last couple of years, Given the way airflow hits the front of a corrado and that looking at the bumper support panel profile(the one that goes rusty) the intention appears to have been to have air enter the lower wider grill underneath the numberplate and be pushed through the radiator that way.

 

Given that the upper radiator grill (the one with the badge) on VR's was a sealed unit (no airflow through it) then I guess there must have been turbulence caused by the two airflow streams meeting creating slower airflow through the radiator at speed. Obviously a grill with slats in it will give better airflow when in traffic and the radiator fan is operating.

 

If you look at the post facelift bumper cars Karmann/VW also decided to fit a smooth underside in the corners to the wheel arch, I dont know if this is an effort to improve flow through the engine bay or not, but given that it appears at the same time as VR's are introduced and we know there were cooling issues with the engine in the Corrado.

 

The trays for the diesel passat (1992-1996) are the same as Mk 3 Golf items, there is also a tray for the MK 2 Golf and the Audi 80 (all similar era cars) they slot into attachment points on the front bumper and are fixed to the subframe at various points usually finishing around the bottom of the front bulkhead area. The reason they are fitted to diesels is not on of economy, it is to keep noise down in the vehicle as the undertray stops the diesel engine noise being reflected by the road surface.

 

There was a guy on ebay flogging plastic undertrays for mk 2 Golfs but it does say they wont fit mk 2 gti spec models, cant seem to find the link now. I would also like to investigate a similar set-up for the back end of the car, the rear bumper is a dirty great big air scoop as it stands so it would be good to fit a panel from around the rear passenger footwell area to the rear bumper.

 

Would definitely be interested in an undertray, what sort of gauge aluminium are you looking at and will there be a cut-out around the sump to allow for oil drain plug access?

[KipVR 1]

TBH it's not something I'm going to do soon, probably in a month or two when I've finished my engine install. I just wondered if it had already been done.

 

But when i do get round to it I'll make sure it's spot on :D , I would like to put sound absorption material on the inside face of it too, like on the underside of the bonnet. yes it will have a hole in it for the sump to go round and a bit of spare to allow for engine movement.

[pete_griff 0]

i would be loving one of these as well if they do indeed materialise!

 

hope all is well by the way kip - am back at work now, so i'll try and get in touch in the next few days :)

[KipVR 1]

Hi Pete, bet that was a nice six weeks off eh? Congratulations on getting your car done btw, I have read your updates and it all looks really good, cant wait to see it. :clap: Give me a bell when you have it finished :D

 

Yeah this was a little idea I think a lot of people have thought of doing at some point but never got round to doing....I'll keep it posted...