shimming wastegate

[dan2288]

Im running a big 16g right now and I can get it to 25psi but it cant hold that to redline. If I would shim the actuator, would I be able to hold more boost up top?

 

[My1GLaser]

It probably won't.

I have shimmed my WG actuator, added a "helper" spring to the actuator arm, and added a spring to the MBC. I have decided that my 18g wont hold 28 psi to redline. It drops to about 22 by 6500 unfortunately. They are just too small of a turbo to keep up with the airflow demand at that rpm. Although I do hit 32 psi in 3rd easily and have hit about 36 in 4th accidentally, but it only lasts a second or so and then tapers off rapidly.

I am going to get an ext WG setup so that the boost is more stable, but I am upgrading to a Holset this season because I am tired of dicking around with the smaller turbos.

 

[dan2288]

man, thats some bad news.

 

[My1GLaser]

Maybe its not the norm and its b/c of my cams and ported head & +1mm valves, but I am starting to think that I just need a bigger turbo. Hopefully some others will chime in, b/c I am still curious. And I got the new one with the 6SL2 turbine wheel that is more efficient, but maybe I am still missing something.

 

[dan2288]

yea, I would love to have 25 plus psi at redline but it seems nobody can make it hold that much. Anyone able to hold a lot of psi at redline on a 16g?

 

[pboglio]

Sounds normal. I'm seeing about 28 psi dropping to 22 psi on an Evo3 16g. I can hold more in the midrange but it always drops off. Its just the fact the turbo can't supply the engine at higher rpms.

 

[dan2288]

okk, looks like I gotta go bigger next year

 

[JusMX141]

okk, looks like I gotta go bigger next year

No, you just need to build one of these:

http://www.dsmtuners.com/forums/tur...oking-strong-internal-wastegate-actuator.html

One of the guys that I fabbed this actuator for is holding 24psi to redline with this FP 18G, even with a 34mm flapper in place.


The problem with the Mitsu actuator is the spring doesn't provide enough tension to safely run more than double the spring's pressure without spikes/drops. Anything over 20psi and you're going to have issues with boost dropping once the flapper opens because the spring isn't strong enough to pull the flapper shut again once boost begins to bypass the turbine housing.

 

[dan2288]

hmm, anyone where to get a used holset actuator? Are the ones from the hx35 and hx40 the same spring pressure?

 

[dan2288]

No, you just need to build one of these:

http://www.dsmtuners.com/forums/tur...oking-strong-internal-wastegate-actuator.html

One of the guys that I fabbed this actuator for is holding 24psi to redline with this FP 18G, even with a 34mm flapper in place.


The problem with the Mitsu actuator is the spring doesn't provide enough tension to safely run more than double the spring's pressure without spikes/drops. Anything over 20psi and you're going to have issues with boost dropping once the flapper opens because the spring isn't strong enough to pull the flapper shut again once boost begins to bypass the turbine housing.

just wondering, is that the most boost he sees? I mean, Does it hit 24 psi and stay there to redline, or does it spike to like 30 and then drop to 24 psi? It would be nice to have 25 psi across the rpm range, without any high spikes.

 

[pboglio]

What is the pull force required to move the 16g actuator arm?

 

[JusMX141]

hmm, anyone where to get a used holset actuator? Are the ones from the hx35 and hx40 the same spring pressure?

At the time I created that thread there were three or four of them on eBay; I've now discovered they're rather hard to acquire. I do have one used HX40 actuator in my possession- I believe the HX35 and HX40 actuators have the same spring tension, but I did get one from a customer from an unknown Holset that had a much lighter spring tension than the 35/40 actuators I've had. He wasn't able to hold the same peak boost, but the tension was still stronger than a factory MHI actuator.

just wondering, is that the most boost he sees? I mean, Does it hit 24 psi and stay there to redline, or does it spike to like 30 and then drop to 24 psi? It would be nice to have 25 psi across the rpm range, without any high spikes.

http://www.dsmtuners.com/forums/tur...ernal-wastegate-actuator-2.html#post151776842

Sounds to me like he's able to run 24psi pretty much to the number. He quotes- "I didn't try to go over that amount of boost but I am sure you could easily."

