Fredysan

Hi:

I have my TD05FE for a while but I have had some problems... First it was a hesitation trouble but it was solved by decreasing the plug's gap from 1.1 mm to 0.8 mm (Denso Iridium IK20) but now there is another problem. The turbo gets 20 psi at 4000 RPM and holds fine up to 6100 RPM but after that begins to fall up to 15 psi@7000 RPM... My goal is hold 20 psi up to 7000 RPM which it seems TD05 should happily do. This is very disturbing because I only have a narrow power band of 2000 RPM...

My mods are:

- Impreza Turbo MY98
- HKS supermegaflow Air filter
- Denso Iridium IK20 plugs
- Polished Stock headers
- Custom Upippe
- 3" Exhaust
- Greddy ProfecB boost controller
- Stock By-pass valve

Is this normal? Anyone with this problem have solved it?

Thanks in advance

Regards

Keigo

1.37 bar on a MY98 with no fueling mods does sound rather high. Have you got uprated fuel pump, regulator and injectors? A remap with the mods? I'd put it down to the ECU not coping with the boost properly.

Delboy2

I think you will find 20psig from 4000 - 6100rpm is very good for a TD05-16g and that 15psig @ 7000rpm is due to the engine consuming more air than the turbo can produce. Currently mine is set up similar but tapering the boost off from 6k - but I am running a FMIC etc

Cheers

carlos_hiraoka

do the following test ..... turnaround the "stock by-pass valve"

haz la sgte. prueba ..... voltea (invierte) la válvula blow off

Carlos H.

Fredysan

Sorry, I forgot to add:

- Walbro GSS342 High pressure
- Fuel pressure regulator with 46 psi vacuum line off...

Also I checked the A/F with my LM-1 showing VERY rich mixtures at 10,1:1, even in some points with 9,8:1...

I made the questions because some of my friends have VF22 in his Legacy's RS and imprezas but they don't have this problem, that turbos can hold very well 20 psi up to the red line...

One of my friends told me it could be the stock bypass valve leaking some boost... Any idea?

Delboy2, What boost do you run from 6500 to 7000?

Thanks in advance

Fredysan

Mmmmm, but by doing this, Do the By pass won't work as a bypass? I mean, Will only block the flow and not opening?

Gracias Carlos

Delboy2

Hello M8 - tailing mine off to 1.18bar(17psig)


Cheers

Fredysan

Mmm, that's What I should espect... but in my application tails off much more...

carlos_hiraoka

just block the BOV and u will see ..... it definetly leaks at higher boost levels, and yours is the black plastic one, while the later units are bolted onto the intercooler and can hold more boost.

Carlos H.

Delboy2

Also I am not using the oem recirc d/v - Using a Blitz Bov

Cheers

Fredysan

Yep, it's the black plastic BOV (Phase 1)... So I'll test later and I'll post the results

Thanks!

Fredysan

Last nigh I tried to turnaround the Bypass, but the bypass was already at this way.... I made this mistake when I first replace the old aftermarket BOV for the stock one (I didn't know how the stock BOV was, because I didn't chaged it the first time). Well now the Bypass is in the right position and now the turbo gets 17 psi@7000 RPM... which is better than before.

Now, based in the compressor maps for the TD05, this turbo should boost 20 psi@7000 RPM without problems, so if I change the "leaking" bypass for a HKS SSQV by example, Did the turbo holds more pressure to the redline?

Regards

john banks

You can make 340 BHP at 6000 RPM using only 1.25 bar with the right setup, and this is about the limit on Optimax without additives. No need for mad boost, airflow is what you want. Go higher on the boost and you may well gain torque and lose top end power. Let it taper and work on the rest of the setup.

The taper usually occurs because the exhaust gas back pressure is blowing open the wastegate against its spring, this should tell you something.

EMS

Well said John! It's exactly what I have experienced. However I like to run it at 1.2 bar @ 6000 and 1.1 - 1.15 @ 7000. Anything above this boost (at high revs!) and you have to reduce advance massively and you won't gain any power. (on 98 RON fuel this is) Perhaps 1.25 @ 6000 will work, but you have to map it realy to the limit to gain some extra power.

My advise: you can run 1.4 bar without problems in the midrange, but let it drop at high revs.

Mark.

Fredysan

Thanks John!!

I haven't thought that, because my exhaust is 3"... mmm

At the other hand, that's exactly what I thing, but I guess in order to get good torque and power figures, it's necesary some sort of ecu remap which sadly I don't have, and the worst here in my country nobody do this... Tipically the way to improve performance is to get the max boost the turbo can give. Is not uncommon see TD04's with 20 psi of boost, VF22 with 2 bars or more with only a Apexi S-AFC, AVC-R and a fuel pressure regulator...

I think I was getting seduced by the dark side of the boost, without realize...

At this point, How should I improve the airflow of the engine? in a budget, of course...

Thanks in advance.

Regards from Chile

carlos_hiraoka

Mark, the boost profile you are suggesting works and delivers extremely well (depending on the fuel, it can be >350bhp) but with the help of a set of headers like the Gruppe-s unit .....

Pavlo

open neck downpipes tend to lead to better WG flow and often result in less held boost.

You can try tightening the actuator if it's an adjustable one, but only a turn or 2. However I would agree with those warning of trying to hold more at high rpm.

Paul