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Old 09-20-2016, 09:30 PM   #741
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no point of porting if you're nearly maxing it's flow capacity.
boost creep, in your case, is good
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Old 09-20-2016, 09:30 PM   #742
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no point of porting if you're nearly maxing it's flow capacity.
boost creep, in your case, is good
Se weld the wastegate shut, got it.
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Old 09-20-2016, 10:52 PM   #743
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Did you ever figure out the manifold to turbo stud size? Is it m8x1.25?
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Old 09-20-2016, 11:33 PM   #744
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Did you ever figure out the manifold to turbo stud size? Is it m8x1.25?
It's not M8 on my manifold, M10 it looks like assuming it's metric. I didn't caliper it to know what thread pitch it is.
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Old 09-25-2016, 05:13 AM   #745
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Haven't made much progress, been busy. Did some research and I'm getting less and less confident that a miata auto is going to hold anything over 400whp no matter what I do to it. I did find one spec that says the max input torque is 375 ft*lbs for this transmission. If there is even a 10% safety factor built into that then it should max out around 400 flywheel torque, so around 330wtq. I can easily exceed that so.... I'm guessing anything over around 20lbs it's going to be sad.

Apparently the older Jatcos from the 1.6 miatas can be built to handle more though.

It got me looking into the GM 4L80/4L85 and honestly if the miata auto ends up not being strong enough or will cost too much to have one built, I think I'm just going to put a GM 4L80 in it. Those are cheap, strong, and have cheap/readily available upgrades. It looks like a stock healthy 4L80 would probably be enough for my car, which would certainly keep cost down.

I mocked up the turbo, it barely fits but it does fit. Gotta completely redo my downpipe. :( And wastegate dump. And a few other things. And the turbo oil feed fitting I ordered is wrong too, so gotta order a new one, it's some weird size of course.
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Old 09-25-2016, 07:28 AM   #746
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Haven't made much progress, been busy. Did some research and I'm getting less and less confident that a miata auto is going to hold anything over 400whp no matter what I do to it. I did find one spec that says the max input torque is 375 ft*lbs for this transmission. If there is even a 10% safety factor built into that then it should max out around 400 flywheel torque, so around 330wtq. I can easily exceed that so.... I'm guessing anything over around 20lbs it's going to be sad.

Apparently the older Jatcos from the 1.6 miatas can be built to handle more though.

It got me looking into the GM 4L80/4L85 and honestly if the miata auto ends up not being strong enough or will cost too much to have one built, I think I'm just going to put a GM 4L80 in it. Those are cheap, strong, and have cheap/readily available upgrades. It looks like a stock healthy 4L80 would probably be enough for my car, which would certainly keep cost down.

I mocked up the turbo, it barely fits but it does fit. Gotta completely redo my downpipe. :( And wastegate dump. And a few other things. And the turbo oil feed fitting I ordered is wrong too, so gotta order a new one, it's some weird size of course.
hey pats amazing build thread

the 4ln71b out of the factory 1.6 is a 4 speed but iam pretty sure the bellhousing off the factory 4 speed with fit a 3 speed 3n71b which can be built to a rated 500hp well atleast here in oz i just dont know how much i can ask what parts are needed as the guys i used are very very helpful the only issue is the rear extension has no spot for a power plant frame as the box is shorter so you need to make a trans mount too which is why i went 4 speed

hope that may be some help
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Old 09-30-2016, 05:11 AM   #747
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hey pats amazing build thread

the 4ln71b out of the factory 1.6 is a 4 speed but iam pretty sure the bellhousing off the factory 4 speed with fit a 3 speed 3n71b which can be built to a rated 500hp well atleast here in oz i just dont know how much i can ask what parts are needed as the guys i used are very very helpful the only issue is the rear extension has no spot for a power plant frame as the box is shorter so you need to make a trans mount too which is why i went 4 speed

hope that may be some help
Thanks man!

So, small update.

I added water fittings to the motor for the water cooling for the turbo. Will be 3/8" hoses for the water cooling.

