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MG Midget and Sprite Technical - Engine bay temps and body modifications.

Rather than send Andy's fuel vapour lock topic, "off topic", I thought I'd post a sepearate but related question.

Speaking of engine bay temps, how much contribution to cooling the engine bay, do the triangular hole sections behind the front suspension make? If they were blocked on the outside in the wheel arch, to prevent water/crap ingress from the wheels, would the engine bay notice much difference in temperature?

Say a removable cover?

Has anyone done this?

Here's a pic of some poor owners car I trawled from the web, just to ilustrate the bit I mean if it's not clear to all.


Lawrence Slater

lawrence,
I think they make a MASSIVE difference, with scrutineering my car closely i have been all over it and can tell you an enormous amount of heat goes through those holes.
having said that, i cant prove it... maybe ill try blocking them up with something and running my test again....
Andy Phillips (frankenfrog)

thinking about this, maybe you’re onto something...... if some ducting was made to go behind the radiator which forced the hot air each side of the engine and out of the triangular holes then it would stop the hot air from the radiator adding to the heat in the engine bay, the air flow would stop a lot of the spray entering the holes, and the holes would always be hot, so that any water which did get stuck in there would soon evaporate away...
Andy Phillips (frankenfrog)

Racers will confirm, but I believe that reinforcing the front end by welding a plate over those holes is a not uncommon modification on race cars. Or is it K series cars? I forget. Either way, they do get blanked off, and presumably the owners' experience is that they don't add to engine cooling.
Guy W

Guy,
Thats interesting...i would have thought it makes a big difference. With the car stationary, i can feel lots of hot air coming through those holes. But whats it like when the car is moving and there are other factors at play...? maybe then they dont do so much.. and if youre racing then the car is moving all the time .

Maybe also my car is different as i have a bigger radiator which is angled backwards so that it fits. This makes the fan blow air downwarda at about 15 degrees from vertical....
Andy Phillips (frankenfrog)

There is a space between the top of the inner guard and the engine bay. How much air goes through this?, There are also small gaps between the guard and the A pillar at the sides and at the top, air has to be coming out here also. IMHO a discrete (not tacky blingy chrome) vent in the guard at the sides just forward of the A pillar would work wonders. Anyone got any thoughts???
Rod
R W Bowers

Hi Rod,
Not sure what the guard is that you describe... i don't think ive got one on my car.. ive got a one piece flip up frogeye front so maybe its different..

do you have any pictures, or maybe a reference to the moss catalogue that shows it ?
Andy Phillips (frankenfrog)

My race car had the triangular sections welded up but on the nearside there were holes drilled to let the air out. ( It also had a row of holes at the top edge near the scuttle on the bonnet) I found that with sealed sections the carbs(split webers)misfired slightly on really hot days. Drilling the holes seemed to solve it. The engine water temp was unchanged.
Bob Beaumont

So nobody know if the triangles being blocked would cause a problem? I'll give it a try then, and let you know. :)

How about the g/box tunnel? If you remove the lever gaitor, you realise how much hot air gets blasted through the tunnel. The original g/boxes suffer from this as the 20:50 oil ends up as thin as water. I often used to think a g/box oil cooler might help, but then I changed to a Ford sierra box.

But what I'm wondering is, could a section of the floor of the tunnel be removed to allow the heat to escape? (in addition to the hole at the back where the prop emerges, as this doesn't allow the heat to get out fast enough). Or would this weaken the tunnel?
Lawrence Slater

I think Rod means like this:


David Smith

Lawrence,
You could try welding blades or an Archimedes screw to the prop shaft so that it blows the hot air out of the back of the tunnel. Added jet propulsion power boost perhaps? In fact I know someone in the USA who would really go for that idea. Its already got his name on it!
Guy W

This is a common mod on big healeys as they suffer significate underbonnet heat.
Bob Beaumont

Brilliant Guy. That made me cry laughing. Are you reading this Prop? :)

Which mod Bob? The screw on the prop, the holes in the wings, or the holes in the tunnel?
Lawrence Slater

oops thread jump, I meant the triangular cut outs in the wings although I like Guy's idea better!

I wonder if too much hacking of the tunnel would weaken the chassis. The hole which the prop shaft emerges is pretty big! The tapered tunnel must have a venturi effect anyway.
Bob Beaumont

Andy. The guard is what Australians call the wing and what Americans call the fender.

