Bongo Fury

Rhinoman wrote:Well strictly speaking the purpose of the EGR is to reduce NOx emissions however it does that by reducing combustion temperatures. I probably should have qualified my statement by saying its not a good idea to blank it off if your cooling system is marginal.

Regarding the EGR, I see it as an enviromental "add on", rather than a crucial element in temperature or combustion control & I think the negative effects of a fubar EGR system would outweigh any (if there were any as far as the vehicle's efficiency etc) advantages that might be expected, especially when the air intake ends up looking like this



But as you say, if the cooling system is marginal, or doubtful in any way, that should be sorted asap anyway. Not sure if any/many people have succeeded in/bothered with reviving a duff egr system, or if it's even worth the bother.

Rhinoman wrote:You are correct that the intercooler is there to make the air more dense by reducing its temperature, the question is how much can be gained by a bigger intercooler? I think I should take some temperature measurements. First task is to find the engine, I looked under the bonnet but it was nowhere to be seen

Be interesting to see how much difference there is in intake temps before & after cleaning the standard intercooler & pipework, & maybe even with the egr blanked or left as is (working or not?), before looking at bigger intercoolers.

If you can't find the engine, lift the AFT, the previous owner may have left it up in the roof?

I found a spare engine that had fallen down between the front seats it seems to be a bit like my sofa, whenever something is missing its down the back or sides of it.
It'll be a week or so before I get a chance to play with this, I'm considering hooking up a boost gauge and a temperature sensor either side of the intercooler then logging both temperature with boost. If we're really lucky my EGR and intercooler will be all choked up
Meanwhile I've an ECU to hack.

As long as the engine turned up somewhere, that's the main thing
Better get on with that ECU or Steve'll be nagging

Rhinoman wrote: If we're really lucky my EGR and intercooler will be all choked up

Can but hope

What about these devices that spray water/evaporant on the intercooler then and use latent heat of evaporation to cool the matrix then? Do they work? Could we DIY something?

mikeonb4c wrote:What about these devices that spray water/evaporant on the intercooler then and use latent heat of evaporation to cool the matrix then? Do they work? Could we DIY something?

Its feasible, the alternative is water injection as used on WW2 Spitfires. Don't forget that getting more air in is only half the equation, you need to match that with extra fuel. I've done a lot of tuning on petrol engines but diesels currently are a mystery, I'm guessing that you will either get detonation (too hot?) or retarded timing (doesn't go bang soon enough?) if you run lean.

Rhinoman wrote:

mikeonb4c wrote:What about these devices that spray water/evaporant on the intercooler then and use latent heat of evaporation to cool the matrix then? Do they work? Could we DIY something?

Its feasible, the alternative is water injection as used on WW2 Spitfires. Don't forget that getting more air in is only half the equation, you need to match that with extra fuel. I've done a lot of tuning on petrol engines but diesels currently are a mystery, I'm guessing that you will either get detonation (too hot?) or retarded timing (doesn't go bang soon enough?) if you run lean.

Yes I was wondering about that. I guess the electronics etc. on an old Bongo don't detect and adjust the mix? Interesting to think that denser air should create a stronger venturi. Could any kind of venturi device be in service on the Bongo setup. Thinking about it, temp variations between a Siberia winter and a Russian summer are extreme in any case. Maybe it does not not matter as all the denser air needs to do is promote more complete combustion of the diesel. There was an interesting debate on here about LPG injection with the Bongo diesel (Hembracho has this on his) which served to promote more complete combustion - larger intercoolers got discussed at the same time. It all happened after I met a Landie owner at RAF Cosford museum and he had upped his MPG considerably by doing this. He kindly joined us in discussion on here.

Diesels run "lean" at anything less than full throttle - as lean as 40 : 1 at low revs/throttle. They only run stoichiometric (around 15 : 1, like petrol engines) flat oot

No need for a venturi on a diesel either - there's nothing mixing in the airstream

can you clarify please dandy,are you saying that if you were to restrict air in, the burn would be better. sorry for being thick just trying to keep up

I sort of understand, its quite different concept to a petrol engine. If I have it correct there is no throttle, the engine always breathes as much air as it can. The accelerator pedal controls how much fuel is injected and the amount of fuel is what gives the power. The amount of available air defines how much fuel can be burnt and how much power can be made so that implies that power either reduces if you go too rich or remains at a constant level. Is that correct?

Its a big and complex subject I reckon, taking in many things.

I'm not proposing that a venturi in this situation is a necessary mixing device (the injectors presumably have that job). I'm simply observing that a venturi could be used anywhere there was a need to ensure more fuel was pulled into a mixture if the airflow properties (volume and desnity) change. As an example from ancient memory, didn't the old vacuum advance and retard devices used to alter 'dwell angle' by detecting the increased vacuum caused by pressing the accelerator pedal?. So maybe a venturi might/could be used somewhere to advise the system on adjustments to rate at which fuel is delivered.

A venturi creates an area of low pressure, which if tapped can be used to pull in and entrain a liquid with a stream of flowing air. I think some airbrushes may work like this. The rate at which liquid is pulled in is linked to the strength of the low pressure, which in turn is linked to the shape of the venturi and to the momentum of the airflow over the venturi, which is in turn linked to its velocity and density of the airmass.

As to correct fuel/air mix ratios, there it must surely get more complex. But you would think that over-riding considerations were to ensure the engine did not develop hot spots as a result of combustion, and that fuel was as completely burned as possible. That lot, put together, must present a complex equation for designers to solve.

Northern Bongolow wrote:can you clarify please dandy,are you saying that if you were to restrict air in, the burn would be better. sorry for being thick just trying to keep up

no, I'm saying that there's no need for a venturi like a petrol carb. has as the fuel isn't mixed in the venturi, it's pumped into the cylinder head via the injector. The venturi in a carb. lowers the pressure in the carb throttle tube to allow the fuel to flow into the airstream.

Hope that makes sense

Sorry to be a noob butting in but I'm thinking of this too!

has anyone attempted to play with the intercooler.

It's only a glorified radiator with 2 pipes that holds air pressure
I'm thinking of changing mine for something more efficient and of a similar size like this...



Here's the standard Bongo one.


I know my old man got a good 50 bhp increase with an intercooler upgrade on his range rover. Made a massive difference to the low end torque and turbo lag. If a 'better' intercooler holds the pressure and cools the air more efficiently it's got to be an improvement.

However, something too big could reduce the pressure due to it's size...Boyle's law anyone?

I'd love to hear from someone who has successfully fitted a beefier intercooler. Go on someone - have a go

mikeonb4c wrote:I'd love to hear from someone who has successfully fitted a beefier intercooler. Go on someone - have a go

Why not bypass it first to see if it is actually improving performance?