agent712

Well, got the RE ecu put on today... Mods include Racing Beat catback, mid pipe, and downpipe. Still have the stock intake and intercooler. We put on a couple el cheapo manual boost controllers off ebay, but I'm going to rip them back off and throw them away. The adjuster screw doesn't even thread in far enough to touch the springs. Argh..... So anyways, boost spike, we've got it. Part throttle is the worst. You don't dare mash the throttle at cruising speed/high load... it'll creep up to 15+ if you do. WOT w/ the ball and springs removed on the boost controllers (They still have the bleed off portion, so if I take them off completely hopefully that'll make it a little better) is like 11 pre, and 14 secondary. A little much for 91 octane. So I need to get the thing to stop spiking and come down under wot. I just ordered a catco 3" cat to put on the midpipe. Figure that will hopefully give us enough backpreasure to make the boost a little more controllable. But until I get that, you guys have any suggestions? I'm thinking maybe if we put a 2.5" restrictor on the exhaust that would help... Unless there is something else that would be easier. So let me know what you all think. I really don't want to loose my turbos yet

Thanks
Chuck

spurvo

I have a related newbie question: By my limited understanding of how our system is controlled, we are attempting to regulate the boost pressure by regulating the amount of actuation of the turbo input stream from the exhaust. This is how the inline pills to the wastegate and turbo controller operate, right? And the Home Depot mod? And the aftermarket turbo controllers? This seems a little problematic to me, in that if you don't have super fast, super tight regulation if the input controller, you can have overboosting and spikes and creep.... All because you are trying to regulate the turbo output by controlling the input. Right?

Why aren't we putting pressure regulators on the output? Namely, why not a pressure regulator that begins to open at, say, 10 psi, and just vents excess boost? Thus, no matter WHAT the input side is doing, or the turbos for that matter, you can't waste the motor through lean out by over boosting. Right? AM I stupid? Flame my *** heavily, tell me to search (for WHAT, though? The Greddy Profec site? Just marketing lingo there, not a "how this works", and you are STILL trying to control the turbo input, near as I can tell..), or just tell me to go home...

Of course, you still need to control the turbo so you don't cause them to overspin, and this is a great place for the input controllers. But still...

maxpesce

You have answered your own question - when you attempt to controll bost by venting excess - the turbos quickly overspeed (not enough load on them) and self destruct - you have to control the amount of energy spinning the turbine in either case, so it is just easier to regulate boost by controling how much exhaust energy gets fed to the turbine.

The problem w/ the FD's stock boost control system is that it is NOT a feedback system - the WASTEGATE SOLENOID (WGS) duty cycle is mapped based on rpm & throttle position. That is why the boost goes up when you open up the exhaust - The ecu still sets the same WGS duty cycle for a given RPM & Throttle Position even though there is more exhaust energy! and the revverse - boost drops if the exhaust gets more restricted like when the cat clogs.

spurvo

OK, but why not do BOTH? Control the turbo speeds through normal means, this protects the turbos. Control the overall boost with a pressure valve, this protects the engine.

So my question would them be, given the situation you describe, duty control of the WGS with a more freely flowing exhaust, coupled with a pressure relief down stream from the turbos, what would be the outcome of the engine rpm/throttle position duty control. Would you have a brief overspin condition when the pressure relief activated, then disappear when the duty control caught up with conditions, opening the wastegate and slowing the turbo, or would we just have runaway? HOW MUCH overspin? 2%? 30%?

BTW, if 'yall want me to quit with this thread, just pipe in and tell me to re-read the turbo activation resources again! I'll take no offense. Just trying to figure out why these seemingly obvious steps weren't implemented?

Too bad we can't just directly monitor turbo speed and duty control the turbo control, pre-control, and wastegate with that data.... frequency counter? Measures the whistle from the turbo? Balanced magnet on turbo fin mounting plate and coil pickup? Science fiction?

redrotorR1

Looks like you're in the same boat that I'm in. I just put on some new RZ turbos (w/DP and catback) and I'm getting 12psi spikes with boost creep when the secondary comes on ... got up to 15psi before I let off (one time only). The cooler weather isn't helping the situation any.

I'm looking into a digital boost controller. From what I've searched and read about, it appears that the manual boost controllers are good for controlling the amount of boost but not so good at controlling spikes. There are lots of options ... just depends on how many features you want and how much you're willing to pay. The Greddy Profec B is a test-and-tune controller as opposed to controllers like the Blitz DSBC/SBC-iD or the HKS EVC which are somewhat negative feedback loop controllers; and apparently are more capable of controlling the pre-spool actuator to prevent boost spikes.

One other thing, do you get 93 octane in Nebraska? That would be some extra insurance against detonation ...

agent712

Funny you would say that, because I was just coming on to say how I disconnected the manual boost controllers and fixed the problem entirely. No more boost spike... and only 9 psi max.... whew So, the problem was not the exhaust at all. It was those stupid piece of junk 15 dollar manual boost controllers off ebay!!!!!!!!!! ARGH! So, I figure we'll put an AVC-R or something of the like on our wish list. Do electronic boost controllers like the AVC-R control spike well? I want something that I can set, and forget (it's my brothers car, so I won't always be with him to make sure things are running right). I don't want to have to worry about spike under part throttle like I was with the manual controllers...
Nope, 91 is the highest here... sucks. But, we have a 55 gallon drum of 110 racing fuel in the back that I can always tap into if need be 1-2 gallon of that to each tank should be worry free boostage

Later
Chuck

JimmyJimboJet

chuck, if you don't mind me asking, do you own a shop or something? and no offense to you or your bro, but maybe he should be on the forum also, so he can learn about his car and know what to do if something happens and you aren't there.

congrats on gettin the spike fixed. and it's nice to see you picked up an ecu

jimmy

ps do you ever go to scribner?

HeatTreated

SCC mag did a cover on boost controller a couple months back.. the Apexi & Blitz controlled boost spiking extremely well, you still couldnt complain about the Profec B for the money though. Glad you solved the problem. *to those who purchase Manual Boost controllers, dont. You can easily make them for under $10 from your local hardware store.

agent712

JimmyJimboJet- Nope, don't have my own shop yet. Working on it though. I plan to go to SAM (samracing.com) in Houston starting next year so I can get all the hard core building skills under my belt. Then I'd like to come back and start a shop. I may try to start a little dyno business this winter. Do some dyno/tuning on the side. We'll see...
As for my brother, he browses the forum quite a bit, but he's just not very mechanically minded yet. I'm trying my best to teach him stuff with this car. And he's learning. He's made a lot of progress and is starting to understand things better. Whenever he gets something new for his car I try to make him to it, and me just stand back and tell him how to do it. So I'm happy about that. Sooner or later he'll know exactly what's going on. These cars are a totally different breed. So I'd say we're both in a learning process with them.
Scribner... been there once with the GM club (gmmodernmuscle.com) I'm in. I'd like to go more often, but it's a 3 hour drive. Kearney Raceway Park is only 45 minutes. Do you go to MAM? I think we're going to try to get there more often starting next season...

HeatTreated- Yeah, I was actually planning on reading that article tonight.....

Later
Chuck