Bernie.
b higginson

ok, makes sense now... Wing is what i would call it as well.
Andy Phillips (frankenfrog)

Ive been looking at this for several years and to do it without alot of body hacking and do it economically

I personally do not think that blanking off the holes will have much effect other then to reduce wind turbulance at high speed....the issue I see isheat rises and the hotter the heat the more it wants to lift

Getting air into the engine bay isnt hard, its EXITING the air flow thats the problem...there is just no good way to.exit the air and the air heats up fast

The problem with just drilling large holes in the wings is it works when the car is stopped or moving slow, when the car is moving at higher speed, the outside air flow acts as a wall and will not allow inside air out...aka stagnation

To correct this, you need to think in terms of an air plane wing to create lift...you want to make a lip on the hole of the wing to Force a low depression over the hole thus forcing the air out of the engine bay...aka, creating an air plane wing of lift


That is why the triangle cut out on the wing is so effective in evacing. The heat out because with slats in the triangle it creates the low depression are over the triangle hole and because the hole is not round its difficult for the out side passing air to act as a wall because its being broken up

But ... how to make a triangle with slats that.looks good, functional, and resonable priced is the issue... figure that out and you just put a millon bucks In your bank account

I think the tranny hole is also a red harring.. the air has to fold around to many obstructions and move in a down ward position to enter the tunnel

Prop

Prop and the Blackhole Midget

Lawerance...

Instead of the tranny tunnel ...explore this idea where I left off

Use the cars heater duck works....remove the heater box and the matrix and make a vent to capture the heat where the heater box used to be (remember heat rises) to vent thur the duck work and extend the cars duck work thur the bottom of the car or into the tranny tunnel or some other means of evacing the car

My 1st prototype ... did sorta this, but I used an aluminum dry hose from the front of the car to a baking pan attached over the heater hole on the battery shelf ...to get fresh cooler air into the cockpit....ive got a pic somewhere... it worked ...OKAY, I.didnt live cook in the car that Summer


Anyway... its an idea if you.want to persue it

Prop
Prop and the Blackhole Midget

Ehat about my thought above but use the demister hose ...just new longer vacume hoses and attach them to the triangle side windows that way the heat is captured up high thur the heater box ...vented thur the demister hoses even highrer and vented out the triangle windows..which is even higher

Maybe even modify the heater.box to.accept the heater better and us the fan to help pull the heat out of the engine.bay

It only takes about an hour to reinstall and hook up the matrix for winter time driving

Or just have 2 heater boxes ...one modified for summer for the above and a 2nd orginal set up that can be used in winter

Prop
Prop and the Blackhole Midget

Prop, you got the wrong end of the stick.

I'm not trying to get rid of heat, I just want to block up my triangles and not cause excess heat in the engine bay.
Lawrence Slater

Hmmmm...

So lawerance ... adding an A/C into the engine compartment isnt an option....hahaha

Sorry I got lost in the thread as to what was asked

SERIOUSLY... I Cant imagine it would make a big differance in the amount of heat it would hold...the triangles are fairly low and heat rises

Would it affect the actual act of introducing a cool air into the engine bay... yes but only during the heat of summer and thats never more then a few weeks

The reason I know This is because that is where I installed my ignition coil to get cool air to it during the hottest part of summer...it works


Beyoud that 2-4 week period the triangle hole is just a weight saver and would not contribute cooler air that would amount to anything meaningful

If you do make a cover... id make 4 covers, 2 covers per side with a layer of rubber sheeting on the inner side of the covers to help provide a good seal and install them like bookends and just a long screw thur both covers with a wingnut to hold them into place....no welding needed, super easy to make, install, and remove so as not to disturb your concourse garage queen ....lol

Prop
Prop and the Blackhole Midget

The advantage would be you can easily install them for year and remove them during that 2 week period when its broiling hot and you want that extra air flow into th engine bay

An idea they make plastic sliding furniture movers that are hard plastic with a layer of stiff foam glued on one side and in various sizes you could get those and drill a hole thurand install a long screw with a wing nut to do the same thing...there not expensive about $1 each at a deep discount store

Prop
Prop and the Blackhole Midget

http://item.mobileweb.ebay.com/viewitem?itemId=261187221496&index=0&nav=SEARCH&nid=99803035606Ebay saves the day

Prop

Prop and the Blackhole Midget

David this is exactly what I mean. I think Prop was scouting around the concept of high and low pressure areas, until we get some advice as to where these are this discussion is aimless (IMHO). I may experiment with an air dam under the cross member in order to block air flow under the car and lower the air pressure allowing more hot air to exit via the tunnel and the space under the car.
Cheers all
David where can I get such a vent??


