Ok - I have a question...

When BDC did some dyno tuning for me, we found out that I had the wrong wastegate spring installed. HKS told me that inorder for me to run 10psi of boost I needed the yellow spring for my application. This was not the case, as at anything over half throttle, the boost would go to about 15psi! I have since replaced the spring with the blue one, supposedly 9.7ish psi. Well, I took the car out and drove it, and at half throttle, it holds near 10psi easily. If I go more than about half throttle, the boost will go up to 12-15psi.
I know that with stock turbo/wastegate setups, boost creep is an issue, especially in higher gears, but I dont think that with an HKS race gate there should be any creep at all.
My setup is as follows

Stock ported S4 block
T04E 60 PTrim .7AR cold 1.15AR hot
Rice Racing manifold
HKS Race Gate with blue spring
3.5" custom exhaust with Borla XR1 muffler
Greddy 3 Row FMIC
BDC ported throttle body
720/1680 injectors
Haltech E6K

I took a picture of my wastegate today for some more clues into my situation. This wastegate came from Rice Racing. He ran it on his car with a yellow spring installed. The screw going into the top of the gate was his way of controlling the boost. Supposedly, crank it down to increase spring pressure and back it off to decrease. Makes sense to me, but why the spiking? There is a vacuum port on the side of the gate that I have running to the large vacuum nipple on the UIM. There is another port on top of the gate that goes to nothing. Do I just have the wastegate installed incorrectly? Is there something I should be doing that I am not? I have a Profec B in the car, just not fully installed, mostly because I dont know where to run the vacuum sorce to the gate.
I have checked on HKS website and cannot figure anything out. BDC even messed with it and told me it should be fine the way it is.

ANY ideas on whats going on?!?!?!

update to above - took the vacuum line off the the wastegate completely so that the boost should be spring controlled....result: boost spiking more rapidly - would be well over 15psi in 1st gear had I not let off. Reinstalled it (from the intake manifold to the lower vacuum port on the gate) and slower spiking. I was under the impression that boost could be controlled by spring pressure alone, and could be raised by installing a boost controller?? Please give me a hand figuring out what is going on with my setup?! I would REALLY love to finish the 93oct tuning and do some WOT passes at 10psi!!

 

Yes it should be able to run off spring pressure and stay pretty close to what the spring is rated for, it will just be a little more laggy.

If you havent dont so already you might want to take the bolt almost all the way out and see if that helps. Could it be leaking somewhere? Is it sealed around the bolt?

Maybe you need to get with Peter (Rice) and talk to him about it.

 

Thanks for the input Shane. I have tried backing the bolt almost all the way out and the results are the same, I have not, however, tried taking it out completely. I have read other posts on here about this same sort of issue involving the HKS cast manifold. It has been suggested that the manifold is not efficient enough to vent all of the necessary exhaust gasses at a low target boost pressure.
I would think that one of Peter's manifolds coupled with that gate would be? Perhaps I am just aiming for too low of a target boost level? BDC did not want to start tuning much higher than that for safety reasons. I know the car will handle more pressure, but we wanted to play it safe in the beginning. Would it be a smart idea to dump some 110 or C-16 in the tank and see how how the boost will go?

 

To run off spring pressure:
- connect wastegate side port to the pressurized part of the intake tract (you MUST do this, or the wastegate won't open at the spring pressure)
- leave wastegate top port open/vented

It sounds like you had it all hooked up correctly, but that something else was wrong. Maybe too much spring tension adjusted into the wastegate? Is anything blocking the dump tube? Is the manifold new, or has it worked satisfactorily on another vehicle in the past? Perhaps try moving the wastegate control line closer to the turbo, like right at/after the compressor housing instead of on the UIM.

-Max

 

I just looked at your pic -- is the wastegate top port plugged? If so, unplug it. It needs to be open.

-Max

 

I was wondering WTF that was!! Thanks for the advice, Max. I will check into that as soon as I can.

 

I am still stumped here. I have been emailing with Peter, and his concensus is that the manifold wont hold 10psi, as its more designed for higher boost levels.

from our emails:
I asked about the boost spiking, and his reply was....
You will find that manifold wont hold low boost.

