[GThound]

Extra wires and customizing seem to be part of the game when modding an old analog car to FI. My present car has a 1990 Motronic system and I had to eliminate half the wires. There were a lot OBD1 diagnostic wires, plus ones for controlling a modern electronically controlled auto tranny, anti-lock brakes, etc., that all had to go. If I had decided to run my oem system with an aftermarket controller, I would probably have had to cut off many, if not all, the plugs and graft them onto the new system's wiring harness.

Makes sense, I will just go into slice and dice mode as the Holley Terminator seems to be the best option for me after weighing all of the factors.

Consider mounting your ECU and extra wiring in the passenger side footwell, which would require cutting a decent size hole in the firewall on that side. I'm customized and don't have the heater there anymore, so I have plenty of room to mount all that stuff behind the dash.

I like this idea. the passenger side footwell is the future planned home for my Opel GT ECU.

I understand your fascination with the latest, coolest, injectors, but, remember: You're rigging an old, weird, car for FI and you're making your own unproven manifold design that may or may not have the optimum injector positioning and general flow of air. Plus, you're thinking of throwing a turbo into the mix? You've got all sorts of variables going on and almost all of them are unproven. The older, larger, injectors were used for decades and nobody complained, I hardly think that the latest gee-whiz injectors would make any noticable difference. The oem FI had the injectors squirt right at the head ports, your concept has them a few inches farther away, Holley Snipers have them all the way at the beginning of the line before the throttle plates, my system will have them just after the throttle plates, carbs introduce the fuel before the throttle plates and various carbs set ups are near and far from the engine, and they all seem to work just fine.

I acquiesce. After a bunch more research, I agree with you, there is not that much of a difference and I will just go with readily available / compatible injectors. I have not yet acquired the fuel injectors. But that day is coming soon. I will focus more on getting the lbs/hour right and fabricating my fuel rail.

I contacted Holley late last week to ask how to configure the system to run the spark and injection like a 2-barrel Holley Sniper. They said to wait 3-4 days for a response and I'm still waiting.

I downloaded the free Holley Terminator X software, and it is actually quite helpful in figuring out what is configurable. Also, the 4th Holley call I made I talked to someone really helpful. He pointed out that on their web page if you select the picture of the item you want and scroll down to the bottom there is an area called "Tech resouces" that has all kinds of info that was helpful for me designing my system.

Are there knock sensors also?

My research indicates that the main wiring harness that comes with the Holley Terminator X does have a place to plug in knock sensor, but the knock sensor itself doesn't come in the kit.

But figuring all that stuff out is half the fun. 😀

Agree! This is a fun project with much problem solving on the way.

 

[Verrostet]

I acquiesce. After a bunch more research, I agree with you, there is not that much of a difference and I will just go with readily available / compatible injectors. I have not yet acquired the fuel injectors. But that day is coming soon. I will focus more on getting the lbs/hour right and fabricating my fuel rail.

I don't think this is the correct point of view- I recommend using the injectors that are populated in the drop down menu or aftermarket injectors where you can get full information on the injector dead times an flow characteristics. This information is important to making your life easier insofar as the ECU self learning feature and tuning the system in general. If you get this information incorrect you can end up chasing your tail and may have problems with idle etc.

The whole point in recommending the Holley systems is that if you use options that are pre-defined in the software you will get an initial tune using the wizard and that will allow the system to be in the ball-park so the self learning can get you even closer to an OEM like experience. Deviating from these parameters (such as using injectors that you don't have dead-time information on as well as ill-defined flow characteristics) can make your life much harder and end up costing more time and money down the road.

If you want to tinker- then that is fine and you can make almost any combination of parts work with time and tuning. If you want minimal frustration stick to parts and options that are defined in the software.

 

[DavidF1972]

will focus more on getting the lbs/hour right and fabricating my fuel rail.

Roughly 0.5 lbs per hp...

