Intake manifolds
- Thread starter Alky V6
- Start date
Adding the additional fasteners for the runners caused a very slight shifting in the assembly. A final porting was done after the parts were assembled and tightened. A rough finish was left on the walls of the runners.
The total runner length is 2.75". Very close to what the runner length is on a 1987 Buick GN intake manifold. This is the length that a sim that I use picked as the best length to use with my combination.
Every intake runner should have some degree of taper to it. The taper angle that I picked is 5.38 degrees included. All of the taper is in the floor of the runner. The top and side walls are perpendicular to the intake to head gasket surface. This produced a straight shot down the middle of the intake runner of the head.
The total runner length is 2.75". Very close to what the runner length is on a 1987 Buick GN intake manifold. This is the length that a sim that I use picked as the best length to use with my combination.
Every intake runner should have some degree of taper to it. The taper angle that I picked is 5.38 degrees included. All of the taper is in the floor of the runner. The top and side walls are perpendicular to the intake to head gasket surface. This produced a straight shot down the middle of the intake runner of the head.
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C
coach
Guest
How are you sealing to the head???
Hey Donnie,
I am checking out your design, and it is sweet. I am just wondering how you are going to seal off the bolt head being that close to the intake port??? I have built an intake or two myself, and this looks to be a problem area in the design. Please explain how you are going to do this. Knowledge is something I always like to hear from other fabricators. I keep it in mind for future projects.
Thanks
Coach.
Hey Donnie,
I am checking out your design, and it is sweet. I am just wondering how you are going to seal off the bolt head being that close to the intake port??? I have built an intake or two myself, and this looks to be a problem area in the design. Please explain how you are going to do this. Knowledge is something I always like to hear from other fabricators. I keep it in mind for future projects.
Thanks
Coach.
You're right. That is a problem area. Particularly the bottom row of bolts. The upper row of bolt holes are completely clamped by head surface. The gasket does well to form a seal around them. With the bottom row, the intake ports at the heads are lacking in surface material in order to completely clamp around the bolt holes. Even though the intake gasket I use completely covers the countersunk holes, some of the hole and gasket is not supported by cylinder head material. The chance is there for a leak to the lifter valley due to a lack of gasket support completely around the holes.
If you'll notice in the post with the picture of the head side of the intake manifold flange, the bottom row of bolts have been shaved down and the surface of the head of the allen bolts flattened. I made some aluminum plugs that will lightly tap into the holes covering and bottoming against the head of the allen bolts. In the center of these plugs are tiny threaded holes so that I can thread a bolt into the plug to remove them when necessary. I make the plugs a tiny bit on the thick side, and then once they're installed, I take a fine mill file and bring them down to the mating surface of the flange. The plugs end up being about .090" thick installed. I'll post some pics of the plugs in place later. They work well to fix that problem.
I'm impressed that you noticed that. I didn't think anyone would catch onto that until my plan to bring it up later.
C
coach
Guest
Very good fix...
I must say "Bravo", that is exactly how I was going to recommend to fix. I was going to do all the bolts. In the Moldmaking industry, we do that sorta thing all the time. The blower intake I made for my 409 is o-ringed on the head surface also. No more intake gaskets at all. I was wondering if you knew the horsepower you were going to make with this engine. After I saw the 100mm TB , I was thinking 750-800 min and I am probably low. Well thought out intake, I must say. Be sure to blueprint your design. It will serve you well in the future for modifications. How did you figure the area and flow needed for your doghouse? I never intend on getting my GN to this level, but I saw a white T that looked to be a real canidate for some serious mods with out hurting the value of my low mile numbers matching original.
Keep up the good work and keep the pics coming. If you get in a jam, PM me. I have been a high tolerance moldmaker for 17 years and have fabricated over 50,000 dollars worth of parts for my 409 and Max wedge car. I am building lower trailing arms right now. I will post pics as I go.
Thanks
Coach ( Donnie also)
I must say "Bravo", that is exactly how I was going to recommend to fix. I was going to do all the bolts. In the Moldmaking industry, we do that sorta thing all the time. The blower intake I made for my 409 is o-ringed on the head surface also. No more intake gaskets at all. I was wondering if you knew the horsepower you were going to make with this engine. After I saw the 100mm TB , I was thinking 750-800 min and I am probably low. Well thought out intake, I must say. Be sure to blueprint your design. It will serve you well in the future for modifications. How did you figure the area and flow needed for your doghouse? I never intend on getting my GN to this level, but I saw a white T that looked to be a real canidate for some serious mods with out hurting the value of my low mile numbers matching original.
Keep up the good work and keep the pics coming. If you get in a jam, PM me. I have been a high tolerance moldmaker for 17 years and have fabricated over 50,000 dollars worth of parts for my 409 and Max wedge car. I am building lower trailing arms right now. I will post pics as I go.
Thanks
Coach ( Donnie also)
Thanks Coach. I calculated the engine to be producing around 930hp using ET/mph time slips. With the new turbo setup and the changes I'm in the middle of doing, I'm going to be pushing it to around 1200hp.
What I used to pick the throttle body size was an engine analyzer simulator. All I can tell you is that you want the airflow velocity through the throttle body to be 300 ft/sec or less. Anything over that will cost hp. I just plugged different sizes into the simulator until I found a size that gave acceptable hp loss.
A pic of the cover plugs in place. This time around I used steel instead of aluminum to make the plugs. They'll be more durable this way, and I won't have any problem reusing them if I do have to remove them. The tiny hole was threaded using a 4mm .7 tap. The plugs are thick enough to give me 3 to 4 threads.
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This is a piece of angle aluminum. I use a piece at the front and back sealing areas of the lifter valley. The idea is to minimize the thickness of the silicone sealer that is normally used at these locations. It also limits how far the intake can sink down between the heads when it is tightened to the heads. As the intake valley plate makes contact with the filler pieces, the intake flanges are now forced to move sideways to the heads as they are tightened. The flanges are free to slide sideways off the valley cover plate and the plenum material thickness also allows for this movement. The thickness of the filler plates can be adjusted to get the intake runners to line up correctly to the intake ports.
You can also see a pen line that I scribed onto the intake gaskets. The gaskets will be trimmed along these lines.
You can also see a pen line that I scribed onto the intake gaskets. The gaskets will be trimmed along these lines.
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The intake being installed. I use 2 hardened washers for each bolt. The bolts that are under the plenum have the washers recessed into the intake flanges. The main reason for doing this was because of the limited room I had to get a bolt in and out of these locations and still have enough thread engagment into the heads. The recessed holes make it possible to angle the bolts into their holes even with the limited space. Without the recessed holes I would not be able to angle the bolts in. The bolts would have to be installed into the holes before the flange was attached to the plenum.
Notice also that the intake gasket was trimmed to be flush with the upper edge of the intake flange. That will be important later.
Notice also that the intake gasket was trimmed to be flush with the upper edge of the intake flange. That will be important later.
