L-Jetronic conversion to microsquirt 1975 Ascona A 1.9

[ghcoe]

Been sometime since I have posted anything up here. My fuel injected '75 Ascona A (almost a Manta) finally went down due to a cold start condition a couple yeas ago. While trying to sort out the condition, the dual relay came apart in my hand and arced out on the body. After that I could not get it to start again. Figured I had taken out the ECM all together, although I do suspect the cold start circuit was already gone by then.

The Ascona has been sitting a couple years now waiting for me to figure out what I was going to do. I do have a carburetor manifold laying around and though maybe just convert it to a Weber, however, I do really like the FI.

I have been doing some research on converting the old L-Jetronic to a more modern FI system during this time. Not really a lot of information out there. Most info I have found out there peter out about halfway through the project, but I think I have found enough info to get me going in the right direction.

I just wanted to start a post to document my L-Jetronic to micro squirt project and hope I don't get frustrated with it like others have in the research I have done.

 

Basically, I will be using the original L-Jetronic plenum, but that is all. Different injectors, Cold start injector deleted, different throttle body, real TPS, IAC added, wide band oxygen sensor added, map sensor added, IAT added and CLT changed. I think that covers most of it.

Most parts will be sourced from the salvage yard. Microsquirt and Oxygen sensor will be new.

 

 

STEP 1

So, I know that I will need/want to replace the injectors. Basically, the main reason is that the Microsquirt will not run low impedance injectors. You can install resistors in the system to run low impedance injectors or use the existing resistors if you want. To make things easier I am opting to go with high impedance injectors.

From what I found the stock L-Jetronic injectors 0-280-150-105 flow at 18.1 lbs/hr at 43.5 PSI. These injectors are also a barbed style injector, which of course makes it difficult to find substitutes. It seems about the time they went to high impedance injectors was about the same time they went to a fuel rail design which did away with the hose barb. I had already known about the Volkswagen Vanagon 1.9 from previous research. The Volkswagon Vanagon injector is a 0-280-150-206 and has a flow rate of 16 lbs/hr at 36.25 PSI.

While searching for this info, I also found a part number for the Opel LE-Jetronic 0-280-150-205 which are high impedance injectors. These have a flow rate of 16.2 lbs/hr at 36.25 PSI.

This is where I get some conflicting information. One site shows the 0-280-150-205 with 36.25 PSI and the other at 43.5 PSI. The flow numbers are the same, however. I feel this really is not a game changer.

I dumped the numbers into a couple injector calculators and the flow rates came out perfect for stock 1.9 HP.

I did find it odd that the newer LE injectors flowed a bit less than the L injectors. I think this was because the system ran dumb. I do believe I have read before that the L did tend to run a bit rich until higher RPM. That is probably why their MPG dropped when they went to FI over the previous carbed models.

I have sourced the LE-Jetronic 0-280-150-205 so I hope to order some in soon.

STEP 2

Now that I got the injectors figured out it is time to take a look at the Throttle Body. It seems most people think that going with a bigger throttle body and/or injectors makes more power. That is wrong. Engine design, Injectors, air delivery and throttle body need to be compatible. Get one wrong and the rest will be an uphill battle.

So here is where I think most people converting their L-jetronic go wrong. From my crude measurement attempt (plenum not removed) I came up with a 52mm diameter throttle body on the stock L-Jetronic. With the pivot rod measurements removed it is probably a 50mm. This is way too big for a 1.9 90hp motor. The throttle body should be about 40mm. Since just adding a few more mm to a throttle body makes a big difference you can see 10mm is way off.

Here are the comparisons:
Calculated recommended throttle body size 40mm - 92 HP (still a bit fat but closer than OEM 50mm)
Stock L-Jetronic throttle body size 50mm - 144 HP (way off)

As you can see that is a huge difference in Horsepower output. A Opel engine would have to be built pretty crazy to put out 144 HP.

Now let's add this. I saw on another thread this Information:

I will be using a 94 Altima 2.4L throttle body and the cam off a 1.6L Sentra as it used a cable operated throttle, while the altima used a rod and socket style.

I do recommend the body from a 2.4L over the others, as the others are smaller than the Opel, and the 2.4L is a bit larger. But they all will fit the manifold.

