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Discussion Starter · #81 · (Edited)
Make sure you bolt the intake tightly to a cylinder head and/or fixture plate. It will warp like crazy when you weld it.
Bolting the head flange to the I-beam seems to have worked (to the naked untrained eye). The welding of the runner arms to the head flange is complete.


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I’ll find out more when I do the next round of test fitting under the Opel GT hood.
 

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Discussion Starter · #83 · (Edited)
Did some initial porting after welding the head flange on the runners and conducted some flow bench testing. Seems to have significant variability across ports and had some weird pulsations on port 1. More work to do. When I first cast the arms, they went from round to square, but I cut off the squarish end to shorted the intake manifold design for better under hood fitting.

Here is a before rough porting look.
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Here is an after rough porting look.
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also, the whole intake surface does appear warped after closer inspection, despite being bolted down. I can only Omaha one how bad of a twisted mess it would be without bolting it down. It seems that the ends stayed down, but the flange pulled away from the steel beam in the middle.



The belt sander test shows ends being sanded while middle is not.

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Discussion Starter · #84 · (Edited)
Sniper EFI, why not design the intake to have a forward opening like most modern intakes do? This is how the Bosch L-Jetronic systems were designed and I bet those intakes flow pretty well
The more I think about it, The more I like the idea of the individual port injectors. appealing for both control and under hood clearance. Still leaning toward the sniper brain, but maybe not the sniper throttle body injection. I may parallel path these projects.

For 1.9-2.0 Engines you can use the 1975 Opel L-Jetronic Intake manifold and injector plates or weld in injector bungs (probably best solution) but you will have to make a fuel rail (the 1.9 L-Jet setup uses ancient injectors with hose barbs and hose connections which can be made to work but I'm not sure it is worth the effort). If it were me I would make a fuel rail and use the stock injector plates (which I have done) which is a good solution but a better solution would be weld-in injector bungs and a custom fuel rail. Not really expensive but does take some work. For the L-Jet intake manifold you will have to use/adapt an aftermarket throttle body because the Opel L-Jet TB does not use a Throttle Position Sensor (potentiometer) but rather a Throttle Position Switch which is not compatible with any modern EFI
Does anyone have a Bosch L-tronic manifold? Seems like that would be a good starting place.

If not, I may do some initial design work on a DIY port injection intake. This picture captures the basic concept (I realize it is not Opel).

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Here is an early thought on how I would fabricate.
  1. 1/2” aluminum head flange. Let me know if others are interested in get some water jet cut. Possibly designed for weld in injector bungs. I have the low flange 2.0 head.
  2. Cast aluminum runner arms (would make 2 sets of arms with 2 ports each) TIG welded to flange. Alternatively, I could skip step 1 flange and include in the casting.
  3. Build a plenum out of sheet aluminum or cast aluminum. TIG welded to runners
  4. Forward facing 1/2” aluminum flange TIG welded (or integrated cast flange of cast plenum) for throttle body mounting
 

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Discussion Starter · #87 · (Edited)
What all is in your toy box other than the tig welder?? Mill??
i am blessed to have a home shop and a bunch of tools. It started off as mostly wood working, but now Have built metal working capability recently.
  • TIG welder (got last summer)
  • Mini mill (upgraded to Digital Read Out)
  • Home Foundry (Built over Christmas)
  • 3D printer (make prototypes / patterns for foundry
  • Various saws, cutters, sanders, drills, taps, die grinder, etc
 

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Discussion Starter · #89 · (Edited)
I pulled the intake manifold today off of my GT today and tried to fit the SLANT draft intake manifold.
Several observations:
  1. The head flange plate warped enough so that it won’t quite slide on the alignment pins. I am hesitant to force it on. Maybe I can straighten it in my press. Worse case is very slightly enlarge alignment pins and flatten the flange surface with machining.
  2. There are issues with the hood clearance (see yellow circled area below)
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RallyBob posted this solution to trim the hood bar and relocate the hinge point on the DIY intake manifold thread.

The hood latch issue is not uncommon and has been done for 45-50 years in GT’s at least. No biggie there either. I’ll see if I can dig up pics. View attachment 444576
This solves my problem! (see yellow circled area)
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Thank you for the picture! I have been at an impasse and could not see a clear path on how to resolve the conflict of the SLANT draft with the hood latch mechanism.
 

