Turbo limit or BCS limit - Install restrictor?

[awdonly]

I've been running Chrome with ECU boost control of my DR650s via the stock 3 port FPS without any restrictors and have run into a limit now that I'm running E85. I'm running aftermarket wastegate actuators with 1 bar springs. I'm hitting around 21 PSI peak boost at 85% duty cycle and have no apparent increase in boost curve between 85% and 100% duty cycle. Not sure if I'm hitting the limit of the turbos, but doubt it, or if the BCS (former FPS) is at its limit. Anyone have any thoughts or suggestions?

Was going to experiment with a restrictor pill in the boost feed line to the BCS. Does anyone know the orifice size used in the stock BCS line or if they are still available? Mine is long gone.

[Chris@Rvengeperformance]

I couldn't even get more than 16 or 17 psi on the stock bcs.

[awdonly]

I didn't get diddly out of the stock BCS either, but the 3 port FPS worked wonders up to this point.

[Dougal]

Can you borrow a mates 3 port boost solenoid to test that the FPS (now being used as a BCS) is the limiting factor after 85% Duty Cycle?

A 3 port grimmspeed, tactrix or MAC solenoid would not cost a lot to purchase (afaik $100 approx) and will cater for the additional boost your wanting to use.

[awdonly]

I was looking at that option. I suppose I could just disconnect the wastegate hose from the solenoid and see what happens. I'd know if the turbos are maxed really quickly. On second thought - maybe that's not the wisest idea ;-)

[RealMcCoy]

I think your biggest problem is that you have to be over 85% at all... I doubt the solenoid will flow much more at 100% than at 85%. (you do have to factor in latency)

Are you on stock wastegate springs? If that's the case, you're near the point of blowing them open regardless of duty cycle.... Get some 12psi springs in there, and I bet you can hit any number you want and never get over 75%...

[awdonly]

I'm running upgraded springs - but I think you are right that the limits are likely in the repurposed FPS

[Chris@Rvengeperformance]

The upgraded springs did nothing for me on the stock bcs. 16 psi either way. Right now I am at zero duty cycle on the aem and mac solenoid. 12 Psi, creeps to 16.

[Jimvr4]

I agree the upgraded springs don't help you. I had them installed for a long time and for a while used the stock BCS in the bleeder configuration. It worked however I got uncontrollable boost spikes and with 91 octane I wasn't able to hit more than about 16-17 psi without knock.

Unlogic and I are using the Tactrix 3 port solenoid and it works very well. I went back to stock springs and now I can control the curve much more so since everything above 7 PSI is controllable. Chrome wastegate control allows you to put in a factor to prevent the spiking.

[awdonly]

Thanks Jim. I just purchased the plug/play solenoid from 3swarehouse - https://3swarehouse.com/product/plug-and-play-3-port-boost-solenoid/ to try. It appears to be MAC based. I like the Tactrix solenoid form factor better from what I can see online. What boost levels is it capable of supporting? Are you using a restrictor with it?

[RealMcCoy]

I agree that the stock springs are much easier to control at pump gas boost levels...

If you're trying to run psi numbers in the mid twenties, they are going to cause you problems.

[Jimvr4]

Thanks Jim. I just purchased the plug/play solenoid from 3swarehouse - https://3swarehouse.com/product/plug-and-play-3-port-boost-solenoid/ to try. It appears to be MAC based. I like the Tactrix solenoid form factor better from what I can see online. What boost levels is it capable of supporting? Are you using a restrictor with it?

The form factor of the Tactrix is good and it zip ties in easily to the BCS mount point. It's simple to make an adapter harness to avoid modifying the stock harness. I personally haven't gone higher than about 21 psi with it but I think it will hold much more than that. My pressure tester lets me pump up the stock springs to the mid 20s.

I don't have any experience trying to push higher than mid 20s.

[Chris@Rvengeperformance]

I agree that the stock springs are much easier to control at pump gas boost levels...

If you're trying to run psi numbers in the mid twenties, they are going to cause you problems.

No, I mean you could set the wastegate table to 90%, 70%, etc and still get the same 16 PSI. Installed a hallman mbc and three turns later 25 psi.

[KeithMac]

I run Forge actuators (red springs) and Forge Unos MBC (blocking type), holds rock steady from 18psi all the way to 30psi.

