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AAR when fully closed will it still leak boost pressure

I am currently fabricating my new intake for my 914 Turbo project. While test fitting where vacuum hoses are going to be located above and below the throttle body I started to wonder if when the AAR is warmed up and fully closed does it seal up well enough to prevent boost pressure from leaking past it.

Another thing should I let the AAR upper hose connnection vent to atmosphere or air cleaner, or could I attach it to the charged air intake pipe above the throttle body.
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Last edited by iamchappy; 02-08-2007 at 07:23 AM..
Old 02-08-2007, 07:14 AM
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yes I believe it does leak to a point.. I am in the process of hooking mine up right now and checked it and does leak a bit. but maybe 930 guys no better
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Old 02-08-2007, 07:59 AM
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The AAR will not seal tight when closed.
If the inlet is not routed before the throttle body you will introduce unmetered air into the system at idle.

Edit - I meant AAR, not WUR
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'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
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Last edited by RarlyL8; 02-08-2007 at 05:09 PM..
Old 02-08-2007, 08:08 AM
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The AAR pictures that I have seen show that the AAR's 19mm upper hose is attached to the air cleaner before the metering plate and the lower hose to the lower manifold.

On cold startup it allows unmetered air to enter the manifold bypassing the throttle plate once warmed up it closes off, am I not correct on this.
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Old 02-08-2007, 08:46 AM
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Quote:
Originally posted by iamchappy
The AAR pictures that I have seen show that the AAR's 19mm upper hose is attached to the air cleaner before the metering plate and the lower hose to the lower manifold.

On cold startup it allows unmetered air to enter the manifold bypassing the throttle plate once warmed up it closes off, am I not correct on this.
yup that is what I have seen as well.. But again to different things as I am not metering air like you guys
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Old 02-08-2007, 09:17 AM
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We need to clarify if you're talking about the AAR or the AAV.
The AAR is plumbed into the intercooler and behind the lower intake manifold. If you disconnect the hose to the intercooler it will bleed air into the lower manifold at idle and blow it out under boost.
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'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
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Old 02-08-2007, 05:13 PM
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Brian I am referancing the AAR, the valve that is electrically opened and closed during startup. I have seen photos of the upper hose attached to the air filter intake box before the metering plate.
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Old 02-08-2007, 05:52 PM
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AAV = Valve. Electrically switched valve, on or off only.
AAR = Regulator. The AAR is both electrically controlled and engine heat controlled, slowly closes as the engine warms. Attached to the intercooler and the intake manifold (bipassing the throttle).

Sounds like you are describing the AAV. Is this from a 930 or SC?
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'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
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Old 02-09-2007, 05:35 AM
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86 930 intake CIS system with a Euro fuel distributor that I am using on a modified 79 SC 3.0 engine with the 91 3.3 pistons and cylinders, twin plugged. Should I hook it up venting to atmosphere or to the intake before the throttle body.

Brian I appreciate your suggestions.

I think I am talking about the AAR and it is the same valve that you have responded about on threads I have searched in the 911 forums. In the PET manuel it is described as an AAR in your factory manuel I guess it is described as an AAV.

Quote- RarlyL8 "stand by my comments.
The red guy in your picture is an AAV according to my Porsche factory shop manual. As I said before the names are transposed on many schematics. They are all Auxiliary Air "Devices". Physically the two devices are very different so it is not so hard to describe them and make someone understand which part you are referring to."

"Pix are worth a thousand words. I agree with the reasoning behind calling something a "valve" vs a "regulator". I will now call this device with the metal gate and electrical hookup an AAR, even though it does a piss poor job of regulating."

AAV Testing?

AAR Revisited
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Old 02-09-2007, 07:14 AM
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I remember all of that, it is still confusing. HA!

The long device that sits by the WUR and has the metal "moon" gate needs to be plumbed before and after the throttle body. A buddy of mine had one with an air filter replacing the intercooler line, really screwed up the idle and CO% readings. Those gates do not seal when closed and some models purposely are machined that way, to assist with smog stuff I guess.

I know you live in the great white north but I do not run an AAR or an AAV on my car. You might leave them off until you get your car tuned and running to uncomplicate things. You can always add them later.
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Old 02-09-2007, 09:47 AM
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I considered leaving them off but I am building my car so I can use it for 3 seasons of use. Even though my car is stored in a heated garage if I ever had to park the car while out to dinner in the Spring or Fall I may never get it going. I installed a set of Heat Exchangers so I could have heat to extend the use of the car, so I think I will start off using the cold start valves and regulators and see what happens. The 930 intake came off of Lincoln's AKA (Schnele) 1986 930 when he switched over to EFI. He lives in Michigan and it was working fine when it was removed so hopefully if I have my electrics wired properly it should work. I suppose if I did do away with them I could use my hand throttle and manually fire my 7th injector for cold starts.....

Note: Air Filter.. I wonder who I got that idea from..


