Sure, you could do it but it is best to have some type of boost control(EBC, MBC, ECU, or hybrid). It is a pain to get down in there and try to adjust boost on the fly via the turnbuckle on the actuator rod. This is especially true when the engine, manifold turbine housing are glowing hot. Unless you wear giant asbestos gloves

 

The rated WGA pressure is what the car will hit without the aid of a boost controller. I know its not quite same ballpark but my factory WGA failed on my MazdaSpeed protege (factory boost level was 6.5psi, I was running 13) I replaced it with an AGP 10 psi unit off an SR20 and never had another issue. The issue the jacked up WGA caused was overboosting.

 

This isn't necessarily true. Yes, you can adjust the actuator so that boost hits the same boost level as the advertised rate of the actuator spring. It depends on if you install the actuator with zero preload or not. Also since it is adjustable you can adjust boost above or below the advertised rate of the actuator spring.

 

The 25# that I have preloaded, lands on 22 psi lower RPM creeeps to about 25ish then by 7k has 24 and 7500 about 22psi.

The factors of preload are determined by your exhaust housing on your turbo as Sparky and I were discussing about a week or so ago. On a Green/Red/Black the curve might be VERY different because of the turbine differences from stock. I have a 71 HTA, so Im on a stock turbine wheel. I use a Hallman to get a 27ish psi spike then let it taper off...

Formerly had a 18 # actuator too as well as stock.

 

Strange. I happen to be missing a 25 pounder from my garage.

 

Thank you sparky. It seems to be I need some port work done for sure!

I'm planning to go stroker in the next year or so.

 

Ratty's observations based on his own empirical data are pertinent. His experiences can shed light on the OP's questions regarding the differences between FP's two HD actuator options.

 

Sure Ratster! You bring up some interesting points. In comparing the real world properties and performance differences between the two FP actuators for the 16G application. And in fact comparing across the available actuator options from the different manufacturers, some of which(Forge, & Turbosmart) have interchangeable springs of different rates, while others(stock MHI. FP & MAP) have fixed rate springs gets further complicated by several factors.

One of the factors which Ratty points out is that the turbine wheel/turbine housing combo has an impact on the way that the different actuators react real world. This contrasts with how the manufacturer merely performs a static rating test in the lab up on their test bench. In the lab they are tested and rated simply by connecting a compressed air pressure source to the vacuum port on the actuator's canister.

This static test essentially can only evaluate the cracking pressure, rate of spring compression, and full open. This test by the manufacturer is done without the actuator connected to the turbocharger to which it will be mated. Thus, the actuator rod itself is not even connected to the flapper valve. So, they are only dealing with axial actuator rod motion, spring compression/diaphragm expansion and displacement movement.

The manufacturer's rating method since it is not a real world, dynamic test does not take into account other factors the most important of which is turbine inlet pressure. Once you install the actuator onto the turbo and fire up the engine and exhaust gases could be flowing through a variety of different turbine housing sizes(9.0, 9.8, 10.5) with different turbine wheel designs, different A/R's and different major and minor diameters, then turbine inlet pressures, back pressure and overall exhaust pressure will vary and should be taken into account.

Turbine inlet pressure essentially acts to lift the flapper valve up off its seat. Even at idle there is a measurable force that is lifting the flapper valve and taking up the play or initial set of the actuator spring. Turbine inlet pressure increases exponentially as turbine shaft speeds increase and increasingly higher volumes of exhaust flow through the turbine.

As exhaust gases enter the turbine housing they enter the turbine inlet area. For sake of discussion the face of the flapper valve sees turbine inlet pressure since the bypass ports branch directly off the turbine inlet area.

Turbine inlet pressure directly acts on the face of the flapper valve, real world, combining with manifold boost pressure and thus both forces, in concert, exert pressure on the actuator spring. By contrast the way that the actuator manufacturers rate their product does not take turbine inlet pressure into account because they merely hit the diaphragm with compressed air and they do not hit the flapper valve with exhaust pressure at the same time. They are clapping with only one hand...not both.

Sorry for the rant.

 

Correct, if you plan on carrying over the HTA 71 with its stock TD05 turbine wheel onto your stroker motor, then it would indeed be a good to get the turbine housing ported.

So, pick up a used 10.5 housing cheap and ship it out to my California address. I will pick it up and take back down to the jungle with me where I can do the porting myself. Then I'll ship it back to you.

What I don't like about the 71 HTA on a stroker motor with its increased displacementis is that we would be limited to the smallish minor diameter/exducer. This is going to impact exhaust back pressure as porting would be a full inlet side job, while the turbine exit area of the housing can not be opened up significantly, due to the smallish minor diameter of the stock wheel.

It sure will spool fast though although it is going to want to creep bigtime and you'll have to run the FP flow advancement compressor housing, since that is surge ported. Otherwise part throttle driveability will be a major issue, big time.

 

It's safe to say that waste gate actuators only play a part of the boost equation. Pretty small at that. Overall back pressure, and consumption efficiency are bigger factors that determine your needed wga#.

Sparky, I do have a FAP already and I'm quite the fan of stroker small turbo motors with rocky mtn boost/tq. Something I'm missing with my skunk 2 intake manifold and s2 cams.

I'd put a td04 19t in there if I had one !.

For a sparky port job though I'm stoked

 

Well, if you decide to then just send me a 10.5 housing and I'll port the inlet area and the bypass port(s) for you. I realize that it is a gross oversimplification, but turbochargers work on the principal of pressure differential across the turbine. If you improve flow on the inlet side while maintaining pressure constant on the outlet side of the turbine while at the same time increasing exhaust volume and flow by upping the cylinder swept area by roughly 15-20% you dramatically alter the pressure ratio. Back pressure becomes more of an issue,

 

I'm not sure what you have as your sig and info are different.
But here's your answer

Evo X
http://www.maperformance.com/map-sta...-cg40-o2e.html

Evo 8/9
http://www.maperformance.com/map-sta...-o2e-cg40.html

This was the greatest product I've boughten for my car after the Red. Honestly just bolting it up, it woke up the cars response and entire powerband like you wouldn't/couldn't believe. I don't have any dyno or track results but my @$$ guarantees it!!

I've had this thing on my car for over 2 years daily driven and couldn't be happier. I wanted something more free flowing but could wake up when I wanted it to and this was the answer. Even if you already have an o2 and down pipe this is so worth it.

 

Thats cool and all, but that negates the twin scroll dynamics of the stock turbo...

 

To my surprise the city I live in got it's first E85 station ever, this month!
It will be E85 from April-September, and E70 the rest.

Now I am certain I can take advantage of a high psi actuator since I will be pushing 30lbs or so...

 

How much boost do you plan to be running? What turbo?