[TheBlade]

Well turbo is all in and stuff, but I´m only pushing 3lbs of boost. Well I tried to turn up the boost a couple pounds and everytime I hit 4.3k rpms my gauge goes to 0 and I loose my boost

I had my friends shop run a smoke test on my intake manifold...no leaks. So we tried my intake from the filter to the throttlebody...no leaks.

When I hit 4.3k it sounds like my BOV, but we´ve put packing washers in the BOV so the scort couldn´t even blow it during a shift and same thing still happens.

I´m guessing it possibly could be the wastegate, but would it cause me to loose all boost?

Likewise, when I loose the boost on my gauge and I loose the pull....when I shift it still blows off.

Any idea´s or simular stories ?

 

[TheBlade]

Anyone ?

 

[Onegimp]

You sure your boost guage is working right? You say the bov still sounds when you let off and shift. Sounds like it still has boost pressure.
Denis

 

[TheBlade]

Gauge could very well be messed up, but I can feel the loss of pull BIG TIME. and to top it off I can hear the sound that I´m loosing pressure.

I have a TurboXs H-RFL BOV, the thing sounds at .5psi boost.

 

[91sleeper]

If the wastegate opens even a little bit at that low of boost you would lose all boost pressure. If you disconnect the wastegate you could see if that´s it but you´ve got be careful not too overboost it.

 

[James92Scort]

How much boost are you looking at trying to create when you get the wastegate goin, Blade? I want to try to double the power output (127x2=254) out of my 1.8L when i rebuild it. That´s a long way off though. By the way...what is the engine code for the 1.8L EGT? BP?

Red 92 EGT

 

[TheBlade]

Yeah, I´m down to believing its either the wastegate not working 100%, or I know on Merkers they get the problem of reversion, where theres too much back pressure and the exhaust can´t flow...I´m thinking it could mean my cat-converter is melting shut.

James, with all the numbers I´ve pushed around, 14lbs of boost will put like 260hp at the fly, meaning about 24Xhp to the ground. Here´s something to keep in mind...14lbs is pretty much the upper limit of the VJ-20, and with some serious timing retard, total fuel system, and high octane fuel, you CAN produce that on your stock internals.....Gotta Love MAZDA!

Yeah, EGT´s 1.8L is the BP series motor. BPD actually 9.0:1 compression 16v DOHC motor. BPT is the GTX/GTR motor with a little less compression.

 

[PPC-Racing]

two things the turbo is over spinning and the compressor blades are getting tip stall, what is the turbo you are using ?
Or your getting boost creep and the wastegate is opening slightly this could be from bad VAC lines to your waste gate or a worn out diaphram..

If this is an internal wastegate then check the vac lines then check the adjustable rod by pulling on it to open the bypass valve if you can pull it the rod by hand to open the vavle then the inernal wastegate is shot, if you need a new one you can contact me or go to turbocity or turbonetics. If none of that is the cause you may have a badly cracked turbine housing around the wastegate apature ( I´m going to assume this is a TB03 from a ford) to check this take off the down pipe elbow and check the housing around the wastegate apature, you should see tiny hairline cracks, ( unless this is a brand new turbine housing every 80´s Tb03 turbine housing has them) if nothing then I´m going to say your turbo is too small. but that´s an outside chance.

while you have the elbow off check that the wastegate valve is affixed tightly to the pivot post.. even the tinest bit of play can act as a vent at high RPM.

 

[Onegimp]

This is a IHI VJ-20 series turbo.

If you checked all your vac lines and intake pipes then I would move back to your waist gate rod you had to shim to lower your boost. Just a thought but you tried to set it to run around 5psi. What might be happening is when it starts running in that pressure and into higher rpm the waist gate is openning to much and letting all your pressure go. Just a thought.

If you pull the vac line off the waist gate accuator it won´t open so it would hold boost, but could overboost it quick, so be carfull doing that. If it dosen´t hold boost waist gate accuator is bad.
Denis

_________________

[ Edited by Onegimp On Date 10-03-2002 ]

 

[AChristopher]

If the wastegate isn´t it. Make sure you disconnect your exhuast and run it straight from the down pipe to make sure you didn´t burn your cat up and your exhuast is clogged. Mine did the exact same thing- boosted 3psi and nothing, BOV would release and checked all the I/C pipes for leaks, bought another turbo and tried it... here the cat burned up and clogged the exhuast. So it´s worth it to check that out.

 

[TheBlade]

Actually, Chris has the same idea I got last night. I´m really starting to think its a clogged cat and its backspinning the turbine.

When I get out of the car it smells like burned cat-converter...and this isnt´ the first one I´ve melted. If its the cat, I´m going to fix it with a crowbar

I still have an idle problem due to a vac leak. I´m thinking besides a bad cat-converter (had an idling problem last time), I think the flange I had made to go to the compressor side of the turbo isn´t seating right. Its where un measured air is getting into the system.

Last night we found the restriction of the stock fuel system. I hit 5lbs and the scort fell over on its face. Just "felt" lean. I don think my vortech fpr is working right.

