Good stuff right there.

I think Chicken is just mad cause my dive buddies were giving him **** too! LOLZ

 

It was hard to tell thru your drunken texts, tho

 

Touche...

 

ok here is mine as promised...had a boost spike that we couldn't tune out with the bc....*sigh*
BC was set to about 10psi. This is Fluid Motorsports "upgraded" GReddy turbo...

 

Cool 05rex8, nice torque... once you get the boost spike sorted are you going to re-dyno? How is the Fluid turbo modified from the regular TD06? The boost looks like it drops off pretty dramatically in the upper ranges like the TD06.

 

We eliminated the BC and ran it off wastegate pressure. Still had a boost spike in the same rpm range.
Therefore, it's the turbo and/or wastegate actuator; most likely the latter. No tuning of the bc will make it go away really.

 

You have the issue with boost controller that I thought you would
read this:
https://www.rx8club.com/series-i-major-horsepower-upgrades-93/cheap-two-stage-boost-controller-greddy-turbos-177007/
and the boost control and wastegate section of this :
https://www.rx8club.com/series-i-major-horsepower-upgrades-93/getting-most-out-your-greddy-turbo-without-breaking-bank-172542/

 

People need to get boost and AFRs recorded as well as their hp and torque so we can see what is going on and help with how to rectify .

 

yeah I have seen those
I already tightened the w/g actuator arm, which did not do much for me
I suppose I should try a bigger actuator before I conclude that the turbo is the problem

 

I have afr's but not boost; signal was not working at dyno

i can include a new chart with afr's if you want

we had to run it pig rich to compensate for a lean condition from the spike...it's not a pretty looking graph lol

 

/\ you need to take the lock nut right off , shorten the actuator arm by 3mm (i used a disc grinder to do this) then screw the arm in as far as possible .Trust me - you will not be disappointed with the results . That turbo you have there will do 300whp easily .

 

crap I didn't know about shortening it 3mm. I must have missed that part. I will try it.

 

Run it without a boost controller to start with and be careful to watch your boost and afr guage as you take it up the rpm range . Your turbo will act differently to mine due to the clipping but this should get you close ....

 

When you cut the arm what does it put your minimum boost at, Bret?

 

this is what it does on mine with no boost control :

3500-4500....8psi
5000.............9psi
5500............10psi
6000-8500...11psi

 

 

Damn Brett that's nice. I need to preload my actuator arm...I'm going to do it tomorrow or something

 

It is actually perfect for racing from a roll in 2nd gear - someone told me ...
Because you typically mash it at around 4500-5000 and if you are making too much torque in that range you just light up the tyres and the traction control starts modulating the throttle . With progressive boost you can mash it and know your tyres are right on the limit and you get maximum acceleration.
I have changed my boost control setup (again) after seeing Chickens dyno so I can switch on the boost controller and get 12-13psi boost all the way and get a dyno similar to his . But for most situations I really like the progressive boost i have now .

 

I think I know what happened in your run ...

Everything is good up until 4000rpm at which point your "higher flowing" wastegate is pushed open by the pressure inside the turbo because the actuator spring was only built for 5psi and the extra area opened up by the porting means a greater force acting on the wastegate than stock .
Now because you effectively have a pre turbine exhaust leak AND your turbine is clipped , you are making pitiful power all the way up till 6500 . This is when the aux port opens and there is a suddend rush of air into the motor . This rush of air spools up the turbo to an extent but the wastegate is still being pushed open despite yopur atempt to control it via the boost controller .

So what do you do ? You need to get as much of the exhaust gasses as possible flowing through the turbine .
A bigger actuator would help a lot but i think you can control it using the stock actuator if you are prepared to muck around a bit .
Shortening the arm is the first step - so i'm interested to hear what effect that has ....

 

i ran across this very thing after porting the wg port and the manifold. So it was either replace the wg with one that larger diaphram, or shorten the actuator arm.. The arm mod was quicker and easier.

It did take some fiddleing around with too get right though.

 

I don't really understand why Fluid and BNR insist on porting the wastegate in combination with clipping the turbine . It is counter to what we want i believe .
With the upgraded compressor wheel the turbine wheel now becomes the weak link . IE the turbine housing/wheel combination is too small to power up the compressor .
This means more backpressure is created as the engine is constricted by the small turbine . Porting the wastegate just makes it harder for the already undersized actuator to control boost .
Clipping the turbine exacerbates this effect because when the turbine is clipped you want pretty much all of the flow to go through the turbine and you dont get that if the wastgate is being forced open .

Shortening the arm actually closes off the wastegate significantly and on my turbo induces boost creep . Something which I have found very desireable for getting the most from the turbo without it creating drivability issues.

 

i believe that BNR actually works with the WG actuator as well.

 

The turbine on the GReddy turbo has a fairly substantial AR, so increasing the WG bypass probably isn't necessary.
However, even on a totally original GReddy turbo, the provided actuator is incorrectly sized for any output above 6 PSI.
The actuator diaphragm diameter should be increased by the same ratio that the boost is upped.

 

I believe the spring is more of an issue than the diaphram diameter. If you could just put a bigger spring in the stock actuator I think you would get better control than putting a bigger actuator on there .
This is because the exhaust pressure on the wastegate is applying a higher % of the force required to open it than on other applications .
So a small (stock) diaphram in combination with a bigger spring is what we need for decent control of boost - only if we want to max. out the turbo that is .

 

Nope.

That is to say, you could try to fix it that way, but you would not have the linear control you would have simply controlling the ratio of wastegate area to actuator area.

I already spent a considerable amount of time on this 3 years ago and wrote about it extensively.
If you want to reinvent the wheel (again), that's up to you.