kcobean

iTrader: (2)

Assuming a properly operating system, yes. In the case of this overboost issue, I'm running a 5 PSI spring and boosting to 11+ PSI. I hope to be able to obtain near 5 PSI once this fix is in place and then set for 7.5 or 8 in the winter time, 9 in the warmer weather, which is what the car was tuned for.

SleeperZ

Please add me to the list (T' netics ST boost creep concern). I have a custom exhaust system. At the connection by the rear axle, it splits up into two 3" pipes with two Jic Magic Titanium mufflers. With the stock exhaust, boost creep was around 9.5 psi. Now with 3" pipes, it is going up to 10.5psi and I have seen it is high as 11 psi logged in the Utec under the MAP column. On the dyno, boost is just out of control. No good with my stock internals. With the Utec, 550cc inj. and a fuel return system, I am able to supply enough fuel to the engine, but it will not last long with that high of pressure. Please help in the solution to this matter. Thank you.

35ounces

iTrader: (5)

Hey SleeperZ you had better PM (or call) Reggie if you want the fix. Also, curious as to what kind of power you are making with your setup and I'd be interested in getting your UTEC maps as a base.

taurran

iTrader: (18)

Yes, the two issues are ENTIRELY different. People confuse hitting 9.5psi on an aftermarket exhaust with boosting uncontrolably past 11psi. Your case, Kelly, is different than many of the people posting in this thread.

Unless you're hitting 11+ psi on a regular basis, then the boost isn't "uncontrollable". For those getting 9.5psi, the system is functioning as intended, they just need to install an alternate method of boost control rather than relying on the wastegate spring. Which, by design, will supply varied levels of boost based on many other factors. In this case, exhaust backpressure is the deciding one.

35ounces

iTrader: (5)

I am not sure I agree. I mean, where do you draw the line?
I would say that if you are able to drop in a lower pound spring and your boost is affected at some proportional rate than it is working more or less as expected and you can or should be able to install a boost controller for fairly accurate boost control. However, if that is not the case then there is a problem. In my opinion, you should expect reasonably precise boost control assuming exhaust backpressure is not an issue (a relatively free flowing exhaust).

kcobean

iTrader: (2)

And realistically, if you're running the Tnetics flash, you're perfectly safe at 9.5 PSI for the most part (dyno to verify of course). Unfortunately, installing a boost controller won't help you to achieve 8 PSI if you're hitting 9.5 PSI on a 5 pound spring. Anyway, all that aside, I'm excited to receive the fix for this now that my car is back from the Auto Show.

ETA: I ran my car for MONTHS at 10/11 PSI with just the Tnetics reflash and never had detonation issues...Of course the reflash was also VERY rich on my car. I wonder if the exhaust had something to do with both?.......

taurran

iTrader: (18)

Your opinion doesn't change the laws of physics. The more free flowing exhaust will cause an unregulated wastegate to hold more boost.

You have the Nismo exhaust, which is also the exact same exhaust as my fujitsubo. I, too, was getting 9.5psi. But, I installed a 7psi spring and a boost controller, and now I can regulate boost down to 7psi.

taurran

iTrader: (18)

True. I wasn't referring to hitting 9.5psi on a "5lb spring". I'm talking about those who are hitting 9.5psi on the stock 8lb spring, and are blaming wastegate placement. This isn't the case in that situation. Boost should still be controllable by downsizing your spring and running electronic (or manual) boost control.

If there is anyone who has experienced otherwise, I'd like to hear about it...

kcobean

iTrader: (2)

Agreed. I would be interested to hear if others experience this as well. Not sure if I'm the only one, but I can't imagine that's the case, especially since at least one other person is using the same exhaust as I am.

As an aside, the three spring rates that Tnetics offers are 5,7 and 9. so if you have a 9 pound spring installed, 9.5 is about what you would expect. The 9 pound spring is what is installed in the gate from the factory, so the first course of action for people hitting the mid-9's should be to break out a Torx wrench and replace the spring in the gate with either a 7 or a 5. I've done this already and still hit 11+

taurran

iTrader: (18)

o rly? I thought [assumed?] it was an 8lb spring. But then again, it's all relative...

35ounces

iTrader: (5)

You are mis-quoting me. I don't think anything I said would go against the laws of physics.
A free-er flowing exhaust will create more flow and require more exhaust gas to flow through the wastegate. As long as the wastegate opens at the specified pressure and flows enough, boost will be reliably regulated. If it doesn't open at that pressure or cant flow enough then boost will build. Its pretty simple. Without a boost controller, the wastegate is regulated by the spring that is installed so none of them are actually "unregulated." But if I understand the point you are trying to make, it is that the kit in stock form will flow enough with a stock exhaust and a free-er flowing exhaust will therefore create higher boost levels. Again, if the wastegate flows enough and opens at the specified pressure then boost should be regulated properly.
In fact, that is exactly what is happening with the relocated WG. Regardless of the exhaust used, a 9 psi spring will regulate the boost to around 9psi just as it should.

