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PWR air-water intercooler installation guide
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emoore924  



Joined: 13 Apr 2004
Posts: 2797

PostPosted: Sun Apr 13, 2008 2:01 am    Post subject: PWR air-water intercooler installation guide Reply with quote

Introduction

There has been some excellent work done recently by board members regarding intercooling their 931s. I’d like to offer the following writeup covering my installation. It is fairly exhaustive and covers pretty much all you need to know to set up a PWR air-water intercooler on your 931.

These instructions are specific to setting up a PWR intercooler on a 1980 USA Porsche 931 with an existing Holbert superwide body conversion (no pop-up headlights). Please note: I DO NOT KNOW IF THIS WILL WORK IF YOU HAVE POP-UP HEADLIGHTS, so check fitment beforehand. It also had an intercooler previously, so some sheet metal on the passenger side had already been removed to accommodate the earlier assembly, making this installation easier.

The setup is reasonably simple, and can be accomplished by someone with modest mechanical aptitude. If you have some basic hand tools and a some patience, you should be able to complete this installation in an afternoon.

Here's the original Holbert Racing setup...



Here is the design as layed out on my workbench...



Tools

Hacksaw
Hand Drill
File
Dremel
Various and sundry box-end wrenches and deep sockets
New, sharp razor blade or razor knife.

Parts and Materials (source)

PWR Intercooler kit (eBay)

(1) PWR 4x6 air-water barrel intercooler , 2.25” inlet/outlet
(1) Jebsco centrifical pump
(1) 10x10 radiator

Note: The full factory kit comes with a billet coolant inlet and a fan. My setup was from eBay (used) and didn’t include these parts. I substituted a snomobile coolant tank for the billet inlet and have not mounted a fan (yet…)

Intercooler air ducting

(3) 90 degree, 2.25”, 5”tight radius polished aluminum elbows (Ancla Motorsports, eBay)
(12) 2.25” T-clamps (CX Racing, eBay)
(1) 10” piece of 2.25” aluminum pipe, beaded end (CX Racing, eBay)
(6) pieces silicone (not nitrile) 2.25” hose (CX Racing, eBay)
(1) piece silicone 2.5” hose (CX Racing, eBay)

Intercooler water plumbing


(1) Snowmobile coolant tank (eBay)
(2) 5/8-1/2 brass 90 degree elbows (Lowes)
(12) feet ½ “ heater hose (Carquest)
(4) push-on plastic ½” 90 degree hose fittings (Carquest)
Many ½” hose clamps

First: Moving the fuel dizzy

Ultimately, you need room to snake the intercooler piping beneath the right edge of the fuel distributor so it can make the bend away from the turbo oulet, up, then back to the charge tube. This is accomplished by moving the fuel distributor up about 1/2” and about 1/2“ to driver’s left.

Here's the bracket



To do so, remove the air cleaner housing, unbolt the fuel distributor from the bracket that attaches it to the frame rail, undo the turbo inlet hose, and remove the distributor. Plug the turbo inlet with a rag so that nothing inadvertantly falls in there and ruins your day.

To get the space you need, you’ll need to cut the tab off the bracket that extends to the passenger side (the tab with the 1 mount/hole in it), and elongate the other two holes in the bracket by about ½” so you can slide the whole bracket left (these are the holes for the bolts that go into the frame rail). Use a hand drill to elongate the holes and a hacksaw to remove the tab from the bracket.

Once the holes are elongated, you’ll need to remove the rubber mounts from the other edge of the bracket, place 3-4 ½” washers beneath each mount and reattach them. This takes care of the height you need.

Here's the workspace with the bracket removed.



Here are the washers placed under the rubber mounts on the bracket...



File/dremel the edge until you’ve cleaned up the sharpies from the hacksaw so it fits nicely against the frame rail.

Remount the bracket. This takes care of what you need to do to get the fuel distributor out of the way to driver’s left.

Here's the trimmed bracket remounted



Since everything’s shifted up and over now, you might need to get some of that back to get the air cleaner housing to fit back onto the car. So you may also have to trim 1/8” off the boot that attaches the metal air cleaner housing to the top of the fuel distributor and/or elongate the holes used to mount the bottom half of the air cleaner housind. But wait and see how your unit fits before you do this.

After test fitting, leave the bracket off for now.

Here, you can see the air cleaner moved to driver's left

[/img]

Stock charge tubes - removal

Remove the stock 2-piece charge tube from the run from the turbo outlet to the throttle body. Set aside. Put a rag in the turbo outlet so nothing inadvertantly falls in there and wrecks your weekend.

