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Finally got around to removing the turbo yesterday. Here is a before and after of the porting... Not a guaranteed fix, but I'm hoping this will fix my boost creep. If not, I'll test boost with my stock cat-back before I attempt to go external.
It's weird that you are having boost creep issues. It just doesn't make sense. Remind me, are you running just off the wastegate for now or is your boost controller setup?
Couple of things. First, where are you measuring your boost - in the intake manifold, or before the throttle body? Depending on your setup, when you're at half throttle you'll probably see a lot more boost pre-throttle body than you will in the intake manifold. Plumb the boost gauge into the manifold to get the actual reading of what the engine is seeing.
The other thing is that you said previously you tested the wastegate actuator. You will also need to check how far the actuator arm is pushing the wastegate open. To stop boost creep it should move the wastegate at least 45 degrees. The best way to check this is to climb under the car and watch the arm extend as you apply air pressure to the WGA signal line. A less preferred method of testing is to pull the actuator arm so it's extended out as far as it will go to see how much this moves the wastegate. This second method isn't as good as it won't show up any issues with the extension mechanism for the wastegate arm. I put a small dent in my wastegate actuator when I was re-installing it one time and the dent stopped the arm extending the full way, causing boost creep. The second method would not have picked this issue up.
Good luck.
It's best to sort the boost creep with the WGA plumbed directly into the boost signal, not through a boost controller. Even when you set a boost controller with values of zero it still can behave very differently from if it's not there at all.
It's weird that you are having boost creep issues. It just doesn't make sense. Remind me, are you running just off the wastegate for now or is your boost controller setup?
Still just off the wastegate. No EBC till boost stays stable without the controller connected.
Originally Posted by JimmyBlack
It's best to sort the boost creep with the WGA plumbed directly into the boost signal, not through a boost controller. Even when you set a boost controller with values of zero it still can behave very differently from if it's not there at all.
The sensor is receiving pressure from the manifold.
I did test it with the arm connected with the air regulated to 10 PSI and it opens up past 45 degrees. As mentioned before, me and Brett came to a conclusion to port it because even with the wastegate flap left all the way open, boost would be obviously laggy, but it would build pressure quickly and still go past 6 PSI at 6K
Edit: This is with a 7 PSI WGA set to 6 PSI with no preload.
Hope everyone is enjoying their holidays. Just finished doing a test run after putting everything back together and so far so good. Boost stayed at a stable 8 PSI according to my boost gauge from a 3rd gear 3500 WOT run till 7500. I had to let off early since my AFR was climbing up close to 12. Unless my pressure sensor is inaccurate, the logs from the AP are showing 351 g/sec @ 7500 RPM/8 PSI. I'll do several more test runs sometime this coming week and will finish hooking up the EBC solenoid and water meth to be on the safer side. So far though, things are looking pretty good.
nice man, happy to hear it's coming along.
Now get the Kiwi mad scientist to finish up your tune so we can do a little head to head racing..errr...'testing'
Sorry everyone, it has been a while since I last posted updates. I didn't want to be another boosted RX-8 thread without having a conclusion on the final outcome. Work has kept me very busy and I just don't have the time to work on this car like I used to. I want to finally summarize everything I've experienced from the beginning to up to where I'm at right now. If you're not ready to deal with a lot of newbie mistakes, close this thread
A while back, I managed to get around 314 WHP up top relying solely on just the spring with the actuator rod a couple turns tight after the wastegate porting. Biggest problem was the spool up was obviously far too slow to be enjoyable, I was not seeing those numbers till near redline (Lowered to 8000). I also had no clue how to configure my SCG-1 back then after fiddling with the settings for DAYS; I nearly gave up on working on the car for a while due to my lack of experience with working and tuning a boosted car. I just couldn't get it to properly work until I realized I was configuring the EBC wrong this whole time.
But, thanks to gregs, I finally got the SCG-1 hooked up to an RPM signal at the PCM for logs, which answered A LOT of questions.
I started over with the entire setup. Wastegate flap is neutral with no tension from the rod. Did a run with no solenoid interference as a base run and finally figured out my base pressure. Slow spool up from 2 to 4.8 PSI from 3500 to 6800, then creeps up from around 5 to 7.4 PSI from 6800 to 8000. Keep in mind, this has a 7 PSI wastegate spring installed.
