[NC] 7.5lbs per HP build thread / xpost from M.Net - Page 7 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 07-20-2016, 11:07 AM   #121
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Went to check the fan wiring connector, gave it a mild tug and it popped right off. Derp. Plugged it in correctly, and viola my fan now works.

Mostly been working with Joe on the lower RPM load cells. Idle started out flakey and low RPM low load (constant cruise anywhere between about 1500 and 3k) would hitch and buck a bit. Hot restarts weren't so hot, cold starts were fine but idle would tend to wander until the car warmed. A few hundred miles and three flashes later, idle is completely fixed, hot starts fire immediately, there's still a bit of hitching around 2500rpm under mild load (~15" vacuum) which should be cleaned up with the next flash update tomorrow.

Also with the focus on lower RPM load cells, partial throttle boost response is getting better. Lots less fuel, and of course more boost sooner. Intention here is to be transparent with the progress, not to tell anyone it's the best thing since Gay Miata Jesus.

Last edited by albuquerquefx; 07-20-2016 at 11:11 AM. Reason: stupid photo host dorked up my image
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Old 07-20-2016, 03:02 PM   #122
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nice when it's the simple, easy fix!
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Old 08-04-2016, 04:51 PM   #123
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Default 1150-mile update

Just a minor update bump...

Been fighting an occasional idle wandering issue, and still some lazy off-idle throttle response along with continued minor surging at low rpm cruise. The symptoms read just like a small vacuum leak, but vacuum seems pretty good as-is and I wasn't able to discover any obvious leaks with carb cleaner spray... Then I finally turned on my brain and realized the valve cover vent is open to atmosphere. Duh.

Three bucks at AutoZone for the fitting, some Permatex white thread sealant for my 5/8" NPT tapped hole in the MAF tube, and Permatex black to seal the vacuum nipple portion (and a black ziptie to help, applied after the photo was taken...)


Boom. Rando-wandering hot idle solved, throttle response is dead-nuts, the surging is still around but WAY less. Part of the remaining stumble may be the computer re-learning the fuel trims and target A/FRs after running with the leak on this tune for ~200 miles. If it doesn't clean up after the next tune update, I'll start working through the entire intake manifold. I built a Deezums catch can for the PCV but haven't installed it yet; might just yank the PCV line this weekend and solve that too.

Anyway, not much else to report except for REALLY good gas mileage. I'm now averaging better than 28mpg per tank fill, this is about 2.5mpg over the running average for the car being normally aspirated. I keep meticulous records; every fill up I document date, total odometer, gas in, price, and calculated MPG. I've put five tanks of gas in the car since turdblo, and it's continually trended up every tank. Nice.

Oh, and I had a chance to shame a FursBurz earlier this week. We both hit the front row of a red light in city traffic, he had the fartcannon exhaust, some chrome blingy stancenation wheel thing going on with a pretty solid drop. Figured he would want some, and he did. By the end of first he was already a car and a half back, and halfway thru 2nd he gave up. At least I got a thumbs up at the next light Not much of a brag to beat on a normally aspirated Toyobaru, but hey it's the only person who has decided they want to try.
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Old 08-04-2016, 09:10 PM   #124
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You're going to want a bigger hose and fitting for that valve cover vent.
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Old 08-04-2016, 09:13 PM   #125
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that's what she said (and was right)
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Old 08-04-2016, 10:08 PM   #126
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Quote:
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You're going to want a bigger hose and fitting for that valve cover vent.
That's actually the OE hose with the end diked off. Do I still want moAR?
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Old 08-04-2016, 10:14 PM   #127
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Yes. You're going to have more flow out that port in the head with boost.
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Old 08-04-2016, 10:22 PM   #128
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Yes. You're going to have more flow out that port in the head with boost.
Out of that port? The PCV is drawing in from the block using the vacuum from the intake manifold, and includes an OE check valve to prohibit reversion. Even under boost, the valve cover vent is pre-TB so it's likely to be a higher pressure area than the intake manifold itself. Air shouldn't be coming out of that port under any regular circumstance, unless I'm getting reeedonkulous ring blow-by? What else am I missing here? The whole point is to have the suction from the PCV pull the nasty fumes from the block, and to some degree suck the rings into the cylinder walls. You want some "draw strength" there to evacuate, but you need the air input from the valve breather to get the circulation moving.

