914-SHO Project Thread
- Thread starter 3d914
- Start date
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OK, spent the rest of the day getting the tranny mounting squared away. By using a level on the engine bar I was able to adjust the spacing between the stock tranny mounts and the mounting ****** on the body. It worked out to be 3/4 inch.
So off to Ace to find all the appropriate hardware. Got the 8mm bolts with some extra length and found some steel spacers that fit nicely.
Also added some large washers on the 12mm bolts (not shown in pic) since the positioning is a little forward of stock. Still sitting squarely on the ****** of the arm though so I think this will work fine.
So engine is sitting level and I have plenty of space (approx 1 inch) between the front firewall and the surge tank - thanks to Charles' idea about cutting down the front two poly intake couplers which gave me an extra 1/4 inch.
So off to Ace to find all the appropriate hardware. Got the 8mm bolts with some extra length and found some steel spacers that fit nicely.
Also added some large washers on the 12mm bolts (not shown in pic) since the positioning is a little forward of stock. Still sitting squarely on the ****** of the arm though so I think this will work fine.
So engine is sitting level and I have plenty of space (approx 1 inch) between the front firewall and the surge tank - thanks to Charles' idea about cutting down the front two poly intake couplers which gave me an extra 1/4 inch.
Hoo-Raa! Another milestone. The engine cradle is down and the motor/tranny is mounted in the body!
OK, so the last two positional checks are for the stock shift bar and my exhaust mockup. The shift bar fits as expected and clears the engine bar, the oil pan, the adapter plate, and the exhaust. Even though the exhaust appears to touch - my mockup is oversized and the radius' are too sharp.
I had to remove the ATX manifold on the left (front) side because I'm going to use the MTX version on that side since it fits better. Wasn't that bad getting the manifold off. Lots of space - more probably than in the stock SHO.
The right (back) side manifold off the ATX stays since it drops straight down - and this is where I'm going to blend the 2 inch pipes into a single 2.5 inch pipe. Except my blend will be a vertical one instead of horizontal.
Looks like its time to go mandrel shopping so I can fab the exhaust.
OK, so the last two positional checks are for the stock shift bar and my exhaust mockup. The shift bar fits as expected and clears the engine bar, the oil pan, the adapter plate, and the exhaust. Even though the exhaust appears to touch - my mockup is oversized and the radius' are too sharp.
I had to remove the ATX manifold on the left (front) side because I'm going to use the MTX version on that side since it fits better. Wasn't that bad getting the manifold off. Lots of space - more probably than in the stock SHO.
The right (back) side manifold off the ATX stays since it drops straight down - and this is where I'm going to blend the 2 inch pipes into a single 2.5 inch pipe. Except my blend will be a vertical one instead of horizontal.
Looks like its time to go mandrel shopping so I can fab the exhaust.
Wanted to see how the engine lid would fit so I cut up the one that came with the car to illustrate where I'm going with this. You can see there is plenty of clearance with the cross-support removed. I'll add the cross piece back after I modify how it mounts so the cross-section extends up into the cavity instead of down into the engine bay.
I'll be using this lid & the trunk to mock up my final parts. I already have a new engine lid that will be customized and covered with grill all over like the GT/6 version. But the middle section at the back (where its cut out) will have its shape/height match the front section & then I'll transition the two side pieces in.
I'll be using this lid & the trunk to mock up my final parts. I already have a new engine lid that will be customized and covered with grill all over like the GT/6 version. But the middle section at the back (where its cut out) will have its shape/height match the front section & then I'll transition the two side pieces in.
Took a few hours before dinner to work on the trunk and air filter location. The air filter will have a custom box built to hold the 8-1/2 x 11 inch air filter. The box will need to be deep enough to feed the 4-inch diameter supply tube to the MAF sensor.
I can adjust the position of the air filter/box as needed based on how I decide to size/locate the NACA duct(s) that will feed the air through the trunk lid.
I want the filter to sit as high as possible so that there should be some room left under the filter box, and it will require some legs to elevate it.
Of course there are some obstructions on the underside of the trunk lid I'll have to adjust for also.
I can adjust the position of the air filter/box as needed based on how I decide to size/locate the NACA duct(s) that will feed the air through the trunk lid.
I want the filter to sit as high as possible so that there should be some room left under the filter box, and it will require some legs to elevate it.
Of course there are some obstructions on the underside of the trunk lid I'll have to adjust for also.
Here's what it looks like with the trunk lid on. It's been modified to fit around the surge tank and throttle body. Cutting through the support channels weakened it of course, so I'm planning to scavenge support channels from another used trunk lid and add them to my final lid.