12psi is where it will sit normaly at wide open throttle

10psi IMHO is far too low, dont worry as it will not go any higher than
12psi,
which is totaly fine mate

I responded about removing the plug from the wastegate, and that I cant go WOT as I dont know where the boost will stop at and his reply was....
Nup not the plug, as its vented anyway.

Its just the WG pipe design its for higher boost applications the
maximum I
think I recorded (minimum boost was) 13.4 psi in that ball park at very
high
revs.

Pete.

P.S. Again single turbo (lol FD talk !) you want to be running around
15psi
anyway or otheriwse your realy wastign your time (not making enough
power).
20psi is nice too

So I guess I dont really know what to do here. Anyone get BDC in here for his opinion? Hes doing all my tuning so I guess he should see this...

I am nervous about taking the car WOT at this point without knowing what to expect as far as boost levels go. I am a novice tuner with a very extensive mechanical background. Needless to say, I cannot afford to break the car, cause if its broke, it must get scrapped.

Any suggestions?
TIA!
Joe

 

What manifold?

 

.

 

Put in the weakest spring you can find, loosen the bolt all the way, make sure its vented. Then get Brian (BDC) to add a lot of fuel in the high boost ranges just in case then hit the gas and see what it does. Use the boost controller to get the boost level and then tune the car. If you have a decent engine there isnt anything wrong with running 15psi on pump gas. If tuned good and conservative it will be fine.

Stephen

 

I had to go all the way down to a 4# spring in my HKS wastegate to get boost below 11psi on spring pressure alone. It must be an HKS thing

 

I think I have the situation figured out. It seems that, and BDC agrees with me on this, a super high flow exhaust (read 3.5" or more) tends to outflow the wastegate. I believe that Tony (Asleep) agrees with this also. The theory being that because its such a low restriction the exhaust gas can generate such a high velocity that the turbo will hit very hard and spool very fast, but those gasses will simply be moving too fast to properly feed the wastegate. It makes sense in a weird sort of way.
What I did to my car was to remove the wastegate spring pretensioner bolt that was installed in the top of the wastegate completely. I then richened the boost curve by 1% at 3500rpm, 2% at 4000, and 3% from 4500 and up just to be on the safe side should there be a spike. I drove the car, and in second gear boost seems to hold at 12 psi on a 9.6psi spring. My AFRs start out in the 13s go into 12s then settles in the mid 11s, eventually seeming to bottem out at around a very conservative 10.9-11.0. I did not see 15psi even in 3rd gear at high engine loads so I am thinking that I have mostly solved whatever was going on. Maybe there was still a little pretension on the spring, esentially making it act like a heavier one. I need to drive it with a co-pilot to verify this, but it seems that its pretty safe.
The turbo spools fast - if at around 3000rpm I stab the pedal, I have 10-12psi around 3500 to 4000rpm. It does not fall off at all, and the car is much faster than it was when pedaling it. For comparison, I paced a 310awhp STi and he could not pull away from me while I was pedaling the car to keep it at 10ish psi. I am interested to see how I fare now. By my and BDC's estimates I should be in the 300-330whp range now. Not too shabby of a starting point for a stock ported motor on such a large hotside.
I am in love with the T04E turbo, and going with the P trim wheel and a 1.15 hotside seems to be the perfect choice for relatively fast spoolup time and not running out of breath at the top. He is coming back up here (Ohio) in July and I will be getting back on the dyno to finish my 93oct tune and then dabbling with 100 unleaded and then some C16! Cannot wait to see what 18-20 psi will feel like!!!

 

It is harder to control low boost with a wastegate and manifold designed for higher boost. You would need a more effective (careful choice of words) design (for low boost) to vent gases to the WG. A larger WG, piping to support it, etc.

When the boost level approachs the most effective design boost level for your manifold you should find it easier to control boost...maybe even spot on.

When you run 15psi (you little sissy, Joe) you should be seeing different and much smaller variance in actual boost levels (when running off of WG spring.)

When Brian comes in town make sure you let me know, would be good to buy him an adult beverage.

Come out next nice Saturday night to the East side.
Tony