RJC manual boost controller makes it overboost

[INEEDAGN]

This is with an atr external wastegate. I have it unscrewed as far as I feel safe running it (about 1 1/2 threads left) and when I put it in the wastegate line, I jump 5 psi. Luckily the car is liking it (no knock) but I don't feel comfortable running it there all the time. went from 16-17 to 21-23 with no other changes, and had it on and off a couple times and played with hose length to verify its the valve. Is this because of the small bleeder hole drilled in the outlet side? I'm sure that's a necessary evil to vent it after the run but I think I'm gonna have to ditch the thing and adjust it with other methods. Anyone else experience this? Can't dial the gate back any farther and I have piss poor luck finding weaker springs for it.

 

[1KWIKSIX]

Yup, I found the same thing as well. Had to remove it. Went back to stock factory electronic wastegate set up. I'm only on pump gas too.

 

[Phoneguy]

How much spring are you running? Is the turbo wastegate hole ported?

Bryan

 

[INEEDAGN]

The spring? Well, I must confess, I sorta made it fit. It was a bit small on the diameter. It was a spare from a turbonetics gate I have here and was a little weaker than what I had in it prior. Funny how sensitive this gate is to exhaust backpressure. With the stock IC through the original muffler it was a 14 psi spring. Add the rjc valve and it was a 17 psi spring through the muffler. Then with the new fm and the rjc valve it was a ~19 psi spring until I opened the dump and then she hit 24! But if I remove the valve it still goes back to about 16 or 17 even with an open dump. The gate is pretty consistent under boost but the boost level changes any time I change anything air flow related and always has with any spring. I don't know the diameter of the wastegate hole, I had that connection off once, maybe 7-8 years ago and it was ported to some degree but never measured. Theres a turbonetics deltagate on my other ATR pipe out in the garage but I never tried it. I put a new diaphragm in the ATR gate and told myself that next time it needs a new Turbonetics evolution gate. Kirban has the diaphragms and they come with springs, tried contacting kirban at the time and never got a chance to pick my spring color. Put a want add out for ATR springs once and heard crickets. It's a dinosaur and needs to become a paperweight someday but for now it's still working.

 

[Phoneguy]

You will get better control with a lighter spring. I run a 6 lb spring on my Turbonetics Racegate.

Bryan

 

[INEEDAGN]

Id sure try it if I could locate one!

I'm pretty convinced its because of that small bleedoff hole. I'm going to peen it most of the way shut tomorrow and see if it helps it any.

 

[TurboBob]

since there is a built-in bleed in your external gate (past the valve stem in the gate) closing the bleed hole in the RJC may help.

but it may never be consistent, the "bleed" past the valve stem may be temperature sensitive.

with dual-port wastegates, for mechanical boost control I always used a pressure regulator to feed a balance pressure to the top of the
diaphram. Everything else would vary with the weather.

Bob

 

[INEEDAGN]

Good point! I guess I will peen the mf'er shut completely if its not sealed too tight in the gate. Thanks for the tip.

The car had a bleeder valve setup on it when I bought it and I'm sure it's still in that black hole that is my trunk. I took it off because I could never crack it open anyway because I CAN'T FIND A GODDAMN WEAK ENOUGH SPRING FOR THIS POS! Sorry, not shooting the messenger, just had to vent my frustration. Again.

I need an evolution gate...

 

[TurboBob]

find an old air pressure regulator, or pick one up at sears or "harbor fright"

find an old spring laying around that you can squish by hand and build yourself a 15 psi regulator.

every 1 psi you put on the top of the gate will raise your boost EXACTLY 1 psi.... no guessing....

of course this will all make your part throttle surge worse.... but thats another story.

Bob

 

[TurboBob]

for custom wastegate springs, assuming a Tial spring or similar won't work, measure your current spring and check Centuryspring.com and see if there are any that will work.

