# Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder



## wclark (Mar 28, 2001)

So what are peoples opinions on the results of changing over the 1.8 8v to a modified Audi 5-cylinder turbo intake manifold?
I picked one up on e-bay for cheap along with its TB with the notion of cutting it down and at some point bolting it up. The runners seem a bit larger which would probably be good for my top end which seems air starved above 6000, and I may need to do a bit more work on my head intale ports since I dont think I opened them up that much when I did the P&P last year. I matched the intakes ports to the stock gasket.
What about using the Audi TB? And what about plenum sizing? Did people try to stay close to the 1.8 plenum volume? Any dyno or engine data logger info to share?
By the way, I have read and in many cases bookmarked most of the threads in this forum on this conversion. They generally focus on the how part (some done beautifully) but - unless I missed this part - not so much on the performance results.



_Modified by wclark at 6:06 AM 11-5-2006_


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## ny_fam (Apr 3, 2004)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (wclark)*

I did this mod and ported the head to match, but never drove the car with the intake on since I couldn't close the hood. The throttle cable mount hit the hood. It was suggested that I switch to a 16v throttle cable and cable to TB mount for better clearence. I got the parts but never made the switch.
I figured that I should use my own ported intake manifolds on my car. Im currently running a %25 improved air flow intake manifold. Which I have to mention flows better than the semi ported audi 5 cylinder intake manifold.








Granted the plenum volume of the audi intake is better suited for the 1.8liter engine. As the 8v VW counter flow intakes are only 1.1 liters.
the audi intake measured 1.5 liters.
Cheers


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## fast84gti (Mar 2, 2003)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (ny_fam)*

I just traced the audi 5k gasket onto the a1, and ported it to match. Still finishing it up







I still gotta finish my manometer. Haven't had time







I am boostinating, so plenum may not make as much of a difference (look how small a 1.8t intake is)


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## Issam Abed (Feb 12, 2004)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (wclark)*


_Quote, originally posted by *wclark* »_So what are peoples opinions on the results of changing over the 1.8 8v to a modified Audi 5-cylinder turbo intake manifold?

You allready know mine...


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## fast84gti (Mar 2, 2003)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (Wizard-of-OD)*

Nice


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## wclark (Mar 28, 2001)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (wclark)*

So, a question on the how part after all...
The Audi manifold angles the TB down. 
I have seen where A1 owners block the original TB location off and weld a suitable flange to the end that was cut, giving them the flexibility to pick any TB and angle it any way they choose coming out the drivers side of the engine.
A2 owners. Was running a flexible duct to the Audi TB in its angled location, around the timing belt cover hassle? What did you use, or did you make up an adapter to straighten the TB?
I have cut the 5th runner off and welded an end plate on mine, cleaned it and the Audi TB and determined I need to rework the idle/WOT switch assy from it. I also did a little runner porting, just to smooth the bores a bit. I plan to weld a couple bosses to the plenum to hold a throttle cable bracket next.


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## ny_fam (Apr 3, 2004)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (wclark)*

I've run this mod on my car for a few minutes. The issue was how to close the hood. I'm not willing to cut a spot out of the raintray or the hood to make room for the tb cable mount.
It was about 1" was needed.
It was recommended to use the 16v throttle mount and cable on top of the throttle body.
I would make sure that when you relocate the TB mount on the plenum keep the space to the hood in-mind.
If you plan on cutting the plenum and reducing the internal volume of the plenum, try to keep the plenum as large as possible for all motor setup.
Cheers
ny_fam


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## wclark (Mar 28, 2001)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (ny_fam)*

