I guess if it was, I would have noticed turbo flutter. I'm not really pushing the capabilities of the turbo, anyway.
Honestly, a smaller turbine might have been better for the level of power the builder was shooting for (~350 at the flywheel).

Reading the manual for the HKS EVC, I think maybe some of the vacuum hoses might be undersized (supposed to be 6mm ID hoses, but might actually be 4mm hoses).
Also, the stepper motor unit seems to be installed upside down.. The nipples should be pointing up, according to the manual.

 

one less thing to be a problem! can't leak if its not there

 

I wonder if I don’t have an exhaust less leak. It almost sounds like I do when the engine is cold, but it basically goes away when hot. I also get smoke off the downpipe, which usually goes away after a while, but I think it’s just oil contamination on the heat wrap.

As for testing for boost leaks, there's no way I'll be able to do that without something to plug up the compressor inlet. Tape or a hand isn't going to be enough.

 

get creative, i used the press tool for a rotor bearing, or i have a container of metal polish that is the right size too

 

Is that smoke or water flashing to steam as the pipe heats up - seems extreme. Usually oily fingerprints and anti-seize smoke off when near operating temp for a minute or two and clear. If that's continuous and it is emanating from the wrap it might be telling you it's time to replace it - or better yet, coat the pipe with zircotec.

 

I am pretty sure its smoke.

Years ago my turbo hose started leaking and I am pretty sure I got quite a bit of oil on the wrap.
Though I can't remember why this didn't result in a fire... Wait, no, there was a little bit of fire, just not on the downpipe. Haha.

I am pretty sure it has always gone away after a few minutes. I guess it's never going to completely go away until I replace the wrap.
I could probably use something wrapped a bit better anyway, considering how much heat the downpipe lets off.

 

I will see if I have anything with an ID of 120 mm...

 

I just did a cold, wet track day.

The cold side of the intercooler stayed perfectly cool, but I still had lowish boost pressure. Basically the first time I open the throttle, I more or less get peak boost on target (0.8 bar) and then it settles in the low to mid 0.6 bar range.

Considering the wastegate is like 12 years old, I wonder if it just hasn’t gone a bit soft. Maybe I’ll just try upping the volume on the controller so it stabilizes in the mid to high 0.7 range.

 

Few notes -

- Quite possibly the waste gate itself getting old/tired/something. External waste gates are ALWAYS the world's biggest pain in the ***, they ALWAYS have problems for some reason. Also could be worth adjusting the preload on the waste gate spring up some and do a few runs with the boost controller off, see if you can increase or get steady the base pressure.
- You don't have to be super fancy with a boost pressure test. I sometimes get a thick plastic bag, double it up on itself, and clamp over the turbo inlet. Then get an air blow-off gun type thing and whatever reducers you need to get it down to a standard vacuum hose size, find a good vacuum nipple, and there you go. If you want something you can use at the track they have little portable air tanks you can pressurize up with an air compressor then use on site.
- Back on the waste gate, it may be a case of it not sealing well once hot. If so, it's diverting pressure around the waste gate and bleeding off turbine inlet pressure. A similar thing can happen on the twins, enough cracking around the waste gate flapper door hole and you have a loss in boost pressure.

Dale

 

Thanks, that is some very useful info/advice. I had no idea external wastegates could be so troublesome. Is it possible to rebuild them?
Though used external wastegates are a dime a dozen here...

Yeah, I had considered adjusting the preload, but that will have to wait until my next track day (probably not until next year) or when I finally make it street legal (which will cost $$$$).
Yesterday, I forgot all my tools except my tire pressure gauge, so I had to drive with only 20 psi in my semi-slick tires (25 psi hot), which were so cold that the car was basically undriveable.
Honestly, my daily driver Legacy B4 with winter tires would have probably been just as fast...


On the straights, I can definitely hear (over my massively loud exhaust) what I assume is one of three things: my wastegate dumping exhaust gases (probably just this), the sound of charge air being forced through intake piping (general turbo noises), or a sizeable boost leak.
I wonder if a bicycle pump wouldn't work...

 

Go read the single turbo forum, there is always people who have too much boost with an external, not enough, torn diaphragms, leaky waste gates......they are a constant pain in the butt. Yet another of the reasons the Borg Warner 8374 is such a winner with an internal waste gate.