I pulled the 01 fuel rail I've been running. Did some pressure drop math, and at 80 gallon/hr, (max for my fuel system with these pumps/injectors at 100% duty cycle) I calculated I have 5.6 psi pressure drop in the ~5 inches length of factory 5/16 hardline on the fuel rail! And about 1 psi pressure drop in the 6AN feed going to it, and probably another 1-2 drop in the rail itself as it's feed by the line 5/16 line across the top of it. So that's a total of about 8 psi drop from the regulator to the rail! I had a fuel rail from some other BP (maybe a 99, don't remember) and I'm cutting it up and going to modify it with 6AN fittings and whatnot to get rid of most of the pressure drop. Math shows it should be around 1.5psi drop from regulator to rail with the new larger fittings and reduced bends, maybe only 1 PSI if I can get rid of the bends all together.

Going to redo the fittings in the tank as well with a big Y-fitting (to replace a small T-fitting) to connect the pumps together, and a 6AN bulkhead fitting (replace factory 5/16 hardline) and high flow 6 micron filter and new hose between them (replace stock stuff). Haven't done pressure drop calcs for stuff in the back, but it's probably 10+ psi as it sits if not more. I'm hoping once fixing this stuff I can hold pressure to redline.

Finally got a shipping quote for transmission parts and paid that, so hopefully it all ships tomorrow. Took a month, but I should have everything for the conversion show up on a pallet, all removed from a 99 automatic miata.

Hopefully will get some good progress going and take some pics. Haven't had a lot of time to work on it much so progress has been slow...
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Old 10-03-2016, 06:27 AM   #748
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......
Attached Thumbnails
Pat's Ebay Turbo Compound Boost Build-20161003_022001.jpg   Pat's Ebay Turbo Compound Boost Build-20161003_030821.jpg   Pat's Ebay Turbo Compound Boost Build-20161003_032351.jpg   Pat's Ebay Turbo Compound Boost Build-20161003_032400.jpg  
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Old 10-04-2016, 01:13 AM   #749
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Got it finished today. Fired it up and let it idle for about an hour while checking over everything and checking for leaks. Did have one oil leak (screwed AN line to turbo by hand and forgot to tighten it... lucky it didn't spray everywhere just a slow leak) Took it for about a 1 hr drive to do some tuning and see how it works. Turned the rear turbo as low as it will go (4 PSI) so I could evaluate the new ebay 3076 on its own.

No surprise it went lean everywhere with a bigger turbo up front. About 0.5-1.0 AFR lean in boost. And the funny thing is, I swapped to a modified fuel rail that has a 6AN fitting welded right into the rail (replacing the 5/16 hardline with a sharp bend in it). Math shows old setup had ~ 8 PSI pressure drop at max flow, where this setup has 1 PSI drop at same flowrate. So despite the injectors getting better pressure, it was still lean.

For the front turbo, the EBC is setup to deliver 24 PSI over the rear turbo, so with the rear at wastegate that should hit 24+4 = 28 Total. It spiked to 30 though so I have data for that!

Also no surprise a 57mm turbo spools slower than a 47mm turbo. But it's not that bad. I've always figured an ebay turbo is going to be about 500RPM slower spooling than the garrett.

From a 3,800 RPM pull in 5th, this turbo makes
10 PSI @ 4,200 RPM
15 PSI @ 4,400 RPM
20 PSI @ 4,600 RPM
25 PSI @ 4,900 RPM
30 PSI @ 5,200 RPM
First drive with new setup so didn't go any higher yet.

I'm sure the numbers would improve with the 2K pull. I'll probably do that tomorrow to see what affects it has.

More good news, the front turbo now moves enough air to spool the big turbo while the small turbo is spooling. Before the front turbo would spool and go, then finally the rear turbo would light off. Now the rear one starts spooling while the front one is spooling. So much improved time to full boost in everyday driving.

Water cooling on turbo works well. After the drive I parked it and left it running popped the hood, and the turbine housing was 580*F, manifold 560*F, CHRA 215*F. After 2 minutes of idling CHRA was 205*F. Shut it off and checked it every 2 minutes, highest the CHRA ever got was 230*F.

Overall it's pretty much what I expected. A big laggier down low, but once the front turbo starts spooling it actually gets to full power a lot faster now. Very happy with this, lots more midrange torque now in the 4-5K range.

I think my plan is to set the front turbo to 25 or 30 PSI, and let the rear do the rest. That should get it to make big torque as fast as possible.

