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They are completely variable. The solenoids are pulsed a few hundred times a second to vary the vacuum, which varies the position, which varies the boost.Quote:
Originally Posted by the_grubb
Ain't PWM great? Sure it's just on/off. But it's a whole lot of on/off happening continuously.
You certainly are a clever dude Matt. I think if we reflect back on what Inside was asking and look at what we are talking about now and the control systems. A variable vacuum or electrical control system may seem a little extravigant/complicated/unrealiable but it can solve all the limited choices you have now.Quote:
Originally Posted by rovercare
Have to agree with Dougal on part load boost levels and EGT - that is what the control is for.
All this information is here to help. Use it as you wish as some of us still have N/A 4BD1's :(
Well, I had a little more of a play today, I've found
Its to hard to work out, need to dyno run it, altered adjuster for boost to lessen boost, but to hard to tell the difference, I've also got the fuel screw sitting next to the seat, so its full fuel, worst I can hit is 750c preturbo......needs more fuel
Anyhow, it'll hit the backburner, 355 lux diffed RR to strip, LS1 GQ to fully wire, 100series to strip, SR20 and gearbag to be fitted to a bluebird, then work aswell and some water tanks to catch off my shed, big list.....
I found the following info and links in a thread for controlling vnt turbos on a Cummins 4BT forum.
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here is a free programmable standalone VGT turbo controller. the code is open source, and the microcontroller is ~$35. the program can also do fuel control too.
dmn's playground - Standalone VNT controller
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the arduino is already build, the drivers are easy to install. programming requires downloading the source code & SDK and hitting the upload (via USB) button on the SDK....
then uploading maps can be done over the serial terminal
now mapping on the other hand... different story..... you gotta know what you want it to do. he has examples on there on what to do..
you can set it for target boost (based on RPM & TPS)
so if you know what you want the turbo to do then it should be easy
map editor
dmn's playground - vnt-lda engine control / Map Editor
video of it running
VNT turbo control - YouTube
My Dawes valve turned up today. Now that I'll be able to control the VVT I should see faster spool up and ultimately better performance. I did look at these but the issue is that it's going into a 110 and I like that it has no electronics. This electronic option I'm sure is better from a tuning point of view but the simplicity and robustness of what really is a spring and a ball valve makes more sense for what my vehicle will be used for.
seems that wouldn't be hard since he is apparently wrong anyway :DQuote:
Originally Posted by the_grubb
Well got this hooked up and performance is a lot better. Spool up is very quick and reaching peak boost is now earlier in the rev range. Just need to play with the needle valve and its setting, it'll be interesting to see how this all works on the highway.
So $45 US delivered for the Dawes valve, about $110 for the needle valve and tubing and about $30 in brass fittings. Recommended if you have a VVT.
So you've gone from a pressure can to vacuum and dawes valve?
What rpm and boost do you have before/after?
I went from no actuation to the Dawes valve so the vanes were not moving at all and this is why I'm seeing quite a difference. The turbo is now working as it should and is more effective at low rpm allowing faster spooling.
As for change in rpm and boost I'm not sure as I have no tacho. At a guess the turbo boost has moved 5-700 rpm down the rev range, before it was very linear building boost through the rev range. Now it builds boost quickly to about 12 PSI and then gradually builds to about 16 PSI before I change gears. To put it simply it has more torque down low which is where I want it.