R W Bowers

Rod, have a look at this link.
http://www.autospeed.com/cms/A_2160/article.html
interesting read.
The guy experimented with spoilers and undertrays and decided on an undertray which increased the pressure differential across his radiator/intercooler.

i would be interested in this idea... let us know how you get on..


other interesting things on that site as well..
Andy Phillips (frankenfrog)

Hi Andy
Verrry interesting, I'll definitely be cable tying etc some piece of flexible plastic as an experiment.
However some measurements would be nice, however its now getting on to winter here and the temperatures are down anyway.
R W Bowers

What a really cool Website...I just dropped 3 hours on it and.barly scratched the surface

It reminds me of the old 1960s popular mechanics magazine all hands on hacks and Modifications

What a gold mine of hacker info

Thanks for posting

Prop
Prop and the Blackhole Midget

Rod - I saw that style of vent in some old pics of - I think - Sebring sprites; I liked it so drew out a template and placed it in different positions until it looked right, then simply marked and cut the fibreglass.
David Smith

Prop,
somewhere on the site are instructions on how to make your very own formula 1 telemetry kit like mine...
then you can bore everyone to death with facts and figures like me....
Andy Phillips (frankenfrog)

Andy...

Are you aware of my 10 gauge radio consel... it can take up to 20 readings plus the other dash gauges gives me a total of 14 gauges plus with my smart phone, I can down load an app that will measure a whole bunch of of other factoids... such as g force, 0-60, 1/4 mile, braking effancitcys ect ect

http://db.tt/ATNyiM2S


Prop...
Prop and the Blackhole Midget

Andy.... what does yyour telemetry kit looks like...got a pic.

Prop
Prop and the Blackhole Midget

My simplistic view on this is that you need to ensure the volume of air entering the grille is at least matched or exceeded with vents sited in lower pressure areas.So blocking off the triangles will create a buffer which will reduce the flow of air to some extent, as well as giving rise to a pressure and temperature build inside the bonnet. Think of the improvement in flow porting a head or inlet manifold makes - air likes to pass unobstructed through smooth passageways and managed in and out,so asking it to squeeze down a transmission tunnel as a primary route may not be all that effective. I think you might consider bonnet vents above the carburettors. I've never taken temperature readings off mine, but sitting at a traffic light the heat haze can be considerable - and I never suffer vapourisation. Additionally wing vents will contribute when the car is on the move. Again no data, but judging by the pattern of dirt on the bodyside,air certainly gets shifted through them.


F Pollock

prop, see my other thread with the word "science" in it... theres a picture
Andy Phillips (frankenfrog)

Lawrence
The bottom of the tunnel is important for torsional strength. The sills are narrow so although they are deep enough for a useful amount of bending strength, their narrowness means they don't contribute much to torsional rigidity. The closed in tunnel the other hand has generous dimensions in depth and width by comparison. It is also tied in well to bodywork at either end.
So I wouldn't be opening up the bottom of it.
Paul Walbran

prop,
how do you get your legs in as well as that console ?

Not sure if youre joking, but you actually can download an android app that gives you all those figures on 0-60, g force etc.

ive not yet wired up my speedo, so i use my phone as a speedo at the moment...
Andy Phillips (frankenfrog)

fergus, do you have any closeups of your side vents ? from inside and out preferably...
Andy Phillips (frankenfrog)

Sorry,no pictures.The original version was just a hole so that was easy. Version #2 was aluminium with riveted louvres similar to a Big Healey, but without the giant surround, and attached to a return flange. The bonnet now only has the top vents.
F Pollock

http://www.ahead4healeys.co.uk/VENTS---FRONT-WING--ALUM---FLANGED--PR--id3376.aspx
Andy Phillips (frankenfrog)

Similar to that. The same timber former did both left and right hand versions and provided the position for the rivet holes. Of course on a Sprite with a fiberglass front, the top ledge is in a perfect position to open and close the bonnet.
F Pollock

OK, so going back to my original question, it seems that the triangles should remain open.

That helps the engine stay cool, but it also helps the footwells rot. Water and crud gets in the triangles, thrown in by the wheels, and splashed in via the useless drain hole in the bottom, -- if it's not already blocked by rubbish and muck that is.