Now I could not find the actual throttle body size for the 94 Altima 2.4L motor, but I did find the size on a later 2.5L motor and that is 70mm. So, for a sake of argument lets half the size from the L-Jetronic of 50mm and the found diameter of the Altima 2.5L of 70mm and call it 60mm.

94 Altima 2.4L Throttle body not known, estimated to 60mm - 207 HP

As you can see going bigger is not better. Now imagine a ECU trying to compensate for that much air load. Yup going to be a problem for sure.

So why did the Opel L-Jetronic have a 55mm throttle body and still run well you ask? Well so did I.
I could not really find any definitive information on this, so it is merely my speculation at this point.
First, the L-Jetronic has to drag the air through the MAF sensor which probably does constrict air flow some.
Second, is that the air filter has a horn that directs the incoming air directly to the swing door on the MAF sensor. It is square port, but when I measured it, it was 40mm. Pretty close to the recommended throttle body size for the motor. In my reading it was noted that no matter how large a throttle body is it is limited to the smallest port before and/or after the throttle body. Makes total sense to me...

Now, don't get me wrong you can go up some with throttle bodies. Usually not 10mm though. The larger you go the less throttle response and drivability you will have. Also, low end torque will be compromised. But If you want most of your power at WOT then bigger is better.

So, I will be looking at getting a smaller throttle body in the 38-42mm range. Maybe the Nissan 1.6 throttle body would be a better match.

Edited November 27, 2023 by ghcoe

[Jessopia74]

Well good to see someone else going with an aftermarket option. There are other options for injectors (with some minor work to pipes) that are higher flow and newer that will fit into std plenum easily, from SAAB with Trionic5 setup.

Reading through your setup, are you going ignition map too? 
As for compensating from the std plenum butterfly, I would leave it standard. The restriction comes after the butterfly anyway, and once you add an air filter into the flow the rates you expect are not going to be as high. You can always limit the opening angle if you want some restriction, or make a restrictor up to fit on the end. 
 

presume you also interested in going sequential with the Micro choice. 

[ghcoe]

40 minutes ago, Jessopia74 said:

Well good to see someone else going with an aftermarket option. There are other options for injectors (with some minor work to pipes) that are higher flow and newer that will fit into std plenum easily, from SAAB with Trionic5 setup.

Reading through your setup, are you going ignition map too? 
As for compensating from the std plenum butterfly, I would leave it standard. The restriction comes after the butterfly anyway, and once you add an air filter into the flow the rates you expect are not going to be as high. You can always limit the opening angle if you want some restriction, or make a restrictor up to fit on the end. 
 

presume you also interested in going sequential with the Micro choice. 

I am in the U.S so some things may be difficult to source for me or visa versa.

As mentioned above.  The old L-Jetronic seems to be a bit fat on both the injector flow rates and throttle body size. Plugging in the known engine data (when new) shows that the injectors flowed too much and the throttle body was too big. I believe the early technology they errored to the high side to keep the motor from running to lean. The FI vehicles, in the U.S., lost about 2-3 mpg going from carb to FI in 1975. 

I am not planning on going with electronic advance of sequential at this point. The idea is to find an economical solution for a replacement ECM. Once I get to that point and everything runs well then, I may try my hand at the electronic advance. Although you may get a bit more fuel economy with sequential, I don't think it is worth the extra effort for me. 

I ordered in the Opel 0-280-150-205 injectors this weekend. These were used on
Opel Ascona Astra Manta Carlton Senator 1.8-3.0L LE-Jetronic Systems

More info here:
Ascona B Injector info:
Bosch EV1 fuel injector
Crimped hose type injector
Long size injector
Jetronic Port
Pintle Nozzle
Flow Rates @ 43.5 psi / 3 bar
16.2 lb per hour
122.5 G per min. (N-Heptane)
170.3 cc per minute
12 Ohm resistance
Opel Cam in head motors
1.9L
2.0L
Bosch 0280150205
Opel 90141740

As noted before there is some confusion on the sites weather the Flow Rate is rated at 36.25 (2.5 Bar) or 43.5 PSI (3 Bar).

From the pictures of the supplier it also looks like these are 4 hole injectors. It is not noted though.

