arutha

iTrader: (2)

Trying to find out why my engine decided to let loose. I found the top nipple on the waste gate was able to be moved with little effort, like the bolt had come loose a little, didn't have play up and down, wasn't that loose but I could turn it with ease. Could this allow an over boost? I am using a boost controller

Thanks

Howard Coleman

iTrader: (6)

you will need to look elsewhere.

the top of a Tial resists the WG opening. if it were leaking the WG would open more easily.

HC

rx72c

iTrader: (8)

Have a look at the Tune?

arutha

iTrader: (2)

Actually found that both the top and side were movable. Can I use some type of thread lock on those?

So far I am two for two this past year with motors, both due to over boosting. Have a Blitz SBC controlling boost with the Tial. Both times at a track, I am pretty confident the tune is not at fault, car was tuned for 15psi on 93 octane (by a reputable tuner), but was running on a full tank of race gas with 2 stroke added and the controller set to 12psi. I run the race gas as an extra safety precaution and OMP is still in use. Not that either of these cause over boost... The car was fine for the first two days at the track and then this happened. So looking for the cause and can't seem to find anything other than blaming something around the wastegate. Might do away with the boost controller and just use springs to possibly simplify things but not sure it's necessary?

And I am about to do my first rotary rebuild, I can't afford to keep paying others to do it.

Vicoor

While eliminating the boost controller will simplify things, that wouldn't have changed the outcome in this instance.

The plumbing to the waste-gate, as you have already learned, is very important. Certainly worth extra attention to detail to make sure it's bullet proof. Safety wire or lock-tite are good ideas. Also find some way to insure the hoses aren't damaged by the heat.

IRPerformance

iTrader: (41)

Get a mityvac and apply pressure to the side port of the wastegate. It should open.

arutha

iTrader: (2)

Finally took the motor apart, both rotors had an apex seal break, could it be anything other than over boosting to cause that?

Slides

Pre ignition could have caused it, could have been a lean out or over advanced or that it just wasn't tuned to the load it got to on overboost which caused one of the conditions mentioned.

Surely if running a track car with an aftermarket gate which will hold much more boost than target without applied diaphragm pressure (ie just EMP trying to open it) you would run a tight overboost cutout to rule out that possibility?

arutha

iTrader: (2)

I tried this and it will not build any pressure, seems to bleed off as fast as I can squeeze the mityvac. It bounces to about 2psi and is gone.

arutha

iTrader: (2)

Afraid I am new to this but I do know the boost controller is set to cut boost just over 15psi which it is tuned for. Had boost set for 12psi on the controller. The wastegate springs are for 10psi but the controller overrides that from my understanding?

Vicoor

If it won't hold pressure, you've found the problem. Take it apart and inspect the diaphragm. Likely to find it torn, not seated properly, or some other cause of leakage.

billyboy

^^Not necessarily....and a tial or similar won't hold pressure anyway. With a mityvac, you're probably only going to get the valve to lift off the seat before the air bleeds down between the valve guide and stem, no matter how quickly you pump. Need something a bit bigger pump wise, or a low regulated compressed air source.

Banzai-Racing

iTrader: (11)

Billyboy is correct. Tial, Turbosmart and others will not open or hold pressure with a Mityvac.

R-X-R

iTrader: (9)

who is ur tuner?

arutha

iTrader: (2)

Tuned by Ray at PFS, must admit I am not worried about that though. Probably another issue, just not sure what.

I took the wastegate apart and it looks fine from what I can tell, I do not see any tears or holes in the diaphragm. I emailed Tial and they did state that the top port should hold vacuum, which it doesn't, the side port will leak down far too fast like the others mentioned. Guess I'll mention that to them and see what they say.

I'll keep looking, just not sure what to look for, fuel pressure was good and tested it afterwards as well.

billyboy

The wastegate should only be able to leak through the diaphragm, nipple or flange where the halves bolt together. Putting a few pounds of pressure in through the top with a bit of dish washing mix around the valve stem in the outlet port and the other two points should identify if there's an issue with the wg.

Whole host of possible causes for things to go awry, short of logs, you're only going to get guesses - and here's my contribution, did you get into a boost cut, if so, how was it set up?

arutha

iTrader: (2)

I dont think I hit the boost limit and I have to admit I don't remember feeling a ton of power either but I was about to brake so it could have been a quick spike that I didn't really notice I guess. Something I do remember was a sound that I thought was a boost leak, that sound happened a few minutes before too. This happened on the second track day and at no time before did I notice that sound.

Just throwing things out there in case it helps

billyboy

Probably wouldn't feel much in the way of power increase, typically on these things, over boost is only a few pounds more before a hard cut.....which can be felt and heard....inadequate solenoid to wg plumbing can be the culprit there, especially on track.

I doubt you'd hear a boost leak above wind, tyre, engine and exhaust roar, unless it was gross. Exhaust leaks on the other hand, you can generally hear them if they're mildly bad, even pin holes are evident at idle, but can't offer much in the way of suggestions otherwise.

arutha

iTrader: (2)

There was definitely a sound under wot and at the same time power was affected, a few minutes earlier that session, lift off the gas and then back on and it was fine again. But didn't happen the previous sessions and I was on the last day. Not sure it was a leak at all, just a fluttering sound, possibly I hit the boost cut and then it started working fine again until the end.
I have an apexi pfc, would a datalogit be able to run during events to be reviewed later or does it have to have a laptop to do anything? Just trying to find a way to help figure these type of things out in the future. I need to do some research.

Sadly I still don't know the cause and am worried that even though the items check out visually and with the limited tests I can perform they could just fail again.

Thanks guys