To cover the surge tank & intake I'll continue the slope and curvature of the forward part of the engine lid, down along the trunk to the stopping point. The sides will be tapered in & upward toward the centerline at 22.5 deg. This will match the angle on the 914's L & R sail panels.
To cover the surge tank & intake I'll continue the slope and curvature of the forward part of the engine lid, down along the trunk to the stopping point. The sides will be tapered in & upward toward the centerline at 22.5 deg. This will match the angle on the 914's L & R sail panels.
Falconvan
Active Member
Looks awesome! Did you use the engine harness for the injectors as is or are you making a new one?
I responded to your other thread, but yes, I worked from the stock wiring and removed the wires for items I wasn't using. Also tested all wires/connectors for no broken wires. Not fun, but necessary & a lot easier to do when out of the car vs. in the car.
Spent some time trying to finalize how I'm doing the air intake. Here are the primary requirements/constraints:
Searching the internet turned up many options for for the ducts - from ABS plastic to FG or CF. Decided to go with the ABS since I can heat it slightly if necessary to conform to the lids curvature.
Many of the ducts use 3" outlets to connect hoses to. Unfortunately this restricts the intake area to a mere 7 sq.in or less. I'd like to have double that - so maybe two NACA ducts - OK.
Here's my rough sketch on how it all would fit together. Not shown is a sheet metal support frame to support the air box and give me little bit of storage under it.
Thoughts - feedback?
- 1-2 NACA ducts for nearly 14 sq.in. intake area
- ABS plastic air box
- Drain tube in air box for water
- Air filter - rectangular or cone
- Air box needs to soft-seal against trunk lid
- Duct material needs to be able to conform to slight curvature of trunk lid
- Everything to fit within approx 12 inches along trunk lid centerline
- Air box width is flexible
Searching the internet turned up many options for for the ducts - from ABS plastic to FG or CF. Decided to go with the ABS since I can heat it slightly if necessary to conform to the lids curvature.
Many of the ducts use 3" outlets to connect hoses to. Unfortunately this restricts the intake area to a mere 7 sq.in or less. I'd like to have double that - so maybe two NACA ducts - OK.
Here's my rough sketch on how it all would fit together. Not shown is a sheet metal support frame to support the air box and give me little bit of storage under it.
Thoughts - feedback?
The craftmanship just awesome. Love you idea. Only thought I have and you know your type car more than me. Is that area a negative pressure air because of air flow of roof or is pressurized? I just don't know. Keep up the pictures and info. Maurice
Maurice,
It is a high-pressure area. I've reviewed data from a buddy who did testing of the 914 rear section so he could install an oil cooler. The first 12 inches of trunk are low pressure (off roof) and gets drawn into the engine bay. rear of that it goes back to high pressure area - so I'll be somewhere around 20+ inches back from the front edge when the NACA duct starts. That's another reason I want as large an intake as possible because there's no added ram effect.
Well spent the day mostly indoors on the computer. After I pulled the necessary dimensions, I needed to bring my air box design into CAD and make sure things fit. Good thing I did. The tight angle of the MAF and the size of the K&N filter I chose didn't work. I also mis-measured the MAF intake size. I was going by the coupling that was on there - which isn't needed in my case - so that reduced the needed hose ID down to 3.5 in.
Because space is tight I don't really want to have a straight sleeve between the filter's ****** and the elbow to the MAF. So I decided to size the ID of the filter to the OD of the elbow. The silicone elbows are rigid enough it shouldn't capsize. I got lucky and the filter I found has an offset ****** - so that works to my advantage also.
The only thing that's not ideal is the amount of space between the end of the NACA duct and the back wall of the air box. I wanted to keep the box under 12 inches since it's easier to find material in that width. ox width is at 10 inches now, so I may decide to use the rest of the space - but I'll wait until I have the material in hand and can mock it up first.
Here's how it looks so far:
Because space is tight I don't really want to have a straight sleeve between the filter's ****** and the elbow to the MAF. So I decided to size the ID of the filter to the OD of the elbow. The silicone elbows are rigid enough it shouldn't capsize. I got lucky and the filter I found has an offset ****** - so that works to my advantage also.
The only thing that's not ideal is the amount of space between the end of the NACA duct and the back wall of the air box. I wanted to keep the box under 12 inches since it's easier to find material in that width. ox width is at 10 inches now, so I may decide to use the rest of the space - but I'll wait until I have the material in hand and can mock it up first.