 

[The Scifi Guy]

I agree that you don't want to grab any old injectors you find laying around. My comment was in regards to only focussing on using the latest, state of the art, short ones. I would go with whatever the Terminator X system recommends. Do they only recommend the latest, coolest, injectors? Or do they suggest any injector within a certain flow rate and other factors?

 

[GThound]

I recommend using the injectors that are populated in the drop down menu or aftermarket injectors where you can get full information on the injector dead times an flow characteristics.

Spot on. Thank you for clarifying. That is exactly what I am doing. What I gave up on was insisting that I had EV6 connector injectors. I did not understand what well characterized injectors were at first. But eventually, I downloaded the Terminator software so that I could see which injectors they have characterized. That is great advice.

Here is an example of what injector characterization looks like in the software pull down menu. it is basically how long it takes for the injector to open (in milliseconds), how long it takes to turn off (as a function of voltage), and flow rate at a given pressure. I love the thought of not having to do this myself!

Roughly 0.5 lbs per hp...

Using this rule of thumb, for a car in the 160-200 hp range / 4 cylinders, would yield roughly 40-50 hp per cylinder * 0.5 lbs/hp = 20-25 lb / hr injectors. This seems to be on the low end of what is offered and you really don't want to go much beyond the 85% duty cycle (too small), or go too big (poor atomization). I will probably select some injectors in the 24-30 lb / hr range, although there are limited size / flow-rate options.

Do they only recommend the latest, coolest, injectors? Or do they suggest any injector within a certain flow rate and other factors?

Here are the injectors listed in the pull down menu from the software. There are a mix of injectors from a variety of manufacturers, with a variety of lb/hr ratings and connectors. Many are OEM injectors through the various years and some are new high performance, non OEM options. Of course Holley would like you to use their injectors. The 2300 Sniper which some have installed on their Opels have 2 x 100 lb injectors.

Any suggestions from amongst the list? In terms of best bang for the buck?

 

[GThound]

So progress of the day. My 1994 Nissan Altima throttle body arrived today. It is 60 mm diameter and 60 mm bolt pattern, which matches the 1975 Opel fuel injection intake manifold, and of course has the built in throttle position sensor. It was a filthy mess (being 28 years old), but should do the trick. I don’t know how you guys figure this stuff out, but I am going with the tried and true.

I had a hard time finding the mid 90s 2.0 Nissan Sentra or Infiniti G20 intake manifolds, but the Nissan Altima one seemed much more prevalent. Thank you to those on the forum that shared their experiences and pointed me in this direction..

I cleaned up the manifold and cut off the hot water line fittings with metal band saw.

I drilled out the 4 bolt holes on the Opel intake manifold with 17/64 inch drill bit and tapped then with 8 mm x 1.25 mm thread tap. I also ordered M8 x 35mm button head stainless steel bolts to secure the throttle body to the manifold.

 

[RallyBob]

I don’t know how you guys figure this stuff out, but I am going with the tried and true.

I used to do a lot with the Sentra GA16DE and Sentra SR20DE engines, so I had a bunch of intakes and TB’s laying around.

Of course I also had Opel intakes laying around, so it was only natural I’d compare notes.

Turns out the 60 mm Nissan TB’s were also used on KA24’s and VG30’s, so they are pretty common.

Not only are they the correct bolt pattern, but they have throttle shaft bearings with seals (Opel uses brass bushings which tend to wear out, with no seals), and of course the TPS.

 

[GThound]

Back to fuel injector selection.... I typed the list of the characterized GM injectors from the Holley Terminator software as mentioned above into an Excel spreadsheet. Then, for each option, I did the folowing:

1. Entered the injector lbs/hr from the software
2. Calculated the horse power supported (lbs/hr/ injector * 4 injectors * 2 hp / lb fuel * 85% duty cycle)
3. Figured out the connector type by looking at pictures via google

All of the sudden, the big overwhelming list of injectors that I could not navigate got very small. Most of the injectors either flowed too much or had the wrong connector. The 4th and 5th ones down are my target. That is a relief, because they are modern, relatively cheap, available, use the EV6 USCAR connector, are designed to run at 60 PSI and have 2 holes (better atomization), and have the right O-ring size for the injector bungs I am preparing to TIG weld to the Opel manifold.