 

[Trooker]

I'm guessing the BMW E30 and parts for those will be more plentiful than Opel parts in the US - there may be some pointers for you on this WIKI, the L-Jetronic to Motronic conversion guide is interesting reading too.

https://www.e30zone.net/e30wiki/index.php?title=Engine_Management

 

 

Edited November 27, 2023 by Trooker

[ghcoe]

25 minutes ago, Trooker said:

I'm guessing the BMW E30 and parts for those will be more plentiful than Opel parts in the US - there may be some pointers for you on this WIKI, the L-Jetronic to Motronic conversion guide is interesting reading too.

https://www.e30zone.net/e30wiki/index.php?title=Engine_Management

 

 

Looks like some light reading there for sure. Thanks! 

[ghcoe]

Well, I have been doing more research to make sure my numbers are correct. Writing down some numbers here for future reference and maybe help others down the line.
So, I have seen the low compression 1.9L hp numbers from 47-52 hp @ the wheels to 78 ps at the flywheel (78 PS = 76.93296 HP Ps to HP Calculator - Calculatorway). My original calculations were for 90hp which I am not really sure where I found that at. So, since I started with 90hp that is where I am going to stay since all the previous data seems to reflect L-Jetronic was designed with that (90hp) in mind. I have to keep in mind that with the microsquirt the HP may increase a bit anyway so cross the fingers with that.

So now we go back to the injectors. Original injectors were rated at 18lbs. The injectors I ordered in are rated at 16.2lbs. (170.2cc), which are for the later LE-Jetronic 1.9L, 2.0L engines. Typing in a 1.9L @ 90hp here Flow Calculator we come up with 13lbs (132.79cc). It seems that even the later engines were running a bit too big an injector as well. Adding more HP to the calculation I found that a 16.2lbs (170.2cc) injector should be good to 115hp, but optimal rating was 112-115hp. These numbers are hp at flywheel/crankshaft.

More info on the throttle body. While trying to make sure everything jives, I looked at a few different things. Since carburation and Fuel ejection should flow a similar cfm, I found this calculator https://www.summitracing.com/newsandevents/calcsandtools/cfm-calculator. Converting the 1.9L to 116ci and a max RPM of 5500 we find that a carb should flow 156.92 cfm. So, it looks good that even dropping down to a 40mm throttle body I should still flow plenty of cfm, even for a race engine, going by these flow rates listed per throttle body diameter.
40mm = 266 cfm
50mm = 416 cfm
60mm = 600 cfm
70mm = 815 cfm
Here is a throttle body size calculator Injectors and Fuel Supply (megamanual.com) Typing in 1 for throttle bore and 40 in throttle bore diameter (mm) we find a hp number to be 92hp. Or you could do the long calculation that I found online.

THROTTLE BODY SIZE CALCULATION
So I'll just go through this calculation here.
for a, let's say our little 20 valve 4AGE here.
we've got a 1.6 litre engine, so if we divide 1.6 by 4 because we have 4 cylinders, that gives us 0.4, multiply that by 7500 RPM
which there or thereabouts is about the rev limit for that engine.
And then what we want to do is put that to the power of 0.5, giving us a result of 54.7, let's call that 55.
And then we want to multiply that by about 0.8, there's a bit of wiggle room in here but that gives us an outcome of 44 mm
rounding up.

My Calculation for a 1.9L@5500RPM=41mm Throttle Body.

In staying in what the injectors could keep up with (112hp-115hp) it seems I could go with a 45mm throttle body. This is substantially smaller than the stock L-Jetronic which is 55mm which again is too large for the 1.9L. Information found online about too large a throttle body.

There are some drawbacks to a too large throttle body:

• At low rpm, you go from low kPa to 100kPa with very little throttle movement, making driveability 'worse'. For example, with a very large throttle body you may get 100 kPa at 20% throttle at 2000 rpm. This means if you want to hold it at 40 kPa for cruise, you have to be very steady on the throttle, as small movements may produce large changes in engine output (so it's harder to be smooth), and
• A small throttle movement (and a small V/sec TPS signal change) can result in a very large change in MAP (as mentioned above) at low rpms. The result is little (or no) accel enrich when the engine needs it most. However, you can usually tune around circumstances like this by richening the VE table at low rpms and higher kPa (say < 2500 rpm and> 70 kPa) by about 5-7%. This has a negligible affect on fuel economy, since you likely never see 70 kPa while cruising.

Well that is all for now.

