Turbo stall,,,, slow down????

[DieHARDmitsu.]

Just curious, what BOV are you running?

Reason why I'm asking is because I've had an issue with a Blitz BOV back in 99, it leaked like a muther, over 12psi and the motor fell flat on its face. I've had a similar issue with an RFL BOV on another car but that was remedeid with a couple of washers benind the spring.

 

Same deal now, if my type S Greddy BOV isn't adjusted right, it will causes all kinds of wierd surges and bucking on the T4/MPI car.

[StarquestRescue]

Any chance the intake hoses to turbo or the air filter is collapsing. from the suction?

[Indiana]

That's not it, the pressure would keep them open and the turbo just boost even more. I think its your wastegate sticking.

[scott87star]

Can't be the wastegate because the manifold pressure drops into the 20 KPa region, that's way high vacuum to a motor. Wastegate or BOV issues would limit it to atmospheric pressure.

[DieHARDmitsu.]

If the BOV spring can't hold @20psi, that may cause a major hicup and throw everthing back to atmosphic pressure or vacuum; even more so, if there is enough vacuum on the diaphram at this point to keep it open for an extended period, stalling effect. Edited September 5, 2012 by DieHARDmitsu.

[wrngwae]

i have removed the BOV and it still does it. i cant remember the name on it but ist not a cheap knock off. it think its a megasonic something or other. and i tried it without the air filter too John,,,,,, same thing. it is the weirdest thing.

[StarquestRescue]

You using a holset 9cm housing? Maybe that is not enough turbine a/r. On the log it looks like right before the "stall" the map line goes almost strait up. Ie the turbo appears to be hitting it's point of rapid spool. All that air has to go some where and if it has no where to go maybe the turbo goes in to a elongated compressor surge cycle.

 

Another thought is that turbine back pressure maybe spiking at the same point and pushing the waste gate open at the same time the compressor starts to stall resulting in the complete lack of boost till the turbo starts all over again.

 

What gears or gears does it happen in? Does it act different in different gears? Did the turbo ever work properly on this set up?

 

On the oil pressure thing. I once put on a brand new turbo charger. After about 30 miles i noticed my oil pressure was low. The turbo was found to be missing a snap ring. That let the bearings shift out of place and the oil was dumping past them, lowering the oil pressure in the whole engine.

 

Just some what if ideals.

[wrngwae]

Thanks SQR. it is a 9cm housing and no it has never boosted correctly. it is more noticeable in the lower gears than the higher ones. 4th and 5th i don't think it will do it but i don't think i want to push it that far in them gears as my butt will be hauling by the time it is spooled up. lol but i will try here soon i hope. and on the oil thing, i drained the pan again and once again filtered the oil thru a paint filter and i found some small aluminum shavings... so i pulled the pan last nite and will be inspecting the bearings and oil pump, fun fun, but at 3k rpm 70mph down the toll road from work i was only pushing 25psi oil,,,,,,not cool. the turbo has an oil restrictor so the turbo should not affect the oil pressure i wouldn't think but it is possible, i upped my restrictor once trying to see if it was oil starving and and causing the stall but,it made no difference it was 1/8 restrictor but i am back down to a .070 and it didn't change the oil pressure at all.

[NotStock88]

So it's settled... Buy a bigger turbo lol

[nomofwd]

Although the final solution isn't clear, it is not hard to narrow it down greatly. If the throttle plate is open and the engine is able to go from boost to vacuum then there is absolutely no way that there is not a restriction be it turbo or intake. With the throttle wide open on an NA engine there is no way possible for an engine to go into vacuum. You have a large gaping hole eliminating the possibility of that. It doesn't matter what rpm you hit, aside from the limiter which will only fluctuate a few inches or less for split second near atmospheric. SO you know that something is putting a cork in your intake stream. In boost your engine does not start consuming more air than it would N/A on its own. The turbo is not a catalyst that physically changes the way the engine works Remove the boost and remove the airflow, it doesn't continue at the higher rate. The pistons will only pull in the displacement of the cylinder plus a small difference for air velocity.

 

I know you have an external wastegate but has anyone else ever tried driving with the wastegate linkage unhooked? You are for the most part allowing the turbo to free spin at the same flow rate as the intake stream with small influence from the exhaust depending on how restrictive the wastegate is. I did this by pure accident last week. The car makes a very small amount of boost, ~2psi, at high rpm due to the wastegate restricting and diverting flow to the turbine wheel but it most CERTAINLY does not create vacuum. You could hook a vacuum to the outlet side of your turbo (don't, you need oil flow) and kick it on and without any exhaust flow at all and with no help the turbo will spin up and match the flow that the vacuum had beforehand minus restriction from the drag of the turbo and the disruption to the air stream. Your engine is like the vacuum. Unless something is slowing the turbo down or blocking off your intake stream the engine will never go back to vacuum at wot, it would only go to atmosphere. Your turbo is actually spinning slower than your engine can pull in air on its own, your intercooler piping is being crushed, or the intake is being blocked off.