I think the hood and rain tray clearance between the Rabbit and Golf must be diffrent. If I had a tall block I think I would have an issue with the Audi TB (the idle/WOT switch pack actually) and the firewall, but it looks like I have room to run a throttle cable across the top if the plenum if needed (I plan to mount the throttle cable bracket toward the front of the plenum in line with piece on the TB that the cable clips to.
I have an Audi rubber boot coming for the throttle body to inlet air tube connection but I still am having trouble believing the downward angle of the TB wont be an issue since space is so tight between the timing belt cover and the strut tower. I am thinking about making up an adapter to set the Audi TB horizontal if I need to. Maybe a couple flanges made from a couple gasket shaped pieces of 1/4" aluminum plate and a piece of 2 1/2" - 3" aluminum tube between. Welding it to the intake looks like a hassle because of the poor access to about 1/3 of the existing flange. That would also increase my plenum a little. I measured 1.1 liters after finishing up with the end plate. 
By the way, I really like this Audi TB. Single plane, 60mm, simple mechanics AND an elegant idle/WOT switch setup.
I am also not comfortable with the alignment of the Audi intake with the RD ports and the usual blending approach. I have already opened up the ports on my race head to the stock gasket and blended the stock intake runners to that - this gets me to the stock diameter of the Audi runners. The misalignment at the top of the ports isnt much of a concern since Ic ould grind and blend that OK but the amount I need to grind the bottom of the Audi intake runners down and trim the Audi gasked there as well to line them up concerns me from a potential air leak standpoint. Right now I am planning to make a transition piece from 1/4" aluminum that mirrors the RD intake gasket on one side and the MC gasket (Audi turbo engine code) on the other. That should let me blend the intake runners to the RD ports without having to hack anything up too bad and making it impossible to go back a step if I dont like the performance of the intake.


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## ny_fam (Apr 3, 2004)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (wclark)*

yea the golf must have more clearence
As for the ports aligning with the ports on the head. I did the same grining of the head and the bottom lip of the manifold ports. The adapter sounds like a good idea also.
Since the mounting surface is so thin I had to make a gasket with sealer. Stock gaskets no longer work( and I'm now using a A1 intake manifold with head ports grinded for the audi intake)
Good luck
Cheers


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## wclark (Mar 28, 2001)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (ny_fam)*

I made up a proto of the adapter from 1/4" HDPE (easy material to work and remake). Basically I cut it after marking the 8V gasket on one side and the Audi gasket on the other with the bolt holes already drilled to provide alignment. The 1/4" thickness looks like it will work well. The bottom of the intake runners line up nicely with the bottom ports on the head. The top of the runner is still a little high compared to the port, resulting the adapter squeezing the opening down about 1/8". I will probably open up the top of the ports, the 8V gasket and the re-taper the adapter that amount to better line them up so the incoming air doesnt get too turbulent right at that point.
I also have the Audi throttle body boot in hand now. I can see that I will need to fabricate a new throttle body mounting on the intake that levels out the throttle body as its downward angle cause several clearance issues with the air tube formthe fuel distriibutor. I was going to make an adapter for it but am probably going to go ahead and cut away some of the old mounting flange to square it up some and weld on a short length of aluminum tube to square it completely and a mounting flange I will make up.


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## ny_fam (Apr 3, 2004)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (wclark)*

that sounds like a nice setup you've got going. I'd be interested in seeing the adapter you made with HDPE. Is that just a prototype material?
Got any pictures to share ?
Cheers


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## wclark (Mar 28, 2001)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (ny_fam)*


_Quote, originally posted by *ny_fam* »_that sounds like a nice setup you've got going. I'd be interested in seeing the adapter you made with HDPE. Is that just a prototype material?
Got any pictures to share ?
Cheers


Yes, just a form/fit proto. I used a soft material so it would be easy to cut using a bench router and shape with a Dremel. Being so easy to cut I took a chunk out of it when the material hung on the router bench then jumped...not critical though. I still have a 3d piece that tells me exactly what I need to do. 
I only cut one port hole to get a feel for the angles amd material I need to remove. I will cut the aluminum piece with a plasma cutter to the smallest dimensions then remove the remainder of the material with my porting kit. 
I can take a couple pics later.


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## wclark (Mar 28, 2001)

*Photos*

Some pics of the HDPE proto.








On the intake with gaskets








CLoseup of adapter on intake








Another angle








Without 8V gasket








On head. Note this is my old spare engine, not ported.