[Jessopia74]

A couple of points. The injectors are better running high psi, high flow and reduce the pulse length (open number in the map). Since you’re going to a fully mapped injection table, then higher pressure is better for atomisation. Other factor to consider is the fact you need two injection pulses per rev, and then you will have the Lambda anyway. Dont get too dragged into top end max bhp no.s if you are searching for bottom end torque, the map and cam choice will differ. 
 

Your effectiveventuri diameter is the injection plenum tubes and they are way under 45mm, not got one here to measure, but probable closer to 38-40mm. so as I said previously keep the buttery standard. There was a reason by Opel that size was chosen after many hours in design and dyno. 
You are looking to improve the fueling across the rpm range, without really impacting performance, that’s the ECU and map. 
 

And you can’t just substitute carb Venturi size calcs for injection plenum, they both flow air into the engine and that is about the limit of similarity. The FPR dies adjust the fuel pressure slightly based on load ascertained from vacuum pressure in the plenum a little to lean it off a little at high rpm, low load conditions. 
 

Here is what I would do if it was me, based on fact I have a bench MS2 setup that I have been working with all manner of injection setups for years. 
‘How are you pulling the crank sensor, 36-1 wheel?

Keep OEM plenum/butterfly and injectors. Swap the FPR to an adjustable one with a guage. Get basic map installed and setup with base map to get running on semi-sequential injection (2&2).

Tweak from there. 

[ghcoe]

2 hours ago, Jessopia74 said:

A couple of points. The injectors are better running high psi, high flow and reduce the pulse length (open number in the map). Since you’re going to a fully mapped injection table, then higher pressure is better for atomisation. Other factor to consider is the fact you need two injection pulses per rev, and then you will have the Lambda anyway. Dont get too dragged into top end max bhp no.s if you are searching for bottom end torque, the map and cam choice will differ. 
 

Your effectiveventuri diameter is the injection plenum tubes and they are way under 45mm, not got one here to measure, but probable closer to 38-40mm. so as I said previously keep the buttery standard. There was a reason by Opel that size was chosen after many hours in design and dyno. 
You are looking to improve the fueling across the rpm range, without really impacting performance, that’s the ECU and map. 
 

And you can’t just substitute carb Venturi size calcs for injection plenum, they both flow air into the engine and that is about the limit of similarity. The FPR dies adjust the fuel pressure slightly based on load ascertained from vacuum pressure in the plenum a little to lean it off a little at high rpm, low load conditions. 
 

Here is what I would do if it was me, based on fact I have a bench MS2 setup that I have been working with all manner of injection setups for years. 
‘How are you pulling the crank sensor, 36-1 wheel?

Keep OEM plenum/butterfly and injectors. Swap the FPR to an adjustable one with a guage. Get basic map installed and setup with base map to get running on semi-sequential injection (2&2).

Tweak from there. 

Thanks for the info. The idea of this build is to basically change over the L-Jetronic from analog to a digital ECM. My ECM finally gave up. If I gain more horsepower well that will be nice too. 

I thought this was going to be a simple switching of inputs required for the new FI system since they work differently. Started to go down the rabbit hole and found a lot of the older FI stuff really did not jive with the newer recommendations.

Yes, the original system was probably tested by Opel, but this was still new technology at that time. As mentioned above, the original throttle body was 55mm but the intake trumpet in the air cleaner was only 40mm. This would effectively restrict the throttle body to 40mm as well. Removing the air cleaner by itself would effectively change the throttle body from 40mm to 55mm, maybe Opel and Bosch already knew this information to make the vehicle perform properly. So, I think if you did keep the 55mm throttle body it would be worth putting a restrictor in the system to drop down it's effective cfm. You want some air velocities in the plenum for some performance benefits. Using a throttle body that is too big slows air velocity in the plenum. Sure, it might work well/ok but your loosing some extra power gains that the smaller throttle body would provide. I went through a lot of reading years ago on how all this works on carbureted engines so now I am learning how the same things effect FI. 

Of course, a lot of this is for future tuning. Right now, I just need to get the Ascona running again. 

I will be running the microsquirt just for fuel at this point. Once I get that running well, I might take a shot on timing as well. Since I will not have a crank or cam sensor, I will be using the same two injection per revolution as the L-Jetronic did which is fine. 

looks like you guys got some pretty trick options for your Opel's over there. I saw a crank position sensor and missing tooth crank trigger pully running a serpentine belt. Not sure if it was a OEM upgrade but it was pretty cool.  