ANWAYS, ROOKIE MISTAKE...AHEM... The SCG-1 duty cycle wasn't even kicking in at all. I had the starting pressure set to 5 PSI (2 PSI below the wastegate spring pressure as per recommendation from the SCG-1 manual). I wasn't even seeing upwards 5 PSI till around 6000 RPM... So duty cycle wasn't even turning on this entire time. With 3500 RPM used as a reference point, I was only seeing 2.5 PSI at that specific range. I reconfigured the SCG-1 with a starting pressure of 2.5 and ramped up the duty cycle. Result? I finally managed to get the turbo to spool much much faster.
At this point, I'm slowly configuring the duty cycle to have full boost by 3500-4000 RPM and hopefully stay stable around 8 PSI till redline. I do not have any final numbers yet to provide, but I can guarantee it won't be 314 WHP; in fact, it may be significantly lower. I wanted to chase 10 PSI, but Brett has convinced me to stay at 8 on a stock motor. With things finally looking good though, at least I can go back to enjoying driving my car with a much quicker spool up. Once we achieve a solid powerband, the only thing left is to solidify the tune and call it a day; I'll post the final numbers from there. Thanks for reading everyone, I've certainly learned a lot from trial and error and once again thank you to Brett for being patient with my rookie self and sticking throughout the process!
Anyways! Three year update, car still runs and idles real solid, never done a compression test and will likely just run this thing till it quits. Been doing a lot of pulls at a solid 8-9 PSI and an occasional creep to 10-12 in higher speeds.
Parts Changes:
Switched to E30 ethanol mix per @Brettus@gregs recommendation a couple of years ago. I'm using a GM Flex-fuel sensor inline the fuel line, in conjunction with the Fuel-It bluetooth reader; did this just to avoid having to install another gauge.
JDM 5-speed swap and went back from 4.77 to stock 4.44 diff. (Thanks Yoshiya @NeptuneSpeed@Jedi54 for the recommendation.
Exedy Stage 1 clutch with stainless steel clutch line and OEM throwout bearing (didn't feel comfortable using the bearing that came with the kit), new slave and master cylinder.
Re-did the battery relocation, switched over to an Odyssey PC680.
Installed Stance Parts air cup kits and switched over to Fortune Auto 500 coil-overs, this has been a life safer for me on many occasions when driving around LA.
Mazdaspeed wing and RE hood installed, car got repainted.
Engine has cheated death several times with issues I've failed to notice over the years, one is failing to cap the jet air port which was the culprit for slow spool-ups.
BHR V1 adapter harness was rubbing against the engine hoist bracket, decided to go with global compliant coils to get rid of the extras.
Eliminated the breather filter on the oil filler neck and now run a catch can. Oil was dripping very slowly from the filter (never noticed this, the red filter made it difficult to see how soaked the filter was from blow-by) and started slinging towards the alternator, which caused it to die prematurely.
Disconnected the SCG-1 from the RPM signal from the PCM and uninstalled the turbo timer. Had immobilizer issues, EPS, and gauge cluster spazzing along with random lost of communication UXXXX codes.
Re-adjusted the wastegate location position. Rod was crooked before, which added extra tension, now moves straight/freely.
Water pump was creating a knocking noise during idle, replaced with a new one and went away.
Exhaust hangers were torched and bent on the mid-pipe which caused squeaking noises during acceleration.
Greddy manifold was tapped by previous owner to install an AN fitting for a sensor, the bolt that was used to plug it up came off while driving and car drove like crap. Used a proper fitting to plug it shut.
Can you see the hood vents from the drivers seat? I've been trying to decide which style of SE hood (yours or Jedi's) and was wondering how they look from the seat.
No problem. I’m currently at work, but I’ll get them first thing tomorrow.
Also decided to turn up boost, we’re at a stable 10 PSI now. Unfortunately, there’s been multiple occurrences of lean spikes near up top that’s interrupting the process… Wasn’t like this before, Brett believes it could potentially be the injectors based off logs.
They’re used OEM blues and yellows, and they’ve never been flow tested. I sent them to Injector-Rehab, hopefully that will solve the issue.
12-19-2016, 02:21 AM