Note: There is a small bolt on the backside of the short charge tube that secures the tube to the side of the block that must be removed for the tube to come out. Otherwise it is a press fit and just pops off.

The larger charge tube just requires dosconnecting of the various hoses and wires, and once the two clamps are loostened at the throttle body and the securing bolt removed from the TB bracket, it can be removed and set aside for later. Put a rag in the TB inlet so nothing inadvertantly falls in there are wrecks your month.

Setting up the airway

Creating the airway for the intercooler is pretty straightforward. You essentially asssemble the pieces, slide on the silicone tubes, slide on the clamps, and when everything is assembled, you tighten it all up (a LOT).

A couple of words of advice before beginning:

Except for the turbo outlet tube and elbow, don’t tighten *anything* until *everything* is in place (this includes all the water plumbing).

Don’t do anything permanent until you’ve prefitted the whole setup a couple of times and you’re sure it is right.

First thing to do is to take a piece of the 2.25 silly hose and fit it over the turbo outlet. Push it all the way down until it won’t go on any further. Insert one of the alu 90’s into it and check that it butts up against the turbo outlet. You want NO gap here between the flange on the turbo outlet and the flange on the elbow and if the hose is too long it may push the elbow up away from the turbo outlet. You don’t want this. Carefully, trim the silly hose with a sharp razor blade if needed. Take elbow out, put a t-clamp on the turbo outlet where you can reach the nut. Tighten it down. 11mm. Put a t-clamp down over the hose for the turbo outlet and insert the alu elbow again. Important: Aim the elbow so that the run will parallel the edge of the wheel well. Tighten down both clamps. You don’t want this part of the setup to move again.

Here is the silly hose and the first elbow in place, taken from behind, on the passenger side



Put a piece of 2.25 silly hose over the end of the elbow. Put a clamp on (don’t tighten). Take the straight 10” beaded piece of 2.25 alu pipe and insert it into the silly hose. Put a clamp on (don’t tighten, in fact, don’t tighten any more clamps until I tell you to Keep assembling parts, elboes, clamps, clamps, elbows, intercooler, until you’ve got the intercooler facing the spot where the shortened charge tube will meet up.

Here’s the whole parts sequence from the turbo outlet to the intercooler outlet, connected with T-clamped silly tubes of course…

Turbo outlet to (Elbow + 10” alu tube + Elbow + Elbow + PWR intercooler) to factory charge tube

If you looked at it all from the driver’s side, it would look like a U, tipped so the top was open to the right, the 10” 2.25 alu pipe on the bottom and the intercooler on top.

You can adjust the length of the whole thing by changing the length of the 10” alu tube as needed to match your specific setup and miss the frame rail, the fuel dizzy, and the lights if you have them. Just don’t cut it too short, of course.

You’ll need to test fit and cut the factory charge tube now. This is kind of a pain because you have to reassemble then disassemble it each time you want to make a measuremen (Make sure you get the charge tube ALL the way into the TB hose each time or you may end up with fitment problems later.) Get as even and tight a fit as you can with the match up to the outlet of the intercooler. The transition from the round piping to the sqareish charge tube presents the greatest opportunity for pressure loss if you don’t get it right.

The connector used for the transition from the 2.25 intercooler outlet to the factory charge tube is special. You have to silicone a shortened piece of 2.25 inside a piece of 2.5, then slip the 2.25 over the outlet of the intercooler and the 2.5 over the cut end of the charge tube.

I would recommend that you carefully dress and de-contaminate the cut-off edge and run a small bead of J-B weld around it to give the hose and clamp something to bite into. The problem is that you’re going from a round tube to a squareish tube, and things like to leak under such circumstances. Also, I used three clamps in this location; a T on the intercooler, a T right at the bead I just spoke of, and a band clamp a little further down the silly hose to squeeze the hose better to the square shape of the factory charge tube. The T clamps don’t form to non-round shapes very well so I thought this particular joint needed a little extra help.

Here's a pickie of the round tube to factory charge tube connection with the extra clamps.



Setting up the coolant circuit

On the PWR are two water fittings. Place short pigtail hoses with 90s already in them over each fitting. You need to find a home for the tank, the radiator (in the air flow of course, or with a 9” fan), and the pump. You’ll need to plumb it all as well and run wiring to the pump to turn it on and off (or power up on key on, you pick the circuit), and to the fan if you use one.

Here's a pickie of the i/c with the pigtails in place.



I can’t speak to your exact setup but here are some helpful hints:

Plumb the hose run like this:

Tank out
Pump in
Pump out
i/c in
i/c out
radiator in
radiator out
tank in

This will put the coldest water to the pump and then to the i/c inlet.