 

If the intercooler piping is being blocked then the wastegate would TRY to regulate the boost level to your set amount but you are then essentially causing a dead head of the turbo and I would expect the boost pressure (at the turbo, not the manifold) to spike very high rapidly and then either taper off to the set amount or even higher due to the wastegate flow. If the turbo slows or the intake becomes restricted then it would just drop like a rock through the whole intake stream.

 

What I would try before pulling things apart if you have a nipple on the compressor housing would be to attach your boost gauge reference line there and watch carefully to see if the boost spikes before the car falls on its face. Just dont forget to tee in a reference for the wastegate if that is where it was attached previously. If the wategate reference were attached to the intake manifold then when the intake goes into vacuum but the compressor is still in boost the wastegate would try counteract the vacuum until the turbo broke something be it piping coupler or the turbo overspinning.

Edited September 6, 2012 by nomofwd

[StarquestRescue]

Do you by chance stuff rags in the intercooler piping to keep stuff out while the car is being worked on? Perhaps there is something like a rag laying in the inter cooler. When air flow hits a certain point it get sucked against the tubes and blocks the air flow. And will not fall off till the engine rpm drop enough.

 

With out some sort of obstruction, i would think the turbo would recover from the stall much quicker than what yours does.

[wrngwae]

SQR, there is nothing there. im sure of it. i did do some mild re routing of the piping under the battery. and i elevated the battery tray about 1/4 inch just in case and no luck. i have a log exhaust manifold, wonder if i need a tube style, but i dont think that would make a go/no go type affect. that 9cm housing should be plenty big to sustain higher boost. its not too far off from the HX35s that people are boosting to the moon, i just wanted a quicker spool. short of fabbing up a non innercooled setup, i think the inner cooler is fine. it is a 2.5 in from tip to tip and a 70mm ford TB..... it should flow Edited September 7, 2012 by wrngwae

[NotStock88]

By

[NotStock88]

^ sorry, dumbphone attack

 

I am not sure how to do this but has anybody plotted this turbo on a turbo graph using our engine? Won't that show us if the turbo isn't matched appropriately ?

 

 

Edited September 7, 2012 by NotStock88

[CaliConquestAlex]

Have you tested for boost leaks on your intercooler piping?

[wrngwae]

^^^lol,,,Eric..... i dont know if any one has ran this turbo on our set up. Cali, i did a full pressure leakdown test at 30psi....... did find a leaky TB gasket for the ford 70mm but i fixed that, and it was small. the way i read things is it is basically an hy35 just a different dump arrangement.... anybody running an hy35?

[CaliConquestAlex]

What is your ignition setup? coil pack or distributor? could it be that your actual timing at that psi is jacked up and is making the engine do strange things? What about cam or cam timing?

[NotStock88]

What is your ignition setup? coil pack or distributor? could it be that your actual timing at that psi is jacked up and is making the engine do strange things? What about cam or cam timing?

 

he has a locked dizzy like me. With Scott87star doing his tuning/maps - he has nothing to worry about the tune.

 

The cam being degree'd is obviously something to look at but the timing being off slightly is not going to cause the engine to go in to vacuum under boost.

 

Faulty MAP sensor possibly? Maybe the reading we are logging/getting is not accurate? GM MAP sensors do go bad.

 

IMO we need to get that turbo graph plotted and see if the turbo goes out of its efficiency range

[wrngwae]

like eric said, locked dizzy and a cr125. and my vac/boost gauge shows the same as the map.....

[NotStock88]

Can you do a video while your driving

[StarquestRescue]

Interesting, the surge line for the hy is to the right of the hx. And if i am doing the math correctly he would be close to it at 20 psi if the tune is conservative and the engine is not moving as much air as it could.

 

But it is hard to believe it completely stops and takes 3-5 seconds to re spool.

 

http://www.dsmtuners...ed-systems.html

 

http://metricsystemc...tml?func=detail

[StarquestRescue]

20g map

 

http://www.rbracing-...ps/td06-20g.gif

[wrngwae]

Eric, right now i cant,,,, the car is down. and it will mostlikely be down for the meet too. sorry. And SQR i have seen it reach up to 25 psi than drop like a fly. but that was only trying to set the boost controller.

[StarquestRescue]

I am certainly not an expert, but i looked at the numbers again and i think you are crossing the surge line. Now with a hx35w, what i think most guys have with a bulleye housing, you would probably be to the right of the surge line. Ever see a diesel pulling tractor just stop with a big puff of white smoke when the rpms drop to low to keep the turbo spooled?

 

The question is what to do about it? If the engine flowed more air at a given rpm that would help. But it looks like you have all the right stuff. The only thing easy to change would be to try degreeing the cam or maybe a cam change.

 

Short of that working maybe limit the boost till higher rpm. That is what i do.

[StarquestRescue]

Edit, this is an old thread I bumped,

What ever became of this? I think I heard in chat the turbo bearings had failed again, along with every other bearing in the engine. Now that the cars running again was the same turbo rebuilt and used, If so what was changed in the set up.

Edited August 25, 2013 by StarquestRescue