KRRZ350

WOW, Anyone else want to join me on a cruise aboard the fail-boat? I am now even more pissed at myself, it's definitly reverse threaded, I can see it in the pic & visualizing which way the wheels spin confirms this. Damn it.

Now that you say that about the pnuematic actuator, it does appear that it is designed with a chamber on the other side and would function like you said, I got it now. I like the idea of failsafe. My slider assembly seemed to be sticking in the closed condition and overspinning it was a concern if it re-clogged on me, but running that is out of the question since I don't have or want to be bothered adding any kind of high pressure air set-up like that.

Thanks, I put the pic up of the back of the compressor because it looks like cast titanium to me, but I'm not an expert by any means. I have a customer coming by tonight who is a mechanical engineer for seimens and he's teh master @ identifying metals, I'll see what he thinks.

aero

That sucks dude. I've done plenty of stupid ---- in my time though. lol

I don't think mine was TI, it seemed too soft but I'm not positive. I would be pretty happy if it was though!

Since I assume you would be running one on a gasoline ongine you will need to run an external wastegate the way I have it. The VGT doesn't open far enough to keep the boost down. With it fully open I creeped past 24psi by 4400 rpm and it was climbing at an increasing rate the VGT is fully open by ~9-11 psi. The good thing about that is the external gate will act as a safety to keep it from overspinning.

fe3tcourier

A good lesson learned incase I ever need to pull mine down, your pain wasn't wasted entirely. Still, couldn't you see the thread before hand, it's not a dome nut is it?

aero

I cant tell how much threads are showing, but it might be enough to tell. I'm sure he just didn't think anything of it. There aren't that many reverse threaded items out there that you have to deal with. The Garret I took apart was LH also if I remember right.



Pictures of the pneumatically actuated HE431Vti that I was talking about above.

fe3tcourier

Looks to have 2 or 3mm of shaft sticking through, you only need a good eye and 0.5mm to see the pitch, so even if its not cut right to the end if you looked you could probably tell. Gutted that you missed that mate, such a waste :-(

hatchkid91

nice

KRRZ350

There is/was definitly enough threads showing for me to tell beforehand, not an acorn nut or anything, & yeah that pretty much sums it up- the thought never crossed my mind.


Ditto on the external wastegate, but thanks for the heads-up. That's pisser that the external wg will keep it from overspinning in the event of a failure, glad you mentioned that as it makes perfect sense. Now, I was planning on setting the external wg & the vgt actuator @ the same pressures though, unless you recommend against that? & by "the same pressures" I'm thinking the vgt just 1-2 psi lower.

I think it was somewhere in the VW vertex thread that someone had questioned whether or not having a manual actuator on the vgt wouldn't be the optimal set-up/slower spool. There reasoning being that once full boost was reached & the actuator opened the veins that it would be to far open/not optimal. Basically he was saying/questioning that once Xpsi boost was reached and the actuator opened up that the a/r would then be to much and it would slow down. Hopefully this makes sense, I'm having a hard time conveying it, but I wanted to run this by you and get your thoughts on it. It makes zero sense to me, my understanding is that this is wrong and that the spool would still be optimal because once the desired pressure was reached the actuator would open gradually & only enough to keep it at the point where it would still make the required boost to continue opening it. Errrr, what I mean is it wouldn't open it to far and have to spool back up, linear instead of on/off like he was wondering.

But my main question is if there will be any problems with setting the vgt actuator right to my desired boost, or will there be any situations where in certain conditions it would either A: overspin B: make boost when I wouldn't want it to, or C: close up and function as an exhaust brake (I geuss that goes hand in hand with A since it would overspin). I'm pretty sure that with the external wastegate also having the added feature of being a safety from overspinning etc that all of those possible issues would never arise, so I geuss what I'm really wondering is if there was any particular reason you didn't put a mbc on the vgt actuator and have it open at your desired boost?

Thanks in advance guys, turbos are not where my expertise is (Neither are LH threads, lol), but I'm constantly learning and starting to understand more of the advanced stuff.

KRRZ350

Side note, yes gas motor, Nissan VQ35, and shame on people who frown on DSM's, I've got a 1G tsi in my shop right now that is practically bone stock asides from the silencer removed, a very nice 3" exhaust, and a flywheel + ACT2600. The motor has 215k on it and it's fading fast. I always treat others cars better than my own, but I had to see what it was all about once that clutch was broken in, so a quick yet smooth slip and launch at 5K & that thing came out of the hole quicker than breaking a rubber while having sex with a crack-----!

aero

As long as the VGT is set to be fully open slightly before the external gate opens you should have it as good as it will get with a mechanical system like this. Opening the external gate before the VGt is fully open will most likely actually slow spool, and will reduce overall turbine efficiency. Keeping the VGT transition low should help with tuning inconsistancies too.

Boost rises fast initially until the VGT is open fully at 9-11psi, then it spools slower from there to 15psi . Boost doesn't fall off or decrease, the rate of rise just slows down. If the VGT actuator was set closer to the final pressure it should spool fast right up to that point. I only had one MBC so that is why I didn't try it on the VGT. I would have made another MBC but I spun the bearing before I got the chance.

I could see someone wanting to have it set the way I do, fast initial then a bit slower for a way to slow the torque hit to help with traction issues.

TurboGuy

Aero, did you ever get your ride back on the road?