Porting the FAST90 Manifold
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Joined: Jan 2000
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From: Florida
Porting the FAST90 Manifold
Note: I have lots of pictures, but can't seem to get them into the post. If someone can help, I'll put them in.
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At the recommendation of Spin, I procured myself a FAST for an upcoming install. It arrived Friday. It is a beefy piece, with the following immediately obvious advantages over the stockers: bigger and longer runners, absolutely smooth plenum floor (stocker is full of casting ridges), and 3pc construction. It has lots of material, and has many extra details such as additional runner bosses etc. I expected it to be plug n’ play in terms of degree of finishing. When I took it apart, I quickly discovered this is not the case. All in all, I invested 5-6 hours porting, sanding, and finishing it to my satisfaction. It is important to understand that my purpose was not to remove material or “hog it out” etc., nor was it to smooth the runner surfaces. There is no need for this. NO material was removed at the port itself other than the flash ridge that I smoothed.
But there is a lot of work that needs to be done, particularly in the port area, to eliminate minor airflow obstructions. The manifold works just fine as is, but because it is expensive, it makes sense to maximize its performance. I used a Dremel with a cable drive extension to do the rough work. Bits were a sanding drum and a small rasp. Finishing was done with 60 grit paper, then 220. I have a good bit of woodworking experience, so I know how to control material removal and an eye for contour. The manifold material responds well to sanding, but it is VERY easy to remove too much with a power tool. Hand finishing and use of your tactile abilities is key, because this will reveal surface imperfections you cannot detect by sight. Think like air as you work. Runn your fingers in the direction of air travel. This will save you doing unnecessary work (like removing material in the opposite direction of the airstream.
The manifold top piece (gray) unbolts from the middle and bottom with 16 allen bolts. Gently pry off the top piece, working your way around. I used a sawsall blade laid flat to not gouge the pieces. The seal is laid into the bottom and mid pieces with silicone. Some silicone may have migrated to the top piece, attaching the seal there. Therefore, be very careful to avoid pulling the seal bead out of the bottom grooves when separating the top piece. The bottom and middle pieces are held together with Torx screws. I DO NOT rcommend separating these pieces as the alignment may be slightly different when you reassemble, and there is no reason anyway: removal of the top piece and the Dremel will provide all the access you need. Most of the work focused on three areas:
1. Runner entrance from plenum – this involves removal of casting ridges ringing the entrance to smooth airflow. At first, I worked by hand, but there is really more material to remove than you think to achieve a smooth surface.
2. Runner 1 inch in from Port – where middle piece mates up with bottom piece. Major work here. First, there is a significant ridge on the middle piece which can be removed. This is on the side wall, right where middle piece meets bottom piece. It is probably less detrimental than it looks, but it would certainly create an eddy current and it reduces cross section in this area. There is plenty of material on the other side, so no fear. Second, the bottom piece sticks out beyond the middle piece where they mate up (i.e. mating surface not flush), creating a ridge facing the airflow. This gets more pronounced as you move towards the opposite side of the runner from the aforementioned large ridge. You will need the smaller rasp to work here. Be very careful as the rasp will not give you the “surface read” you get with the sanding drum.
3. Port itself - First, There is cast flashing at the port which protrudes into the airflow and must be removed. Be careful with power tools here, this is best done by hand. Do NOT increase port size. Second, on the top of the bottom piece near the injector bosses and along the seal, where it mates to the top piece. I almost missed this one. This area is at least 2mm further in than the top piece, creating a major ridge in the direction of airflow, at a point where the air stream must turn. Not good. I suspect even the stocker does not have this. You must VERY CAREFULLY remove material at a 45 deg angle to the top edge until you have almost a knife edge following the seal contour. At that point, still being very cautious with material removal, you can blend in and smooth your work below your bevel work.
4. Finally, I removed some minor cast flashing on the top piece and did some beveling work on the throttle body ring. I also removed the lettering on the outside of the manifold and painted it black so as not to draw attention.
[IMG]
[/IMG]
Runner near port, before.
