I spent some time researching this but could find my answer so here it goes.

I have an XO2 60mm w/g in my setup....

https://www.theturboforums.com/smf/index.php?topic=101396.275

Sooo...I did some testing on my local streets, mild 2nd gear roll ins then shift to 3rd....wastegate has the weakest spring installed but the boost was alot higher than I expected. 1st test made 12 psi, 2nd and 3rd tests showed 14 psi. The LM-1 showed it to be lean while in boost...like 14 - 14.4 lean. During the last test, the engine had a large backfire which bumped the carb hat off slightly but it still stayed on...car never died and I limped back home. She actually drove fine. After checking it out...we noticed antifreeze around the radiator cap and that side of the radiator, all over the battery and inner fender....basically as if the rad cap seal let go and it sprayed that area under the hood. I immediately thought blown head gasket and the boost pressurized the cooling system. But NO this is not the case...we replaced the rad cap and it feels like its alot tighter than the old worn out cap. So I think this antifreeze issue is fixed.

Now we had to figure out why the XO2 w/g let 12-14 psi to be made instead of the 6-8 psi which is what the weakest spring is supposed to be good for.
We tested the w/g for general operation by pumping compressed air into the rear w/g port...as we did this with 20 psi, the w/g did nothing but we could hear the air leaking out of the w/g. We then bumped the psi to 30 psi and the w/g opened and the spring made a "clanging" noise like it wasnt seated before and it slid into its proper spot inside. we then kept retesting it at different psi....it would not open for anything less than 20 psi and it was hissing and leaking the whole time. What I mean is that when we apllied the test air to the w/g, the w/g would allow the air to leak out and not hold the pressure.

So now...my question.....is there supposed to be ANY air leakage during this test? I was told by someone that the boosted psi air should go into the w/g and not leak out at all and thats how the w/g limits the applied boost to the engine properly. IS this normal or do i need to fix this?

After reading the limited info I did find...I am removing the w/g tomorrow, taking it apart and polishing the w/g shaft and putting some anti-sieze on there so it slides better.
Thanks for reading and I would like to see some quick responses so I know exactly what is normal with this XO2 w/g.

If I can get this thing limited to under 10 psi and see nice safe AFRs then I'll probably be going to the track for some real T&T !!

Thanks guys !!

 

All WGs of that style will leak. The valve shaft can't have any decent sealing since it gets so hot - no possibility for an O-ring. So most are "sealed" just by the bushing the valve stem rides through. A bushing is not a seal. But it is enough of a restriction that the boost feed is essentially an infinite source - pressure under the diaphragm will always be at boost pressure.
The only style of WG that I'm aware of that can be made not to leak are the internal WGs with the remote diaphram can. Since those are "pushers" anyways, there is no need at all to seal the shaft.

A wastegate regulates based on two things - boost pressure and exhaust backpressure. Boost pushes on the diaphragm against the spring, backpressure pushes on the valve face against the spring. If your system has low backpressure, boost pressure has to go up to overcome the spring. If your system has high backpressure,boost pressure required to open the gate will be lower. So whatever "rating" a wastegate spring has, it is only a general guideline. It can be significantly higher or lower, depending on the system.

 

i pulled apart my x02 wastegates and indeed they use a viton seal in the spring pod on the valve stem. they fuck them up on assembly i should of taken some pics.

 

With the lightest spring in my wg (turbonetics newgen)h I can easily depress the valve with my thumb. With a slightly heavier spring that came in the gate I could still depress it with both of my thumbs, and it slides smoothly. Is your wg vented to the atmosphere? Could your hear it open?

 

Lightest spring on mine, with a single Xo2 60mm gate made 3.6psi. With an S480 1.32 a/r hotside. the next made 9.7psi. haven't used the highest one yet since i'm running a boost controller.

 

thanks for the replies.

I took the w/g off and unassembled it. Found the set nut on the back side of the valve stem shaft to be very loose...so loose that it wasn't even seated down and there was about 1/2" of play. Also, I had the stiffest spring in there. So we bench tested each spring and now know the installed height spring pressures of each one. This calculated out to be 6 psi, 9 psi, & 15 psi of estimated boost pressure. There is no shaft seal so I'll put some anti-sieze on the shaft. The shaft just slides thru the center section. I will reassemble the w/g and then do some mild street testing. If all goes well then we should be good to go for some 1/4 mile runs.

thanks guys.

 

Also remember as well. That it seems like cracked pressure is what she'll actually run PSI wise. So as soon as the gate start to move that .5psi around where it's going to sit at. That is just some observations from bench testing compared to what it ran on the car. The 3.5Psi spring would go wide open at around 5.5-6psi, and crack at around 3.5psi. And the car ran at 3.5 psi. Something to keep in mind in case it's acting weird on ya again because we thought for sure it would run 6psi, but on both my can and our truck (76mm) they both ran at 3.5 psi.

 

I hear ya....good info there...thanks bro. I know the actual boost psi that the engine and gauge will see will definitively be different than the formula showed. If the lightest spring only makes 3-4 psi then I'll have to tighten the adjuster to stiffen it up some (until I can get it apart and swap to the middle spring). It's time for some testing and tuning and then more t&t. I feel confident that the setup is as good as it's going to get as far as initial setup.

 

I always like putting the softest spring in, then using a boost controller to turn it up. That way if the boost controller fails(the good ones fail open) then you have lower boost. Putting stiffer springs in can hurt the engine on the first pull if you get higher boost than expected(ask how I know )

 

Backpressure has a large effect on the wastegate opening point. I went from a 383 to a 400 engine that was much better built and dropped in boost by 4 psi. I measured backpressure and it was alot more opening the valve sooner.

 

Yo, buddy, just checking in to let you know I'm on the board with you now. I have to give you a nice swift kick in the crotch for dragging me kicking and screaming into your turbo project. Oh, you just HAD TO HAVE A TURBO, didn't you? The one damned application I don't know diddly-squat about! 10.99s on a nice, simple nitrous system was right in front of your nose but you just wouldn't go down that road, would you?

Heh heh. Just kidding. I just want to see that pig-heavy Chevelle suck the headlights out of a new ZR1 Vette and then I'll be able to sleep again. We'll ge it there. Have to admit this turbo stuff is kinda fun. Racing 10,000 feet below sea level does have it's advantages!

I posted up in a new thread about the boost-referenced power valve we talked about earlier today. Hopefully somebody will chime in and point us in the right direction on that.

 

It will all pay off real REAL soon when Cecil kicks me out for running too fast. Thanks for the help man !!
Now let's "get-er-dun".

 

what is the wire dia on the softest spring??

 

I don't know. I do know the softest spring had the largest dia. When I swap it out for the medium 1, I'll measure it and let you know. I don't really know when that's gonna be though...hopefully soon.

 

where can i find the lowest psi spring for my x02 wastegate? i bought it from a guy locally its brand new never used its a 60mm and i have no clue what size spring is in it or where can i buy a new spring for it

 

thanks

 

are there any springs avaaiable i can buy to change out

 

Thanks again VSRacing for your input.