[awdonly]

Looks like manual boost controllers are a workable option. Has anyone had success with controlled boosting into the mid/upper 20's with a boost control solenoid under Chrome control?

[Hans@GZP]

We will be experimenting with our boost solenoid and different restrictor pills to see what works the best. We did do a test with just putting our solenoid on a totally stock VR4 and seeing what would happen. It ran the same boost levels as the stock BCS. With the OEM restrictor pill installed, our boost solenoid hit fuel cut (17 psi). So, we're going to get some different sizes and see what works.

[murphys_law]

Mbc here with stock actuators. I can peak about 21 psi and control wherever I want below that.


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[KeithMac]

My limit on stock actuators at higher revs (5000+) was 22psi, the exhaust pressure blows the wastegate flappers open (on my td04-16g's).

[awdonly]

I'm running Kinugawa actuators (http://shopping.kinugawaturbo.com/turbochraupgradekitmitsubishi6g72t3000gttd04-19t-2-1.aspx) with 1 bar springs that, oddly, boost only to 9PSI (raw data) with BCS off - maybe due to the preload I'm using. I'm at 5200ft so I have an offset in all my logging of +3PSI to get the MAP to zero out with engine off, but for this post and the remainder of this thread I'll use the raw, unadjusted PSI for consistency.

I just received my GZP boost controller which is MAC based and I'll be receiving the Tactrix BCS soon. I'll post a comparison of the boosts I'm able to achieve with each (within reason) against my 3 port stock FPS acting as a BCS. GZP included nice brass fittings with a .150" bore (thanks Hans/Emilie) vs the stock FPS' .100 bore. I think a larger bore is likely to be more capable of avoiding boost spikes/overshoot which may be the downside of using a restrictor. In theory it should also be able to vent more boost away from the actuators. We'll see what experimentation shows.

[DocWalt]

1 bar springs and only boosting to 9PSI? Seems kinda off.

[awdonly]

Not sure how they calibrate them. When testing on the engine stand they seemed to be fully open at about 14PSI

[Jimvr4]

Do you have a MV8500 pressure tester? I would hook it up to the Tee and check what pressure causes both WG to crack open.

[awdonly]

I do and did. Cracks at 12psi gauge (9 PSI raw). This altitude offset thing sucks

[awdonly]

I think with actual exhaust pressure in the system the pressure on the wastegates makes them open earlier than when testing static

[KeithMac]

As awd only says, when the car is running and under load the exhaust flow puts pressure on the flappers basically reducing the relative spring stiffness in the actuator.

[awdonly]

My testing of MAC and Tactrix vs 3 port FPS delayed due to family/work issues. In the meantime, I found this link to similar Evo research - http://www.evolutionm.net/forums/ecuflash/379043-bcs-testing-data.html

[awdonly]

Tested MAC and Tactrix and both were indistinguishable from the 3 port stock FPS pressed into duty as a boost controller. Next test - Hallman MBC. In theory the 100% duty cycle on the EBCs should be mirrored by maxed out MBC, but others have reported an ability to get to higher boost levels With the MBC so I'm very curious.

[murphys_law]

Tested MAC and Tactrix and both were indistinguishable from the 3 port stock FPS pressed into duty as a boost controller. Next test - Hallman MBC. In theory the 100% duty cycle on the EBCs should be mirrored by maxed out MBC, but others have reported an ability to get to higher boost levels With the MBC so I'm very curious.

My mbc is ~21-22psi maxed.


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[KeithMac]

You need to work out if your turbos are capable of producing boost at higher levels (with good octane fuel).

Secondly you need stiffer wastegate actuators.

Thirdly you then can start tesing different solenoids/ mbcs, if the springs are being forced open no solenoid/ mbc will address that.

[awdonly]

I suspect I'm at the limit of the turbos and not limited by wastegate springs/actuators. At 100% duty cycle I'm peaking at 21PSI on a 90 degree day and at 25 PSI or more on a 70 degree day. The springs shouldn't be impacted by temp.

[murphys_law]

I suspect I'm at the limit of the turbos and not limited by wastegate springs/actuators. At 100% duty cycle I'm peaking at 21PSI on a 90 degree day and at 25 PSI or more on a 70 degree day. The springs shouldn't be impacted by temp.

Yup, sounds correct.


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