Here's how it looks so far:
Off Road SHO
Moderator
Don't ask me how I know this, but make sure there is enough distance in front of the metering tube of the MAF sensor to get nice laminar flow of air. If there is a bend near the meter's hot wire, the air "burbbles" across the hot wire and doesn't cool the wire. The PCM interprets this as much less air is going into the intake than is the case.
I fixed one of my SHO buggy buddies car just by getting rid of a sharp bend near the MAF intake side.
Tom
I fixed one of my SHO buggy buddies car just by getting rid of a sharp bend near the MAF intake side.
Tom
Which maf are you using?
Tom, how sharp of a bend? This one is a gentle 30deg bend. If push came to shove I could soften the MAF's angle and change the angle of the back of the air box to be perpendicular to it.
Does it matter what orientation the MAF port has? It's about 100deg of the arc, but not sure what the stock orientation is. My guess would be up or down. I still have to come up with a mounting bracket for it.
Toolman, The stock unit.
The stock 55m has a mesh 'air straightener' that assists in preparing the air to better interact with the hot wires. You can get away with more in comparison to an aftermarket MAF with no such mesh.
Off Road SHO
Moderator
If near a bend, the MAF should be on the outside of the track, where the air has to take the longest path. Air does the same thing that water does in a bend, the faster water is on the outside of the bend. If the bend is sharp enough the water or air on the tight side will form eddy currents and whirlpools ( also known as burbbling) in the short radius side of the bend.
My educated guess is that anything less than a 3" radius turn will cause you problems. But that is just a guess.
You can prove it out by running your engine with just a snorkel tube attached to the intake side of the MAF sensor. With the car running at a fast idle of about 1500 rpm's, start bending the snorkel tighter and tighter, with the tight radius side on the same side as the sensor's intake slot or port. When you start to disrupt the smooth flow of air to the MAF's heated element(s), the elements will not cool down as much, indicating to the computer that the engine is running at 600 rpms and therefore only needs enough gas for 600 rpms.
Tom
My educated guess is that anything less than a 3" radius turn will cause you problems. But that is just a guess.
You can prove it out by running your engine with just a snorkel tube attached to the intake side of the MAF sensor. With the car running at a fast idle of about 1500 rpm's, start bending the snorkel tighter and tighter, with the tight radius side on the same side as the sensor's intake slot or port. When you start to disrupt the smooth flow of air to the MAF's heated element(s), the elements will not cool down as much, indicating to the computer that the engine is running at 600 rpms and therefore only needs enough gas for 600 rpms.
Tom
Haven't been completely ignoring the project over the last two weeks. Between work and other activities - haven't put in as many hours.
Did get some time last weekend to work up an alternate air box design to provide straight-thru flow from filter to MAF. I'll probably start with this design and if it builds well using the ABS plastic - that's what I'll go with. Otherwise I'll revert to the simpler design above.
Did get some time last weekend to work up an alternate air box design to provide straight-thru flow from filter to MAF. I'll probably start with this design and if it builds well using the ABS plastic - that's what I'll go with. Otherwise I'll revert to the simpler design above.
Spent yesterday working on the welder my neighbor let me borrow- Hobart 170. The shielding gas wasn't getting out to the weld - so I checked all the hoses to verify nothing was clogged. Turned out to be the gauge - it was misreading. Now to find a 10-50 CFH dial gauge for argon. Also tested the wire feed. It has infinitely adjustable feed rate, but when I had it on the first setting it was too fast. After testing there was only 20-IPM difference between setting 1 and setting 10. Up to neighbor whether to get it serviced or not.
I'm off to buy my own. Gonna go with the Longevity 140 since it has optional spooling gun for aluminum.
I'm off to buy my own. Gonna go with the Longevity 140 since it has optional spooling gun for aluminum.
Its not so much the faster-moving air (although this is true), it is that the air also has mass, and because of that the air wants to go straight at the curve - so there is more mass of air at the outside of the curve, and you are trying to measure the mass of the air flowing past the sensor, so you need the sensor in the area of the cross-section where the mass is.
The challenge is to get it located in a spot where the mass of air moving past it is representative. This is tricky because the mass-density of the airstream changes with the velocity of the air in the curve (the faster the air moves, the more uneven the distribution of mass across the tube). The fact that air is compressible makes it even more of an issue, but if you have ever looked at a river at a curve you might have noticed the eddys and dead spots that Tom mentioned, while nearly all of the actual flow is at the outside of the river curve.
The net of all that is the admonishment that you should have the air flowing straight for a while before the mafs, so you don't have to screw with all of that.
