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Miata scroll supercharger (homemade setup)

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Old Dec 21, 2011 | 01:18 PM
  #41  
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Not yet...
I will make a dyno run in spring time. Then we will can compare to roots and rotrex 's boost, Hp and torque curves.

my boost is not reaching more than 8psi because I must have a leak in my new piping setup. I will fix this later.

I've started my engine rebuild during this winter.
Old Dec 21, 2011 | 11:29 PM
  #42  
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Originally Posted by phenixmt
my boost is not reaching more than 8psi because I must have a leak in my new piping setup. I will fix this later.
Seeing less boost, is normal when you add an intercooler(with a SC). When the air cools the density goes up, and the pressure goes down. Check your datalogs for injector pulse width. If your pulse widths have stayed the same, or increased, without a change in AFR, then you don't have a leak.
Old Dec 22, 2011 | 06:51 AM
  #43  
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With all those couplers I would still do a leak test. I have piping routed almost the same with a ton of couplers and I was leaking a tiny tiny bit and never knew it until I did a boost leak test.
Old Dec 22, 2011 | 09:45 AM
  #44  
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Originally Posted by oreo
Seeing less boost, is normal when you add an intercooler(with a SC). When the air cools the density goes up, and the pressure goes down. Check your datalogs for injector pulse width. If your pulse widths have stayed the same, or increased, without a change in AFR, then you don't have a leak.
Yes, before IC installed, I was running 10psi at 5000rpm. Now I've got 8psi. I'm aware about air pressure loss. But I've check my piping after a drive and I find "condensation" on some edges of couplers.
Old Dec 22, 2011 | 11:07 AM
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After looking at some photos... you need to invest in t-bolt clamps. The worm drive clamps are useless.
Old Dec 22, 2011 | 11:22 AM
  #46  
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Well, I bought some T clamps.

But at the intake manifold, I have a silicon hose (grey) and it is more slim than the others and my T clamp can hold it tight enough. So I've put a worm clamp.
I need a smaller T clamp or a new silicon hose (4 ply or something) for it.

You're right, I will go full T clamp in the future
Old Jan 24, 2012 | 09:07 AM
  #47  
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Engine is out for rebuild!




Attached Thumbnails Miata scroll supercharger (homemade setup)-20120122170148101.jpg   Miata scroll supercharger (homemade setup)-image1yq.jpg  
Old Jan 29, 2012 | 04:37 AM
  #48  
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Engine open but big surprise...



rings broken



And 3 pistons damaged





I was planning to keep the OEM pistons for the rebuild... :(
Attached Thumbnails Miata scroll supercharger (homemade setup)-2012-011.jpg   Miata scroll supercharger (homemade setup)-2012-012.jpg   Miata scroll supercharger (homemade setup)-2012-013.jpg   Miata scroll supercharger (homemade setup)-2012-014.jpg  
Old Jan 29, 2012 | 11:35 AM
  #49  
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That is so strange looking... Your secondary compression rings show much less damage, and no extruding the groove out as in the top ring. Its probably a lean condition with some deto causing that.
Old Jan 29, 2012 | 01:21 PM
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Originally Posted by TravisR
That is so strange looking... Your secondary compression rings show much less damage, and no extruding the groove out as in the top ring. Its probably a lean condition with some deto causing that.
Thanks for you analyse

Here's another picture




For Info:
-rev limiter set at 5000rpm
-100miles done with the supercharger
-max boost 8psi
-AFR 10 at full throttle

Maybe rings were like this for before...
Attached Thumbnails Miata scroll supercharger (homemade setup)-20120128181320109.jpg  
Old Jan 29, 2012 | 01:35 PM
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Picture of top of pistion? It looks like you can see some pocking of the aluminum near the top on the side which would indicate the piston was overheated. Again excessive lean condition indication. Still I've never seen piston ring do that to the top Lan. My first thought was who assembled this thing, but from your post it looks like Mazda did it!
Old Jan 29, 2012 | 01:41 PM
  #52  
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Piston n°1 (ring OK)



Piston n°2 (ring KO)



Uploaded with ImageShack.us
Attached Thumbnails Miata scroll supercharger (homemade setup)-20120110155521304.jpg   Miata scroll supercharger (homemade setup)-20120110155526999.jpg  
Old Jan 29, 2012 | 05:29 PM
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Those little light colored spots indicate detonation. What were you using to control the spark timing when the engine was in boost?
Old Jan 29, 2012 | 06:36 PM
  #54  
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nice. but why,.. on my golf 2 rallye, it was removed and a autorotor screw type sc installed instead. much better(but noisy as nothinge else)
Old Jan 30, 2012 | 03:30 AM
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Originally Posted by sixshooter
Those little light colored spots indicate detonation. What were you using to control the spark timing when the engine was in boost?
detonations... maybe when I was running without intercooler. Manifold's air intake was so hot.
I use 98 octane gasoline but it was not enough to prevent detonations at this time.
Old Jan 30, 2012 | 03:39 AM
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Temp is pretty irrelevant, you should still be able to tune the car to not det.

I've had extended 150degC intake temps on track, pulled the head and not a hint of detonation.
Old Jan 30, 2012 | 03:53 AM
  #57  
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Well, I'm confused.

I though I was running in a kind of secure mode (8psi, 10 AFR, 5000rpm, 10 BTDC). So I don't know why.

Any ideas?
Old Jan 30, 2012 | 04:27 AM
  #58  
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I realise that my spakplugs maybe a bit responsible, they're maybe too hot.
I will order NGK bkr7e-11
Old Jan 30, 2012 | 06:11 AM
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Originally Posted by phenixmt
Well, I'm confused.

I though I was running in a kind of secure mode (8psi, 10 AFR, 5000rpm, 10 BTDC). So I don't know why.

Any ideas?
Did you tune whilst listening for det? Or just assume that it was all OK?
Old Jan 30, 2012 | 07:49 AM
  #60  
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I didn't make any tuning yet. Only use theory.
I though old engine could handle 100miles like this.

Here, was the plan:

-Finish the install of the supercharger,
-rebuild the engine before going further. (it was needed...)
-make fuel and spark tuning

Maybe engine was "fragile" before supercharging it



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