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Without seeing the actual tune file I have no idea what is going on there but it's certainly spiking. Personally I would recommend setting up your boost solenoid in a traditional configuration like you would see in any wastegate setup manual for troubleshooting purposes, it behaves better and is easier to dial things in initially.
Yes I think I am going to give that a try and see how it acts. With the 10lb springs in there now I should be able to get to 18psi when I go back to e85.
Have you ever just tested running the boost reference line to the side port of the gate and run off spring with the dome vented to atmosphere? I mean just to sort it and see how it responds. I mean the turbo is a bit small, but the less you you are demanding of the turbo the less backpressure is likely the issue. What is your intercooler setup?
Have you ever just tested running the boost reference line to the side port of the gate and run off spring with the dome vented to atmosphere? I mean just to sort it and see how it responds. I mean the turbo is a bit small, but the less you you are demanding of the turbo the less backpressure is likely the issue. What is your intercooler setup?
Whenever I tune a turbo combination I always insist on starting with low boost and simple wastegate controlled boost. This is the best way to tell if the mechanical boost control is working with the wastegate. Once the tune is nailed down for low boost, then it is pretty straightforward to add boost.
Whenever I tune a turbo combination I always insist on starting with low boost and simple wastegate controlled boost. This is the best way to tell if the mechanical boost control is working with the wastegate. Once the tune is nailed down for low boost, then it is pretty straightforward to add boost.
Andrew
Word up I totally agree I mean you could chase something forever or just start simple with the KISS principle.
You can have rock solid very easy to control boost if you just set it up properly. The lower line leaks plenty around the valve shaft of the WG. If the top is super tight just put a small bleed hole in the fittings or even the hard line going to the top gate reference. You don't leak enough boost out to hurt a darn thing and control is very good in my experience. Done it dozens of times.
you still dont know your backpressure? hook up the wastegate to the exhaust and you will get an idea.
otherwise this whole thing is a good example of how overcomplicating boost controll can give you headaches. pid/pwm/co2? what for? trying to get boost in 200 rpm earlier? what for? a "manual" boost controller always works and you dont have to second guess it. two orifices, one adjustable (and be it by sticking wires into a bleed off hole).
or, as mentioned up thread, run it on that spring directly to see how it is.
Just a quick update and answer to some of the questions I see in the thread here.
The car has been together and running for 2 years. I did have it on a manual boost controller last year. It worked fine with the exception of the boost falling off over the course of a run. It was set for about 12psi and would drop off to about 9 over a pull. This is one of the reasons I switched over to Holley since it had the ability to run boost control.
I see a few asked about the intercooler it is just a VS racing unit that I bought with one of their Denmah kits. I just am using these parts as starting points and have no problem upgrading if I need to. Also the turbo is a T4 7875 with .96 AR.
Over the weekend I rerouted the 3 port to the more traditional method and was able to make a run where the requested dome was 12psi and the Holley system held it within a half pound and no more spike. The pull felt good and didn't feel like it nosed over so I am pretty happy with those results. I also verified that my cam ICL is good and so is pushrod length. So I am convinced at this point the dyno peaking early and then dropping off was mostly due to the boost control not being set up to well. I also plan on installing the backpressure sensor as well. Hopefully the weather holds out to test it.
I still plan on going to a 4" downpipe with a cutout over the winter which should help things and I will most likely make a some changes to the wastegate location as well.
I did get the logs from the dyno runs and the dyno graph I posted pretty much follows the boost curve that was logged. It basically spiked to about 15 psi right where peak torque occurred 4200rpm and dropped off to about 11psi by the end of the run. It looks like the torque curve pretty much followed the boost curve. So fixing the boost control should get this thing squared away.
I don't plan on going more than about 12 or so on pump and then go to about 18ish with e85. I will definitely be adding some extra fuel as well until I can get it back on a dyno next year.
You can have rock solid very easy to control boost if you just set it up properly. The lower line leaks plenty around the valve shaft of the WG. If the top is super tight just put a small bleed hole in the fittings or even the hard line going to the top gate reference. You don't leak enough boost out to hurt a darn thing and control is very good in my experience. Done it dozens of times.
Is this just something you do automatically on every build or is this something you do when boost control is erratic?
For twin gate applications, would you do a single pin hole in the main line or a pin hole in the line at each gate?
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