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  #71  
Old 23-11-2017, 11:20 AM
jondee86 jondee86 is offline
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Question Re: Nozzle spray angle...

I have made a few logs since starting to use the 50/50 v/v mix of methanol.
One thing I noticed was that on a short pull in second gear, the spray only
started to have an impact on IAT when the engine was almost at redline.
This is even though spray will have commenced early in the run. Most of the
cooling effect happened after I lifted off the throttle.

So I made a bit of a run in fifth gear...



This slows things down to the point that the cooling effect can be seen in
effect during the run. The s/c discharge temperature rising and the IAT
falling. Presently I calculate that I am injecting about 21% mix to fuel ratio,
but I do have one smaller nozzle available.

This brings me to my question... should I be aiming for the kind of temp
drop shown in the graph, or should I be aiming to simply hold the IAT more
or less steady ?? Currently I don't have any fuel or ignition compensations
geared to the IAT, but the tables are available in the ECU.

The engine is running too rich at the top end, and I am working on that at
the moment. And my apologies for the clunky graphs, but the laptop I use
for logging is old and can't keep up with the sample rate at high rpm's

Cheers... jondee86

Last edited by jondee86; 23-11-2017 at 08:31 PM.
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  #72  
Old 24-11-2017, 09:21 PM
rotrex rotrex is offline
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Default Re: Nozzle spray angle...

IAT sensors are rather slow. We talk 10-30 second response times for most.
The reason you see the air temp dropping is largely due to evaporation of excess methanol covering the walls of your intake wall and internal surfaces of the SC. They take time to cool down. The fluid films rapildy evaporates closing the throttle. IATs drop further.

I would aim for the amount of mix you need to maximiye torque. The IAT for this is only of secondary importance.

Due to the many turns, there won|t be too many fine droplets of water left.
I would therefore expect even better power with more methanol. It is more tolerant regarding droplet size.
Try 50:50 by weight. This is more like 100:80 methanol to water by volume.
It will do its thing even as entering the chambers as big droplets or streams.


IAT correction mapping work well for me starting with -1 deg at 50, -3 at 60 and -5 at 70C and up.
Base timing with cold IATs was optimized on the road. On track, the only way to get heat into a CC system, I then adapted the IAT correction table to prevent knock at these higher IATs. Worted a treat. The car was charge cooled, so it would maintain low IATs for single pull.

I found direct port to be the most efficient knock surpression for a given amount of injected mix. It also prvented me from bothering with cooling effects of methanol on the sensor. I got fluctuations from liquid droplets on the sensor that then translated into timing fluctuations.

Last edited by rotrex; 24-11-2017 at 09:28 PM.
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  #73  
Old 25-11-2017, 10:24 AM
jondee86 jondee86 is offline
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Thumbs up Re: Nozzle spray angle...

You must be using slow sensors. I "accidentally" hit WOT in first gear
yesterday, and my AUX Temp (same sensor as IAT) went from 70 to
100degC in just over 3 seconds according to my log.

Thanks for the input. As I don't have any practical way of knock detection
due to the amount of mechanical noise in the knock spectrum, I shall have
to leave ignition optimising to the dyno tuner. However, I will try the 50/50
w/w mix when I refill the tank. Currently I have 1 x 0.6 nozzle just after the
s/c discharge and 1 x 0.4B nozzle in the last bend before the intake manifold.

The intake manifold has an ugly rightangle bend which will be quite good at
inertial separation of droplets. My intention was that the 0.6 nozzle would
contribute to charge cooling and the 0.4 nozzle would get some droplets into
the combustion chamber.

If I can find a clear stretch of road, I want to do a WOT run using 2nd, 3rd
and 4th gears to see how high the s/c discharge temp will go. The s/c is
good for up to 150degC discharge temp according to the manufacturers.
Depending on what I discover, I may have to look at implementing a small
nozzle in the s/c intake manifold.

Cheers... jondee86
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  #74  
Old 25-11-2017, 04:03 PM
rotrex rotrex is offline
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Default Re: Nozzle spray angle...

Have you tried a external knock detector or indicator?
I first used a TurboXS knocklite. Worked well as a indicator.
I then installed a J&S Vampire knock controller. it also worked really well even on my engine running forged pistons. IT did a great job when I had a pump pressure issue. Engine was bogging and spitting flames, but the full 10 deg retard due to heavy knock kept the engine together.

There is chap in russia selling a reasonably priced knock indicator using a Bosch knock sensor. You'll be surprised how well such devices work.
Knock is also pretty audible in a car lacking sound insulation. It sounds like sparking. I can be heard even through loud engine noise.

https://www.ebay.de/itm/Knock-contro...19.m1438.l2649

https://youtu.be/vztEn3wLi_c
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  #75  
Old 25-11-2017, 11:46 PM
jondee86 jondee86 is offline
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Wink Re: Nozzle spray angle...