I used water with aluminum-friendly glycol coolant in it – maybe 25%. Don’t forget this mix in the winter time or you’ll have a very unhappy and very frozen PWR.

You want the coldest water going into the i/c fitting closest to the TB, and warm water coming out from the fitting away from the TB. Something about maximizing heat transfer pressure or something like that.

I had to cut the fittings going in/out of the tank so they could receive the barbed brass 90s from Lowes. I did this because the molded factory in/outs were aimed in the wrong direction to easily connect the tank hoses the way I wanted. I simply gooped the brass 90s up with some j-b weld, shoved them into the cut off openings, and twisted to suit. So far so good.

I mounted the 10x10 radiator on the 45 degree longitudinal that comes from the radiator support back to the main frame rail. The edge of the rad fit into the shape of the metal nicely. While it is not optimal because it is at an angle, I already have an opening in the air dam there and I’ll fair in a duct and it will be fine. Most of you will probably want to put it in front of the radiator. That would probably work better.

Here is the radiator mounted on the 45 degree strut.



And from a wider angle:



The underneath of the tank, pump and radiator



You may not have this but I also have a clearance issue with the ground – the radiator is too close to it and I’m going to bash it to smithereens any day now. I think I’m going to change over to a scavenged heater core which will be more compact allowing me to move the cooler away from the ground and square it up to the airflow better.

Don’t clamp the pump down too hard or you’ll warp the housing and it will make horrible noises.

You can’t undo the plastic 90s without some sort of papal dispensation apparently, so don’t press them on the hose until you’re really ready.

Don’t worry about bleeding the system. The bubbles pretty much work their way out.

There’s a grommit (sp? apologies to Wallace) over the driver’s footwell that I used to pass the wiring from the switch I placed in the console to power the pump. I use 18ga. Speaker wire in case I needed two wires, but I didn’t. The setup is: power -> switch -> fuse -> pump -> ground. Works fine so far and I have a wire that runs right past the battery in case I need to set up my own fused power circuit.

Final Fitment

Ok, now that you have everything in place, you need to test fit the whole setup. Lightly assemble all the clamps, hoses, and most importantly, mount the fuel dizzy and see how everything fits. Muscle, push, twist or otherwise motivate the whole setup into the configuration you want/need. Be sure to clear the fuel dizzy, the timing belt housing, the strut tower, and the headlights if you have them.

Tighten all the clamps. Replace the air filter assembly and adjust as necessary to be sure all of it fits back on the car (remember, it is now 1/2” higher and ½” more to driver’s left…)

Fill the tank. Let it bubble until it stops. Have an assistant turn on the pump and fill until the bubbling stops again. You should see the fluid moving through the tank.

Start things up and check for air leaks, water leaks and general operation. The i/c will be cool to the touch.

Test drive, tighten clamps as necessary and you’re done!

Here's a pickie of the done setup.



And one from the other side...



And one more, just for Rasta



Last edited by emoore924 on Sun Apr 13, 2008 11:29 am; edited 9 times in total
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Rasta Monsta  



Joined: 12 Jul 2006
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Location: PacNW

PostPosted: Sun Apr 13, 2008 2:19 am    Post subject: Reply with quote


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emoore924  



Joined: 13 Apr 2004
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PostPosted: Sun Apr 13, 2008 2:37 am    Post subject: Reply with quote

Um, I know, that's why the first line says pickies to follow shortly
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ideola  



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PostPosted: Sun Apr 13, 2008 2:47 am    Post subject: Reply with quote

Nice work Eric...and congrats on getting the photobucket thing to work
Cheers
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88 924S SE | 82 931 Holbert | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition


Last edited by ideola on Sun Apr 13, 2008 10:27 am; edited 1 time in total
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emoore924  



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PostPosted: Sun Apr 13, 2008 5:55 am    Post subject: Reply with quote

Thank you ideola. I appreciate your hosting the pickies for me. Now that I have photobucket figured out, watch for lots more interesting images from me

Could someone please PM or email Rasta and let him/her know that there are pictures to go with the words now.


Last edited by emoore924 on Sun Apr 13, 2008 10:50 am; edited 1 time in total
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tuurbo  



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PostPosted: Sun Apr 13, 2008 8:23 am    Post subject: Reply with quote

That's purdy
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morghen  



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PostPosted: Sun Apr 13, 2008 9:00 am    Post subject: Reply with quote

looks great, very easy to install and the piping is very short....but do you think that you could put into perspective the performance of this intercooler?
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emoore924  



Joined: 13 Apr 2004
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PostPosted: Sun Apr 13, 2008 9:34 am    Post subject: Reply with quote

Sure, here are my initial impressions.