I will plumb in that hose to the intake side above the throttle body. it would suck if the valve was open and it allowed bypass of charged air and vacuum. The wastegate and BOV wouldn't work to well.
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Old 02-09-2007, 10:24 AM
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I ran last year with mine off but now I find myself putting one back on to make morning startup a bit easier. even in the summer early mornings as an issue. The VW rabbit one works pretty well if yours does not seal well.. remember you can turn in the air bleed to compansate for the little leak??
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Old 02-09-2007, 12:42 PM
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Wow! That's a wild looking setup. How do you plan to plumb the air inlet to the turbo?

With a hand throttle you do not need the AAV or the AAR - they do not help start the car, they only help keep it running, the same way a hand throttle does. Early CIS cars had a hand throttle, those devices came later.
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'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
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Old 02-09-2007, 12:51 PM
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I have a 90 3" to 2.5" reducing elbow from the throttle body and an aluminum 2.5" 90 bend pipe that I have welded bungs on to and barbed fittings, and a plate I fabricated for the 7th injector just before the throttle body . Aluminum pipes run back to feed the turbo which are connected with hump connectors and the charge side runs back to the intercooler. Here is a picture of how I had it plumbed before, using a 911 SC intake.

The 930 intake will make for a much cleaner install. I should be able to post some pictures of it soon.

The thought of eliminating the AAR and AAV sounds like I may have to consider it all over again.




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Old 02-09-2007, 03:12 PM
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Another shot of the engine for you to enjoy!
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Old 02-09-2007, 03:18 PM
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I have seen the in-car picture before but did not realize you were using CIS. Very innovative and nice job. I love it when folks do this kind of stuff.

No doubt in my mind about it - ditch the AAR. You do not need it in your application. The hand throttle will suffice and the plumbing nightmare goes away.

I assume you know that the header tube length is going to hurt you and you chose a good turbo to compensate. The distance from the air metering plate to the turbo inlet and back to the throttle body will likely sponge your throttle response a bit as well. Low tranny gears? Problem solved! Is that a 915 from a 914?

What is the 7th injector for? Boost enrichment? The stock 930 intake was not designed to handle fuel in that manner. The fuel tends to puddle and a couple of cylinders run leaner than the rest. If you are shooting for under 400RWHP fuel enrichment would not be needed, further simplifying your engine.

I am not picking at your project, just thinking out loud about my past experiences and research concerning these issues.

That is gonna be one fun ride when you're finished!


PS - nice air cleaner by the way. Ha!
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'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8

Last edited by RarlyL8; 02-09-2007 at 04:58 PM..
Old 02-09-2007, 04:54 PM
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I have not really experianced any considerable turbo lag with the K27, if you look at Clewetts setup he has the same type long exhaust runs.

http://www.clewett.com/

I havent run the engine using the stock diameter heat exchangers but it should help it to spool up faster.
The car is light enough and I am running short gears with LSD in a 901 transmission with a cooler. I can assure you this car scoots even off boost! The tranny will be the weak link but by rolling on the throttle and avoiding power shifts it should hold up ok.
I was using a 7th injector with the SC intake but thought it would be nice to have it there if it is needed on hot days or high boost. I inject it about 6" before the throttle body so it gets full atomozation before it reaches the manifold. It will be mostly used as a safety devise if needed to keep the ar's rich.
I put this project together not trying to build the ultimate highest tech HP engine or fastest car on the road I was just out to build a 914 turbo Carrera because Porsche didnt and I thought it would fun.
Maybe when I get bored I will go the way of EFI but for now I hope to enjoy it as it is.
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Old 02-09-2007, 06:31 PM
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Crap, I don't have enough stuff apart, and now I have to go think about the air devices too...

Chap, that powertrain looks pretty good. Glad to see you have the heater boxes on those headers.

Pat
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Old 02-10-2007, 03:24 PM
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They will come in handy if I can get the damn car together next month.
The more I have put thought into it I think I will eliminate the AAR and AAV and use the hand throttle to keep it going. Once I find the magic spot to initiate getting the car to start, it should work fine. I doubt I will be driving the car in weather like were having up here right now in the below zero temperatures but will be driving when it is around freezing.
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Old 02-10-2007, 04:17 PM
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Re: AAR when fully closed will it still leak boost pressure

Quote:
Originally posted by iamchappy
I am currently fabricating my new intake for my 914 Turbo project. While test fitting where vacuum hoses are going to be located above and below the throttle body I started to wonder if when the AAR is warmed up and fully closed does it seal up well enough to prevent boost pressure from leaking past it.

Another thing should I let the AAR upper hose connnection vent to atmosphere or air cleaner, or could I attach it to the charged air intake pipe above the throttle body.
David, Connect the AAR line to the back of the TB above the plate or anywhere on the charged air intake. This way the pressure is always equalized under boost and there is no need to worry about any leak thur it and past the plate.
When lifting off the throttle, the BOV will react and you still won't get any leak. Same for AAV plumbing.
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Old 02-10-2007, 05:48 PM
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