We didn't have much time, we just funished tuning the non-WI map and just switch on the pre-turbo as "wait and see". We have to move on to post turbo (will print later) and combined etc.

We may not have inject enough water. I guess we were injecting some 4 litre of fuel per minute so w/f ratio is 150cc/4000cc X 70% DC = 2.6%

Not really a great deal of water. We wil be continuing as soon as we have time.

Any chance of posting your dyno plot?

Yeah, if you run as rich as most people do (looking by the AFRs on that diagram), then to get 700horses you may have to use as much as 4000cc/min.

But where did the 150cc/min come from?
None of the 'normal' Aquamist nozzles gives out so little, right?

As for my dyno graphs, I've got to scan them first and highlight the relevant curves, there are a few runs on each printout.
I'm gonna need another long session though, running more boost, and more water *hint* *hint*

We are running twe 0.3mm jet, one in front of each turbo. At 100% DC, each jet passes 75cc/min of water. Since we are only running 70% fuel dc, so 75+75 x70% = 105cc/min.

Fuel flow is estimated at 4000cc/min. so w/f ratio is 105/4000= 2.6%.

As soon as I have time, I will start increase the jet size. The effect will be more dramatic for sure. At 2.6%, the effect is already very noticeable. Doesn't really know what was going on.

Do you have your dyno plot at hand? If you can't post it, please describe it.

http://www.aquamist.co.uk/forum/gallery/gtart/32.jpg

Ay 2.6% w/f and 11.5a/f ratio, the amount injected is less than a rainy day !! Quick calculation: 0.22% of water of total mass inhaled by the engine.

0.3 jets, are they now available then? I thought 0.4 is the smallest (what I was using)
Also in my experience the 0.4 flows more than the rated 150cc/min. I use up easily half a litre after a blast on the road, or a few dyno runs. And that's injecting at 14psi
my w/f ratio was higher than that, and still was nowhere near enough :lol:

I'd need two things at this stage:

1. the Aquamist turbine gizmo that measures waterflow. I wouldn't dare lean out further without it.

2. that screw-in adaptor to secure the nozzle on a silicon hose. Can't really swap nozzles on the dyno without one.

Let's hope that the Aquamist R&D fund can stretch that far, he he... :wink:

I saw clear power loss when injecting water with stock fuelling (no surprises there, eh?)
I saw clear power gains when leaning the fuelling and using WI on top
I saw greater power gains when injecting water at 8psi instead of 14psi (that WAS a suprise to me, I expected it to be the same or worse)

It took me a few hours on the dyno overall, this is not a cheap sport. I definately need more runs now, knowing what I know.

The 0.4mm jet flow 180cc/min - it has been for a number of years.

1. The flow sensor is available on its own, require a volrtage meter and DDS3 is not used.

2. The adaptor is a press-on type, only abailable for 6mm thick hose - too loose on 5mm hose.

If pre-turbo cooler rate is increased, do you think it is able to use up the excess fuel to gain extra power? If this is the case, pre-turbo has in-build failsafe mechanism.

Richard

I'd swear it is over 200cc/min, 250cc/min perhaps.
But I haven't measured it precisely with the precompressor setup running in real situation, so can't tell for sure.
The voltage is different under those conditions, and so is the pressure difference across the nozzle.
Holding it full boost for 15 or 30seconds in one go is out of the question too, I only have it injecting once both turbos are on-song, and speeds would get silly indeed.

I've swapped it for a 0.6mm now and see how we're doing.

I'm not sure what the thickness of this hose is, it is not silicone though, more like plastic-rubbery. I've managed to hack some traces of thread (courtesy of the Aquamist tap!) on a steel hoseclip, which is secured right on top of the hose hole.
So the nozzle is much stabler now, it should do the trick for a while, until you guys bring press-on adaptors for thinner hoses.

There is always vacuum in that hose, so it cannot pop off, it's just some mechanical stability that it needs

What excess fuel, you have to get rid of all excess fuel for water injection to work properly. That's what I've been saying all along :wink:
You have to run LEAN under full boost.
It's not for the faint of heart.

Can you return the 0.4mm jet and we can test it for you, I will replace it with a new one.

0.6mm: - we have got that far yet, you must be getting some exceptional response, based on the 0.3mm jet we tried.

Excess fuel: - almost all factory turbo cars run rich, so if pre-turbo is so effective to lean-off a/f ratio, then there is little tuning needed to gain power plus point is the in-built fail-safe mechanism?

The power you're making is about 200-250bhp higher than what I'm working on, so my water/fuel ratio is even higher.

Also I am on *stock* turbos, that are outside their efficiency range from 1 bar upwards, so my gains could potentially be higher.
It all depends on HOW MUCH rich we're talking about.
Mine for example runs AFRs of 10.0 at 1.1 bar with stock fuelling.
Simply adding modest precomp WI (trigger at 14psi) on to this setup loses me 10bhp and 10lbft (around 3.5% loss). Boost also drops by 0.05~ 0.1bar with W.I.

If you're already running rich, W.I. makes things worse
Running even richer (after an ECU reset) doesn't even stop it from detonating, mine pulled timing immediately despite the WI (at 8psi) and running rich as hell. Resetting the stock ECU also resets the timing advance to the max values, so first time round the ECU 'hunts' for det, which it found.

I was running 99RON fuel by the way, Tesco's finest, nowhere near race fuel --- I want realistic figures, without fancy FMICs, airfilters, open bonnets etc.

After a few timed runs on the 0.6mm nozzle, the results are not very encouraging.
The difference of water injection in total is minimal 1~2%, barely measureable in fact. You only get on-the-wheels figures with the accelerometer, but using the same stretch of road same day etc gives very repeatable results (not nice curves as the dyno though!)

I thought that maybe the higher boost pressures would be happy with the bigger nozzle, but apparently I went too far.
It didn't even *feel* different either (the 0.4mm nozzle felt different back to back)
Good thing perhaps, because it used around 400cc during 5 runs of 40-100, quite a lot actually...

Fitting the 0.5mm next time, and see how that goes...
(I've measured again the flow of the 0.5mm nozzle, it is 240cc/min with the engine on idle, it would be a bit more with a strong vacuum inside the pipe, wouldn't it?)