Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) placement of the "Union Jack" on Bonnet sides

Ruut ... the factory seem to have much the same idea when it comes to placement ... but it's still a matter of personal choice and other placements do work (and I guess some wouldn't

Monty ... are your bonnet-side louvres 'ins' rather than 'outs' like mine? (Why do I have a bad feeling I might be re-opening some previous 'louvre-wars' thing from before my time here as I type that! 🙂)

K

My louvres are 'Ins' on the bonnet sides, they are designed to bring air into the engine bay and create a positive pressure within the engine bay when the car is driven at speed.

My louvres on the top of the bonnet are 'Outs' so that's where the positive pressure vents, and carrying with it the hot air it's picked up on its way out.

This arrangement makes perfect sense to me given heat rises, afterall the purpose of the louvres is to evacuate heat from the engine bay, so it seems logical to have the 'Outs' at the highest point possible.

It's the basic principle of a chimney, even without airflow and the positive pressure in the engine bay created at speed, the hot air at idle when the car is stationary will still naturally rise to escape from the bonnet top out louvres.

The side louvres were "out" until 2004/5 when the Roadster S1 had the air intake right up against the nearside louvres. This was given as the reason that the side louvres were flipped.

Somewhere on You Tube is a clip where somebody covered a Morgan bonnet with tufts to check the airflow, and what that shows is that the air around the side louvres is very messy and turbulent. It also showed that there is a high pressure zone in front of the screen which forces air down into the heater intake through the back four top louvres. So the optimum place to get air into the engine is where the heater box is located.

However, when stationary the air will naturally rise through the top louvres, and when stuck in traffic you can see the haze rising.

Wonderfully logical ... but from racing I know cooling logic, like military plans, never survives contact with the enemy! 🙂

I seem to remember a past thread where someone had done real-world 'wool tuft' airflow pics out on the road and air was going in and not going in surprisingly strangely.

Fortunately my car doesn't suffer from overheating (touch wood) but if it did I'd have a few mods I'd try after seeing that.

K

Possibly this one ?

Very interesting....

Yes, from Morgan Club de France https://morganclubdefrance.com, but you have to be a member to access the boutique.

Not wishing to undermine the efforts of an enthusiastic amateur here, but I'm not really sure what that video proves? I'm also certain any student aerodynamics would pull it apart in seconds, and such efforts would be certain to have the Godfather's of this science Malcolm Sayer and Frank Costin rolling in their graves

I'd like to read the full report as to me the wool tufts don't seem to be telling us much, if anything at all, and without understanding what’s also going on inside the engine bay the data is double useless. Heaven only knows what’s going on as air passes beneath the car as it’s really aerodynamically messy under there, let alone what happens when the air gets trapped inside the sail like front wings of a Trad Morgan?

I can however accept there will be a potential for a high pressure zone in front of the screen, you don’t really need a degree in aerodynamics or run any tests to predict that one, just take a ride on a motorcycle over 60mph and tell be what you learnt. However, air often behaves in mysterious ways, for example as the air gets stopped by the very vertical screen and then tumbles, the roll could easily create the opposite effect of negative pressure at a certain point that remained unmeasured in the video. The datum points in the test simply aren’t tightly enough packed or comprehensive enough to understand what's going on everywhere, the louvres on the test car's bonnet sides also appear to be 'Outs' not 'Ins', so that throws any data out for my application anyway.

Finally, because we have no real idea what's genuinely going on under the car, inside the wing voids, and especially within the engine bay, I really can't see what we are meant to be learning from this video? I don't mean to flame the attempts of an enthusiastic amateur, but as we all know 'part data is often worse than none at all'. So, despite the valiant attempt I’m calling this video out as 'Null & Void' in terms of usable data, there are simply too many questions unanswered, indeed for me it actually raises more questions than it answers.

One thing we should all accept is that a Morgan has very poor aerodynamics, but let’s be honest here none of us bought a Morgan for its slippery shape, we bought it for its classic flowing lines that are pleasing our eyes, and personally I take great pleasure in ripping past modern cars driven by Joe Public and young lads with their baseball caps on backwards who have no idea what they see as a relic could have such a surprising turn of speed.

Anyway chaps, my own fuel economy and engine load analysis also proves the effects of poor aerodynamics only really start to ramp up aggressively over 70mph, I've proved I can hold 80hph in Monty and still deliver 38mpg by running 39 BTDC and a 15.5:1 AFR, obviously the 900kg mass plays its part here as does the super highly efficient breathing and very low pumping losses of the excellent 2.0 Duratec engine, you just need to un-strangle the poor thing by removing all the emissions junk.

As part of these tests, I've also logged IAT (intake air temp) data that proves there's very little difference between the Mondeo airbox and my open element filter mounted just forward of the heater intake, indeed if we exclude idle and take our data from just 15mph and above, my open AEM Dryflow filter delivers lower IATs than those recorded with the Mondeo airbox recorded at the same road speeds. I would also argue by far the biggest improvement available to us all if we want to lower out IATs and increase the density of the incoming charge, is to stop pumping superheated exhaust gasses directly into the inlet manifold (exhaust gas recirculation).

On other projects I've directly recorded EGTs (exhaust gas temps) as part of my tuning data set, and what you see is typically somewhere between 900–1300°F at the header. This will vary depending on inlet port length, engine load/cylinder pressures and ignition angle, but believe me even at their coldest exhaust gasses are super-hot, so the impact EGR has on IATs is massive and way more than any open filter that doesn’t actually have any impact in my Morgan above 15mph anyway.

If you want to increase the density of your incoming charge and fill your Plus 4's lungs with a nice cool and pure mix of lovely air an fuel, all you need to do is fit a Duratec ERG delete kit. If at the same time you delete the stupid 'Swirl Flaps' you'll likely pick up the easiest and cheapest 10hp you'll ever add to your Duratec Plus 4 Morgan, a £10.00 ERG blanking plate and an afternoon removing the plastic inlet manifold is all it takes.

https://www.ebay.co.uk/itm/18595296...IgFcmmvYwe7hYSDO4GO675-nV2gaAiZLEALw_wcB

My take-away from the vid (and I think the one I saw originally had tufts elsewhere as well) ... is that there's an awful lot of the grille intake area where the air isn't going through the rad. Which, for a car that can sometimes have marginal cooling isn't something I'd want.

It would be interesting to see a proper wind-tunnel exercise done with the Mog .... just as long as I'm not paying for it 🙂

K

Definitely an awful lot of wind passing through that rad Image, but the real question is what happens to it after that?

My Plus 4 runs at 82c, so I'd put money on Morgan (or the previous owner) having fitted an 82c thermostat, perhaps when he previous owner had my SiFab ally rad fitted he also went with the 82c stat?

These 82 degree Duratec thermostats are available and typically used by people converting a Mk1/2 Escort to Duratec power, personally I'm not a fan of them because 82c is actually a very cool operating temperature for a Duratec.

Ford designed the engine to run at 105c -110c. I know that’s largely for emissions, but I'm looking to go up to at least a 95c thermostat and blank the lower exposed part of the SiFab rad, my Morgan doesn’t overheat, it doesn’t actually run anywhere near as hot as it should!