t28 actuator boost pressure

[reecegze]

Hey guys ive got an ae86 with a 4agte running an s14 t28 turbo , its running stock actuator at the moment i am just wondering what the stock boost for the t28 with standard actuator ?
i am only getting 6psi max on full throttle

Thanks people

[YLD-16L]

Have you clocked the housings at all to fit it to your car?

[Duk]

I'm pretty sure most standard Nissan/Garrett wastegate actuators are around the 7 psi mark, with any more boost usually achieved by the factory electronic boost controllers (Nissan).
If you believe you should be seeing more boost, double check for leaks in the plumbing and check pressure drop across your intercooler.
What sort of 'cooler and exhaust are you using?

[reecegze]

i am running a dump front pipe only .. to test the setup out took it for a drive thats how i found out its really laggy takes like 3500-4000 to hit full boost of 6psi max, i am certain there is no leaks in the system also... YLD 16l yes i have over clocked the t28 to topmount position does this affect boost ?

[YLD-16L]

If you clock the housings independently of each other it can affect the tension on the actuator and therefore boost levels and lag depending on which way you clock them.

I can have a base pressure on my t28 of anywhere between about 8 and 12psi depending on the actuator tension.

[1JZ-Rolla]

i am running a dump front pipe only .. to test the setup out took it for a drive thats how i found out its really laggy takes like 3500-4000 to hit full boost of 6psi max, i am certain there is no leaks in the system also... YLD 16l yes i have over clocked the t28 to topmount position does this affect boost ?

That seems way too laggy.... my 4AGTE with S14 T28 made 5-6psi at only 2500rpm. What compression is your motor, 8.0:1 ZE, 8.9:1 ZE or a higher comp GE?

7psi is quite normal for a stock actuator

[reecegze]

ive got a dli ae92 bigport.. 8 0 1

[reecegze]

Hey ive got no idea how i clocked it lol .. i just clocked it to suit the engine bay... Does clocking actually affect the performance of the turbo ?? i hope not but there alot of lag build up before it starts hitting 6psi... 1st gear pulls good but 2nd 3rd gear just doesnt feel like it turbo !!!!

If you clock the housings independently of each other it can affect the tension on the actuator and therefore boost levels and lag depending on which way you clock them.

I can have a base pressure on my t28 of anywhere between about 8 and 12psi depending on the actuator tension.

[legend]

carefully try it disconnected see what boost u get by bringing it up in revs slowly

edited stuff up

[YLD-16L]

Does clocking actually affect the performance of the turbo ?? i hope not but there alot of lag build up before it starts hitting 6psi... 1st gear pulls good but 2nd 3rd gear just doesnt feel like it turbo !!!!

Clocking it does nothing to the turbo as such, it only affects the relationship between the compressor and exhaust housings thus shortening or lengthening the distance between the wastegate actuator mounting point and the wastegate.

What you describe is sounding a lot like a lack of tensions on the waste gate actuator i.e. you've shortened the distance when you clocked it. If you do a loaded run (i.e. up a hill or on a dyno) in 4th it will most likely have a rapidly falling boost curve.

6psi is never going to feel good in taller gears though in a 1.6L so keep that in mind when making your diagnosis.

[-GT-]

i am running a dump front pipe only ..

Do you mean you have nothing off the back of the dump pipe or you've connected the dump pipe up to the old/stock exhaust? If you've bodged up a restrictive exhaust that could be contributing to lag.

If you're running an open pipe don't mind me.

[Cuzzo]

Arent you still running the stock ecu?

[reecegze]

yes i am running the stock afm ecu cuzzo...
GT ive only got an dump/front pipe connected atm to test things
yld-16 when i clocked the turbo i modified the actuator to suit the new position "bent it into shape" i made a bracket to keep the wastegate full closed all the time only when actuator wonts to open etc

[YLD-16L]

yld-16 when i clocked the turbo i modified the actuator to suit the new position "bent it into shape" i made a bracket to keep the wastegate full closed all the time only when actuator wonts to open etc

Try some more tension on the actuator then. On my car, which will be different to yours, 1mm additional tension makes about 1psi increase in peak boost.

So you can see, while it all may look alright, if you've messed up the distance between the actuator and wastagate by a few mm it can cause issues.

The last part of what you said I don't understand - "to keep the wastegate full closed all the time only when actuator wonts to open etc"

Try explaining that again or post a pic. Just because the wastegate is closed and is held closed under some tension doesn't mean it's enough tension or that it's right

[Cuzzo]

Pull dump pipe off set the compressor to a certain pressure 6psi? and connect air compressor? Would that work?

[YLD-16L]

It's the combination of the wastegate actuator and the pressure on the waste gate that open the wastegate.

So for example if it took 10psi of pressure to make the wategate actuator move then the wastegate would open at lower than that because the exhaust gasses are also trying to force open the wastegate flap open.