Yes some external waste gates can be rebuilt with a new diaphragm. But it depends on if or what is bad really. Also depends on if you can actually get parts, some waste gates are from companies that don't offer replacement parts.

Bike pump won't work for a boost test. They develop pressure but no volume, you need 15psi but at a substantial volume to pressurize that whole tract and fill with air.

Since it is a track do they have somewhere you can air up tires? That could be helpful.

Boost leaks are hard to identify while driving sound-wise. I've seen a large leak where the car literally made no boost and made no sounds whatsoever.

Dale

 

They have air supply at the track, but I forgot my hose and chuck…

Trust (Greddy) offers diaphragms, but they are surprisingly expensive.

I can see how the fail deadly nature is a problem.

 

kind of an oops. i posted the following from Page One of this thread not knowing that there was a Page Two. perhaps some of this is relevant...

thanks for posting the pic of your bay.

i doubt a boost leak is your problem. a 4 psi leak is easily heard from the driver's seat.

i am totally onboard w Slides post 2. heat is your problem. as you have mentioned, you are sucking hot exhaust air from your intercooler. at 14 psi the air coming out of your turbo is 300 F. IF your IC is working the heat is transferring to the core and being further transferred out the back and into your turbo. V mounts need to be fixtured to avoid this (negative) positive feedback heat cycle.

the downpipe on your car is poorly wrapped w insulation. this is an important factor. you also need a heat barrier between the pipe and the LIM runners. many, many rotaries have been broken due to the LIM runners being overheated and transferring the heat to the IA. aluminum is almost the single material on the planet as to receptive heat transference. Cam was dynoing a single turbo motor that had the turbine close to the front runners. it wasn't going well. he found a piece of SS and simple laid it between the housing and runners. the AFR changed over one whole point. since only the front was the problem that meant the front and rear changed by two whole points. your setup is different in that you are heating both runners approx equally... heat breaks motors. more wrap and a barrier will greatly help you.

and no AI on a road course? i hope you have a good engine builder on speed dial.

a number of your remedies are fairly simple and relatively inexpensive, especially when compared to a rebuild..

the highest and best use of the FD is road course. it is also the most demanding as to heat management.

edit: agree, a wastegate issue could be among your issues




.

 

You are probably right that heat is an issue, but the difference between a hot summer day and a cold autumn rainy day was only about 1 psi. Though I was definitely making more power on the latter.
My temperatures were actually probably too low the other day, and they aren't too bad even after a race on a hot day.

Wrapping the pipe is probably something for next year, since I have at most one event left. I might be done already for the year.
I already have a nice little list of projects... and I hope to get it registered at some point (will cost thousands though).

What is IA? Intake air?

Is alcohol injection really necessary for someone who is only making a little over 300 power to the wheels on a good day?

 

I finally got around to doing a leak test.....and immediately discovered that both of my cold side couplers were leaking.

I'm probably going to replace all of them, along with the clamps. Just need to find out what the sizes are...

 

Hopefully a simple fix.

 

It should be trivial. They were more expensive than I would have thought, though...

 

I did my first track day since fixing the boost leaks.

I still have the same problem.

I get perfect boost (0.8) for about one lap, then it settles down to about (0.6) for the rest of the session. Once the car cools down I’ll get full boost again.

My IATs were peaking at about 55-58 C but I think they’re usually a bit lower.

I saw maximum timing was 54 degrees. Not sure if that’s a lot…

I did block off the bottom of the radiator.

Am I going to have to get a Dataloggit to see exactly what is going on?


I’m gonna pull the downpipe to wrap it, in part to help keep the transmission from spewing oil…


Considering it does the same thing whether it's cold or hot out, or whether my boost is leaking or not, I wonder if it's not a wastegate thing.
I think maybe it's leaking, which would also explain why it almost sometimes sounds like there's an exhaust leak when I try to get it up on ramps.

 

I had boost leaks again...One being that the brand new vacuum hose air filter I bought had cracked. I ordered a proper HKS one this time.

I pulled the wastegate and I did find the valve wasn't holding water at first.

After taking it apart (I accidentally sent the hat flying and almost cracked the windshield on my Subaru...), putting it back together (HARD), and wirebrushing the valve seat and valve, it held water (with just the occasionally drip). Before, water poured straight through.