I have the factory knock sensor connected to my ECU and there is a
headphone jack on the ECU so I can listen directly to the knock signal. The
problem is that the engine is mechanically noisy and the s/c also makes gear
"rattle" noise in the same frequency band as the calculated engine knock
frequency. The knock signal is high at idle, at low rpm's and on deceleration
even when fuel cut is active.

At high rpm's the knock signal reduces to nearly zero, but when throttle is
reduced and the s/c gears become unloaded, the knock signal instantly
becomes high no matter what rpm's. So I need to be able to program the
background knock threshold levels, and discriminate between mechanical
noise and real knock.

Some of the high end knock monitoring can do most of this, like the PLEX
unit. Only it is a very expensive experiment if it does not work effectively !!

I have been considering trying a Bosch "donut" sensor in place of the
factory sensor, and locating it to a diffrent mounting position. Maybe that
will provide a better signal as I read that the wideband type of knock sensor
is sometimes more effective than the factory tuned type.

The knock light shown in your link is cheap enough to experiment with. But
this locally made product might be a better option...


http://www.nzefi.com/product/knockli...ation-warning/

A visual indication is probably the best option for me, as I will have to make
my own decision if it is knock or noise according to how I am driving at the
time the light comes on. Will have to decide on this soon

Cheers... jondee86
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  #76  
Old 26-11-2017, 10:45 PM
rotrex rotrex is offline
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Default Re: Nozzle spray angle...

I used both devices with the Bosch "donut" type of sensor bolted onto the block near the cylinders.
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  #77  
Old 27-11-2017, 10:24 AM
jondee86 jondee86 is offline
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Lightbulb Re: Nozzle spray angle...

I have been talking with one of our top tuning shops about this, and they
say that at the noise levels I am getting there is basically no way any kind
of detector will be able to separate real detonation from mechanical noise.

However, the human ear is very good at picking up the sound of real knock
even with high levels of background noise. So I will spend a bit of time with
headphones plugged into the jack provided on the ECU for listening to the
knock signal. If I can't provoke any knock by loading the engine at different
speeds, I'll leave optimising the ignition timing until the car goes on the dyno.

It makes sense that you either have to have a knock detection system that
you can rely on to only report genuine knock, or have no knock detection
at all and a good tune

Cheers... jondee86
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  #78  
Old 27-11-2017, 11:03 AM
rotrex rotrex is offline
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Default Re: Nozzle spray angle...

positive displacement superchargers can be very noisy. They oscillate in several vibrational modes of their rotors and cases at certain rpm ranges. This is one of the reasons OEM installed positive displacement blowers are mounted in a pretty stiff way to the block or are heavily braced.
A particular example that suffers form this are the EP§ Jackson racing superchargers on Honda K20 engines. IT pretty much renders the knock detection useless in certain rpm ranges, IIRC some 5000-6000 rpm.

The Rotrex SC runs very smooth and is rather quiet compared to a roots type blower. Although with a cone type of open air filter the intake sounds like a jet fighter, a sound similar (same) as turbocharger intake noise.
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  #79  
Old 28-11-2017, 09:50 AM
jondee86 jondee86 is offline
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Smile Re: Nozzle spray angle...

Quote:
Originally Posted by rotrex View Post
positive displacement superchargers can be very noisy.
Yes. My s/c is a "short nose" version and the pulley is mounted directly onto
the end of the rotor shaft. It is common for "long nose" versions from many
manufacturers to have a coupling with an resilient element between the
pulley and the rotor shaft. The coupling absorbs a lot of the pulsations that
would otherwise be transmitted from the crankshaft to the rotor shaft. This
reduces (damps) harmonics and gear rattle. But it does introduce another
item requiring maintenance into the s/c installation.

You can clearly hear gear rattle from my s/c when warm at idle. But it does
start to make a satisfying whine when the engine gets up to 6000rpm and
the gears are no longer rattling

Cheers... jondee86
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  #80  
Old 21-12-2017, 09:57 AM
jondee86 jondee86 is offline
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Question Re: Nozzle spray angle...

I'm now running the smaller 75dia pulley on the s/c and using 50/50 w/w
methanol mix. I was out for a drive this afternoon and logged a short pull
in second gear that showed 195kPa @ 6000rpm. So with another 1800rpm
available, I think that 200kPa should be possible

The MAT and s/c discharge temps are quite a bit higher now with the 75mm
pulley. I can see as high as 95 MATand 115 degC s/c discharge cruising out
of boost at highway speeds (no injection). So I don't mind running a bit on
the rich side.

Car still runs very rich at WOT (into the 10's) and while I am dialling back
the gas to bring the AFR closer to 12:1 I am wondering if maybe I should go
back to the 0.5 nozzle I was using previously (0.6 currently fitted) ? Is there
any way for me to judge if I am injecting too much mix ?

Cheers... jondee86
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