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Smart quod bastardus
 
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Join Date: Oct 2002
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best place to tap for Wastegate hose

My current wastegate hose to the wastegate inlet is tapped off the inlet side of the B&B intercooler that I installed.
I max out at 0.65 bar on my VDO gage in the dash.
My question is would I benfit with a little more boost by tapping off the actual intake manifold with the hose. Reason being there must be a pressure loss across the intercooler and after the throttle body which would not get picked up currently as it is hooked up?
Anyone have a range of pressure loss across these engine items to give a feel for what to expect. I see this as free hp if it makes a significant difference.
Thoughts?
Old 08-14-2007, 03:09 PM
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When the throttle is closed your wastegate will think there is no boost...
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Old 08-14-2007, 03:46 PM
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It appears this works because the wastegate regulates the boost relative to the signal it receives.

I did this, only to lower my bottom boost threshold by taking the wastegate signal prior to the intercooler (like yours is currently set up).

I was seeing just under 2 psi boost differential by taking the wastegate signal prior to the intercooler versus after the intercooler. This differential correlates to the restriction which I measured across my intercooler at about 1.5 psi. So, the answer is yes, assuming you have a little restriction within your intercooler (most all do) you could increase your boost threashold by taking the signal after the intercooler.

eidt: signal taken after the intercooler, but before the throttlebody. I'm not sure of the effects of linking directly to intake manifold such that the wastegate sees vacuum iduring off-throttle. Diaphram in wastegate might not like this.

Last edited by Jim2; 08-14-2007 at 05:55 PM..
Old 08-14-2007, 05:51 PM
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Don't you just tap a line at the back end of the intercooler?

My Andial intercooler has a nipple on the back, which is where my boost signal is hooked up to go to the wastegate. Isn't this the ideal place for getting boost signals, after the intercooler has dropped the pressure slightly of the intial boost?
Old 08-15-2007, 08:21 AM
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Fred - When you say the VDO gauge in your dash are you referring to the factory gauge within the tach or the typical clock replacement gauge? If its the one in the tack I wouldn't spend a whole lot of time chasing boost as those are just plain useless.
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Old 08-15-2007, 09:02 AM
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No I mean the VDO gage that replaces the clock.
The one in the tach is so inaccurate it makes me cringe. You don't realize how far off it is until you actually see the VDO gage in action.
I see about 0.6-0.7 bar max boost in 3rd or 4th gear on the highway. I thought that was a little low since the wastegate signal is reading higher than the intake manifold sees after all the pressure drops thru the intercooler and manifold.
Was just testing my logic.......looks like some free horsepower if I reroute it......maybe 20hp, just kidding.
Old 08-15-2007, 09:02 PM
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