I'm still cool with upping the size tho; the sizing logic makes sense. The output port on the valve cover is fairly large before it steps down to that puny OE hose pictured. I'll get it measured up this weekend and order the proper matching brass and hose for it.

Edit: The entire reason I fixed this was because the open-to-atmo valve breather was allowing air to seep in (via the PCV sucking it through to the intake manifold) without ever being metered by the MAF. By getting it away from atmo and putting it behind the MAF, the car can now meter the air being drawn through the PCV and it doesn't run lean at lower load. During boost, the PCV check valve clamps down and no "extra" air makes it through, which is why I had no problems under load.
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Old 08-04-2016, 10:52 PM   #129
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That vent needs to go to the intake tube pre-turbo. if you're running a blow through maf well that wont work. You'll just need to put a big checkvalve on that to prevent that port from drawing in air. They make -12AN check valves with breather filters on them just for this purpose.
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Old 08-05-2016, 09:01 AM   #130
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All the modern turbo kits for the NC are blow-thru configuration. I'm pretty sure there are some supercharger configurations which remove the MAFS and convert to speed density (a feature offered by ECUTek for the MX-5.) Solving the breather challenge is significantly easier in those configs. Regardless, in the picture I posted above, you can see the MAFS in the lower right corner, just a few inches upstream of my newfangled vent breather connection.

I'm told there's a Fab9 kit somewhere in Texas experimenting with a draw-thru system, but it's only an experiment at this moment.

In the meantime, because mine is a blow-thru mass-air config, I need the air metered for the car to run right. I'm going to look at a few other factory turbo models to understand how those solutions have been implemented. The more I read and contemplate this, the more I think "bigger" isn't the actual solution. It might be part of the solution, but under boost the PCV is going to temporarily stop functioning regardless.

I'll post in here when I feel like I've got it sorted.

Last edited by albuquerquefx; 08-05-2016 at 09:41 AM. Reason: phone typos, and moAR
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Old 08-05-2016, 05:41 PM   #131
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I've had several hours to read up, and I obviously went down the wrong road trying to mimic an OE boost config. Modern factory cars aren't doing blow-thru, or if they do, it's not well documented. Next google session then surrounded the Nissan KA-T groupies because they're all MAF-based, commonly do blow-thru setups, and thus have very similar challenges. Most of them went stupid and either allowed the crankcase to be pressurized, or blocked off both ports and shrugged, or allowed the valve cover to go straight-atmo and just DGAF about the vacuum leak they cause.

For the few who seemed to "get it", the option was typically either a GM vacuum pump thing (which typically didn't work in some form or another) or an exhaust venturi for the PCV output with the vent cover going to atmo. I would like to avoid dumping oil into the catalytic converter, so I have a similar-but-slightly-different hypothesis. Ready to tell me how much stupid I ate for breakfast? Here goes:

1: Valve cover breather gets a small oiled filter straight to atmo.
2: Solidly plug the PCV intake manifold port.
3: Route the actual block PCV to a Deezums Catch Can (TM)
4: Separately, route the catch can to a new venturi port on the intake-side of the turbo.

Yeah, it's only a tiny bit of vacuum (comparitively) BUT it should be enough to keep the vapors moving. The catch can is there to keep the bigger crap out of the turbo face.

Ok, flame away...
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Old 08-05-2016, 06:54 PM   #132
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your first mistake was reading KA-T owners
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Old 08-05-2016, 09:21 PM   #133
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Quote:
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your first mistake was reading KA-T owners
Yeah, yeah. We've all met at least one KA24DET zealot in our lives if you've been doing car **** for any reasonable length of time. At the same time, couldn't someone say similar things about those **** who turbocharge their faggy Miatas?

I did ask for flames though, so fair is fair. +1 "KA-T"s for you, good sir!

Ultimately, the better information wasn't on the KA-T forums but on the SR20DET forums instead. Yes, I realize that's the NEXT level of Nissan 90's-era douchebaggery... Nevertheless, both have the same situation as my NC -- blow through turbo setups need some asshattery to get PCV working in any reasonable way. Check valves on the valve cover aren't the right option, we need BOTH fresh air moving into the block and we need vacuum to suck out the block (lol homoerotic ) Bigger hoses aren't going to fix this, I need alternate pathways or vacuum pumps or some dumb **** like that.