Terminator Software Injector	Connector	Lbs/hr	Supports HP	Comment
GM 12576341 LS3	EV6 USCAR	42​	286	too big
GM 12680426 5.3	EV6 USCAR	37​	252	too big
GM 12594512	EV6 USCAR	37​	252	too big
GM 12580681	EV6 USCAR	29​	197	choose this
GM 12587269	EV6 USCAR	33​	224	ok
GM 12609749	EV6 USCAR	48​	326	too big
GM 12613411	EV6 USCAR	36​	245	too big
GM 12613412	EV6 USCAR	50​	340	too big
GM 17113553	Mini-Delphi	24​	163	wrong plug
GM 17113698	Mini-Delphi	24​	163	wrong plug
GM 25317628	Mini-Delphi​	24​	163	wrong plug
GM 25320288	Mini-Delphi​	24​	163	wrong plug
GM 25323974	Mini-Delphi	24​	163	wrong plug
GM 25323974	Mini-Delphi	33​	224	wrong plug

This decision then frees me up to work on procuring my ECU. I will likely go after an LS kit since it comes with the LS engine harness with the proper EV6 injector harness. Athough I will need to remove 4 of the injector plugs, I think this is a better fit for me than the universal harness with the EV1 injector harness. Of course I could always custom wire it, but as long as I am paying for it, might as well get it right, minimize rework, and maximize reliability.

Any idea on whether the General Motors LS harness will send me in the right direction in terms of connectors for 1) Throttle Position Sensor, 2) Coolant Temperature Sensor, and 3) Crank Position Sensor?

 

[GThound]

This is where I have landed In terms of the injector placement. The bottom figure in the sketch below is the Opel Head Intake Flange. The gray figure above that is the placement of the 1975 fuel injection manifold slots.The center lines of these two are off by 3.25 mm. I have decided to cheat the center lines closer together. Instead of the new injector bungs being perfectly centered on the intake ports, or perfectly centered (on the off-center) injection slots. I am going to mover them closer to the center. The new injectors will be 2 mm off center line. The new injector placement is shown below in the redline sketch.

I will 3D print out the redline sketch and use it to make a fixture jig to hold the injector bungs in the correct location while I TIG weld them to the 1975 Opel Fuel Injection Manifold.

Before I do this,though, I will get the die grinder out and clear out some of the material on the inner side of the oblong 1975 injector slots so that the injectors have a symmetrical area they are spraying into.

 

[DavidF1972]

Sketch looks like alibre???

 

[GThound]

Sketch looks like alibre???

Yes indeed! You know your stuff. Alibre is my main 3D design software (bought it once and no annual fees). Although for more complex work I much prefer Fusion 360, but can’t afford the annual fee, so I just use the free version of it (only 10 files allowed) for doing really complex work.

 

[DavidF1972]

Yes indeed! You know your stuff. Alibre is my main 3D design software (bought it once and no annual fees). Although for more complex work I much prefer Fusion 360, but can’t afford the annual fee, so I just use the free version of it (only 10 files allowed) for doing really complex work.

Huh, thought you dropped alibre... fooled me...
I've been a long time alibre user, and I do have fusion 360 on the computer also. Most of the cad work I do is dummed down so alibre is very fitting for me.
Not putting down alibre in any way. It's great for 95% of anyone's needs...that last 5% is a mofo by all accounts..
And I still go the paper pencil route first. Lol

 

[GThound]

I have many hundreds of Alibre files and don’t plan to migrate them. And don’t have room in my Fusion 360 account. So alibre gets used a lot. So we, we have alibre and Opels in common and maybe design and engineering?

