You, sir, need some MIL.SPEC high pressure TB shaft seals

 

Can these seals be responsible for a 5psi pressure drop? Are these seals good and then all of a sudden bad?

I'm going to be doing a full teardown and build up for our assault on Pikes Peak next year, and I'm just trying to make sure my car is safe to drive until I tear it apart. The thing that concerns me is that the car was making 26psi, and all of a sudden, its maxing out at 20psi.

Dave

 

Just for kicks, I turned it up to 30psi, and I found another leak on the intake side of the intercooler. When I tightened up this coupler, my Hallman MBC started blowing air out a small hole in it. I'm assuming this is ok, since I'm above the pressure the MBC is set to?

Dave

 

The small leaks in the throttle body, BOV, and boost controller are all typical. The IC pipe is not but it sounds small.

So far none of that should be giving you a 5 psi drop. I would look at the wastegate and make sure it is working like it should.

 

The OEM seals have been found to leak even at pressures around 7 psi. I don't know if the seals are entirely responsible for the 5psi drop (and with all your other leaks, I would assume they weren't) but why take chances when you're racing your vehicle competitively?

MIL.SPEC has found that a majority of all throttle bodies sent to us have compromised seals. Check out this thread:

https://www.evolutionm.net/forums/sh...d.php?t=364108

 

So, just got back from an hour drive around town.

I left my house and headed towards the highway, and when getting on the on ramp, layed into it in 3rd from 2k rpm, all the way up to 65-70mph. When everything was good before, this gave me enough time to see max boost, even if just for a split second or two. I was getting 15psi at WG base. I cranked it a few turns, and on the next on ramp, I was able to dial it up to 20psi. At the next on ramp, I continued to dial it up, but still only 20psi. At this point, I head for home, and as I'm taking the long way home (cause of detour), just cruising at the speed limit, the blue & reds go off. I've got crank windows, and with the cage, I can't roll them down, so I wait for the officer to get to the window and yell that the windows won't go down without opening the door. He opens the door and I hand over license & registration. 10 minutes later he comes back and tells me he couldn't see my temp tags, and asks, 'is this a race car?' I give him the whole rundown on the car's history, where we race it and all that stuff. Tells me to have a nice night, and that's that. Muttered something to the other officer in the 2nd cruiser about how only street racer kids drive cars with so many stickers.

So, I head off for home again, and decide, based on my luck I should do one more on ramp. I cranked the boost controller all the way in, hoping to max things out. Did the same 3rd gear routine, and....25psi. So, I might not have been twisting the MBC far enough, but it does seem odd that the 15-20psi range was in one spot, 5ish full turns further in yielded the 25 range. Happy that everything was sort-of back to normal, I got off at the next exit and turned around and headed home. Wanting to double check the high boost, I did a final 3rd gear pull, and pfffttt pfffttt..., there's that noise again. This time it was loud enough that I could tell it sounded like a blown exhaust manifold gasket.

I babied the car back to the house, and popped the hood. Sure sounds like an exhaust leak to me, but I couldn't pin-point it, so I figure tomorrow AM, I'll remove the factory heat sheilds and fire up the car again to listen closer. Hopefully the noise will still be there, although its weird that the noise only seems to creep up after extended running time and after several high boost stints.

Good point! I'll be adding the seals to my build list for sure, just need to decide if I want to do this at the time of the seals upgrade.



Dave

 

Found the exhaust leak. The gasket between exhaust manifold and turbo, but with the extra noise that came along with it, I'm still not sure if that was the orig. cause of the low boost. Wondering if the orig. noise I was hearing was exhaust getting through the gasket but before it blew off one side?

I'll be ordering up new a new gasket and bolts, and my try to safety wire them this time around.

Dave

 

Not sure if they'd work, but AMS uses those Nordlock fasteners on their turbo kits. Perhaps you might check that option out.