ikrazygluebrokenapexseals

i answered your question above your post. the stock solenoid is for controlling STOCK boost on a stock car!!!! once you modify it all it will do is cause your boost to hit 15psi. ask me how i now this. is that a clear enough answer ?[/quote]

no, it's not an answer at all. let me restate my question from the beginning of the thread:



does the turbo boost control solenoid on s5 turbos prevent the wastegate from seeing a signal at all until the turbo is making full boost (to accelerate spool-up) or just regulate the maximum amount of boost made? it's not clear in the FSM.





no one has given me any indication whether it does this or not. i didn't say anything about my car being stock or not stock, i just want to know how the system is designed to work. simple.

RX7Aggie

i, too, would like a little more info on this matter. my haynes manual is not very specific on all the aspects of the turbo system.



DIAGRAMS WOULD BE VERY HELPFUL.

OKIERX-7

Here's my .02..... take it for what its worth...



When I put in my engine, I initially installed a ball/spring boost controller with a spring rated at 14 lbs. I noticed less lag and higher psi.



I also tried the DCS or stock boost controller, as well. The difference was noticeable. The turbo would spool up quickly, but not suddenly like with the manual controller. I also noticed the rise in psi vs the time was a smaller ratio. Meaning it did not spool or hit full boost near as fast as with the manual boost controller.



I believe the answer you are looking for is "NO, the DCS regulates the wastegate by bleeding boost. Not by waiting for a max signal" Now this was done very sciectific-like by me in my garage with no witnesses. Like I said take it for what its worth, free advice.



OTOH, a ball/spring manual boost controller isn't entirely that efficient either, it will bleed boost as well. Just at a lesser rate than the DCS.



Vosko..... I know you know a lot about turbo rotaries, but why do you say the DCS won't function properly, unless you have stock exhaust? I have extremely free-flowing exhaust(no cats or emissions) and when I use the DCS my wastegate opens around 8-9 psi. Not saying you don't know your stuff but why does mine work?



Later

Mike

vosko

on my TII with the stock solenoid i hit 14-15psi in 4th and 5th gear............ my panspeed is supposed to have it run 10psi i believe..... i'm just stating my experience with it. every car is different mine apparently like to run 5-6psi more than yours LOL my ecu has enough fuel so it won't blowup but i don't want somebody to put full exhaust then spike to 15psi and pop because the solenoid didn't control it to where it should be........... <_<

ikrazygluebrokenapexseals

thanks for the reply. if you're right, i have to wonder why Mazda didn't take the opportunity to cut lag even more with the only-bypass-at-max-boost approach, since they already have a solenoid sitting on the WG signal line, and quick spool was obviously one of the original design goals given the "direct impact turbine" and twin scroll bizness.



i guess what i really need to do is to finish up my car so i can get out there and do some instrumented testing

Scott 89t2

I was talking about the stock one

Scott 89t2

no it's a bleed type. as I posted at the top.

Scott 89t2

I think it does. think about this. the stock one is a bleed one. it'll bleed boost off the wastegate line till the ecu sees max boost. but with the FCD. the ecu never sees max boost. so the controller will contine to bleed so the WG will never be wide open. so'll you'll get more creep.

vosko

I was talking about the stock one[/quote]

oops

ikrazygluebrokenapexseals

I think it does. think about this. the stock one is a bleed one. it'll bleed boost off the wastegate line till the ecu sees max boost. but with the FCD. the ecu never sees max boost. so the controller will contine to bleed so the WG will never be wide open. so'll you'll get more creep.[/quote]

i don't think a FCD will prevent the ECU from seeing the maximum boost that the turbo system was designed to run from the factory. what it will prevent the ECU from seeing is the boost level at which the ECU will cut fuel to the engine. these have to be two different thresholds, otherwise in stock form the car would hit fuel cut everytime the turbo made full boost.



in the case of a clamping FCD, the boost signal will continue to rise along the stock boost sensor curve through the max boost threshold (not fuel cut threshold), at which point the ECU opens the wastegate fully. at this point, any boost creep is a consequence of the exhaust outflowing the wastegate orifice.



in the case of an FCD that produces a percentage reduction in the boost signal across the whole curve, the turbo is just going to make a certain percentage more boost before the ECU thinks it is at the stock max boost level. again, once the ECU 'sees' max boost level, the ECU will open the WG and any creep is a consequence of mechanical limitations.



what actually causes the creep to occur? intake/exhaust mods that increase the pressure drop across the turbine to the point that the internal wastegate cannot bypass enough exhaust gas. if you were running stock intake and exhaust, but with a FCD, i think you'd be hard pressed to see boost creep.



some good info about FCD's here: http://www.teamfc3s.org/info/articles/fcd/diy_fcd.htm