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Boost gauge flutter

580 Views 15 Replies 3 Participants Last post by  Gov Holmes
Just seeing if anyone has run into this or has an answer for it. When giving the go pedal a mash and after rpms climb and boost reaches 30-35psi my gauge starts to flutter pretty violently. Is it because that's around the end of my max boost anyway? It will fluctuate 3-5psi rapidly as I see it. I would think it should stay smooth. I was reading various forums just searching google and one person made the comment that this will happen when the engine can't flow anymore air that the turbo is forcing at it.
My other thought is that I am using a cheap @ss gauge to be honest. Just a $10 Amazon type. But it goes up to 50psi so it's not the normal issue with gauges where it goes bad from pegging out. I don't mind buying a better brand gauge, but it would be stupid if the issue is from something mechanical.

Note that I am running a brand new KC300x turbo. It's not surging or fluttering that way, just my gauge needle. I do leave the wastegate disconnected as well because I like the way the power comes on hard and instantly. Would that effect anything like this at all? The performance of the engine/turbo feel 100% fine and nothing noticable is wrong. If the gauge wasn't there I'd have no second thoughts on it.
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I almost can't imagine it to be the 6637 air filter I'm using. I was searching around and found this thread were a guy with some seemingly physics or engineering background explains some things. Long story short I was surprised to see the 6637 is really only rated at a 430-450 cfm and with similar mods to his and my truck, and at 35 psi, he estimates a 1000cfm system.
Could not enough air filter flow cause this?
Here is the thread:
6637 Flows Less? - Ford Truck Enthusiasts Forums
I know the 6637 is better than stock for sure, just trying to see if it's still good for an upgraded turbo/exhaust/chipped engine. Like I said, I wouldn't think it to be the cause, but I haven't found any other explanations so far the boost gauge flutter at high rpm.
I've decided to give a higher end filter a try. I was taking a hard look at an intake system anyway, but the price seemed unjustified for the gain. I've always had an easy enough time customizing my own "cold air" boxes, so I will do that. But for now I am going to stick with the 6637 style with a new AFE Magnumflow Pro5R. I read several reviews where people went from typical k&n, s&b, banks, etc systems to this and were blown away with how much difference they felt and saw in data. Louder turbo w/ faster spool up, lower EGTs, more power on the high end. Hopefully it makes a difference in the gauge flutter. If not, at least I was looking for a way to feed more air to the engine anyway.
That's a good idea. I already have the high flow filter on the way though. I will still want it on the truck even if it doesn't fix the flutter issue. I will certainly update when I put it in.
I have the filter installed, haven't drove the truck yet. We are having a storm, bad conditions for driving and testing.
The filter change didn't fix the flutter. But it was a nice little upgrade. Turbo sounds loud and spools quicker. Also hitting 33 psi on hydra setting 80hp where I was hitting 30. Haven't tried 100hp setting yet. I don't think any changes in my intake or exhaust will affect what the gauge is doing. I'm not even sure it is really a problem.
A few days after the air filter swap I put in a CSF intercooler I got a good deal on. This also made no difference in the gauge flutter. I suppose it could just be the cheapo gauge. I've come to feel that there isn't really anything wrong with it. Nothing feels out of the ordinary. If I ever change the gauge out I'll see what happens, but I don't really care to mess with it since it's not that big of an issue.
On a side note, I gave the truck a spirited drive and did hit right around 38psi w/ more room to go. I figure the CSF intercooler must have helped out on the top end. I could have hit 40psi easily. I think I'm done modding this thing! As I understand it, 40psi is max safe boost level for stock internals. That being said, the flutter doesn't happen till the very end of maxing out power. So this shouldn't be a big concern anymore as I do not want to be taking it up to 40 psi all the time. I'm guessing the cheapo gauge is the issue anyways.
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