BP kit folks. Question on wastegate plumbing.
 

I got it all back together and everything is peachy but I'm spiking to 13.8 with the 7.5 springs. Trying to figure it out after the 10.1 springs got sketchy on me and I did'nt want to revisit "The incident" so I swapped back. EBC is currently not in the plumbing to keep it simple. Anyone else go through the troubleshooting with spikes. I just reinstalled the WG's so I'm sure all the plugs are there and the diaphrams are'nt pinched. Pickin brains here people.

Could you use an air compressor to pressurize the wastegates to make sure they are both opening properly?

Done. I'm replacing all the vacuum lines but just trying to cover everything before I reconnect the EBC.
https://youtu.be/EymvhSOREog

From charge pipe on the driver side (there is a nipple there) run a line down to where your clutch cylinder is. Install the supplied T fitting at the end of that line, use the remaining two ports on the T fitting, and run one line to the bottom of each wastegate.

Leave one port on the top of each wastegate open to atmosphere (bolt the hose barb on the top, so that debris can't get in).

Really no reason for any spiking if everything is plumbed this way.

I had spikes too. Ended up changing springs, driving around and seeing what I can hold and spike. I cleaned my WG checked the diaphragm, used compress air n guage and everything to check to make sure my ebc/boost guage was reading right. Heck, I even installed a mechanical boost gauge in line wth my ebc. They read the same. So I just changed the spring. Been good since. I think I posted about it in my build.

YzGyz

Which spring did you end up going to **edit I saw you used the 5.5 and plugged the top**. ( Question is did it yield a consistent 9psi? ) I had installed the 10lb spring and it spiked to 16psi with the intention of dumping the EBC. "The incident" quickly came back to mind and I went right back and changed it to the 7lb spring. It seems that the boost spike correllates to the spring pressure though because at 10lb it hit 16 and at 7lb it hit 13. I did'nt do a log graph so I'm not sure of the duration but each time it was a momentary pull but the scary part for me is that neither of them were WOT. During "The incident" when it hit 23.8 and anhillated pistons it was a WOT run with what I know now was bad plumbing.

The current plumb is as Sasha described , but my suspicion is a bad line from the charge pipe may be affecting the wastegates response. According to Amazon my new vacuum lines will arrive today so I'll see how this turns out. I'll also be reconnecting the EBC but leaving it off till I work out the spikes.

I don't remember what spring I ended up with. I just know that when it came out to be something like 7lbs psi. I used my EBC to ramp it to 11.5 psi for high boost and 8 psi for low boost. I left my mechanical gauge on while I dialed it in to make sure that both correlated for a few weeks. After I was sure of the reading, I D/C the mechanical to rid of the clutter.

I posted on my hunt for the overboosting in my build post 248

YzGyz

Yeah I read your post you said the 5.5 spring. I may go ahead and do the same since I'm gonna swap the vacuum anyway. Thanks for the insight.

I already told you how to plumb it :) I guess you "aint calling me a truther"

Mine is as follows:

From port 2 on the EBC to top of waste gates
From port 3 on the EBC to driver side charge nipple boost source
From driver side charge nipple boost source to bottom of waste gates

I am running the 8 PSI spring and with my EBC off I get 7.8 PSI pretty consistently. With it on I have it set to around 10 PSI low and 13 PSI high.... Its currently off until I see get on a dyno for the below reasons....

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Right on target YzGyz. The 5.5 spring got me 7.7 psi EBC off. Started tuning the EBC and inadvertently found the 11.3psi target at 30% set value. I'll back it down to 24% then start working on setting up the gain target when I have a co-pilot. That should ramp up the boost quicker and hit a target short of around 11.5psi but we'll see. Today I'll set up low boost starting at a set value of 2% looking to hit 9psi for a low boost setting. Finally get to set my beautiful gauges in the pods instead of just hanging out in holes today. Kept getting interupted to plug in tree lights , find boxes and help wrap this or that. Feeling Grinchy.

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Yesterday I got low boost sorted with a 4% set value yielding 8.3psi that was a good number considering I'm looking for a 9psi low boost setting. Adjusted the high boost setting to 24% which bought me to 10psi. So now everything is set as far as basic low and high boost numbers. Next phase requires a trip to Mexico and a co-pilot to set up for gain. Overall boost will increase when I set gain which is why the current peak boosts are a couple psi lower than target.

