racer135

iTrader: (2)

Are the people with FPGreen or 20G stock appearance turbos experiencing turbo surge when driving at high loads or boost while at low rpms (under4K) in high gears?

cfdfireman1

iTrader: (11)

No, but you may see bypass valve flutter depending on amount of boost and the type of valve you use.

TakaseEVOIXSE

iTrader: (20)

im getting big time surge w/ my FPgreen when i floor it at WOT on full boost at 25psi. It sounds like BOV flutter but constant while im in boost... then slightly goes away in the upper rpm range. Its an issue we HOPE to remedy tonight by cutting off my HKS BOV and welding on a vband TIAL bov.

racer135

iTrader: (2)

Thats what I though based on some flow maps I made using a 20G efficiency plot. This would be even worse on a stock cam evo due to volumetric efficiency. I will plot my maps later. After 4K RPMs it looks good (at around 22 psi) but from 3 to 4K it appears that it will surge if the turbine has enought time and flow to build high boost, which can be done while in load in high gears.

cosworthevo1133

i have a fp white turbo and i run 24 psi and when i am in 4th or 5th gear at low rpms and i floor it to get around some one it surges, some one told me tht it might be my bov, i have the greddy type rs and heard it leaks

whoang40

iTrader: (26)

My green surges too at low rpm, high gear. I have a Works DV. I'm not sure if it's the DV or turbo.

SICK9

iTrader: (36)

When I first got my Green it did the same thing at low rpm, high gear acceleration.

At first, I just stepped on the gas more and it helped a bit, but not fully.
I found dropping a gear or two works much better.
It likes the higher rpm's much better. (4-6k rpm).
Just my .02..
It was more of driving style then anything else..

I will say, that now that i have the RED, it does not do it as much, but still does it, if i try to.
So I dont, I just drop a gear and BAM, gone.....
good luck...

racer135

iTrader: (2)

Based on the plots I made it should be the turbo. A weak DV will help too but the DV capacity is independent of rpms. Engine flow and it capacity to "swalow" the turbo airflow increases with rpms thats why you will not see it at high rpms unless you have a huge turbo.

whoang40

iTrader: (26)

It must me that the turbo is supply the engine with too much air instantaneously at high rpm. Or else the DV can't release it fast enough.

Boost3dxEvO

iTrader: (135)

Maybe you need to run a recirculated bov... since you are obviously on a pretty basic setup and not high boost... I don't know why you are running VTA bovs ..

dsmfan95

iTrader: (27)

I noticed a bit more surging with the EvoRed over the EvoGreen.

N33d4sp33d

iTrader: (31)

yeah i agree i'm guessing red holds mid range better than green

racer135

iTrader: (2)

That is expected. A stroker will also help with low rpms surge.

dsmfan95

iTrader: (27)

From what I've read, the stroker makes the surging worse.

TakaseEVOIXSE

iTrader: (20)

my ECU has been able to run VTA for quite sometime. I have no issues when it releases, no stalls, in fact it runs better than my friends recirc'd evo as far as idle stability and AFRs are concerned so i havent bothered to touch it. Im using a wideband w/ datalogging capabilities as most of us do... and see no ill effects from it. i dont want to get into another VTA discussion... but the issue is when im WOT not when im off throttle. So the VTA/Recirc is irrelevant to this thread. The surging is happening when the BOV is closed and WOT accelerating full boost. It happens around 2500-4000rpms.
Now, that being said... just to make sure the HKS bov wasnt leaking, we TIG welded a new vband flange for a TIAL bov. Tested and works flawlessly... but the surging is still there. In fact i upgraded the bov for no reason...haha. After reading the above comments... im assuming then the FPGreen just has a tendency to surge at low rpms/high load gears. I just didnt expect it from a 20g... if this was a bigger turbo i would have dismissed it in the beginning, LOL... Anyone else have a green that surges?