Aquamist jet location ????

[JohnA]

...pre-turbo jet location,

I first used it 18 years ago, on an non-intercooled turbo bike.

Extremely effective under those conditions.

 

providing the jet atomisation is small enough not to cause damage to the compressor,

 

In reality it's not easy to damage the compressor, the droplets explode before hitting the blades.

Grit damages blades, not water mist.

 

would this not improve the efficiency of the turbo. ie. Widening the efficiency island of the of the turbo charger map by providing a denser air supply to compress at high boost?

Yes it would

 

Would this pre-turbo location be useful on stock TT set-up where EGT's can soar when trying to run high boost level's ..

That's how I've been running mine for about 2 years now, sometimes at silly boost levels.

Without WI it would have kicked the bucket long ago.

 

Same with my previous car.

[Wez]

So if I wanted to inject using a max 0.9mm jet would a better solution be to have a 0.5mm near the IC and 0.4mm infront of the throttle therefore getting the best of both solutions?

 

 

Would this work?

[Stevie Boy]

In reality it's not easy to damage the compressor, the droplets explode before hitting the blades.

Grit damages blades, not water mist.

 

I thought there was a general errosion possibilty over time, if the mist wasn't fine enough would there not be a scenario where, the analergy I think was used to describe it was "the drops of rain hitting helmet visor" if the droplets/mist is fine enough it's hardly felt but when you get big droplet it hits really hard?

[Stevie Boy]

Would this work?

 

Don't think it do any harm, what you got to lose!?

[JohnA]

Would this work?

Yeah, in some ways it's better to have the same waterflow from more jets. Less chances for 'saturation'.

 

My favourite jet location is not facing the opposite wall of the hose, but the throttle plate itself.

And if you want to be more anal, facing *below* the bottom of the thottle, so as the airstream will deflect the WI mist it will ultimately be aiming at the throttle.

[JohnA]

I..."the drops of rain hitting helmet visor" if the droplets/mist is fine enough it's hardly felt but when you get big droplet it hits really hard?

The tips of the helmet don't rotate near supersonic speeds though, do they:d

Water droplets are not grit - they don't pass intact through the blades and the diffuser. They boil instead because of the abrupt pressure drop.

So we get steam and the obligatory heat absorption as water changes state. Hence the surprisingly low airtemps after the compressors.

Why else do you think I won't even consider a FMIC?

[Stevie Boy]

The tips of the helmet don't rotate near supersonic speeds though, do they:d

Water droplets are not grit - they don't pass intact through the blades and the diffuser. They boil instead because of the abrupt pressure drop.

So we get steam and the obligatory heat absorption as water changes state. Hence the surprisingly low airtemps after the compressors.

Why else do you think I won't even consider a FMIC?

 

Does the hard pipe diameter of FMIC have no advantages over stock arrangement then?

 

They both have nearly the same distance to cover from tt outlet, through wing, along the width of engine bay and up to the throttle housing.

 

I know there's more chance of temps rising travelling along the front width if theres not enough air flow. Just thought from a capacity side of things though, an FMIC would maybe aid air flow as it were.

[JohnA]

It is all give and take, typical engineering.

You trade some of this for some of that. Sometimes the final balance is closer to what you are trying to achieve, sometimes it isn't.

 

A FMIC will have two or three times the mass of a SMIC so it will be able to store heat more effectively. This is important during prolonged full boost runs, especially when they follow each other in quick succession. The core could be heat-saturated in (say) 30 seconds but might need (say) 3 minutes to shed that heat at those speeds. So if you run full boost for 10 secs then for 15secs then for 15 secs there will be a mild heat buildup in the FMIC while the SMIC will have saturated earlier on. On dyno runs this effect will be very pronounced, on the road not as much. But it will still be there.

On the other hand the SMIC typically has more ambient air through the core (per sq inch) so it makes up for the lack of frontal area and mass (partially at least)

 

Then there is the heat exchange *inside* the core.