 

[dan2288]

ok, Im reading that thread right now. Looks like something I will have to try

 

[JusMX141]

Sounds normal. I'm seeing about 28 psi dropping to 22 psi on an Evo3 16g. I can hold more in the midrange but it always drops off. Its just the fact the turbo can't supply the engine at higher rpms.

It's the wastegate, not the turbo. Sure the turbo has a little to do with it, but not to that extreme.

A customer of mine ran one of my rebuilt Evo III 16G's to an 11.98 with his '97 GST using E85 and the stock low end last summer. His was set up with the wastegate flapper removed, 38mm gate off the o2 housing, boosting to 30psi and dropping to 26-27ish by redline.

View Profile: fwdeclipse

 

[black_gst]

i had the same problem with my 20g but as soon as i switch to an external WG the problem was gone and so far ive held 26 to redline and im sure i could hold more then that

 

[pboglio]

It's the wastegate, not the turbo. Sure the turbo has a little to do with it, but not to that extreme.

A customer of mine ran one of my rebuilt Evo III 16G's to an 11.98 with his '97 GST using E85 and the stock low end last summer. His was set up with the wastegate flapper removed, 38mm gate off the o2 housing, boosting to 30psi and dropping to 26-27ish by redline.

View Profile: fwdeclipse

I understand where your coming from. But mods that are suited to high rpm power make the situation a little different and suck every ounce of boost right out of the turbo at higher rpms. My EVO3 16g right now is pulling 44 lb/min at 7000 rpms and 22 psi. I shimmed the heck out of it and it made zero difference in high rpm boost. Remember, I'm on a stock wastegate with no porting. I'm not surprised the 18g can flow 24 psi to redline, its capable of another 20 h.p. over the EVO3 16g. I'm open to trying the stiffer wastegate if it would give me even another 1 psi that would be a big deal where I'm at right now.

 

[My1GLaser]

It's the wastegate, not the turbo. Sure the turbo has a little to do with it, but not to that extreme.

A customer of mine ran one of my rebuilt Evo III 16G's to an 11.98 with his '97 GST using E85 and the stock low end last summer. His was set up with the wastegate flapper removed, 38mm gate off the o2 housing, boosting to 30psi and dropping to 26-27ish by redline.

View Profile: fwdeclipse

Great! I had my doubts that it was just the turbo. I am going ext WG in a month anyways, since the damn boost is all over the place and jumps around 3-4 psi. I will keep the 18g in place and see if I can get an 11 sec 1/4 before I replace it. It is really a sweet little turbo, but I am dying to try a 500 whp Holset. I'll try and remember to post back after I get the ext setup if it helps me hold boost up top.

 

[boostforfun]

Although, a B16G prob. is working hard as hell to make 30 psi. No one could convince me that isnt hard on the turbo to be turning that many RPMs. If you want to make 25-30 psi consistantly and safely, go to a bigger turbo.

Not to mention, you will make more power with the bigger turbo at far less PSI. Much easier on internals and such.

 

[JusMX141]

Not to mention, you will make more power with the bigger turbo at far less PSI. Much easier on internals and such.

Not necessarily. There are plenty of people out there that bought bigger turbos and went slower based on this very same belief.

If you have a big turbo that you're running below it's efficiency range, about the only thing you're gaining is lag. Pboglio is running 22psi on his Evo III 16G and seeing 44 lb/min near redline....and that turbo's probably at full spool around 3600-3800. If he bought some monster turbo like a PTE SCM6152E, he may see the same airflow at the same boost level but the turbo would spool about 1000rpms later so he'd lose almost 1000rpms of useable power.

 

[pboglio]

Small turbo owners don't want to give up their spool. Big turbo owners don't want to give up their topend. Running the EVO3 16g at 25-30 psi allows you to have your cake and eat it too. The downside is a little shorter longevity. I can live with that.

 

[lazyazzdaddy]

I used to have a evo III 16g on my car with an ext. waist . it would hold 20 to redline
I loved that turbo the spool was great but i needed more top end. I upgraded to the bullseye hx35 last year and to be honest was dissapointed compaired to the evo UNTILL i started to crank up the boost. at 28psi that thing is a monster compaired to the evo! remember im fwd but if im driveing along at 65 on the highway and go wot. it'll smoke the tires as i take off !! only trade off i have now is that the hx35 spools for me around 3800 compaired to maybe 3200 with the evo.