chris2712au wrote:hope that interests someone out there ?
I think: Yes! (At least me)
I already have an AVC-R but I think there are a lot of people out there with no external boost controller. It is a pity but in this case NIStune came a few years to late for me.
chris2712au wrote:oh and one last thing... I got a wireless three button mouse.. awesome.. one button for click and the other 2 for add - subtract - now i can drive and just hold the wireless mouse to tune... beats staring at the laptop and is alot safer too.. I have the pointer disabled... would make for a good usb nistune keypad.. cause having your laptop accessible while your driving is an issue.. what do you do put it on the dashboard ? or reach over to the passenger seat..i think not..
That is a problem that I don't have solved yet. I think I am going to map with a friend on the passengers seat as its very risky to drive and map alone. Good idea anyway to use a 3 button mouse in this way!
Very interested! thoroughly looking this thread. Hope to use some methods on R34 once I develop some more understanding of its boost control principles.
Make the bends as smooth and shallow as possible.. better to have two 45 deg bends spaced by 6-8 pipe diameters than to have 1 90 deg bend if possible...
It takes 6-8 pipe diameters to almost stop the air from swirling around corners.. swirling air does not like to change direction..
Silicone joiners are a pain in the butt.. however in some instances it is easier and better for flow to use a 90 deg silicone than two silicones and a mandrel bent 90deg bend..
2. The t28 turbo does like to be ported however surge porting for this turbo had little to no effect.. I believe that the 90deg bend prior to the turbo had a major influence as the air would be swirling badly in the intake snout and the holes and rough surface would of disrupted the flow.. IMO... But I will try it again...
3. The standard boost control responded to being in line alot better than bleeding off.. less first gear spike and easier to tune.. more predictable..
4. The s15 sr20 does like larger throttle bodies... it removes a 1PSI pressure drop from the system by going to 60mm..
5. The recirc hole (4mm) in the standard s15 blow off valve loves to be plugged up..
6. the PCV valve on the s15 stuffs up after a while leaking boost and putting oil in your intake pipe..
7. The flexible intake / cast pipe is crap on the T28...
8. Plumb back BOV's should return the air directed directly into the compressor wheel of the turbo..
9. Nistune is awesome.. people are having a hard time believing the power my car has with standard AFM, ECU, cams, and injectors..
10. dyno figures arent always indicative of how well a car goes..
11. my t28 is starting to run out of puff @ 15psi..
12. I am more interested in a fat torque curve than peaky HP curve
12. A lot of this is off topic but maybe useful for some..
here is a little kind of how to on what I did...results may vary hope it works ok for you... excuse the spelling errors and things just wanted some feedback on it as is..
Nice write up, just a little confused on the diagram for Block method - there is mention of the restrictor but the diagram shows simply intake and the stock solenoid with only 2 feeds from it.
I kinda lost contact on this thread. For some reason I stopped getting emails telling me that stuff was happening. Great to see that you've been forging ahead though.
So putting the solenoid in series is a goer then? Would you care to elaborate on advantages over using the solenoid to bleed air? I thought it'd be better.
My only concern is that with this method it's possible to trap air between the solenoid and the WG actuator. Leaving the WG stuck open until the solenoid opens next. Although a small bleed hole would fix this (like the little hole the Turbotech valves have in the side).
Another thought on maximising the T28. Something we used to do is "highflow" them by boring out the hole that the turbine wheel sits in. Most people increased it by 60 thou (1.5mm). I dunno if this really makes much difference but it used to be quite a common mod. You may well have done this already. I also ported the WG hole on mine to make the hole 1 or 2mm larger.
I've also been checking out the Trust turbos lately. Being plain bearing units, I never really thought much about them. But as it turns out they are a good option on SR's because they offer a number of turbos that sit nicely between the T28 and the 2871. Definitely worth a look. I see they're now doing Taiwanese copies of the Trust units. Might be just as well seeing Trust have gone broke. Hope this link works:
sprout wrote:Nice write up, just a little confused on the diagram for Block method - there is mention of the restrictor but the diagram shows simply intake and the stock solenoid with only 2 feeds from it.