And anyway the drain hole isn't even at the lower extremety of the triangle. Hence an amount of wet stuff sits in the bottom of the triangle, and rots the wall at the back. This exposes the space in front of the footwells to water, and the rot starts there too.

So I thought blocking the triangle might be useful. I'll build an open cover then, that resists the water from the wheels, but lets the hot air out, and block off the hole in the bottom so none can be splashed in from the road.

Only trouble is, on full lock, there isn't much room for a flap to sit too proud of the triangles.

I suppose the only other way is to make it a box section, but that means engine out to weld the insides I would guess, --- not much room.

It's a crap design, that's for sure.
Lawrence Slater

Very early Sprite bodyshells have just a single triangular web there, not the double one. So there was no cavity formed to collect the road muck.

One good thing about it is that it is very easy to direct a hose jet in there when cleaning the car so it shouldn't ever remain clogged with road muck for long. Trouble is, it does, 'cos owners forget / don't bother / don't realise. Same as keeping the two drainage holes clear in the wing below the sidelights. Easily done, but also easily forgotten!
Guy W

Great if you got the car new Guy. I do as you say, and keep mine clean (try). But this midget is already suffering the lack of cleaning.

I didn't know the early sprites had a single web there. It can't be that structural then; -- can it? Or is that why it was modified to a double?

Maybe it could stand the hole in the bottom being opened up to make sure it never blocks.
Lawrence Slater

I think that is why they modified it to a double section. It provides the stiffening to the front suspension tower, bracing it against the box section formed by the footwells/scuttle. I have seen a photo of the double triangular web + hole replaced by square section tubes, top and bottom. But that may have been on a race car.

On mine, I opened out the drainage hole a bit, and extended it downwards to meet the flange that is welded to the footwell front. So at least water that gets in there runs out again without leaving the crud to accumulate.
Guy W

What about filling the gap between the 2 triangle or make a channel cover that can go over the gap of the 2 triangles

Maybe some angled aluminum on epoxey and coated with fiberglass for looks and further sealing

That way the hole remains and the gap is filled and nothing can get in to rust/damage

Prop
Prop and the Blackhole Midget

Yup opening the hole was my thinking Guy. So since you've done it, and it hasn't cracked anywhere, I think I might modify mine a bit more. Cut the hole much larger, and reinforce the edges to replace the strength.

The beauty of a mig is being able to make these mods so easily.

Prop, I've been thinking of that too, But it would have to be truly water tight otherwise no point. Maybe even a strip of plastic or rubber might be able bonded in place the whole way around.

Otherwise, maybe I'll just pull the engine so I can get easy access to the insides of the triangles, and weld the sections up properly. In for a penny in for a pound. Wouldn't take that long.
Lawrence Slater

The double skin is indeed to provide extra strength. it was one of the early modifications to the MK1 (when the rear arch was also reinforced). The triangular section does seem to take a great deal of load. I suffered a fracture crack at the offside front end adjacent to the suspension tower on my rececar and reinforced both sides with square tube as Guy suggested. I was running 8" slicks though!
Bob Beaumont

I I like BOBs idea the best...so simple, fruggle, and easy

if I understand bob correctly... he sort a fluffed over it

A 2nd skin... im guessing bob means something like a spray on or brush on rubber coating of some type

Kind of like flex seal, rhinno linner, or that rubber wrench handle dip stuff

Thats a great idea... id make the drain hole a bit bigger .. add a plastic tube or straw into the hole, clean that channel out spotless so to have a perfect bond and coat the entire area inside and out with some kind of rubbery 2nd skin stuff...just make sure the drain hole is clear afterwards


Thats the best idea of the day...

im a fan, good job bob.

Prop
Prop and the Blackhole Midget

It seems Paul Ivey knew about this cooling and breathing issue back in the mid 60s with Alec Poole's famous TZA 238 Frogeye . Note the one eye and vents behind the wheel arches.


See here and pic attached http://www.classiccarlink.com/profiles/blogs/owner-recognises-his-car-from-a-1966-photograph-here-on-classic-c



Peter Faulkner - Dublin

Hey alec poole,

How about some Fender To support that huge freaken hole ....hahaha

Eeehhhuuu.. now thats a fender vent

Prop
Prop and the Blackhole Midget

This thread was discussed between 12/05/2013 and 16/05/2013

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