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## ToddA1 (Apr 22, 2002)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (wclark)*

Why wouldn't you port the head to the Audi gasket instead of using a reducer? 
I did this years back when Ron's Parts (prior to being RPI) was selling these intakes for $450. Made a couple more after I saw how these were constructed.... I loved this mod. FWIW, I never used the intake that you have. Mine looked like Wizard of Od's.
-Todd


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## wclark (Mar 28, 2001)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (ToddA1)*


_Quote, originally posted by *ToddA1* »_Why wouldn't you port the head to the Audi gasket instead of using a reducer? 
I did this years back when Ron's Parts (prior to being RPI) was selling these intakes for $450. Made a couple more after I saw how these were constructed.... I loved this mod. FWIW, I never used the intake that you have. Mine looked like Wizard of Od's.
-Todd

Read my early reply on my reasons. 
The intake manifolds are the same part number on all the MC engines (85-91 5000 and 200 2.2L 5 cyl turbo). His has had the TB flange added to the end that has to be cut (drivers side). The A2 needs the TB on the passenger side.


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## ToddA1 (Apr 22, 2002)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (wclark)*

missed that part.... I should be working at work, not playing.
-Todd


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## fast84gti (Mar 2, 2003)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (ToddA1)*

Not only that, but when I was doin sum investamigatin on da microfische... I found ALL the 5 cylinder motors use the same gasket. Different intakes for different engines and years, but all the 5 cyl gaskets are the same. I guess the ports are all the same. Difference is going to be plenum and size of it, port length and shape of bend, and location of TB...... But the port into head remains the same. Maybe the heads are all the same as far as port opening, like the 8v's.... Anyhow.. Thanks for the info.


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## Butcher (Jan 31, 2001)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (wclark)*


_Quote, originally posted by *wclark* »_I am also not comfortable with the alignment of the Audi intake with the RD ports and the usual blending approach. I have already opened up the ports on my race head to the stock gasket and blended the stock intake runners to that - this gets me to the stock diameter of the Audi runners. The misalignment at the top of the ports isnt much of a concern since Ic ould grind and blend that OK but the amount I need to grind the bottom of the Audi intake runners down and trim the Audi gasked there as well to line them up concerns me from a potential air leak standpoint. Right now I am planning to make a transition piece from 1/4" aluminum that mirrors the RD intake gasket on one side and the MC gasket (Audi turbo engine code) on the other. That should let me blend the intake runners to the RD ports without having to hack anything up too bad and making it impossible to go back a step if I dont like the performance of the intake.

I did the same thing for my manifold. I too did not like the way it aligned up and the other options were too difficult for me [weld up the holes and redrill the head].
I used phenolic I bought from eBay. I too used .25" and it does line up better. Using phenolic will allow some insulating properties but how much heat will be stopped when you are sitting above a hot turbo? Who knows but mine should work.


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## wclark (Mar 28, 2001)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (Butcher)*


_Quote, originally posted by *Butcher* »_
I did the same thing for my manifold. I too did not like the way it aligned up and the other options were too difficult for me [weld up the holes and redrill the head].
I used phenolic I bought from eBay. I too used .25" and it does line up better. Using phenolic will allow some insulating properties but how much heat will be stopped when you are sitting above a hot turbo? Who knows but mine should work.


Good to hear someone else is thinking this way too. I went with aluminum to minimize the heat barrier between the head and intake. I believe the head needs the heatsink the intake affords. The heat added by a turbo might just make the isolation of a phenolic a good thing there.


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## 4thScirocco (Feb 27, 2001)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (wclark)*

I'm not sure why you wouldn't want to grind the intake port to match up to the manifold. It seems somewhat counter productive to have the large runners on the Audi manifold but choke down the flow. I bought my manifold and head as a set. Head was ported to match with zero misalignment. Post up some pics later.


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## wclark (Mar 28, 2001)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (4thScirocco)*


_Quote, originally posted by *4thScirocco* »_I'm not sure why you wouldn't want to grind the intake port to match up to the manifold. It seems somewhat counter productive to have the large runners on the Audi manifold but choke down the flow. I bought my manifold and head as a set. Head was ported to match with zero misalignment. Post up some pics later.


Re read what I wrote. My port diameter is equal to runer diameter already. Alignment is poor.


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## 4thScirocco (Feb 27, 2001)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (wclark)*

Here's my manifold as compared to stock.








Closeup of the runner.








Head, intake and exhaust combo.


