Miata Turbo Forum - Boost cars, acquire cats.

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-   -   Miata scroll supercharger (homemade setup) (https://www.miataturbo.net/supercharger-discussion-38/miata-scroll-supercharger-homemade-setup-60964/)

phenixmt 12-21-2011 01:18 PM

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.

oreo 12-21-2011 11:29 PM


Originally Posted by phenixmt (Post 809184)
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.

falcon 12-22-2011 06:51 AM

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.

phenixmt 12-22-2011 09:45 AM


Originally Posted by oreo (Post 809457)
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.

falcon 12-22-2011 11:07 AM

After looking at some photos... you need to invest in t-bolt clamps. The worm drive clamps are useless.

phenixmt 12-22-2011 11:22 AM

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 ;)

phenixmt 01-24-2012 09:07 AM

2 Attachment(s)
Engine is out for rebuild!

https://www.miataturbo.net/attachmen...ine=1327414072


https://www.miataturbo.net/attachmen...ine=1327414072

phenixmt 01-29-2012 04:37 AM

8 Attachment(s)
Engine open but big surprise...

https://www.miataturbo.net/attachmen...ine=1327829840

rings broken

https://www.miataturbo.net/attachmen...ine=1327829840

And 3 pistons damaged

https://www.miataturbo.net/attachmen...ine=1327829840

https://www.miataturbo.net/attachmen...ine=1327829840

I was planning to keep the OEM pistons for the rebuild... :(

TravisR 01-29-2012 11:35 AM

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.

phenixmt 01-29-2012 01:21 PM

1 Attachment(s)

Originally Posted by TravisR (Post 827817)
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

https://www.miataturbo.net/attachmen...ine=1327861312


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...

TravisR 01-29-2012 01:35 PM

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! ;)

phenixmt 01-29-2012 01:41 PM

2 Attachment(s)
Piston n°1 (ring OK)

https://www.miataturbo.net/attachmen...ine=1327862518

Piston n°2 (ring KO)

https://www.miataturbo.net/attachmen...ine=1327862518

Uploaded with ImageShack.us

sixshooter 01-29-2012 05:29 PM

Those little light colored spots indicate detonation. What were you using to control the spark timing when the engine was in boost?

hf-mx5t 01-29-2012 06:36 PM

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)

phenixmt 01-30-2012 03:30 AM


Originally Posted by sixshooter (Post 827932)
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.

richyvrlimited 01-30-2012 03:39 AM

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.

phenixmt 01-30-2012 03:53 AM

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?

phenixmt 01-30-2012 04:27 AM

I realise that my spakplugs maybe a bit responsible, they're maybe too hot.
I will order NGK bkr7e-11

richyvrlimited 01-30-2012 06:11 AM


Originally Posted by phenixmt (Post 828130)
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?

phenixmt 01-30-2012 07:49 AM

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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