The restrictors are the stock ones as in the pic below
So putting the solenoid in series is a goer then? Would you care to elaborate on advantages over using the solenoid to bleed air? I thought it'd be better.
My only concern is that with this method it's possible to trap air between the solenoid and the WG actuator. Leaving the WG stuck open until the solenoid opens next. Although a small bleed hole would fix this (like the little hole the Turbotech valves have in the side).
PL
well it is hard to say at the moment, however in my mind the bleed method was not as predictable as the block. In saying predictable I seemed to be able to get it out of control really easy with spike and that the system was not really repeatable in all gears. In the block method subtle adjustments give subtle improvements and in the bleed method a subtle adjustment meant alot. I am still going bit by bit. I will put up some from my latest tune which is a little more agressive again.. concave on the boost side.
As for the trapping of air issue I dont think it is doing it but then again i have my waste gate pre loaded to 15psi as per the little write up I did.. A question is that as long as the RPM is above 2k the solenoid is active ? or does it shut down on tps closed ?
Once on boost the your rpm does not drop that much so your pwm is not changing that much dont really think it is an issue and then you have peak boost wastegate is fully open allowing equalisation in saying that a hole might be on the cards.
I have asked MAtt to add boost duty to the gauges list...
Also my duty cycle for my injectors is not working ? any ideas ?
I haven't tried the DC display in NIStune yet. I'll give it a go this weekend.
Not sure on what the ECU does to the solenoid when not actually driving it to control boost. It could well be held open - meaning that you don't need the bleed hole. It's been awhile since I did my bench testing. Must do some more. Gotta get S14 and ER34 boost control tested out....
I suspect duty cycle for boost control maps is simply based on a percentage of the maximum numerical value in the tables. In reality you need to understand that the solenoid takes a finite time to react. So above/below certain values it doesn't have time to react to the signal so it's effectively either open or closed.
I monitored the signal on an oscilloscope while testing the airflow through the solenoid and only values between about 10 and 90 actually resulted in controlled airflow.
Solenoid response may vary from one unit to the next....
the tune is good I gave it a little on the drive home and was impressed. the boost is nice and smooth doesnt just jump on and break traction like it use to so I must of improved the off boost bottom end torque..
As for the boost map it would be nice to have more than one value for each rpm point.. reason is that then you could start playing with the boost response for each gear as like in the tune normally gear patterns have a distinct path through the fuel and timing maps..
However with the current setup you just have to try again and again but I am happy with this block method..
I still think my PCV is stuffing up.. still not hitting 15 up top its gotta be leaking somewhere just got to find it.. or ... the solenoid cant hold back the boost pressure to the actuator it does make sense that I am now trying to restrict the pressure to the actuator then let it flow then restrict it again.. the problem is am i trapping the air in the actuator by doing this ? I think that is technically sound or am i going crazy ? regardless of shifting gears ? I might try a 1.2mm hole in the boost solenoid.. then back to square one.. bummer..
here is the stage 2 idea... block n bleed.. this way i dont stuff up my solenoid
What do you think ? i might use a needle valve just to start.. then make a fixed restrictor..
it would be nice if there was a solenoid that was push pull design.. you use boost pressure to open and vacuum from the turbo inlet to suck it closed..
Yep, that's what I meant. A very small hole should suffice. Otherwise it'll stuff up your current settings.
The other question is whther your turbo is capable of giving you what you want. The only real way to know is to hold the WG shut and see what it'll do.
Obviously this is a risky procedure but it at least shows you what the maximum boost available really is. I usually remove the hose to the WG and then wire it firmly shut with thick copper wire or mild steel oxy welding wire.
Drive carefully through the 3200 - 4500 area where it'll make 20+ psi if you let it. Then open it right up. Have a passenger watch the boost gauge! If it's been tuned for 15psi then it might pay to knock the IGN timing back a bit too.
(At least me)
