New MBC, I get diffrent boost in diffrent gears

parid · 12-15-2002, 10:07 PM

I’m testing out a Dawes Devices Hybrid Manual Boost Controller (http://www.dawesdevices.com/boost.html) that I borrowed from a friend. I used the directions from Scooby mods and got it in there without a problem. I installed it using the stock hoses. I plug up the hose that ran to the stock controlling device I used one of my spare 3/16th resistors and melted one end shut. I have the stock steering column boost gauge that measures in MPas.

I set it pretty low to start out with about .04 is what I got out of it. My goal is .1 or, from what I gather should be 14.5 lbs (correct me if I’m wrong). So I went out for another run, got it up to .06. Then I got .07 on the next. Finaly I think I got the ratio of turns down and I get it almost perfect at .095. I turn it about a quarter turn more and I’m there.

I had been using a pretty big not so busy road to test it at. I didn’t really get out of first. So I go back to my house, grab my roommate (who’s boost control it is) and we go out to get some Jack in the Box. On the way there, I hoped on the freeway to see what it would do at speeds. I noticed that in 4th, I was up to like .105 and in 5th I almost hit .11.

From my basic understanding of how this all works, it kind of makes sense. I know the stock gauge isn’t too great. I plan on getting a new vacuum line for it, I hear that helps. I’m going to turn it down so I don’t go over .1 in 5th.

Is the behavior normal? What’s happening?

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hotrod · 12-15-2002, 10:16 PM

Its a function of higher engine load in the higher gears ( less mechanical advantage, so the engine has to work harder). More load = more highpressure exhaust to drive the turbo = more boost.

Larry

PaulRex · 12-15-2002, 10:19 PM

hotrod explained it pretty well.. My advice would be to tune your boost controller for .1bar in 4th gear to be safe.

rex n effect · 12-15-2002, 10:53 PM

according to shiv from vishnu performance, you should set your boost in 4th gear at full throttle. I believe he says 4000 rpm, but with a gutted uppipe, you should get full boost at under 3000.

parid · 12-16-2002, 01:10 AM

Thanks!

12-15-2002, 10:07 PM	#1
parid Scooby Newbie Member#: 16336 Join Date: Mar 2002 Chapter/Region: NWIC Location: Eugene, OR Vehicle: 2002 WRX Wagon Black	New MBC, I get diffrent boost in diffrent gears I’m testing out a Dawes Devices Hybrid Manual Boost Controller (http://www.dawesdevices.com/boost.html) that I borrowed from a friend. I used the directions from Scooby mods and got it in there without a problem. I installed it using the stock hoses. I plug up the hose that ran to the stock controlling device I used one of my spare 3/16th resistors and melted one end shut. I have the stock steering column boost gauge that measures in MPas. I set it pretty low to start out with about .04 is what I got out of it. My goal is .1 or, from what I gather should be 14.5 lbs (correct me if I’m wrong). So I went out for another run, got it up to .06. Then I got .07 on the next. Finaly I think I got the ratio of turns down and I get it almost perfect at .095. I turn it about a quarter turn more and I’m there. I had been using a pretty big not so busy road to test it at. I didn’t really get out of first. So I go back to my house, grab my roommate (who’s boost control it is) and we go out to get some Jack in the Box. On the way there, I hoped on the freeway to see what it would do at speeds. I noticed that in 4th, I was up to like .105 and in 5th I almost hit .11. From my basic understanding of how this all works, it kind of makes sense. I know the stock gauge isn’t too great. I plan on getting a new vacuum line for it, I hear that helps. I’m going to turn it down so I don’t go over .1 in 5th. Is the behavior normal? What’s happening? * Registered users of the site do not see these ads.

12-15-2002, 10:16 PM	#2
hotrod Scooby Specialist Member#: 14141 Join Date: Jan 2002 Location: 13.239@102.85 @ 5800 ft on 13T Vehicle: 2002 Impreza WRX e85forum.net	higher gears and engine load Its a function of higher engine load in the higher gears ( less mechanical advantage, so the engine has to work harder). More load = more highpressure exhaust to drive the turbo = more boost. Larry

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12-15-2002, 10:19 PM	#3
PaulRex Scooby Guru Member#: 12454 Join Date: Nov 2001 Chapter/Region: Tri-State Location: Vermont Vehicle: 10 Toyota Taco K8 SV650SF	hotrod explained it pretty well.. My advice would be to tune your boost controller for .1bar in 4th gear to be safe.

12-15-2002, 10:53 PM	#4
rex n effect Scooby Specialist Member#: 15289 Join Date: Feb 2002 Chapter/Region: SCIC Location: from santa barbara to Carp Vehicle: 02 wrx sedan PSM & grey '11 TDi daddywagon	according to shiv from vishnu performance, you should set your boost in 4th gear at full throttle. I believe he says 4000 rpm, but with a gutted uppipe, you should get full boost at under 3000.

12-16-2002, 01:10 AM	#5
parid Scooby Newbie Member#: 16336 Join Date: Mar 2002 Chapter/Region: NWIC Location: Eugene, OR Vehicle: 2002 WRX Wagon Black	Thanks!