Listerofsmeg

Hi all,

Been having a few issues with my cars boost creep so we are trying to go back to basics to figure out what the problem really is. I have a twin 38mm gate setup and a front mounted turbo, the car is running a BW S372R on a sleeved B18.

The issues that we are having is that no matter what spring we put in the gate the boost will creep to 20psi and then stop. Ideally i need the boost to be controllable from ~10psi upwards, as we obviously would like to run much more peak boost too. The car, as far as i recall is plumbed up as the diagram shows in the pdf below.

http://www.tialmedia.com/documents/w..._wginstall.pdf

Are twin gate setups "that" much harder to control? We are trying to use the S300's boost control, with a hondata supplied MAC solenoid.

I have a question around that though.....assuming the gates are plumbed up as shown in that diagram and the "vent" is the NO port on the solenoid, would i need to restrict that flow so that less air is let out of the system? As it seems to me that perhaps there is so much air escaping that the gates are not fully opening allowing boost pressure to continue to rise. Does that sound feasible???

If that is the case, would it make any more sense to run the solenoid air feed on a seperate pressure line? In order for the bottom gates to get a consistent pressure feed?

Im guessing that it must be the plumbing that is causing the creep given that i removed the inner spring from each gate and the result on the dyno was the same....

Has anyone else experienced anything similar? i have eliminated the timing and manifold design as the former has been checked with a timing gun and is spot on and the manifold design appears to be sound. I am expecting the gates to crack and hold ~10psi.

Help!!

cpl rampage

What psi springs are you using? Also the more open the vent (NO port) the better because this allows the gate to open faster. This is because the pressure on top of the diaphragm is vented faster, so the pressure below the diaphragm can pus the valve up.

Listerofsmeg

they are the large single springs that tial put in as standard, i would assume (but i cant confirm) that they are around 8psi.

I dont see how the port being more open can allow the bottom port to presurise quicker, as the T piece to the solenoid runs off the same feed? Meaning surely that some of the pressure in the bottom gate line will be lost to the vent in the solenoid?

crvtectim

What happens if you disable the boost controller, disconnect the lines from the top ports of the gates, and run pressure source lines to the bottom ports only? Do you get accurate pressure with the gates' spring rates then?

Listerofsmeg

well i am yet to try but i would be willing to bet that the pressure will hold nicely at the lower level. Which, assuming that is the case, also points to the vent being an issue no?

I will try this tomorrow as i am not with the car (and its not road legal!!)

The boost controller at the moment is switched off anyway (another issue...)

cpl rampage

the solenoid if hooked up correctly will only vent the air on the waste gate side of it not the side that comes from the pressure feed

Listerofsmeg

ahh interesting, so it could be that the wastegate is the wrong way round!!

Listerofsmeg

i meant solenoid!!

crvtectim

Give it a try. Doing so will tell you whether the 38s can handle the disposal or if dual 44s are in order.

b00stedEKnj

yeah i get boost creep too, boost is set at 20lbs for now with a boost cut set at 21lbs and i can't even get through all of 3rd gear before hitting boost cut...currently using a tial 38mm wastegate but tuner said i need to go bigger because this wastegate was building up too much pressure and causing it to creep, so stuck at 500whp for now lol

Listerofsmeg

ok so i found that the solenoid was the wrong way round! doh! so it was creating a boost leak effectively and reducing the pressure in the feed to the bottom of the gate. I have swapped this round and will now have to wait to test it out. I should not hit w/g pressure though

crvtectim

That's great! But huh? What do you mean you should not hit w/g pressure?

Listerofsmeg

haha i meant "now", sorry....fat fingers. really looking forward to putting it on the dyno now to see if we can get some serious numbers out of it

cpl rampage

Keep us posted, hopefully it works out for you!

crvtectim

Hahaha, ok. Makes sense to me now. Good luck!