ST185 GT4 - Boost Tap Question

[FSRRM]

Hi guys!.

Update on the Celica and she's running mint so far. Installed a boost gauge and shes running 5PSI 1-2nd gear and 7PSI 3~5th gear.

WANT MORE BOOST

I have ordered a standard boost tap and wanting to boost 12PSI.

Would I just be able to turn it up to this OR is the internal wastegate going to hold me back? cheers

[Shrike]

What manual boost tap did you order

I had issues with a generic one even after the mod so it runs the same boost in all gears

Main problem with manual taps is they spike

[FSRRM]

What manual boost tap did you order

I had issues with a generic one even after the mod so it runs the same boost in all gears

Main problem with manual taps is they spike

The Generic one from cheap chinese (LOL - Built in Auto Correct is awesome S C A R L E S) Performance. How bad does it spike? ~1-2PSI? If so I can set to 10PSI it was only $30 bux but didn't think that would matter.

After I put in the Boost Tap I will disable the T-VSV system.

[XS1V]

Bye bye ceramic wheel

Brad

[FSRRM]

Bye bye ceramic wheel

Brad

Aw man, whaatttt. lol should I get the GFB Atomic Boost controller?

[sergei]

The first question you should be asking yourself, is why is it running 7psi and not 10psi?
It looks like T-VSV is off, either disconnected, blocked or not being activated by ECU (limp mode?).
Alternatively your boost gauge is inaccurate, or setup incorrectly.

My suggestion: make sure it is running correctly and leave it alone, unless you are prepared to spend more money than the car costs....

[FSRRM]

The first question you should be asking yourself, is why is it running 7psi and not 10psi?
It looks like T-VSV is off, either disconnected, blocked or not being activated by ECU (limp mode?).
Alternatively your boost gauge is inaccurate, or setup incorrectly.

My suggestion: make sure it is running correctly and leave it alone, unless you are prepared to spend more money than the car costs....

Intense. Ok, So, one thing I thought that the VSV was working is when it was restricting 1st and 2nd gear to 5PSI. then 7PSI in third.

I ran the Boost Gauge off behind the intake manifold(The one that was blocked off)

[loudstealthGT-Four]

Bye bye ceramic wheel

Brad

Aw man, whaatttt. lol should I get the GFB Atomic Boost controller?

No, a manual boost controller will be fine, what he means is the ceramic wheels don't really appreciate the extra boost, and fall to bits.

Id recommend getting a well knowen brand boost controller, as the generic ones are shit IMO.

[sergei]

The first question you should be asking yourself, is why is it running 7psi and not 10psi?
It looks like T-VSV is off, either disconnected, blocked or not being activated by ECU (limp mode?).
Alternatively your boost gauge is inaccurate, or setup incorrectly.

My suggestion: make sure it is running correctly and leave it alone, unless you are prepared to spend more money than the car costs....

Intense. Ok, So, one thing I thought that the VSV was working is when it was restricting 1st and 2nd gear to 5PSI. then 7PSI in third.

I ran the Boost Gauge off the intake manifold(The one that was blocked off)

1st and 2nd gear is not restricted to low boost. There isn't enough load (or time) in 1st and 2nd gear to simply generate high boost.
Hold the brakes in 1st gear and you will see full boost (and smoke from the brakes .
It is simply a myth.

You will need to check if your TVSV is operating, boost gauge could be also inaccurate (the "high" boost on ST185 is around 8-11psi). I can confirm exact figures once I get home and check the repair manual...

On factory CT26 you will not achieve anything dramatic by raising boost. It will just generate more heat and overall will be slow as shit.

EDIT: the manual specifies overall pressure between 0.5-0.83bar (7.1-11.8psi), which I assume means the 0.5bar is low (with TVSV off) and 0.83 is high (with TVSV on).

[FSRRM]

The first question you should be asking yourself, is why is it running 7psi and not 10psi?
It looks like T-VSV is off, either disconnected, blocked or not being activated by ECU (limp mode?).
Alternatively your boost gauge is inaccurate, or setup incorrectly.