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Old 10-04-2016, 01:24 AM   #750
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Two pulls from 4th and 5th.
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Pat's Ebay Turbo Compound Boost Build-5th-pull-3800.jpg   Pat's Ebay Turbo Compound Boost Build-4th-pull-4200.jpg  
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Old 10-04-2016, 01:32 AM   #751
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Oh, I left something out. It feels a lot faster with a bigger turbo up front. I kind of expected that but yes it did make a nice difference. Can't wait to get the front one up to 25-30 PSI and see how that does.
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Old 10-04-2016, 12:02 PM   #752
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Every time you refer to the 3076 as the "small turbo", a big grin spreads on my face. It makes me think back to the early 80s, the times when Formula 1 was running 1.5l engines with gigantic turbos, netting 800hp or more for qualifying. You'll get there.
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Old 10-04-2016, 12:35 PM   #753
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pat reminds me of the evo guys over here constantly saying stuff like: "My baby gt3076r will make way for the real turbo soon" or "I got this little gt3071r for the transient response and street car powerband"

I grin every time too

Meanwhile most other Miata owners are talking about their "mid-size gt2560r"
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Old 10-04-2016, 06:35 PM   #754
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Pat is a dreamer. Pat believes.
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Old 10-04-2016, 08:23 PM   #755
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Originally Posted by stefanst View Post
Every time you refer to the 3076 as the "small turbo", a big grin spreads on my face. It makes me think back to the early 80s, the times when Formula 1 was running 1.5l engines with gigantic turbos, netting 800hp or more for qualifying. You'll get there.
Yeah, I'm pretty happy with 400-500whp. I think my new goal is to get it to make 400whp and be reliable enough that I can drag race it every weekend without anything failing at 400whp. Then try to figure out how to make it do 500whp reliably.


Quote:
Originally Posted by 18psi View Post
pat reminds me of the evo guys over here constantly saying stuff like: "My baby gt3076r will make way for the real turbo soon" or "I got this little gt3071r for the transient response and street car powerband"

I grin every time too

Meanwhile most other Miata owners are talking about their "mid-size gt2560r"
Yeah. My Outback XT has a tiny turbo and an auto, and for daily driving it's sweet to have that low end torque. But that's all it's got, it's slow after like 4,500 it starts choking. It's been my experience that bigger turbo make the car go faster.

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Originally Posted by tehzack View Post
Pat is a dreamer. Pat believes.


A pallet of parts arrived today, everything for the autoconversion that I ordered. Going to inventory the parts in a few minutes and begin the conversion. Plan is to swap it and test it to verify it shifts correctly, then bring the boost up until I find the limit of the stock box where it will not slip. Run it there and buy another auto to build and swap them out when the new one is built and ready to go in.
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Old 10-04-2016, 08:27 PM   #756
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Originally Posted by mx5psi View Post
hey pats amazing build thread

the 4ln71b out of the factory 1.6 is a 4 speed but iam pretty sure the bellhousing off the factory 4 speed with fit a 3 speed 3n71b which can be built to a rated 500hp well atleast here in oz i just dont know how much i can ask what parts are needed as the guys i used are very very helpful the only issue is the rear extension has no spot for a power plant frame as the box is shorter so you need to make a trans mount too which is why i went 4 speed

hope that may be some help
Thanks man. I'm going to swap in a 99 miata auto for now and see what I can get it to hold. If it doesn't work out I'll look into the 3n71b or 4ln71b.
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Old 10-05-2016, 09:22 PM   #757
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Working on auto conversion. Holy wow, what a big mess of work to do. You pretty much gotta tear the car down to a shell to get all the wiring out. I gotta change the entire vehicle wiring harness.... I'm working on removing it now, almost got the 6 speed off as well. Gotta pull the intake and starter, then I think the transmission will come off. Going to redo some of my own wiring I added to the vehicle as well. I'm expecting this to take 7 days to complete the conversion, this is day 2 so far. I'm hoping to get the manual out, and all the wiring out of the car today.
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Old 10-05-2016, 09:48 PM   #758
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Is it really worth the effort of running the full factory harness? How many wires does the automatic add?

--Ian
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Old 10-05-2016, 10:25 PM   #759
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Is it really worth the effort of running the full factory harness? How many wires does the automatic add?

--Ian
I don't know which would be easier, but I figured at least this way it should work since I won't have to actually modify the harness itself, just install it. The auto has its own computer, and the engine computer is different as well. Auto computer has 20-25 wires going to it, the trans has 3 solenoids, turbine speed sensor, VSS, and a big rotary switch on the shift linkage. Inside there is now a harness for the auto shifter as well.
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Old 10-05-2016, 10:52 PM   #760
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Why do you need a tranny computer? Will you not be manually shifting it?
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