[Jessopia74]

57 minutes ago, ghcoe said:

Thanks for the info. The idea of this build is to basically change over the L-Jetronic from analog to a digital ECM. My ECM finally gave up. If I gain more horsepower well that will be nice too. 

I thought this was going to be a simple switching of inputs required for the new FI system since they work differently. Started to go down the rabbit hole and found a lot of the older FI stuff really did not jive with the newer recommendations.

Yes, the original system was probably tested by Opel, but this was still new technology at that time. As mentioned above, the original throttle body was 55mm but the intake trumpet in the air cleaner was only 40mm. This would effectively restrict the throttle body to 40mm as well. Removing the air cleaner by itself would effectively change the throttle body from 40mm to 55mm, maybe Opel and Bosch already knew this information to make the vehicle perform properly. So, I think if you did keep the 55mm throttle body it would be worth putting a restrictor in the system to drop down it's effective cfm. You want some air velocities in the plenum for some performance benefits. Using a throttle body that is too big slows air velocity in the plenum. Sure, it might work well/ok but your loosing some extra power gains that the smaller throttle body would provide. I went through a lot of reading years ago on how all this works on carbureted engines so now I am learning how the same things effect FI. 

Of course, a lot of this is for future tuning. Right now, I just need to get the Ascona running again. 

I will be running the microsquirt just for fuel at this point. Once I get that running well, I might take a shot on timing as well. Since I will not have a crank or cam sensor, I will be using the same two injection per revolution as the L-Jetronic did which is fine. 

looks like you guys got some pretty trick options for your Opel's over there. I saw a crank position sensor and missing tooth crank trigger pully running a serpentine belt. Not sure if it was a OEM upgrade but it was pretty cool.  

You can use the crank pulley off the 2.4 as it’s got the cut outs, or just buy a steel one and gave it welded to your front pulley, easy to make a bracket to mount off the oil pomp cover bolts to carry it. The 2.4 from timing cover already has one cast into it btw. See pic 

If you need help with sourcing parts for the timing setup, then eBay has loads that have free shipping or even your side of the pond. e.g  https://www.ebay.com/itm/184272691918

[Rick H]

I'm looking to go stand alone ECU soon, probably speeduino.

My theory on throttle size is the 50mm plate will act as a 50mm plate up until the airbox or barn door restriction comes into play.

So, in theory, the car will be just as responsive (hopefully more) as it was before using the original tb.

Also if the airbox/barn door are restricting the engine to 90hp, why not let it breath better?

[ghcoe]

12 hours ago, Rick H said:

I'm looking to go stand alone ECU soon, probably speeduino.

My theory on throttle size is the 50mm plate will act as a 50mm plate up until the airbox or barn door restriction comes into play.

So, in theory, the car will be just as responsive (hopefully more) as it was before using the original tb.

Also if the airbox/barn door are restricting the engine to 90hp, why not let it breath better?

You want to build the fuel injection system around the rated horsepower of the motor. Enough fuel and air flow to provide optimal power and response. Building to a bigger horsepower rating than what the engine can actually produce causes issues with the ECM. 

As mentioned above.

There are some drawbacks to a too large throttle body:

At low rpm, you go from low kPa to 100kPa with very little throttle movement, making driveability 'worse'. For example, with a very large throttle body you may get 100 kPa at 20% throttle at 2000 rpm. This means if you want to hold it at 40 kPa for cruise, you have to be very steady on the throttle, as small movements may produce large changes in engine output (so it's harder to be smooth), and

A small throttle movement (and a small V/sec TPS signal change) can result in a very large change in MAP (as mentioned above) at low rpms. The result is little (or no) accel enrich when the engine needs it most. However, you can usually tune around circumstances like this by richening the VE table at low rpms and higher kPa (say < 2500 rpm and> 70 kPa) by about 5-7%. This has a negligible affect on fuel economy, since you likely never see 70 kPa while cruising.

Not only that, too large a throttle body will slow intake air velocity. Too large a throttle body will actually reduce horsepower output. Not only do you need a tune for the ECM to run the motor properly, you also, have to tune the components of the fuel injection to the application for the best performance.   

[Jessopia74]

18 hours ago, ghcoe said:

You want to build the fuel injection system around the rated horsepower of the motor. Enough fuel and air flow to provide optimal power and response. Building to a bigger horsepower rating than what the engine can actually produce causes issues with the ECM. 

