The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support ExtremePSI
Please Support Morrison Fabrication

Internal WG blowing open info

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Kevin Jewer

DSM Wiseman
1,464
277
Jul 25, 2002
LaRue, Ohio
Everyone knows that the bigger the WG valve is, the more likely it is to blow open. (Pressure times Area = Force) Especially on internals with weak actuator springs, and some leverage gained in the flapper arm system. I did a quick experiment since I was in a position to do so. Here is what I found.

I'm on a borrowed 16g setup with a 34mm internal and stock type actuator, but still using the manifold mounted external. I disconnected the internal actuator's vac line. I would see 24 psi falling to ~19 by redline, and 36-37 lb/min airflow. As an experiment I wired the internal WG shut, and it held 24 psi, sometimes dropping to 23, and airflow was at almost 40 pounds per minute across the whole gear, meaning it was opening before boost started to fall. (I'm assuming thats because a certain amount of air in equals a certain amount of air out, and that is what creates the pressure to blow it open. RPM isnt much of a factor if airflow is flatline across the gear.) Thats the highest airflow I have ever seen since I borrowed the 16g. I still ran the same 12.0s at 113-114s, but I did so without having to flog the tranny, though short times sucked that night.

I had previously speculated that the boost was dropping simply because the motor was outflowing the turbo, since I'm relatively well modded. I guess not ;)

Moral of the story, I wouldnt run an internal again, unless it has at least an 18-20 pound spring in it, since I run at least 20 on pump anyway. Going external was a good investment, and I'm gald its behind me. Of course now the issue is my external has the highest available spring at 13 pounds, and the Profec B can only double that.... Dammit.

Just thought I'd share ;)
 
intresting... so where do you get a external gate? do most fit the mistu turbos? and how much do they run etc.

I would like some info becouse i found a 20G cheap and im thinking about geting it even though my car can't realy support it at the moment..
 
Originally posted by 95GSXracer


Moral of the story, I wouldnt run an internal again, unless it has at least an 18-20 pound spring in it

I just installed a PTE 50 trim with 38/39mm internal wastegate. To compensate for the flapper blowing open past 15 psi. I simple added some preload on the actuator rod until the proper boost level was reached. I have had no boost control issues at any boost level or rpm.
 
Originally posted by jdmawd
I just installed a PTE 50 trim with 38/39mm internal wastegate. To compensate for the flapper blowing open past 15 psi. I simple added some preload on the actuator rod until the proper boost level was reached. I have had no boost control issues at any boost level or rpm.

Just for the sake of gathering some info, what is the size of the actuator spring, and what is the boost range you have tried so far? Meaning the miniumum creep level running just the actuator (no boost control) and the most boost you have run yet. Also, how are you verifying that its not blowing open at higher boost? If you can measure it on your car, what is the highest airflow you have seen at that high boost? Thanks.
 
intresting... so where do you get a external gate? do most fit the mistu turbos? and how much do they run etc.

I would like some info becouse i found a 20G cheap and im thinking about geting it even though my car can't realy support it at the moment..

Its not really about what turbo they fit. They are either mounted to the manifold or to the O2 housing. So as long as the turbo you get fits the manifold and O2 housing, and the internal has either been welded (manifold) or removed (O2), you are all set. The gates themselves start around 300 bucks, and it usually costs 100-400 to mount it depending on where you put it. A nice tubular O2 housing with a Tial gate can run about 600- 700 bucks, while My deltagate venting all four exhaust runners cost me less than 300 used...

So how could I go about fixing my internally gated 34mm modded 14b? I have seen people rig up springs of some kind, how do I do that?

People have done this and sometimes it works. It works best when you just need to add a little more tension, or when you have a narrow boost range you want to use. It should be better than the adjustable actuator rods, but I have never personally tried it. With the adjustable rods, as you make them tighter to increase preload and raise the point that it blows open, you are also shortening its travel, and creep goes up. ;) This is why its important to get the strongest spring you can based on the minimum boost you and your setup will run. This goes for internals and externals, especially on the Profec B since it can only double WG spring pressure on "high." ;)
 
Just for the sake of gathering some info, what is the size of the actuator spring, and what is the boost range you have tried so far?

The actuator has a 15 psi spring, I installed the turbo with no adjustment from my previous turbo and it made 15 psi to 8K. Currently im running 25 psi with no creep.

Also, how are you verifying that its not blowing open at higher boost? If you can measure it on your car, what is the highest airflow you have seen at that high boost? Thanks.

I verify that the flapper is not being blown open because once the target boost level is reached. That level does not change until I lift the throttle. In regard to airflow or Hz count, I honestly don't pay much attention to it.
 
Hz is useless, but lbs/min I find very useful. You can see a wg blowing open if you log it. Also, to say 25 psi with no creep kinda misses the point ;) I would hope creep is lower than 25 psi, which is seperate from the maximum boost figure. With the WG set to run 25 psi, what is the lowest you can run, if you've tried it. I'm really looking for the range of boost you get with the actuator arm at that setting. I was stuck at 25 psi for a while and was quite dissapointed at that boost level. ;) I run that on pump now. For me then the ideal setup is a WG that can go as low as 20 psi with no creep when I want to takeit easy, but go as high as 30 without blowing open on race gas... That will cover whatever I want to do with this turbo (20g) and my next turbo.
 
I guess I understand you're argument to some degree, but to run a 50 trim turbo under 20 psi is somewhat a waste of time and money. I currently run 25 psi on 94 octaine. If you plan to run under 18 psi I can see where creep could be an issue. I currently don't plan to make any 30 psi assults,but if that time comes and I experience any boost control issues ill be sure to update this thread. For the price, i dont think you can beat the turbo's that precision turbo& engine have to offer.
 
I would never run less than 20 psi on my 20g or my 50 trim. What I am getting at is when I would set the actuator (also 15 pounds) high enough to get ~24 psi, it would creep to ~22 psi. giving me a whole 2 psi of range, without readjusting the rod. I never did get over 24 psi either, since the actuator couldnt hold the flapper closed higher than that. Some people do get internals to work well for thier application, and you seem to be one of them. I think its great, its a lot cheaper. If anyone tries a 19 pound actuator (SBR is offering them on some turbos last I checked) I would be very interested in the usuable boost range of that actuator as well.
 
Some people do get internals to work well for thier application, and you seem to be one of them. I think its great, its a lot cheaper. If anyone tries a 19 pound actuator I would be very interested in the usuable boost range of that actuator as well.

A 19 psi actuator would have saved me a lot of crispy fingers and knuckles:p
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top