B

 

[INEEDAGN]

The deltagate springs will fit but they are a hair smaller and have to be forced onto that billet block that the adjustment screw pushes on. I had a few extras with this deltagate but all were stiffer except one which was barely better, so I used it and it dropped it 2-3 psi. Maybe I should try the deltagate? Hell theres even a second one here for parts.


To build a regulator like you are saying probably requires a constant pressure regulator like for a paint gun and not a cheapie like what you'd use on a die grinder (or the black screw top one that was on the fender) I assume? I might do that. But why would it affect surge?

 

[TurboBob]

the regulator method really only lets you raise boost about 50% above the spring pressure (depending on backpressure)

yes, a pressure regulator, not a flow control.

regarding surge, say your wastegate is set up for 20 psi (via whatever spring and adjuster device), when you back out of the throttle you are reducing the pressure in the manifold by choking off the flow. The turbo creates a bunch of pressure pre-throttle limited only by the wastegate. So a higher wastegate setting can increase the tendency to surge. And there is a wastegate setting that is low enough to prevent it, like 5 psi. If you had a 5 psi spring for the gate it is likely you would not have surge.

Bob

 

[INEEDAGN]

Epoxied the hole shut. Dropped it a pound or 2 but still higher. Need to either find a weak spring or try the deltagate I hav here. No idea what spring is in it either.

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[Mike Licht]

run a line direct to the gate from the turbo with no control. Assuming the turbo is ported properly the boost you get should be your spring pressure

 

[INEEDAGN]

run a line direct to the gate from the turbo with no control. Assuming the turbo is ported properly the boost you get should be your spring pressure

That's what I have. Any other method/devices gives it too much boost when the dump is open. Id really love to leave the rjc valve in it but it looks like that's not possible till I find a weaker spring or swap wastegates (likely to do the latter). What's another couple hundred bucks, right?

Thanks for the info guys.
Bob
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[INEEDAGN]

My job for the night didn't show, so I did the ol' dining room table rebuild on the better of my 2 deltagates and plan to try it tomorrow. The delta gate diaphragm has a much larger surface area and I think that will drop the boost a bunch even with similar spring rates. Oh, and I noticed they use a positive seal on the valve stem and even go so far as to have o rings on bolts in that area to seal it good. WHICH means, I have to figure out how to remove the epoxy I just put in that bleeder hole in the rjc valve.

Turbobob, I plan to send you my chip for a reburn. I never dreamed that I would need this much more fuel after one mod. Its everything I can do (+14% fuel) to keep the o2s at 720 at the top of the run. I verified today that fuel PSI isnt dropping, the snap on digital transducer shows a couple pound fluctuation through the run but not falling off at all. o2s start at the mid 800s and falls through the whole run. I know its no wideband reading but it could obviously benefit from a new calibration. When it was at +6% fuel it would end up in the 600s, so its responding to the adjustments. Also need to lean out the idle.

Its a curious thing to me, that the extender setup will keep the fueling consistent regardless of boost (o2s will end up at 720 whether its 17 psi or 23) but it didnt compensate for the extra air moved by the new mods. I've gotten lost in all of Bruce's old posts about VE tables and rpm/load stuff so I assume it has something to do with that voodoo. Either way, I will probably ship it out on the 29th or so, car can be down for a while during that time. Suppose I should PM you or something.

 

[INEEDAGN]

I was right about the surface area of the deltagate. Put it on today and went WOT, only to discover the base setting is now a whopping 6 PSI. I'm surprised that it can hold the boost that low. Now I can play with bleeder valve options to try to gain spoolup speed. Maybe it'll help the surge as a side effect.

 

[TurboBob]

you should still try the pressure regulator, I think it will be more consistent.... and perhaps a heavier spring.

Bob

 

[INEEDAGN]

Yeah I was thinking of trying that. I can crank up the spring psi with the adjuster too, plus the rjc valve. Its nice to finally have some options here instead of "tuner style" that starts opening the gate at 1 psi and kills spoolup. Thanks for the help.

 

[TurboBob]

tightening the adjustment on the gate too far is not good, as it will limit how far the gate can open.

Bob