I was hitting 10psi+ in the warmer months (all the time and thats exactly what the dyno showed too) and have been seeing 11's recently. Its not a matter of spiking. But I would prefer to be closer to 8-9.
I originally asked for a lower weight spring to give it a try and was told that it would not help. My intention was to install a boost controller but as you know you have to be able to achieve lower boost for that to be an option.

taurran

iTrader: (18)

I don't grasp how this is possible, as myself and others with the nismo/fuji exhaust haven't experienced sustained spikes to 10-11 psi.

And, how do you *know* that you cannot achieve lower boost with a lower weight spring if you have not tried it? A boost controller/spring install is MUCH easier than a wg relocation... If you want to install the wg relocation, that's totally fine. You might be able to save yourself the headache, though.

35ounces

iTrader: (5)

The list has at least 3 NISMO guys on it. We saw a steady 10+psi when I had it on the Mustang dyno back in the early fall and my gauge reads well over that these days.
Like I said, I wanted to try the spring originally but Reggie didn't think it would work and asked me to hold off. I am planning on using a boost control solenoid as soon as I am able to get the boost down. I suspect that the spring may lower the boost but who knows by how much.

I am also planning on using a different exhaust (plan on hold until this works). So I gotta do the relocation fix. Its not that big deal and its worth it in the long run.

taurran

iTrader: (18)

Yeah, I could add my name to the list too because I was hitting 9.5psi as well... I don't think I really need the pipe at this point, because the stage 2 kit will include a different wastegate and a different pipe anyway.

You're going to need to use a lower spring anyway when you install the electronic boost controller, unless you plan on running 9+ psi all the time.

MIAPLAYA

iTrader: (3)

For those that are running 10 PSI and less what type of boost gauge is it? Some mechanical and even some electronic boost gauges are going to have variances between the absolute manifold pressure and the displayed pressure readings..

35ounces

iTrader: (5)

TN proved that the design didnt flow right. I don't need to do that at this point though I am glad for you that yours is working to your satisfaction.
Are you really thinking of going with the stage 2 and a motor build?

I have already ordered the 5psi spring for use with the BCS. Should be here today.

MIA: In my case, the boost was measured both with my electronic gauge and whatever gauge is used at the dyno (pressure was taken off the manifold). Its moot but the stock kit is advertised at 8-8.5psi not 9-9.5psi. Are you worried that people are running the wrong springs?

636Racer

iTrader: (1)

So what would be a better fix?
going with a lower psi spring and adjust boost (elec or manual boost controller) from there; or the piping fix?

and when is stage 1.5 due?

35ounces

iTrader: (5)

The issue is that the spring alone may not work - depends how much your exhaust flows. Thats the reason for the WG relocation.

kcobean

iTrader: (2)

I think it's important to remember in this discussion that the gate is not a binary system. It's not just 0 or 1, open or closed, there are positions in between. The spring in the gate actually has two functions. The first is determining *when* in the boost building process the gate starts to open. The second is opening an amount equal to allowing x pounds of pressure to vent and y pounds of pressure to flow to the turbine.

This issue that we are experiencing has nothing to do with how far or fast the gate opens (it really has nothing to do with the gate itself at all), but rather that when the gate is ALL THE WAY open, it's not flowing enough exhaust into the dump system to keep the turbine/compressor speed down. Why is that? The exhaust gas is moving at very high speeds. Even with the gate all the way open, the exhaust gas must decelerate, turn 90 degrees to get into the gate, make another 90 degree turn to get into the dump tube, and then another at the top of the dump tube to get into the downpipe. This deceleration isn't able to happen adequately, so the gas is just speeding on its' way to the turbine. In my case (and probably others), I could run with a 1/2 pound spring, and would probably still hit 11+ psi because it doesn't matter what the spring setting is...once the gate is all the way open, it's all the way open and it's all about the fluid dynamics of getting exhaust into the gate. We know that the gate itself has the capacity to flow enough gas, it's how it's positioned to receive the flow that's an issue. If you're hitting 9.5 PSI on a 9 pound spring, then you're not necessarily suffering from this issue. If you switch to a 5 or 7 pound spring and are still hitting 9.5 PSI, then that means your gate is oen all the way and not venting pressure adequately.

Sorry for the long winded post.

MIAPLAYA

iTrader: (3)

Wrong spring? No kit should have shipped with anything other then a 9 PSI spring. The reasoning here is simple. The turbo with the 9 PSI spring produces 9 PSI of air...after that air travels through the intercooler and the intake piping the pressure drops to 8-8.5 PSI. Thats why intercooler ratings show both thermal efficiency and pressure drop.