Anyhow, as soon as I get a few bills taken care of, I´m installing an MSD 6BTM, and fuel system. From there I should be all set to run 8psi on the street safely.

Thanx for all the help peeps. Good to see a few new names on the site too. I guess I´m now apart of a very select few with FI on an EGT. Feels good, really good.

 

[PPC-Racing]

you americans must have shite for gas.. I´ve never hears of so many cats being clogged with crap.. either that or your runing so lean that NOX and HC are stuffing the catylists ...

 

[TheBlade]

Actually PPC, I have been running extremely rich ever since I bought the scort. That and combined with driving the cr*p out of it 24/7 is just producing too much heat. I burned up my last cat-converter driving from San Diego to Prescott AZ driving through the southern AZ desert. I think surface temps where at 110 or so, plus driving 90mph for 5 hours straight did it.

 

[Onegimp]

Ah, the cat, good call Adam. I forget little stuff like that.
Denis

 

[TheBlade]

Good call, but it wasn´t the problem. I unbolted the flexpipe last night and it still happened....although I´m still smelling burned cat when I drive so I´m sure its a problem that´s upcoming pretty soon.

Here´s the only thing we can break it down to now. When I hit 4-5lbs of boost I´m simply running so lean that I´m not producing enough exhaust to spin the turbo, so the turbine stops but the Impeller is still trying to flow a large volume of air. So I´m basically using the impeller to spin(possibly cause a backspin) the turbine.

Well I found a guy that asked me to make an offer on fuel injectors. 89-91 RX7 non turbo....is that the right injector??? Im not possitive, but I think those are the years with the 15ohm high impedance saturated type of injector.

 

[PPC-Racing]

your going to produce the sme ammout of exhaust it´s just going to be much hotter. lean running won´t kill your boost but not having the right injecotrs in the car to begin with is asking for trouble and I can even imagine why you didn´t upgrade them sooner ?!? IF your looking for direct fit injectors, find an old turbo coupe Tbird or an old 5.0L in the junk yard. they will range from 24 t0 28 lb/hr, get them balanced and go .. ( ford colour codes thier injector bodies so you can go to the denso site and check your flow against the colour chart)

Not being overly familiar with IHI´s as they are 8x the cost to repair and replace parts from.. I can make a guess that your overspinning the turbo or your getting what is called ´tip stall´ on your compressor wheel, this will cause cavitation and back flow reducing the blades effectiveness to almost nill and propigating the % to gernade ..

IT may be a simple as not being able to flow the volume you require as you go up the boost range.. but that´s a long shot . Is this a home built turbo setup? or is this a professionally built kit ?

 

[TheBlade]

Its a home built kit, but I really doubt that I´m overspinning the turbo. The IHI RHB5 VJ-20 is the turbo that Mazda put OEM on the GTX block. A couple of the other Scort owners have done this same set up with minimal probs. There´s a guy in town that´s running the Mazda BP in a Capri with the VJ-20. He´s running 14lbs with no problems. I know my motor is super-efficient for any reason.

I still think it could be the wastegate flopping open or something, but either way, I can run enough boost to run the OEM wastegate setting until I get the fuel system done.

 

[Onegimp]

You really need to put a fuel pressure guage on your car even if it´s a cheap one. N/A car sould idle around 30-35 psi and around 45psi WOT. With the FMU hooked up it should boost the fuel pressure up to around 80psi under boost at WOT. If it´s not you way to lean.
Denis

 

[PPC-Racing]

home builts .. shudder!

running .95 bar is all good and fine ( 14 psi for you ´merican´s) but your mising what I´m saying, flow volume means that as your RPM goes up your flow volume throught the turbne goes up, obviously the flow volume of the compressor side rises as well.. however as RPM rises the volume demand goes up, even though your waste gate will blow at 14spi your intake pressure is dropping off becuse the compressor is not large enough to increase the pressure as the engine starts demanding more air volume ...

or , thinking back to my comments about your home made wastegate boost reducer you might just want to pack that in , contack a turbo reseller and order a lower pressure internal wastgate diaphram and push rod.. go ahead, live dangerous, spend the $25 ...

 

[TheBlade]

Well PPC, the design actually worked pretty well. It gave us a good way to test the integrity of motor and other related systems. It was really only a temporary soln. Once I complete the fuel system and the ignition timing is right on, I will be running (hopefully) 8 or 9lbs on the street and 12-14lbs on the track.

Here´s the good news, my friend has a MAP sensor (2 bar), and another friend has his old fuel pump out of his turbo´d car (he upgraded to support his new 550 injectors). So things are coming together. I still have the idle problem, but I´m sure its a vac leak at the compressor out side of the turbo. There´s no gasket there, and the flange isn´t very smooth. I´m still thinking my TPS and angled VAF are playing a part in all of it too. But, we´ll see.

Got more ideas or suggestions, I´m happy to check them out. Likewise, check out the few pics I got. But, due realize they all kinda suck, besides I was too busy laying on my back bolting a turbo in

http://briefcase.yahoo.com/Bladeerau