My suggestion: make sure it is running correctly and leave it alone, unless you are prepared to spend more money than the car costs....

Intense. Ok, So, one thing I thought that the VSV was working is when it was restricting 1st and 2nd gear to 5PSI. then 7PSI in third.

I ran the Boost Gauge off the intake manifold(The one that was blocked off)

1st and 2nd gear is not restricted to low boost. There isn't enough load (or time) in 1st and 2nd gear to simply generate high boost.
Hold the brakes in 1st gear and you will see full boost (and smoke from the brakes .
It is simply a myth.

You will need to check if your TVSV is operating, boost gauge could be also inaccurate (the "high" boost on ST185 is around 8-11psi). I can confirm exact figures once I get home and check the repair manual...

On factory CT26 you will not achieve anything dramatic by raising boost. It will just generate more heat and overall will be slow as shit.

EDIT: the manual specifies overall pressure between 0.5-0.83bar (7.1-11.8psi), which I assume means the 0.5bar is low (with TVSV off) and 0.83 is high (with TVSV on).

Excellent write up! thank you I have a copy of the manual here. Looks like I will have to get a multimeter and check the resistance between the VSV solenoid

[gt4dude]

ultimately boost taps are shit, they have a limited range of adjustment before they simply bleed off everything and it spikes well out of the normal tuning range.

even with a minor adjustment, depending on how good your turbo is, for example if your wastegate has a cracking pressure of 0.5bar and you set your boost tap to bleed off to 0.8 bar, you may see a spike of up to 1.2bar before coming back down to 0.8 when you hit the gas

this is my experience with the GFB tap, which in itself is a high quality item, so obviously the china taps are going to be worst.

the best mechanical boost controller can be made with cheap parts which uses a ball and spring (and you may incorporate a minor bleedoff to reduce spring chatter) have a look at youtube if you want to look into DIY

[dnalunchie]

My flatmate had an ST185 for 2 years. When he first got it it ran 7psi and was slower than an SI (non vtec) civic. He put on a boost controller and set to 12psi and it made a HUGE difference, was a totally different car.

Even accidentally had it at 15psi for a while and it was nutty fun. In terms of reliability its really hard to say. The 3s engines dont seem to be as consistent in terms of what boost they can and cant run.

At the end of the day there are guys on here that have run 14psi for years with no probs and guys that have run stock or 10psi and it goes pop.

I would think as long as the fueling is correct (get you fuel system or air/fuel ratio checked) so that you know your not going to lean it out on more boost then 10-12psi would be a safe bet but again. Its an acceptance situation. Can you accept that it MAY blow up and MAY need rebuilding on 12psi (or less) if not then dont change it.


My vote is fuel sys check then 12psi all day!!!!

[MR2SIK]

Big ends will pop before the engine does due to extra boost
As long as the fuel system is working as it should, then the ct26 won't even come close to troubling it.

[Heylin]

I had good results with GFB Atomic on the MR2, ran 14 psi for 3 years. Stable boost.

On CT20b.

[h8wrxs]

youre only going to get 1-2 psi boost spike if youre only running a stock turbo setup

youll be fine running 12psi. if you were going to wind it up to 24psi then it would be a bad idea

all manual boost taps will spike a little bit unless you go for an electronic one

[Dell'Orto]

Put a chinese downpipe on it, you'll get plenty more boost

[MR2SIK]

Put a chinese downpipe on it, you'll get plenty more boost

until the actuator gets stuck open

[Al]

Put a chinese downpipe on it, you'll get plenty more boost

I can sell OP a Berk downpipe, only catch is its attached to an MR2.

[FSRRM]

Put a chinese downpipe on it, you'll get plenty more boost

I can sell OP a Berk downpipe, only catch is its attached to an MR2.

Will it fit? my cat is leaking and when i boost i get all this #^$%@# gas going into my cabin haha help a brother out haha

[Al]

Yes it will. Lots of hassle to take it out though so I'd want to sell the ct20b as well. I'd need to get a mr2 stock cat and elbow to refit.