The same airflow will shed heat differently if it is high-speed high-temp (stock twins) or lower-speed lower temp (a large single). The higher the airspeed the different turbulators you want inside, otherwise you end up with pressure drop and not much heat-exchange. A good FMIC core might account for that, a cheap-ass core might not.

 

And we haven't touched yet end-tank design.

 

It's not cut and dry.

[Stevie Boy]

It is all give and take, typical engineering.

You trade some of this for some of that. Sometimes the final balance is closer to what you are trying to achieve, sometimes it isn't.

 

A FMIC will have two or three times the mass of a SMIC so it will be able to store heat more effectively. This is important during prolonged full boost runs, especially when they follow each other in quick succession. The core could be heat-saturated in (say) 30 seconds but might need (say) 3 minutes to shed that heat at those speeds. So if you run full boost for 10 secs then for 15secs then for 15 secs there will be a mild heat buildup in the FMIC while the SMIC will have saturated earlier on. On dyno runs this effect will be very pronounced, on the road not as much. But it will still be there.

On the other hand the SMIC typically has more ambient air through the core (per sq inch) so it makes up for the lack of frontal area and mass (partially at least)

 

Then there is the heat exchange *inside* the core.

The same airflow will shed heat differently if it is high-speed high-temp (stock twins) or lower-speed lower temp (a large single). The higher the airspeed the different turbulators you want inside, otherwise you end up with pressure drop and not much heat-exchange. A good FMIC core might account for that, a cheap-ass core might not.

 

And we haven't touched yet end-tank design.

 

It's not cut and dry.

 

As the saying goes; "Knowledge is power!" sounds like you've done your research!

[JohnA]

Knowledge is horsepower

[Stevie Boy]

Knowledge is horsepower

 

[Tricky-Ricky]

There is some confusion here regarding the expected function of WI.

 

1. If general chargecooling is the main aim (say your post-IC temps are too high), then you want to maximise the distance between the jet and the cylinders.

 

2. If chargecooling is the main aim because your IC is totally overwhelmed and heatsoaked then injecting *before* the IC would be an option.

 

3. If in-cylinder cooling is the main aim (your post-IC temps are not far from ambient at full boost but you still get knock) then you want the jet(s) as close to the cylinders as possible

 

4. If a combination of effects is the aim, then you may have to mix and match jet locations, probably making trade-offs.

 

There are also more advanced jet options. It really depends on what the aims of the particular installation are.

 

 

I am beginning to think it might be worth using split jet locations, and i do understand what your saying, but isn't the whole objective of WI to lower charge temps, which in turn will help with more power, but however the end result (all being equal) of lower charge temps is knock suppression?

[JohnA]

..isn't the whole objective of WI to lower charge temps, which in turn will help with more power, but however the end result (all being equal) of lower charge temps is knock suppression?

What you describe is the objective of intercooling.

 

One of the aims of WI can be intercooling. But on a well-intercooled engine it's not what WI is best at.

If the turbo-discharge airtemps are well over 100C and there is no way to fit an intercooler (no space for the core or the plumbing) then WI is one of the very few options available. It can be very-very effective then, because the air is so hot that the water evaporates immediately almost.

 

But if you already are 10-20C above ambient at full boost, the intercooling effect of WI won't be anything to shout about. It may drop it a few degreesC but that's it.

 

Now the in-cylinder cooling effect ---> that is something else.

It takes place inside the cylinders, during the compression stroke. Water is an excellent substance when it comes to absorbing heat as it changes state, we'd be hard pressed to find something else to beat it.

This in-cylinder cooling effect is the main reason engines have to run richer than stoich under boost, using the excess fuel to absorb the heat spikes. But fuel is nowhere near good as water at doing this, like for like water is four times as effective.

So you need less of it, and it doesn't produce unfortunate byproducts like excess fuel does.

 

Of course injecting excess fuel is simple and cheap, because the fuel system is already in place.