As far as I can tell, using the intake-side of the turbo is the ONLY place I can guarantee any amount of vacuum any time the engine is running at enough speed to matter. If I can use this source of lightweight vacuum, I can plumb the valve cover to atmo and be done with this. I think this is the way I'm going, unless someone comes in with a better suggestion.
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Old 08-08-2016, 09:20 PM   #134
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Why do you need fresh air going into the valve cover?
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Old 08-09-2016, 12:16 AM   #135
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Quote:
Originally Posted by Leafy View Post
Why do you need fresh air going into the valve cover?
Because that's how a PCV system works: filtered air comes in via the breather, is drawn through the block, and drawn out via the PCV valve + line via a vacuum source (near-always the intake manifold, sometimes a vacuum pump, in rare cases a venturi tube placed in the exhaust.) The circulation of air is a requirement to ensure the vapors are evacuated properly and fully. This is the defacto operation of a PCV system; this might be contrary to a LOT of misinformation floating in the ether of the internet. Also relates back to the :wtf: reply I first gave when you replied about the breather tube venting: air doesn't come out of the breather unless something has gone wrong.

Still working through how I'm going to be a cheap bastard and fabricate a venturi tube -- and then how I'm going to measure the vacuum created to ensure it's sufficient. I'll post a parts list and pics when I have something to show

Last edited by albuquerquefx; 08-09-2016 at 12:30 AM.
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Old 09-01-2016, 01:36 PM   #136
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I haven't posted much in the way of updates over here, so here goes a small one: Due to a glut of business and personal travel, and a lot of renovation of the back yard, I've had NO chance to work on the PCV yet. I have all the parts ready; a sizable stack of polypropylene vacuum nipples with NPT fittings for building my venturi, a separator can, and the proper hoses to plumb it safely. With the three day Labor Day weekend coming up, I intend to spend at least one day completing my PCV work.

Now, something worth actually posting: Starting basically this week, I have the EBC set to 46% duty, which nets gauge-indicated 12psi on a 4th gear pull. It's already amazing what another ~3.5psi can do. WOT in 2nd gear is now just tire spin, and I've had 3rd gear walk out from under me twice. My target is eventaully 15psi, and I'm starting to wonder if I'll ever be able to use it all. I also admit much of the traction issues are the OE tires. Plenty of tread remaining with less than 19,000 miles, but nearly eight years of age means dry rubber.
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Old 03-06-2017, 11:30 PM   #137
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Been an eon since I updated this thread The tune is nearly complete; it will be coming back from New Braunfels, TX this coming weekend! In the meantime, here are some updates from MONTHS ago which I never posted...

First, I got rid of the Miata braces with a few thin wisps of satin black finish...


The Fab9 exhaust came in, what, like four or five months ago or something. Midpipe and integrated cat (see the bulge just "south" of the flex pipe?):


The Vibrant center-entrance, dual-exit muffler:


Also put a $1k deposit on a set of Rays VOLK ZE40's and Michelin Pilot Super Sport 245/45R17's. Gonna take forever to come across the pond from Japan, so you'll have to wait for pics...

Dyno sheets, time slips and updated driving impressions are in the near future!
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Old 03-07-2017, 07:28 PM   #138
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Why didn't I keep my mint Winning Blue '06 with the factory hard top... I was even in talks with Joe for getting a 2.5 swap!
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Old 03-09-2017, 01:30 PM   #139
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A bit of sneak peek, and to be taken with a grain of salt since this is the tuner's shop... This is the uncorrected dynapack run at ~13psi, which hits the stock MAF (in a 1" larger diameter tube) voltage usable limit of ~4.95v. This was done as a checkpoint before Joe went through the whole process of mapping VE from idle to redline...



The ECU now switches from MAF to speed-density at an airflow rate 150g/sec, or about 7.5psi (2psi short of the wastegate spring pressure.) Car is now running right at 15psi, and was able to take a touch more timing after the SD fueling strategy change. I pick the car up tomorrow night and drive it back to Memphis on Saturday. I'll toss it on the local dynojet on the 14th to get my own numbers, same place I where the bone-stock setup netted 141whp. Should be interesting to see the delta...

Oh, and the torque oscillation was a wierdo combo problem with WG signal line, WG preload and the EBC engagement point. This is all solved now, with the exception of how the boost gain function on the EBC still just "dumps" the extra duty cycle 1.5 seconds into the run which still causes a small peak on the right side of the graph.

I'll be back in here over the weekend to give some road trip driving impressions
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Old 03-09-2017, 05:28 PM   #140
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Very healthy plot. This thing is just starting to wake up
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