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Just Some Dude in Jersey
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There's no need to use that huge Holley 2300, other than that we can get flanges to mount to the 1.9 manifold a bit easier than the Rochester type. The 2GC and the BDD for Jeep CJ has a much more favorable air intake shape than would adapt nicely to common cold air intake ducting. Plus, you can mount them sideways and point the carb forward towards the cold air intake hole in the radiator wall.
 

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Discussion Starter · #91 · (Edited)
There's no need to use that huge Holley 2300, other than that we can get flanges to mount to the 1.9 manifold a bit easier than the Rochester type. The 2GC and the BDD for Jeep CJ has a much more favorable air intake shape than would adapt nicely to common cold air intake ducting.
Thank you for the comment and perspective. I have had similar thoughts and, so this confirms the direction of my thinking to move away from the sniper 2300.

I actually have a return request already at Holley, but have not shipped it back yet as they don’t have a shiny or black 2GC in stock and will not get them in until September. But the Holley tech did confirm that the inner workings of the 2GC and 2300 are essentially the same. Although, Holley said the 2GC does not quite flow as much air, it is still rated at the same 350 HP max with the 2 x 100 lb/hr injectors.

Another bonus is that I have not welded on the carb flange to the slant draft yet! So, I still have flexibility in throttle body style.
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The other reason I have not yet pulled the trigger on the Holley 2GC throttle body injection is that I am pondering the Holley Terminator X to control a port injection application.
 

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Discussion Starter · #92 ·
If I had a Holley Sniper 2GC available / R&D funding, I would proceed to weld on the correct adaptor plate to the slant draft manifold and evaluate the SLANT DRAFT on my Opel GT vs RallyBob style tent bottom ported down draft intake manifold.

but, since funds are limited, I am going to hold off and spend my ECU dollars on the Holley Terminator X ECU. This approach will give me more flexibility (ECU is separate vs built in on the Sniper) with trying different intake manifold approaches. The beauty of the sniper TBI though is the simplicity (fuel rail and injector built in, idle air control built in, pressure sensor built in, throttle position sensor built in, fuel pressure regulator built in). All of that gets rid of a lot of wires for a very clean looking install.

So, hard decisions. But, once have the Terminator X and support systems installed, I should be able to try the slant draft manifold if I can find a low cost 2 injector throttle body / fuel rail combination.
 

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Uhhhh........here's an update on the 2 injector concept I was trying to pull off. I had a discussion with a tech dude at Holley and he absolutely would not give me any advice on how to make the Terminator X use 2 injectors to run a 4 cylinder engine. He said that the software could not be configured to run any less than 4 injectors. I've talked with him before about running a Sniper in a sideways config and he was getting downright impatient with me. He basically said they they would not provide any support to me if I try to use any of their products "in a way that they were not designed to be run".

Could it be done with some clever wiring swaps of the injectors? Maybe, maybe not, but I would be totally on my own if I tried to do anything like that. I don't want to be "on my own", I'm not into engine tinkering and I don't think that figuring out how to make 2 injectors run a 4 cyl engine would be "fun". I bought the Terminator X mainly because their 2 barrel Snipers only use 2 injectors, so......I thought......SURELY their Terminator X system would have the settings to run just 2 injectors. Nope, Terminator X will not normally run 2 injectors and even if I could "fool" the system into thinking that it is running 4 injectors, he wouldn't tell me how to do it.

Mannnnn, am I pissed. This has blown a big hole in my boat and I'm sinking fast.

Is there a solution? Yeah: Run 4 injectors. But, I am really adamant about trying to use my single side draft manifold to make this all work. But it's shape is all wrong for trying to add 2 more injectors somewhere in it's runners. The manifold has just 2 runners, but there is a divider going down the center of each one and it is shaped to give a bit more flow to one side or the other to take into account the unusual shape and length of the runners. This manifold was designed by one of the top manifold designers in the world, but it was designed for ALL of the air/fuel mix to enter at the opening of the manifold. I could easily F-up the whole balance of things if I just jammed injectors willy nilly somewhere in the manifold. The twin throttle bodies have 2 injectors just after the throttle plates I need to add 2 more.....somehow.....in a similar location. That's not going to be easy at all and I've got a lot of hard thinking and designing to do. Or I'm going to have to scrap the whole idea of the SSD manifold and go the traditional route of TWO twin throttle bodies set up the same way as dual side drafts. As I'm typing this, this may be the only logical way to go. The twin throttle body only cost about $100, I would need to buy another one, and 2 shorty side draft manifolds, and possibly a special thermo housing, and a throttle body unifying device to operate both pairs of TB's. I would then need to make an air box to fit and service all 4 throttle body barrels. But I bought the long, side draft-sized, twin throttle body, so that it would match my existing air box I used when I was running a single side draft carb. That would make things tight between the engine/manifold/TB and the heater box, I really should buy TWO shorty twin TB's to free up the space. Hoo boy, it starts getting complicated and expensive the more I think about it.

