I have a Forge Motorsport recirculating valve on my Evolution and when I am in fifth gear the valve “flutters” like it can’t hold boost BUT, it holds boost fine when I take off at full boost and go through the lower gears.
In fact it will hold much higher boost in lower gears.
I am thinking it might have something to do with vacuum or the fact the fifth gear is so huge. Fourth only goes to about 100mh and fifth goes to like 160mph or 170mph.
Any suggestions would be appreciated.
Thanks.
Mike
One other possibility I thought of was the air pressure under the hood at higher speeds.:gotme: (Just trying to guess)
is it still setup as recirc or vented to atmosphere?
It is set up for recirc. still.
Most people don’t have any problems with the Forge unit.
Besides, what the hell are you going that fast for? Hahaha!!
How tight do you have the pre-load? It’s adjustable right?
You might be able to hook a brake bleeder vacuum (Like Mightyvac) up to it
and see what inHg it is opening up at. You might be suprised to find that it is
opening up in lower gears, but you just can’t hear it/or tell.
Yeah, fifth kills 1/4 miles times.
I am thinking that because fifth is so long the turbo can build boost at lower rpm and that is somehow affecting the valve operation.
Again I am just guessing with my amount of knowledge.
Good point, I cannot hear or feel it but it might still be happening.
I can’t hear a thing at WOT.:biglaugh:
That’s exactly what I was thinking, at WOT you really can’t hear much…
I just remembered (duh) my boost gage does not flutter in other gears.:smash2:
So I would think it is working properly in those gears.
so your gauge flutters in fifth?
Which forge valve do you have the piston or the diaphram? how do you have it set up and what spring are you using?
Yeah, it flutters in fifth.
It is the piston type and I am using the stiffest spring it came with because I am running pretty high boost.
Maybe I need a stronger spring.
I am running the softest spring with the piston one, any other stiffer spring and it would flutter for me also. I set it up so pressure from the turbo was on the side port and it went out the bottom when it opened up. If i recall i was told to set it up that way so that the spring pressure was ~vacuum at idle and since when you go on boost there is no vacuum the boost should hold it shut
Also this held when i accidentally spiked to 21psi when trying to figure out my greddy profec settings
Maybe I will try that even though it doesn’t make sense to me.
It seems like you would get massive turbo surge that way.:gotme:
I was told by forge they discourage installing the piston valves in reverse orientation. they said hook the side port to the intercooler pipe and and bottom to the MAF pipe.
Shhhhhh!:snky: :biglaugh: (I wish)
any luck trying that?