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## wclark (Mar 28, 2001)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (4thScirocco)*

If you think the audi manifold is as much larger as it seems from the end compared to the 8V you are mistaken. The Audi manifold runners nominal diameter is 31 and the 8V is 29. The 8V gasket and the audi gasket have the same width (30mm) and a port job bringing the 8V head ports to the 8V gasket makes it very close to the audi nominal runner diameter. One just has to line up the top and bottom edges at the junction somehow to maintain airflow. I have chosen an adapter rather than grinding a lot out of the head (top of the port) and intake (bottom of the runner - leaving a very thin flange and gasket I might add). As it stands right now my port area matches the audi runner pretty well (within 5% of the same area) but I plan to remove a little from the top of the head port, 8V gasket and head side of the adapter to straighten out the airflow in that area better. I need to remove less than half what would be needed if the manifold were bolted up directly without filling, relocating and redrilling the mounting bolt holes (and nothing needs to be removed from the manifold beyond gasket matching and polishing the runners).


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## 4thScirocco (Feb 27, 2001)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (wclark)*

Dont know about port diameters. Like I said, I bought the head and intake as a set. Side by side, the Audi looks MUCH larger than stock. I had to cut out a stock gasket to make it work. Since it's not my work, I cant say for sure but it didn't seem like too big of a deal to line everything up. The runners are smoothed but i don't think it's been ground any to make it fit. All the work was done to head as far as I can tell. And there is zero mis-alignment. If you're using a stock intake gasket then your intake ports aren't as large as they can be.
Going with a spacer wasn't gonna work for me anyway. As it is, I had to cut the raintray to make it fit. The extra height of the manifold + ABA block, well.......


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## Butcher (Jan 31, 2001)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (wclark)*


_Quote, originally posted by *wclark* »_Good to hear someone else is thinking this way too. I went with aluminum to minimize the heat barrier between the head and intake. I believe the head needs the heat sink the intake affords. The heat added by a turbo might just make the isolation of a phenolic a good thing there.

I have heard that the intake manifold is a heat sink and that by insulating the manifold can cause the engine to run hotter. I have issues with that philosophy but it comes from a very reliable source that I trust his experience and knowledge [mkrad].


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## wclark (Mar 28, 2001)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (wclark)*

A couple pics of the aluminum adapter plate...
















...all Christmas themed








I ended up opening up the top of the headside of each passage about 1/8" from the gasket size to better straighten out the airflow so the top of the ports will need a little controuring before it goes on. 
I have the plenum cut now to accept a suitably angled throttle body mounting plate. The TB needs to be horizontal and angled a little toward the front (like the stock manifold) and I decided a proper cut and welding a plate in was easier and would fit the A2 better than trying to make up an adapter . 


_Modified by wclark at 5:20 PM 11-29-2006_


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## fast84gti (Mar 2, 2003)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (wclark)*

You can refute the heat sink claim a little, because dual side draft set ups use phenolic spacers, and I have not seen any well tuned cars "overheat". If you ceramic coat the manifold, and cover the turbo, that will help... Nice spacer. I like your idea. Get the flow from the intake, but not have to take head of and port it. Sweet!


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## Longitudinal (Nov 13, 2004)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (fast84gti)*


_Quote, originally posted by *fast84gti* »_You can refute the heat sink claim a little,

Yeah, definitely. Next to the cooling system and the masses of the block and head, the mass and conductivity of an intake manifold is not significant.


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## Butcher (Jan 31, 2001)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (fast84gti)*

If you ported the head to match the intake manifold you would have a large space which would slow the flow of the port just before it gets to the intake valve. That is the last thing you want. You want a slight taper in the port to increase the velocity as it gets to the intake valve. By enlarging the port to match the intake manifold it would be disturb the velocity and that is not good. Hard to explain it in words unless you have the manifold and head present. Plus you run into gasket issues. The best way is to weld up the holes in the head and redrill the holes to align the manifold. Don't get me wrong, porting is OK but if you port it the way you are saying it is not the best way.


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## wclark (Mar 28, 2001)

*Re: Audi 5 cyl turbo intake manifold on the 1.8 4 cylinder (wclark)*

Pics of the throttle body plate fabrication:
The cut...








With the rought cut TB mounting plate.








Top view.








TB plate cut and welded in place.









Top view.








From front.








With the Audi TB in place.








And the throttle cable mounting welded in place










_Modified by wclark at 2:52 PM 12-6-2006_


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