I have no idea if this actually fixed it, or if maybe the fire ring just wasn't positioned properly when I initially checked for leaks. The valve did look like it wasn't centered perfectly in the middle of the bore, but that might have just been the natural free play of the valve. Now it basically does.

The diagram was fine. The lower port fitting was a bit leaky, so I put some teflon tape on it.

The lower port itself leaks like a sieve, but I apparently that's normal. Seems like a waste of boost, though...

Now I am waiting on a new gasket and some other parts.

Then I will have to wait until the next track day to see whether this fixes it, or whether there isn't something else.

I am trying to come up with a tool that will let me clock the turbo without removing it, since I can't fit any snap ring pliers. Hopefully that will help with the biggest source of boost leaks.

On the upside of all this, I have a much better understanding of how boost control systems work now.


Edit: Looking back at my old posts, pulling the wastegate wasn't as hard as I thought. Putting it back on will be a lot harder, though... But it shouldn't be too bad, since I spent a bunch of money on a new jack and some ramps to be able to work on my car in the parking spot.

 

I finally managed to clock the turbo! It was…. surprisingly hard. I unhooked the v-band clamp and pulled the compressor and center section off the turbine section, which I decided to just leave on the manifold, even though I had partially unbolted it. God, I hope it doesn’t leak.

While I was at it, I replaced the tattered old heat shield tubing on the oil drain and elsewhere. Looks much nicer now.

I guess it made a slight difference? I couldn’t make any fine adjustments to the angle because of how ridiculously strong the c-clip is.


I also rewrapped the downpipe, which it turned out was actually leaking next to the turbo, which I got welded. I also got a new turbo blanket to match, so everything looks much nicer.

Once the ultra copper cures and I get the o2 sensor back on, it’ll be ready to fire back up.

Please don’t leak…

It should sound better, at least.

 

It still sounds like it has a small exhaust leak (unless this particular setup just has a tinny sound?). I will pull the blanket back off and see if there isn’t a leak somewhere.

On another note, I leaned that loose particles of rust on a rotary exhaust will explode like tiny firecrackers right in your face….

 

It was leaking between the manifold and turbine, naturally… I don’t think I had managed to even torque the bolts properly, for some reason. Gonna need to clean up the threads and maybe replace a stud.

 

Finally got to another track day (Ebisu) after doing all the changes…

Boost still basically peaks at 0.84 or so the first time I get on the throttle and then settles in at some lower level.

With the new bumper, my intake temps were around 45 degrees on a 30+ degree day (not sure of the exact temps at the track, but the weather app said it was 30 degrees). The outlet side of the intercooler isn’t absurdly hot, so I’m probably getting decent air flow. The inlet side is scalding hot…

Is 15 degrees Celsius above ambient not too bad? Or is 50% above ambient actually quite bad?

I wonder if maybe this is just a characteristic of my particular engine and it’s tuning…

On another note, I always run with the AC switch on (even though I don’t have AC) because my radiator fans won’t run if I don’t. I know the PFC has different AC idle settings, but I don’t think it charges the tune like some cars…i

Despite the heat, I did set a PB… but it’s clear my coilovers aren’t up to the task. I don’t have nearly enough rest stroke for my spring rate and grip level. Gonna need to get a stiffer set that won’t bottom out and send my car into drift. lol

 

this, it did what it did, and if you went back, it would do the same thing again. if you want to change it, you need to change something...better ducting to the IC, more cold air to the air filter.
if you can lower intake temps, its better, obvs

i was looking at my logs the other day, and mine are about the same ~30c day, intake temps were ~45c, 15c delta. on a 20c day, intake temps were like 38c, so it actually worked better on a hot day.
ive always used the rule of thumb that 50c is kind of a limit, chance of detonation goes up the hotter things get. its been so long though, not sure why i picked 50c.

 

It did it even when the intercooler was cool to the touch. But that was before I nailed down the exhaust and potential boost leaks. Almost wonder if it’s not just the wastegate spring getting hot. I doubt the engine isn’t making enough heat to spin the turbo.

I think I might see about getting some pipe and rerouting the intake in front of my intercooler/radiator. That way I get straight ambient air without having to fabricate some sort of insanely complex airbox…. There should be just barely enough space.

I will also see about getting a simple heat shield to isolate the intake manifold from the downpipe.

Might even consider water injection just be for the sake of more consistent power.