---------------------------
At the recommendation of Spin, I procured myself a FAST for an upcoming install. It arrived Friday. It is a beefy piece, with the following immediately obvious advantages over the stockers: bigger and longer runners, absolutely smooth plenum floor (stocker is full of casting ridges), and 3pc construction. It has lots of material, and has many extra details such as additional runner bosses etc. I expected it to be plug n’ play in terms of degree of finishing. When I took it apart, I quickly discovered this is not the case. All in all, I invested 5-6 hours porting, sanding, and finishing it to my satisfaction. It is important to understand that my purpose was not to remove material or “hog it out” etc., nor was it to smooth the runner surfaces. There is no need for this. NO material was removed at the port itself other than the flash ridge that I smoothed.
But there is a lot of work that needs to be done, particularly in the port area, to eliminate minor airflow obstructions. The manifold works just fine as is, but because it is expensive, it makes sense to maximize its performance. I used a Dremel with a cable drive extension to do the rough work. Bits were a sanding drum and a small rasp. Finishing was done with 60 grit paper, then 220. I have a good bit of woodworking experience, so I know how to control material removal and an eye for contour. The manifold material responds well to sanding, but it is VERY easy to remove too much with a power tool. Hand finishing and use of your tactile abilities is key, because this will reveal surface imperfections you cannot detect by sight. Think like air as you work. Runn your fingers in the direction of air travel. This will save you doing unnecessary work (like removing material in the opposite direction of the airstream.
The manifold top piece (gray) unbolts from the middle and bottom with 16 allen bolts. Gently pry off the top piece, working your way around. I used a sawsall blade laid flat to not gouge the pieces. The seal is laid into the bottom and mid pieces with silicone. Some silicone may have migrated to the top piece, attaching the seal there. Therefore, be very careful to avoid pulling the seal bead out of the bottom grooves when separating the top piece. The bottom and middle pieces are held together with Torx screws. I DO NOT rcommend separating these pieces as the alignment may be slightly different when you reassemble, and there is no reason anyway: removal of the top piece and the Dremel will provide all the access you need. Most of the work focused on three areas:
1. Runner entrance from plenum – this involves removal of casting ridges ringing the entrance to smooth airflow. At first, I worked by hand, but there is really more material to remove than you think to achieve a smooth surface.
2. Runner 1 inch in from Port – where middle piece mates up with bottom piece. Major work here. First, there is a significant ridge on the middle piece which can be removed. This is on the side wall, right where middle piece meets bottom piece. It is probably less detrimental than it looks, but it would certainly create an eddy current and it reduces cross section in this area. There is plenty of material on the other side, so no fear. Second, the bottom piece sticks out beyond the middle piece where they mate up (i.e. mating surface not flush), creating a ridge facing the airflow. This gets more pronounced as you move towards the opposite side of the runner from the aforementioned large ridge. You will need the smaller rasp to work here. Be very careful as the rasp will not give you the “surface read” you get with the sanding drum.
3. Port itself - First, There is cast flashing at the port which protrudes into the airflow and must be removed. Be careful with power tools here, this is best done by hand. Do NOT increase port size. Second, on the top of the bottom piece near the injector bosses and along the seal, where it mates to the top piece. I almost missed this one. This area is at least 2mm further in than the top piece, creating a major ridge in the direction of airflow, at a point where the air stream must turn. Not good. I suspect even the stocker does not have this. You must VERY CAREFULLY remove material at a 45 deg angle to the top edge until you have almost a knife edge following the seal contour. At that point, still being very cautious with material removal, you can blend in and smooth your work below your bevel work.
4. Finally, I removed some minor cast flashing on the top piece and did some beveling work on the throttle body ring. I also removed the lettering on the outside of the manifold and painted it black so as not to draw attention.
[IMG]
[/IMG]
Runner near port, before.
Last edited by TTRotary; Oct 22, 2006 at 03:36 AM.
Safety Car
Joined: Apr 2005
Posts: 4,769
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From: SFV CA
Marc...sounds like you did a fantastic job on the porting, I may be needing you to service my FAST 90. 
Is your car at OCC for the new mods yet?
Have you tried using an image hosting site like Photobucket to host your snap shots?
Is your car at OCC for the new mods yet?Have you tried using an image hosting site like Photobucket to host your snap shots?