The car had a Holbert racing 962 a/a i/c on it when I bought the car. It was located in front of the right front wheel with air coming from a hole in the air dam. The piping was 1 7/8 aluminized muffler piping, with good welds but not the best design -- there were a lot of twists and sharp bends leading from the turbo to the charge tube. I had some trouble keeping the system sealed but after working out some of the kinks, it worked reliably, allowing me to turn up to 15 psi or more.

My first dyno put me at about 155/175 hp/tq at the wheels. Not bad but I expected more at 15 psi. I dynoed the car again after some head work, and it was worse -- something was constraining the system -- I was down to 150/160 hp/tq, but I didn't know what it was (I think now it was the fuel pump coming lose, but see my other thread on that...)

I experienced a cracked manifold (again, see other thread), and because of the super-heated manifold, was able to have the fuel pump problem diagnosed.

To be fair, the current setup is not a lot like what the original i/c had to work with, so the deck is stacked. There's a new manifold, a new turbo, a new i/c, a new TB, a test pipe and a new exhaust. So comparos aren't fair.

But I can tell, even at 7-8 psi, that the car is making way, way more hp/tq than it was before and over a broader rpm range. How much of that is attributable to the i/c, I can't say for sure. BUT, I will say that the outside of the barrel is cool (cold?) to the touch even when flogged, so as I optimize the system, I doubt the i/c will be the limiting factor. It can flow enough for about 290hp and I don't think I'll get close to that (my flow calculations support the PWR factory estimates), and the intake charge is really cold on its way to the TB. Read up on it but I think this outperforms an a/a setup hands down. ('scuse me whilst I go dump a little ice in the tank )

My goal was a reliable 200hp at the wheels. I can't prove it yet but I think I'm already there even at 7-8 psi. That gives me another 6-7 psi to play with to get me to the pressures I was running before.

My recollection was that the car really transformed itself at 12 psi, so I'm ready to give that a shot. I've got 12 gallons of 100 octane, a timing light and a variable boost switch. This is gonna be great

One last thought: Think of a straw, put your mouth to it and blow 15 psi. Then think of a vacuum cleaner hose, put your mouth to it and blow 12 psi. Under which circumstances are you moving more air . THAT'S what I'm trying to do here. Increase flow big time. So far, so good.


Last edited by emoore924 on Sun Apr 13, 2008 10:57 am; edited 1 time in total
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Rasta Monsta  



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PostPosted: Sun Apr 13, 2008 9:47 am    Post subject: Reply with quote

emoore924 wrote:
Um, I know, that's why the first line says pickies to follow shortly


Just teasin' ya man (just as someone did to me)!

As for the fuel, Shaggy's running 12 daily on 92, and I did a few days at 14 also on 92 with no issues (except severe acceleration trauma).
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ideola  



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PostPosted: Sun Apr 13, 2008 10:33 am    Post subject: Reply with quote

One (somewhat disappointing) note...it doesn't appear that this arrangement would work without also converting to fixed headlights...
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emoore924  



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PostPosted: Sun Apr 13, 2008 11:05 am    Post subject: Reply with quote

Hmmm, I dunno, I thought through a lot of options and if you take out the triangular plate in the RH wheel well and mount the i/c *vertically*, it will work. I think there's room even with the headlights still in place. I tested it on my n/a as I was fabbing out the options and it did fit (it still has pop-up headlights). However, I ruled it out on the turbo because the 931 didn't have headlights and therefore there was a better setup than vertical...

I think the key is the triangular plate being removed...
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ideola  



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PostPosted: Sun Apr 13, 2008 2:10 pm    Post subject: Reply with quote

Yeah...I suppose if you removed that thing it might work...but it serves as the "stop" for the headlight, altho you could prob'ly get by without it.

Nice, nice setup, and good job on the writeup. This is a great alternative for L2A intercooler, and it may be the route I go when it comes time to cool the 941.
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mr. dude  



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PostPosted: Mon Apr 14, 2008 11:09 pm    Post subject: Reply with quote

Excellent write up.
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ideola  



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PostPosted: Fri Mar 27, 2009 12:19 am    Post subject: Reply with quote

Any updates on performance numbers, or higher levels of boost???
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RC  



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PostPosted: Fri Mar 27, 2009 1:28 am    Post subject: Reply with quote

Thanks for bumping this thread. Missed it last year round.

Nice install and excellent write up. Good pics too.

So how does it go?
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