Today's stupid idea is...

[will_warne]

If you want more power and cooler EGT why not devise a LOx injection system and have a big bottle of oxygen strapped in the back - that should do the trick B)

I also used to think my intercooler was "heat soaking" because of a slight gradual loss of power on long climbs, nothing major perhaps 10% down on power? Turned out to be a partially blocked fuel filter (I think - a new filter fixed it anyway!)

Turbo. I think to notice a differance you need to have a really fine spray to get the heat out fast and efficiently. The other day my truck was getting a little warm on the motorway so I stopped and propperly cleared the radiator and intercooler (5 minutes and I left the engine running). This dropped the underbonnet temperature down massivly as well as cooling the intercooler. the result was an EGT of about 380 - 400 degrees at 70 (opposed to about 500 - 550) for a few minutes. I think you will achieve a lot more by increasing airflow under the bonnet. This has been my big problem; the 2.8 is plummed in a way that leaves no where for any air to flow meaning it gets a little warm under the bonnet on the road... I'm thinking now about using fans to physically suck air out.

[Turbocharger]

I see what you're saying but, surely there's plenty of space to let the air back out? There's a great big gap down both sides of the engine, my engine anyway. Air comes in through the radiator (which will obstruct 50% of the flow anyway?) and then can escape through two gaps with a combined area similar to the radiator but without any fins in it anyway?

I concur that a fine mist would be better but we didn't have any smaller drill bits for the poly pipe. At the moment I've only really tested it under part-load conditions and the cooler shouldn't be seeing problems there. I'll try some full-load before & after experiments(!) tonight (not the kind which hit metal plates and prove that paint doesn't work).

[will_warne]

I see what you're saying but, surely there's plenty of space to let the air back out? There's a great big gap down both sides of the engine, my engine anyway. Air comes in through the radiator (which will obstruct 50% of the flow anyway?) and then can escape through two gaps with a combined area similar to the radiator but without any fins in it anyway?

Unfortunatly, I don't have much free space under the bonnet. Put it this way; I can't think of the last time I droped something in the engine compartment and it got all the way to the floor

[Turbocharger]

Well, I took the Ninety out last night (with new blingy towbar) and played with my water spray. I've recently turned the fuel down in search of more economy so it's not developing the high EGTs it once would (1/2 turn on the main fuel screw has dropped peak EGT from 730+° to around 682 last night).

I brimmed it with fuel, pointed it down the motorway and nailed the throttle to the boards.

On the flat, indicated 75mph is max speed with EGT around 650°C, although the shown EGT is heavily dependent on engine speed. As the speed drops to 70 or rises to 85 (up and down hills) the EGT goes to 630°C or 680°C respectively. Ambient temperature was around 10degrees.

Given that variability, I reckon the water spray drops the EGT by up to 30°C at full load with the intercooler in 'steady state', ie after 5 mins hard driving. Inspecting the intercooler afterwards it was completely dry. Over the 22 miles of balls-out full throttle driving I averaged 15mpg and used a full washer-bottle of water (filled in Bristol, if it makes a difference).

[02GF74]

ah, you wouldn't placky bottles, egts, intercoolers with a v8.

[simonr]

I'm sure I talked to you or Keir about this at some time?

On my 110, I built something fairly similar. The fine water misting jets came from a garden center and are used for plant watering. They just screw in to the side of a hose pipe. Produced a good mist - but I'm not convinced I could notice any difference in performance. Didn't have an EGT gauge or anything more quantative than how it felt though.

Si

[Troddenmasses]

I'm sure I talked to you or Keir about this at some time?

Not me, guv

[Turbocharger]

To be honest, the water spray bit works quite well, there's plenty of water going everywhere and wetting everything when the car's going along. There's definately an effect on the EGT from spraying water (although little I could actually feel), I just don't think it's as effective as fitting a bigger cooler will be. If I can resurrect my rolling road programme I'll see if I can get anything meaningful out of it next week sometime.

[FridgeFreezer]

Water injection isn't as hazardous as you may imagine, there are DIY kits from Demon Tweeks (Aquamist). OK you probably don't want to be pointing your windscreen-washer powered contraption down the air intake, but something that uses a (Staninless steel) fuel injector to mist water into the intake depending on engine load should be safe.

And yes, I can name a cheap DIY ECU that would run water injection for you...

[Porny]

I've heard that water injection isn't that effective on a diesel.... and just don't get it wrong... clatter clatter bang!!!

I'd be more inclinded to be playing with propane injection or LPG... or even Nitrous

Though I admit these are a bit more expensive.

You can get 200bhp from a 200Tdi without extra's like these... but it's not cheap!!!

Ian

[BogMonster]

I've heard that water injection isn't that effective on a diesel.... and just don't get it wrong... clatter clatter bang!!!

I know nothing about it, but working on the principle that what you need in a diesel is to keep the intake air temp as low as possible I would have thought it would make a big difference to the air temp and so increase the potential power output?

Agree with the don't get it wrong bit though - an extinguisher into the intake for overtaking manoeuvres would probably not be a bright idea

[Turbocharger]

With water injection it's not about air density particularly, you're putting something else into the cylinder that gets MUCH bigger when it turns to steam. Your peak cylinder pressures go through the roof, but that pressure's pushing the piston down. Also, during the phase change the steam reaction is endothermic, knocking the top off the peak in-cyl temperature with a very favourable result on NOx emissions. As has been mentioned though, get it wrong with a little too much water and you'll suddenly regret the whole idea.

The alternative is to inject as much water as you like once the compression process has taken place (so long as there's still enough diesel to initiate combustion). There's already an injector firing at TDC so why not lump the water in with the fuel? Water emulsion in fuel. However, since our government would tax the emulsion as normal fuel (instead of 25% duty reduction because the fuel's 25% water, for example), it's not economic to produce and sell this fuel which reduces emissions & consumption and improves performance. Ho hum.

[simonr]

There is stuff you can buy for boats which emulsifies the diesel with water which has found it's way into the fuel tank. Would this be a reasonable way to achieve the same thing? Seems to me to make little odds if the water comes from rain or my hose pipe?

What would be the best mixture? You have stated 25%, but is there a sliding scale with more power at one end and lower emissions at the other?

Si

[Turbocharger]

In-line emulsifiers are already commercially available too - I believe the PuriNox testing ran up to 20% water in fact but since the volume of 'fuel' is taxed there's no incentive here or in the USA.

With either system you'd need distilled water and doing it at home you'd need to premix and stir the concoction before lobbing it in your tank. That said, even if you kept the same MPG with 20% water you'd be paying less than 75p per litre (equiv).