Will a turbo with a internal wastegate rigged to stay permanently open make boost?

[stidnam]

So basically I will have a fully rebuilt 4AGE that is being built for a turbo. To run this rebuilt motor in I want to use the factory ecu but I also want to fit and plumb up the turbo so that I don't have to make a temporary NA exhaust system.

Can I fully fit up my turbo setup to my 4AGE and somehow wedge the wastegate to open ALL the time (exactly how this will be done is yet to be worked out but shouldn't be too hard) and make zero boost allowing me to use the NA ecu

Now I think that this should make zero boost and allow me to safely use the factory NA ecu to run my motor in. Once run in the wastegate will be fixed and bigger injectors & aftermarket computer fitted to allow for boost.

Will this work? If not why?

I don't like the idea of running in a freshly rebuilt motor with a new untuned aftermarket computer on a dyno so please do not suggest that I just do this.

[-=DV=-]

you could disconnect the wastegate actuator from the wastegate itself, then the gate should flap in the breeze...as for running a setup like this for any amount of time..i dont know whether i would advise it or not

[Norbie]

Unless the wastegate is far too small for the turbo, keeping it open will eliminate boost in most situations. It will eventually build boost at high RPM but I assume you wouldn't be doing this while you're running it in.

[DEW-016]

Have run a 4efte with internal wastegate UN-attached, just like driving with incredibly massive amounts of lag. Still found boost in high revs.

[IN 05 NT]

you can give the ecu a RUN IN TUNE on the dyno where they set it up to run the right ratios,

this is not a power tune.

[stidnam]

I had a sneaking suspicion that this would be the case. I will be using a TD04L from a WRX on my smallport 4AGE.

As I will be fitting a boost gauge couldn't I just monitor the vacuum pressure and just back off whenever there is any boost pressure?

High load situations such as too high a gear for the revs which is perfect for running in a motor shouldn't cause boost with the wastegate permanently open right? its just higher up in the rev range which is not needed to run in the motor?

I have anticipated that this setup will be a lag monster but I would like to use the factory ecu because I have all the bits and the factory ecu is already tuned. I have conveniently glossed over & ignored the fact that the compression ratio will drop from factory smallport setup (10.x:1 CR) as I will be using the 8.9:1 CR GZE pistons.

Feel free to poke holes in my logic as this is still in the ideas stage. As mentioned I don't like the idea of tuning a fresh engine on a dyno. I am aware that this has been done heaps of times but I don't think that it would be as good for running the motor in as with using the factory ecu. If this is wrong then say so and I will consider this option.

Thanks

[JustenGT8]

It'll make boost for sure once the engine is loaded, especially a weanie TD04. Drive gently and you will be able to catch though.

Hardest will actually be once you are up in the higher gears as will make boost pretty easy in 4th if you are too heavy on the go pedal so you have a valid concern there. As i said, just be very gentle on throttle transitions.

Tha factory ECU will actually handle a little bit of boost so i can't see any prob with what you propose if, once again, you are careful.

[Duk]

If you have access to an Air/Fuel ratio meter it will give you piece of mind that your not running lean when the engine is loaded up and generates some boost. Also, adding octane booster of some form will add some extra safety margin to your set up.

[Norbie]

Yeah it's not hard to drive any turbo engine off boost if you keep an eye on the boost gauge and modulate the throttle.

[Joshstix]

Yeah it's not hard to drive any turbo engine off boost if you keep an eye on the boost gauge and modulate the throttle.

True but you're not going to get any load on the engine doing that and are very likely to glaze the bores on a new rebuilt engine.

[PHOBIA]

Why can’t you just remove the plumbing to the intake manifold? The turbo can scream all day long without feeding your engine??

[Aust162]

When i rebuilt my 3sgte i jammed the wastegate open so it wouldnt see any boost while i ran the motor in. It was only making 1-3psi by 5000rpm under a fair bit of load. eg. up hills, take offs etc.

[The Real Roadrunner]

Why can’t you just remove the plumbing to the intake manifold? The turbo can scream all day long without feeding your engine??

with a baby turbo like a td04 it would probly cause it to overspeed the shaft which could root a perfectly good turbo in no time. no restriction= massive shaft speed= dead turbo.

i wouldnt do it but i know of some that have tried and failed.

cheers
linden

[PHOBIA]

with a baby turbo like a td04 it would probly cause it to overspeed the shaft which could root a perfectly good turbo in no time. no restriction= massive shaft speed= dead turbo.

i wouldnt do it but i know of some that have tried and failed.

cheers
linden

I wouldn't run it with the original ECU either.....
but for what is required, your not going to do anymore damage running with an open gate or an unplumbed turbo for the time and revs required.

[off-road]

Why not run it in on the dyno.A good tuner will be able to do this far better than you will be able to do it on the road especially as you are running a different comp. ratio and a standard ECU.
On the dyno the tuner is able to load the motor at different RPM points while monitoring all engine parameter including mixtures.