Florida to Mexico and back to tune? I'm sure you can rent a dyno for less and get more consistent results.

Get real

Not to be rude but you're out of your depth. Seriously.

For clarity and to expand your insight "Mexico" is a euphemism for an out of the way place free of traffic and relatively safe to do things that wouldn't be reasonable or prudent in a congested area or your neighborhood. Tuning an EBC for gain requires wide open throttle runs under load in search of boost drop off at higher rpm. When it's detected you adjust the gain in 1-2% increments and repeat the process until surge. When you get surge you back off the gain until the desired result is achieved. Don't get it twisted I'm new to this but this is the basic concept. And for the record IMO "tuning" on the road is a better tune than a dyno tune for driving. I experienced that with my Titan when I went from full bolt to Jim Wolfe cams. Had to add all this because I don't want to come off as an a$$ and my intent isn't misconstrued.

I'm currently having this overboosting problem! With ebc off I hit as high as 13.6 @ WOT, low boost setting is at 9.5 I hit 10.6. (I have the 8 psi springs that the installation booklet recommended to install)

I shouldn't have posted it in the first place. I know what all this means, not out of my depth. "Mexico" is just a legal cover story and for some reason, i get annoyed when i hear it. GL with your build

Install is the 7.5 Yellow spring and it seems pretty consistent at least in my case that the guage reads 1.5-2psi over the isntalled spring rate. It's done this on me with the 5lb,7lb and the 10lb springs. But my previous problem had several causes and one of them was a small hole in the passenger side wastegate. While troubleshooting all my runs were done on wastegate only. with only the lower wastegates plumbed and the upper open to atmosphere. It only overboosted until I re did all the vacuum lines. After replacing them all the 5lb spring hit 7.7psi consistently. After I got that under control I plumbed the EBC with new vacuum lines. Whatever you do stay out of it until you get past this bump. Piston Glitter looks like artwork but it hurts your heart.

And it equally hurts when she gives the rings back to you.....

So with the BP kit boost spike is somewhat common? Would it be better to just upgrade the whole wastegate assembly right off the start to avoid potentially catastrophic failure. Really curious because I'm ready to buy a BP kit or possibly something else for my 350z HR.

I'm recently more inclined to think it's possible that the actual spring rate is off than the design of the wastegates. But what it would take to prove that is several sets of Tial springs of the same rate. It may not be completely off but maybe small variances between batches. The 1.5 psi consistent differences I've seen aren't "spikes" at all but rather the guage reading consistently above the spring rate. The actual spikes I did have were directly caused by a hole in my passenger side vacuum line to the wastegate lower.

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So I guess this is the solution I've been looking for. I just need to know which spring to use.

This video will help a bit.

https://youtu.be/cPu1J5Xrx8w

I never had any issues with boost spikes with mine ...started with yellow spring and was around 7-8 lbs ....was steady with no issues ....added a mechanical boost controller ...tuned to 14lbs .....I did drop spring to the green one (5lbs) if I remember right ....doing this made the boost controller less sensitive and more stable when increasing ....running like this and holding steady at 14 with no issues

Boost creep is an uncontrolled increase in boost as the RPM's go up. So if you are starting at say 8psi at 4k RPM, and hitting 12psi by 7k RPM, then it is considered boost creep.

I have not had any customers experience boost creep, this includes the local guys, where I installed the same kit you guys are running.

I believe there is something else at play with those that are having issues controlling boost. Two wastegates are more than enough for this system. With the original 350Z kit, I used one of these wastegates, and it was more than enough to bleed off the exhaust gases to keep boost steady at 5psi on spring pressure, with a much smaller turbine to boot.

Sasha in the video I linked , at some point he referenced something I believe you have also said. Basically in the case of boost creep it generally shows up when people use too light of a wastegate spring. A fluctuation in boost in my opinion is not a "spike". Using the graph feature on the Greddy Profec, if I have a boost setting of 12.5 and it bumps momentarily into 12.8-13psi I can live with. A spike is what happened when I went from 9psi to 23psi.With the graph feature it's more observable as literally a bump or a spike.

Yeah, I didn't watch the video, but have been around the block a couple of times :).

I think a variance of up to 1psi is acceptable, and that is why a base map for any and all kits should not be used under WOT. Each kit (TT/ST/SC...etc.) requires custom tuning, not only for maximum performance, but more importantly engine longevity.

If anyone wants to see what boost creep looks like, I can take them for a ride in my car =)