Aarrgghh!
 

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Uhhhh........here's an update on the 2 injector concept I was trying to pull off. I had a discussion with a tech dude at Holley and he absolutely would not give me any advice on how to make the Terminator X use 2 injectors to run a 4 cylinder engine. He said that the software could not be configured to run any less than 4 injectors. I've talked with him before about running a Sniper in a sideways config and he was getting downright impatient with me. He basically said they they would not provide any support to me if I try to use any of their products "in a way that they were not designed to be run".

Could it be done with some clever wiring swaps of the injectors? Maybe, maybe not, but I would be totally on my own if I tried to do anything like that. I don't want to be "on my own", I'm not into engine tinkering and I don't think that figuring out how to make 2 injectors run a 4 cyl engine would be "fun". I bought the Terminator X mainly because their 2 barrel Snipers only use 2 injectors, so......I thought......SURELY their Terminator X system would have the settings to run just 2 injectors. Nope, Terminator X will not normally run 2 injectors and even if I could "fool" the system into thinking that it is running 4 injectors, he wouldn't tell me how to do it.

Mannnnn, am I pissed. This has blown a big hole in my boat and I'm sinking fast.

Is there a solution? Yeah: Run 4 injectors. But, I am really adamant about trying to use my single side draft manifold to make this all work. But it's shape is all wrong for trying to add 2 more injectors somewhere in it's runners. The manifold has just 2 runners, but there is a divider going down the center of each one and it is shaped to give a bit more flow to one side or the other to take into account the unusual shape and length of the runners. This manifold was designed by one of the top manifold designers in the world, but it was designed for ALL of the air/fuel mix to enter at the opening of the manifold. I could easily F-up the whole balance of things if I just jammed injectors willy nilly somewhere in the manifold. The twin throttle bodies have 2 injectors just after the throttle plates I need to add 2 more.....somehow.....in a similar location. That's not going to be easy at all and I've got a lot of hard thinking and designing to do. Or I'm going to have to scrap the whole idea of the SSD manifold and go the traditional route of TWO twin throttle bodies set up the same way as dual side drafts. As I'm typing this, this may be the only logical way to go. The twin throttle body only cost about $100, I would need to buy another one, and 2 shorty side draft manifolds, and possibly a special thermo housing, and a throttle body unifying device to operate both pairs of TB's. I would then need to make an air box to fit and service all 4 throttle body barrels. But I bought the long, side draft-sized, twin throttle body, so that it would match my existing air box I used when I was running a single side draft carb. That would make things tight between the engine/manifold/TB and the heater box, I really should buy TWO shorty twin TB's to free up the space. Hoo boy, it starts getting complicated and expensive the more I think about it.

Aarrgghh!

Your thinking too much... computers are stupid things and only know what they are told. Again. If the TX can be configured to fire 4 injectors in batch sequence then set it up that way and substitute resistors for 2 of the injectors.
Or switch back to the microsquirt......
 

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Just Some Dude in Jersey
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I've talked with our guru, RallyBob, and he agrees that when you start modding injector positions and manifolds you don't know what your end result might be. If your end result works better than the tried and true methods, then great, but you would have to prove that on a flow bench and a dyno. If you find out that it works worse than tried and true, then you just spent a whole bunch of time and money on a failure and you're back to square one.

I'm waiting for info to come in, but I will probably go with short manifolds made for a 2.4 and two shorter twin throttle bodies. All the widgets might cost me $500-$700 and I've already got the operating system. This would be a tried and true set up proven by decades of use by racers in Europe and here and it's all off the shelf. At my age and lack of interest in engine tuning and experimentation, this would probably be the best route for me to follow.
 

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Interesting fitment…FI Tech throttle body EFI mounted at a severe angle on a draw-thru VW turbo. Hmmmm.
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Discussion Starter · #98 ·
Happy to try a slant draft throttle body if someone has one that they want to donate to the cause. I have the slant draft manifold fabricated. I am still working on the other EFI elements, but it would be fun to compare to port injection in a few months.
 
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