As mentioned above.

There are some drawbacks to a too large throttle body:

At low rpm, you go from low kPa to 100kPa with very little throttle movement, making driveability 'worse'. For example, with a very large throttle body you may get 100 kPa at 20% throttle at 2000 rpm. This means if you want to hold it at 40 kPa for cruise, you have to be very steady on the throttle, as small movements may produce large changes in engine output (so it's harder to be smooth), and

A small throttle movement (and a small V/sec TPS signal change) can result in a very large change in MAP (as mentioned above) at low rpms. The result is little (or no) accel enrich when the engine needs it most. However, you can usually tune around circumstances like this by richening the VE table at low rpms and higher kPa (say < 2500 rpm and> 70 kPa) by about 5-7%. This has a negligible affect on fuel economy, since you likely never see 70 kPa while cruising.

Not only that, too large a throttle body will slow intake air velocity. Too large a throttle body will actually reduce horsepower output. Not only do you need a tune for the ECM to run the motor properly, you also, have to tune the components of the fuel injection to the application for the best performance.   

JEvery single thing you describe can be very easily mapped as you say out or limited in a mechanical way though by maximum angle or if you really want to limit the max airflow into the engine, just restrict the pedal throw 😁

the limiting factor for the CIH engine is the head anyway, std they are very restrictive hence they actually artificially limit revs under load as the cylinder fill just tapers off very quickly after 5000-5500rpm. Then the plenum charge tubes are also very small in reality and also limit the air flow and spikes, so do a pretty good job of the velocity at low rpm to help cylinder fill for torque.

Cruise conditions and under load will be mapped completely differently for throttle position anyway based onManifold pressure, that changes the fuel ratio accordingly so I do think you are trying to correct or reengineer a problem that does not exist in the std CIH. 

 

[Rick H]

On 07/12/2023 at 00:39, ghcoe said:

You want to build the fuel injection system around the rated horsepower of the motor. Enough fuel and air flow to provide optimal power and response. Building to a bigger horsepower rating than what the engine can actually produce causes issues with the ECM. 

As mentioned above.

There are some drawbacks to a too large throttle body:

At low rpm, you go from low kPa to 100kPa with very little throttle movement, making driveability 'worse'. For example, with a very large throttle body you may get 100 kPa at 20% throttle at 2000 rpm. This means if you want to hold it at 40 kPa for cruise, you have to be very steady on the throttle, as small movements may produce large changes in engine output (so it's harder to be smooth), and

A small throttle movement (and a small V/sec TPS signal change) can result in a very large change in MAP (as mentioned above) at low rpms. The result is little (or no) accel enrich when the engine needs it most. However, you can usually tune around circumstances like this by richening the VE table at low rpms and higher kPa (say < 2500 rpm and> 70 kPa) by about 5-7%. This has a negligible affect on fuel economy, since you likely never see 70 kPa while cruising.

Not only that, too large a throttle body will slow intake air velocity. Too large a throttle body will actually reduce horsepower output. Not only do you need a tune for the ECM to run the motor properly, you also, have to tune the components of the fuel injection to the application for the best performance.   

Did you find yourself having to micro-manage your foot with the original setup?

I totally agree with you on what you say can happen when the TB is way too big.

My 2L GTE drives nicely, no micro managing the accelerator pedal, I expect it to be the same when I change the ECU & ditch the MAF sensor.

Hopefully I'll get a quicker reacting engine & better mpg using modern injectors, initial setup will just be so I have everything in place for tuning for future mods.

If I were racing then yes I'd look at matching every thing but (in my opinion) port & runner area & length have a bigger effect on power through out the rev/throttle range than air speed to the plenum which is only relevant at WOT.

[ghcoe]

18 hours ago, Rick H said:

Did you find yourself having to micro-manage your foot with the original setup?

I totally agree with you on what you say can happen when the TB is way too big.

My 2L GTE drives nicely, no micro managing the accelerator pedal, I expect it to be the same when I change the ECU & ditch the MAF sensor.

Hopefully I'll get a quicker reacting engine & better mpg using modern injectors, initial setup will just be so I have everything in place for tuning for future mods.

If I were racing then yes I'd look at matching every thing but (in my opinion) port & runner area & length have a bigger effect on power through out the rev/throttle range than air speed to the plenum which is only relevant at WOT.

