will boost build up earlier with MBC or reliaboost
05-09-2003, 02:39 PM
#1
Racer
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will boost build up earlier with MBC or reliaboost
The reliaboost (or LBE) helps to build up boost ealier. What if I have a MBC and a lindsey wastegate installed but running 15 PSI anyway all the time? Would it help my boost to build up earlier if I would install a shimmed stock wastegate plus reliaboost?
05-09-2003, 02:46 PM
#2
Race Director
No... At least as far as I know all they do is help maintian boost at higher engine speeds. You can't build boost any faster or sooner unless you change the turbo. There is probably some effect from piping lengths and from engine (read fuel flow) managment, but nothing from the downstream things like wastegates and boost controller. The exception is if these are not working right.
05-09-2003, 04:01 PM
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my understanding is yes, they will - compared to a stock car - as you're eliminating the cycling valve which the KLR uses to gently "roll-on" boost. this assumes you have chips that can handle the new fuel/timing/boost level needed...
but i wouldn't run an LBE _and_ a MBC, that seems not only redundant but inaccurate.
btw if you already have a lindsey wastegate (did you get a dual port?) why shim? they should hold any boost level you throw at it (within reason) esp. 15psi...
but i wouldn't run an LBE _and_ a MBC, that seems not only redundant but inaccurate.
btw if you already have a lindsey wastegate (did you get a dual port?) why shim? they should hold any boost level you throw at it (within reason) esp. 15psi...
05-09-2003, 08:46 PM
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I hate to be the wrench-thrower, but hey <img border="0" title="" alt="[Wink]" src="wink.gif" /> .
If by MBC you mean a Turbonetics-type airvalve, then yes, a LBE or some other poppet-style boost control device will help build boost faster. I think what some manufacturers refer to as a "gated" boost control device is what these things are. No boost signal pushing on the wastegate diaphragm while your building boost.
I've run both types separately and in conjunction with each other with my dual port Turbosmart 45mm wastegate and boost builds much more quickly with the LBE.
If by MBC you mean a Turbonetics-type airvalve, then yes, a LBE or some other poppet-style boost control device will help build boost faster. I think what some manufacturers refer to as a "gated" boost control device is what these things are. No boost signal pushing on the wastegate diaphragm while your building boost.
I've run both types separately and in conjunction with each other with my dual port Turbosmart 45mm wastegate and boost builds much more quickly with the LBE.
05-09-2003, 10:30 PM
#5
Banned
I have a mbc and when it's set to 15lbs there's more lag then when it's set at 18lbs.
Russ may be right. It may let some by during buildup (mbc). But I have a .8 bar spring. About 12lbs and no matter how much gets by I can't lower the boost any less then 12 lbs so I don't think it's a problem. It may be a problem between 12 and 15lbs though. Spoolup is way before 12lbs. I guess this would be considered mid spoolup. But 12 to 15 happens so quickly it shouldn't matter.
Looking at the maps for my turbo it's also more efficient at 18lbs. So that may have something to do with it.
Russ may be right. It may let some by during buildup (mbc). But I have a .8 bar spring. About 12lbs and no matter how much gets by I can't lower the boost any less then 12 lbs so I don't think it's a problem. It may be a problem between 12 and 15lbs though. Spoolup is way before 12lbs. I guess this would be considered mid spoolup. But 12 to 15 happens so quickly it shouldn't matter.
Looking at the maps for my turbo it's also more efficient at 18lbs. So that may have something to do with it.
05-09-2003, 10:52 PM
#6
Race Director
"If by MBC you mean a Turbonetics-type airvalve, then yes, a LBE or some other poppet-style boost control device will help build boost faster. "
Yup, Russ is right on. There's a difference between how a pressure-regulator type of boost-controller works compared to the check-valve (poppet) variety like the LBE/ReliaBoost.
The pressure-regulator type is typically set to provide a certain maximum pressure-clamp. All pressure below this level goes through unaffected. So as the turbo builds boost from 0-14psi, all of this pressure is going to the wastegate starting to crack it open. At 15psi, the wastegate fully opens and dumps boost, but it's been partially opened already leading up to this.
A check/poppet-valve type of MBC holds back ALL boost-pressure until a set level has been reach. At which point, it lets pressure through to open the wastegate. So these types of controllers tend to build boost faster and earlier in the RPM-range.
However, I think there's something else going on here. Dmoffitt has pretty much the exact same configuration in his car as Christian's. He's found a way to significantly improve the low-end partial-throttle response.
Yup, Russ is right on. There's a difference between how a pressure-regulator type of boost-controller works compared to the check-valve (poppet) variety like the LBE/ReliaBoost.
The pressure-regulator type is typically set to provide a certain maximum pressure-clamp. All pressure below this level goes through unaffected. So as the turbo builds boost from 0-14psi, all of this pressure is going to the wastegate starting to crack it open. At 15psi, the wastegate fully opens and dumps boost, but it's been partially opened already leading up to this.
A check/poppet-valve type of MBC holds back ALL boost-pressure until a set level has been reach. At which point, it lets pressure through to open the wastegate. So these types of controllers tend to build boost faster and earlier in the RPM-range.
However, I think there's something else going on here. Dmoffitt has pretty much the exact same configuration in his car as Christian's. He's found a way to significantly improve the low-end partial-throttle response.