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It's not pretty clear but I lose boost after 6.000.
I pressurized air in the system and the pipes hold steady without leaks.
Also I can't find any leaks in the manifold.

The external wg right now is hooked directly to the compressor nipple and I am using a 0.8bar spring.. With or without boost controller even at 1.5bar or 0.7bar boost drops at 0.5 at high rpm.

Also when boost drop occur the external is shutting (I can't hear it)

 

I would almost think this is a joke, but you posted this before the thread linked below.

Tried this? https://www.miataturbo.net/diy-turbo-discussion-14/boost-sag-no-you-dont-need-ebc-47532/

You say you can't hear your external wg open when the boost is dropping but maybe it's only slightly cracked open?

 

Yes I can't hear it releasing the exhaust gases because she tries to hold boost at a steady level and at this point she is wide shut. So the system tries to build pressure.

 

Yeah...

Tell ya what. Try moving the feed from the compressor outlet over to the other side of the IC, and see what happens. It's cheap, it's easy, and it'll save you a lot of arguing.

 

try this... turn overboost protection on, and just unhook the WG.

Should tell you pretty fast if you can make boost or not....

Cruise up to the rpm that you dont have any boost and then mat it...you will hit overboost, or you have something else wrong.

 

Dude, just put it in your sig. Seriously.

 

Gianic,


Read this thread https://www.miataturbo.net/showthread.php?t=47532

We know what the problem is and we are trying to help you.

 

I read the topic guys, thanks for the reference.
But I don't think it will do the trick for my situation, because a week before I was holding 1.5bar steady as hell.

Something for discussion. I disconnected the servo brake pipe and tapped the hole on the manifold with my finger. The engine stalled. Is it normal ? Should it stall or should keep running?

EDIT: I am not missing 2-3 psi of boost. I am loosing 15 psi of boost geometrically as rpm raise.

 

This is what you said at first:And frankly, I have no idea what "boost drops at 0.5 at high rpm" means. It's cryptic as hell

However, you also posted a screen-shot of a log which shows a boosted run in which, from maybe 5,000 to 7,000 RPM, MAP decreases gradually from ~170 kPa to ~150 kPa. And given that this was the only part about your message that was even remotely comprehensible, that's basically the part that I took as actually being meaningful.


Various people offered advice based on this rather limited data. You choose to ignore it, and then wrote the following:So, I understand that English isn't your first language, and believe me, you speak English better than I speak Greek. But I'm very confused by all of this.

 

I'm talking about boost drop at high rpm. Isn't this sentence clear enough to understand?

DATA:
1st run at 10 psi:
3.000 - 9 psi
4.000 - 10 psi
5.000 - 8 psi
7.000 - 5 psi

2nd run at 21 psi

4.500 - 22 psi
5.000 - 15 psi
7.000 - 7 psi

When boost drops I cannot hear the wastegate bypassing exhaust gases(VTA) and seems that the wastegate is sitting shut trying to build the requested boost target.

I ensure you that the boost reference point is not the deal, because I am using wastegate boost reference from the compressor's nipple 6 months with great success.
This started now, all of a sudden.

My english are bad and I am using a greek style of syntax, forgive me for this.

 

Haha you've just edit bad words

 

Ok, so it worked before, but not now? Have you changed anything? Timing?

Have you checked the turbo to see if it spins freely or is damaged?

 

I felt some remorse after I saw that you were from Greece. The language barrier is a hell of a thing to overcome sometimes.

Wait a minute- the EU is convinced that your country is going to cause the total collapse of all banking and commerce everywhere, and yet you have money to be turbocharging a Miata? I may have to write a letter to Mr. Papandreou. Clearly your taxes are too low.

 

How about you put a T on your compressor outlet where the external wastegate hooks up and put a boost gauge there? You could see what the wastegate thinks it's doing.

Maybe you sucked a small child into your intake and it's plugging your intercooler?

 

god, i hate it when that happens!

 

your turbo making any noise?

My turbo did this just before it stopped spinning entirely.

 

Hahahaha! It's weird that you have all that knowledge for a little country like Greece . Our taxes are already huge. Trust me. I have a small tv production company and I am paying 40% of my pure income to taxes. Fair enough huh?
Consider also the vat taxes 21% and the gas 7.2$ per gallon.

Anyway. The turbo seems to be ok spins freely without any noise (5.000miles on it) although I found some oil on the compressor side, don't know why maybe I need a restrictor.

 

Are you sure your wastegate isn't sticking? If it's a subtle leak, it may not sound like anything at all but may be enough to cause you to loose some boost.

 

If it was stuck open I would here it because is is vented to air. So it's not stucked.

 

Probably not then.