Radiator/Airflow ducting

[speed freak]

Wasnt really sure what to call the title but anyway. I want to know if there is meant to be a section of foam that fills the gap between the top of the radiator and front of the car/chassis?

Iv noticed a few different mx5's recently (from pics) that do and dont have a foam piece that runs along the top.

Iv added 2 pictures to help clarify where Im talking about.

Mine is an NB8B. Shortly after I got it I had the radiator replaced so not sure if they didnt put the foam section back in or maybe there wasnt one and isnt meant to be any? Just recently its made me think if something is missing since Iv seen some NB's with foam along there and with no foam.

Can anyone clarify?

[NitroDann]

I dont know if its stock but you absolutely should have foam there, and an aftermarket cooling panel, and all of the stock undertrays.

the foam has double sided tape and can be purchased easily, notably at clark rubber.

Dann

[hks_kansei]

Yes, there is supposed to be foam there.

But on a lot of cars by now it has either perished and crumbled away, or they've had a new radiator and the foam wasn't replaced.


You should be able to get some appropriate foam from Clark Rubber.
Maybe consider something heatproof (the radiator does get pretty warm)

The other option is to instead buy/make a large plate that covers the whole front cowl section. A little more expensive, and more stuffing about, but it will last forever, and is a useful place to rest tools/beer while working under the bonnet.

[NitroDann]

The other option is to instead buy/make a large plate that covers the whole front cowl section.

I dont know if its stock but you absolutely should have foam there, and an aftermarket cooling panel, and all of the stock undertrays.

the foam has double sided tape and can be purchased easily, notably at clark rubber.

Dann

100%

[speed freak]

Awseome cheers guys.

I hadnt really taken much notice of it until now seeing many different pics etc but when I started to think about it I thought that gap should be filled in. Probably didnt get replaced when my radiator was done.

The plastic under tray is in place. Probably explains why as soon as I pull up in my driveway the fan kicks in, maybe all of the airflow isnt going through the radiator like it should.

Ill check out clark rubber first but might make up a cooling panel.

[Mr Morlock]

just take a look at a standard MX5 and cut out a foam strip. Foam is the perfect choice for this application because it fills the gaps, is easy to work with, is cheap and readily available. Its not really an engineering product- whilst it will have a spec its not critical like an extruded or moulded door seal or gasket.

[speed freak]

Im definitely going to replace that strip of foam now I realized its missing but, I was wondering how much will that foam not being there be affecting the cooling/airflow of the radiator?

[Mr Morlock]

My guess- none at all. If anyone takes a look at some of the cooling and radiator tips I think one would struggle to find any comment on this aspect. I don't see how it affects air flow thru the radiator i.e. the cars cooling is certainly enhanced by the car moving i.e. air passing thru the radiator core -and a gasket on top - how does that improve the flow? Plenty of cars have no foam above the radiator panels. The gasket will however keep out bugs and dust and road grime which can enter the engine bay.

[NitroDann]

Are you joking?

Okay, tell me which design is more efficient at passing airflow.

a fan in a tube, or a fan, Not in a tube?

A radiator with a duct or a radiator mounted in the fresh air on the roof?

This is completion of a duct. Of course many cars dont have one, if the difference between overheating and not was this 5% gap in the ducting there are serious issues with your cooling design, however the very best system will be fully sealed. so seal it.

Dann

[hks_kansei]

My guess- none at all. If anyone takes a look at some of the cooling and radiator tips I think one would struggle to find any comment on this aspect. I don't see how it affects air flow thru the radiator i.e. the cars cooling is certainly enhanced by the car moving i.e. air passing thru the radiator core -and a gasket on top - how does that improve the flow? Plenty of cars have no foam above the radiator panels. The gasket will however keep out bugs and dust and road grime which can enter the engine bay.

There have been studies and tests done on the matter, I'm at work now and can't provide links, but they are out there.


The basis is that air, like water, will take the path of least resistance.
When travelling at speed the air hits the radiator face, some air pushes through, and some simply goes around (since the fins provide more resistance than the empty space)
By blocking off the edges the air pressure increases (since it can't push past the edges) and more air passes through the radiator since that now offers less resistance than the blocked off parts.

The concept of blocking off the edges is sound, but the real world use for a road car isn't as important (ie: removing the foam won't make it go from normal temp to overheating)

[speed freak]

Cool cheers guys. Picked up some foam this arvo so will get onto it shortly. I figured it isnt a massive issue it not being there, since its been like that for months but as mentioned it still allows air to go 'around' the radiator rather then through it. Not as big of an issue as say the under tray not being there (mine is just using as an example) but will seal around the edges.

[kalt]

May I ask where you got the foam, and whether it has sticky adhesive on the side or will you need to use double sided tape to adhere it?

Is it 'foam' or 'sponge' material - the remnants of the one on mine is spongey like a sponge - rather than styrofoam type material.

[NitroDann]

Read the thread, dude.

[speed freak]

May I ask where you got the foam, and whether it has sticky adhesive on the side or will you need to use double sided tape to adhere it?

Is it 'foam' or 'sponge' material - the remnants of the one on mine is spongey like a sponge - rather than styrofoam type material.

I just went to a local foam and rubber supplier. I just got an offcut piece cut to 'size' probably double what I need but yea didnt get a huge piece.

I was just going to use normal foam but he said it would soak up water (which is obvious I just didnt think of it) and not that my engine bay gets wet but he had a slightly different foam that wont soak up water. Its dark grey/black and firmer then other foam but still squishy. Kinda hard to explain but its not anything fancy lol.

[droo]

I haven't been running the under tray plastic on my car, and in the near 3 years i've had it, including over 40 degree summer days, have not had overheating issues in traffic or highway conditions. I havent tracked my car and don't have overheating issues, but my current projects addition is building an air dam (and a few other goodies while i'm at it) at this stage simply, because i can..
The aim is to have have airflow directly hitting the condenser and radiator. The air dam will be covered with a large holed breather mesh to reduce ingestion of birds, small children, their puppies and kittens. The gaps around the radiator will be covered with peoples suggestions of sponge/foams both around this air dam, between the air condenser and radiator etc as well as a very flat full under tray extending underneath all of the front bar to the middle of the engine (in an attempt) to promote lower air pressure in the engine bay to suck air through the air dam.

I'm keen to learn what differences this does, even if nothing appreciable, it's still fun to work on.