I just went to update by Alibre file it is lost (we had a thunderstorm pass through and a power flicker). So, my nice sketch and part model are gone....Argggh.. That is why I like the cloud based system. nothing is ever lost. Oh well, at least I have some of the dimensions above from the post. I'll have to recreate it.

 

[DavidF1972]

I have many hundreds of Alibre files and don’t plan to migrate them. And don’t have room in my Fusion 360 account. So alibre gets used a lot. So we, we have alibre and Opels in common and maybe design and engineering?

I just went to update by Alibre file it is lost (we had a thunderstorm pass through and a power flicker). So, my nice sketch and part model are gone....Argggh.. That is why I like the cloud based system. nothing is ever lost. Oh well, at least I have some of the dimensions above from the post. I'll have to recreate it.

We probably have more in common than we know.
Opels so far have been alot of fun for me, and I hope that doesn't change. Being able to work with like minded people pursuing the same goals helps keep me focused.

 

[GThound]

Here is the printed out template for where to drill injector holes in the fuel rail. I often just print a template to eliminate measuring errors.

here is how the fuel rail lines up with the intake manifolds. I decided to cheat thei injectors even closer to the center line of the air stream of the runner ports.

The original injector slots really are way off center. Time to grind away and try to get them more centered / avoid spray issues.

the shiny spot in the pic below along the opening is where I removed some of the ridge With the die grinder. Hopefully this helps the fuel injector to spray into the middle of the air stream.

and widened the slot the top a mm or so towards the center of each runner to ensure the injector has a clean path to the airstream.

 

[GThound]

Last chance to make any adjustments in the fuel rail layout.

you might say I am committed now.

I made incrementally larger holes up to 1/2”. This is smaller than the final 0.540” for the fuel injectors.

I then cut some 1/2” round stock down to equal lengths. And of course de-burred them, so they don’t gouge up the aluminum injector bungs.

Then placed those 1/2” diameter steel pieces in the injector bungs.

Then placed the metal dowel ends into the fuel rail so I can use it as alignment figure jig. The metal rods basically take the place of the fuel injectors during the TIG welding process.

So now all of the injectors are aligned with the flow of the ports to hold everything square for TIG welding.

I am going to try to get the TIG welding done before it gets too hot today!

 

[RallyBob]

The original injector slots really are way off center. Time to grind away and try to get them more centered / avoid spray issues.

They are, but you have to consider that the intake ports themselves are not straight, and that they ‘curve’ towards the bore center.

The entry of air/fuel into the chambers is also not in a straight line. There is significant air/fuel separation in a carbureted engine, and I’m sure to some degree also in an EFI engine.

All I’m saying is that it’s never as simple as it seems, and any modifications from standard: such as larger valves/porting, a different bore size, chamber unshrouding, etc…affects this air/fuel separation. Even piston design factors in.

 

[GThound]

The intake manifold is some dirty awful metal to weld. I finally got some decent settings with more than usual AC cleaning and a little lower AC frequency.

That said, all was looking okay, until I was working on the back side where it slopes down and melted one of the injector bung seats… that is a critical failure.

Lots of work down the drain. So it is either try it again (although with my meager TIG welding skills that might not be a good idea), or go back to the approach of welding the bungs to the plate. Still tough angles, but more accessible without the plenum and runners in the way.

 

[DavidF1972]

Well that's a bummer....

 

[GThound]

Well,
1) I still have the fuel rail I can use - good

2) Could I somehow repair or replace the damaged bung? The angles just make it so difficult. Could I finish the other welds with a stubby gas lens with longer tungsten stick out? That could help get the heat where I need it. If not, could I salvage the intake manifold?

3) Pondering one of to go RallyBob style with the injector plates. See picture of his prototype below. It has several advantages. 1) all new clean metal, 2) access to weld where the. Lye arrow is below. I should have just done this in the first place.I wanted to get rid of potential vacuum leaks and have a cleaner install, but ended up going down a fruitless path (unless you happen to be an aerospace caliber TIG welder.