Pat's Ebay Turbo Compound Boost Build
#481
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But in my case, I'm 98% sure I was blowing out the spark from too much cylinder pressure. Less gap will fix that.
Anybody wanting to copy this build because they want a cheap turbo build on a budget is in for a ginormous bucket of fail. The level of custom fabrication here is high even for mt.net custom builds.
Pat != avg cheap turbo miata owner (1800 hrs of welding experience, anyone?)
There are ways to turbo a miata cheaply, and there are ways to turbo a miata effectively. The number of people who can do both is extremely small.
Pat != avg cheap turbo miata owner (1800 hrs of welding experience, anyone?)
There are ways to turbo a miata cheaply, and there are ways to turbo a miata effectively. The number of people who can do both is extremely small.
If you do a search for build threads here and a m.net, you'll see I've done several builds before this one. I recommend anyone wanting to build there own setup to check them out.
100 shot direct port w/ progressive controller, a failed twin SC setup that never got finished, then a DIY GT3271 setup that ran for 5 years and worked GREAT, then a EFR7670 setup that was short lived, then a failed FFS/EFR7670 compound build (never ran, design problems stopped the build) then the Whipple build which had its issues but made very good power for a SC miata, but wasn't up to my reliability standards, and now this ebay compound turbo setup.
So if you've never done a DIY turbo build in your life, no don't try to reproduce what I did and expect it to work flawlessly. It has taken me years of time and dollars to learn how to do this. But hopefully you can learn something from this and my other builds that will help you with your future setup. If you look at my old builds, you'll see there have been many mistakes made, many parts broken. I've learned over the years how to make things work reliably through research, trial, and error.
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The part where it's climbing at ~20mph/sec, that's all of it.
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Small update
Did A LOT of tuning today. Got the fuel dialed in a lot closer, it was terribly rich before and yes that was causing a misfire under load as mentioned.![likecat](https://www.miataturbo.net/images/smilies/likecat.png)
Probably made 50 pulls in about 4 hours. Then took it to the track. On the first pass I did the burnout, staged, then launched and it was slow. I let out in 3rd and coasted across as I knew something was really wrong, it just wasn't pulling. Ran a 8.58 with a passenger and coasting the last 150 ft or so.
Turns out the rear wastegate fell apart and thus no boost from big turbo. Was only getting 14 PSI tapering to 12 PSI. Sucks but the good news is that's not a part I designed/fabed, and I think I can fix it. Looks like the bolts vibrated out that hold the diaphram to the valve.
Best part is I made probably 50 pulls TODAY where it worked, and it failed on the way to the track.... Even boosted it twice on the way there, worked great both pulls. Haha, oh well!
Friend has a video from tonight, I'll get it tomorrow.
Until then, here's another video someone at the track took of my old setup. Sounds pretty sweet! My car is the fist one, I didn't watch the rest after the first minute. This same guy put a gopro on my car for the pass I did make, so I hope to get that video tomorrow too.
Old SC vid till I get new vids up.
Plan for the weekend is remove/repair or replace gate/reinstall. And fab cat/muffler.
Oh yeah, exhaust drags the ground in the back in 1st and 2nd on 12 PSI. Uh... Looks like I gotta do something to fix that, probably suspension change so it squats less. What's a cheap/easy way to fix that? Stiffer springs?
Did A LOT of tuning today. Got the fuel dialed in a lot closer, it was terribly rich before and yes that was causing a misfire under load as mentioned.
![likecat](https://www.miataturbo.net/images/smilies/likecat.png)
Probably made 50 pulls in about 4 hours. Then took it to the track. On the first pass I did the burnout, staged, then launched and it was slow. I let out in 3rd and coasted across as I knew something was really wrong, it just wasn't pulling. Ran a 8.58 with a passenger and coasting the last 150 ft or so.
Turns out the rear wastegate fell apart and thus no boost from big turbo. Was only getting 14 PSI tapering to 12 PSI. Sucks but the good news is that's not a part I designed/fabed, and I think I can fix it. Looks like the bolts vibrated out that hold the diaphram to the valve.
Best part is I made probably 50 pulls TODAY where it worked, and it failed on the way to the track.... Even boosted it twice on the way there, worked great both pulls. Haha, oh well!
Friend has a video from tonight, I'll get it tomorrow.
Until then, here's another video someone at the track took of my old setup. Sounds pretty sweet! My car is the fist one, I didn't watch the rest after the first minute. This same guy put a gopro on my car for the pass I did make, so I hope to get that video tomorrow too.
Old SC vid till I get new vids up.
Plan for the weekend is remove/repair or replace gate/reinstall. And fab cat/muffler.
Oh yeah, exhaust drags the ground in the back in 1st and 2nd on 12 PSI. Uh... Looks like I gotta do something to fix that, probably suspension change so it squats less. What's a cheap/easy way to fix that? Stiffer springs?
#497
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The awesome part is now I can go from 5,000cc/min of fuel (5x1,000cc injectors) to 6,200 cc/min of fuel (4x1,300cc + 1x1,000cc). That's another 120whp worth of fuel!
More boost!
More boost!
#498
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Vid from last night. Fuel cut only launch control, 12 PSI, passenger, let out in 3rd before I crossed the line. Ran a 8.58!
I got the wastegate repaired today. Long story but it's a POS. I think I got it fixed now so that it will not fall apart again. Also made some changes to my boost control for the rear turbo. Stiffer spring (12PSI spring instead of 4) and added a bleed hole to the top port as bench testing showed it needed one. I bet the big turbo spools better, and hold boost at target better with these changes. Will drive it tomorrow and test. Might take it to the track tomorrow, we'll see. I haven't fixed the drag-the-ground-on-launch problem yet set I dunno.
I got the wastegate repaired today. Long story but it's a POS. I think I got it fixed now so that it will not fall apart again. Also made some changes to my boost control for the rear turbo. Stiffer spring (12PSI spring instead of 4) and added a bleed hole to the top port as bench testing showed it needed one. I bet the big turbo spools better, and hold boost at target better with these changes. Will drive it tomorrow and test. Might take it to the track tomorrow, we'll see. I haven't fixed the drag-the-ground-on-launch problem yet set I dunno.