No, it drove fine. 

If you get rid of the MAF and not the filter box you probably will not have issues. The Filter box is where the restriction is. If you pull out the filter and look you will see where they built a air trumpet into the air flow. It is suppose to clean up the air flow so as to hit the MAF sensor door with a clean jet of air. Mine measured 40mm across. It is a square shape so it probably flows a bit more than a circle shape. 

Going with the components that I plan on getting (which are smaller than OEM but larger than what is actually recommended) they should support up to 115 horsepower. The FI improvement should gain some extra horsepower over the OEM but I don't really expect that much gain. I would expect better economy too. Time will tell.

I am looking at some Toyota Sentras maybe this weekend. The early 90's 1.6 have a smaller throttle body than the Ascona, but I am not sure how much smaller. I am hoping for 43-45mm but I think they are 48mm. This would be a near bolt on swap. Early 90's Ford Excort 1.9's have a 40mm, but I am not sure if the throttle body bolt pattern is the same or not.  

[ghcoe]

Went to the salvage yard today and pulled a throttle body off of a 1994 Ford Escort 1.9L. The Throttle body on the 1.9L was 40mm. I took one off of a 1998 Escort 2.0L. It looked very similar but was 48mm in diameter.

The flange bolt pattern is different so I will have to make an adapter for it. I liked this throttle body the best out of all the ones I looked at. Most were for larger motors and had too large a diameter. Also, the throttle connections were wonky. What really sold me on this one is that there was a larger one readily available (48mm) if needed in the future and the Idle Air Control Valve was built into it. There were others with this feature, but they were a lot more complicated and had multiple hose attachments. This Idle Air Control Valve is operated with PWM (Pulse Width Modulation) which the microsquirt will run.

I also picked up a GM IAT (Idle Air Temperature) sensor with grommet and MAP (Manifold Absolute Pressure) sensor while I was there.

Well, that was the bulk of the parts that I needed for the conversion. Total cost and the salvage yard was $36.00(US). The expensive items will have to wait till after Christmas, but this will get me going for making an adapter.

 

 

[®evo03]

https://www.opelgtsource.com/

Might be of help, being U.S. 

Some great info on development. 

[ghcoe]

4 hours ago, ®evo03 said:

https://www.opelgtsource.com/

Might be of help, being U.S. 

Some great info on development. 

I am familiar with them. Also, I am on their forum. I have a mirrored thread there on this subject. 

[Jessopia74]

20 hours ago, ghcoe said:

I am familiar with them. Also, I am on their forum. I have a mirrored thread there on this subject. 

Cool, should be interesting to see how close a ‘plug in’ option you can get this. 

[ghcoe]

Here are some comparison photos of the Opel and Ford throttle bodies. Opel on right and Ford on left.

https://imgur.com/0axXzaO

 

 

 

 

 

Edited December 14, 2023 by ghcoe

[ghcoe]

Making a throttle body adapter out of 1/4" (6mm) aluminum. 

https://imgur.com/MRezmPH

[Jessopia74]

Are you going to utilise the idle air valve ? 

[ghcoe]

3 hours ago, Jessopia74 said:

Are you going to utilise the idle air valve ? 

That is the plan. It is a PWM idle air valve so should be easy to set up with the microsquirt. Since the Idle Air Valve is mounted on this throttle body it will clean things up a bit since I will not have to hack in a valve somewhere else. One of the reasons I like this throttle body when I saw it. 

[Jessopia74]

9 hours ago, ghcoe said:

That is the plan. It is a PWM idle air valve so should be easy to set up with the microsquirt. Since the Idle Air Valve is mounted on this throttle body it will clean things up a bit since I will not have to hack in a valve somewhere else. One of the reasons I like this throttle body when I saw it. 

Yes, indeed that will be nice for cold starts too. 

[ghcoe]

1 hour ago, Jessopia74 said:

Yes, indeed that will be nice for cold starts too. 

Yes, and if I decide to reinstall the A/C it will be nice for idle control with the extra engine load as well. 

[ghcoe]

I found a throttle cable that will work with the throttle body. The original cable was too short, and the operation was totally different on the original setup. 

I used a square to slid in the throttle cable groove on the throttle body pulley. This gave me a reference point on where to drill a hole. I used a 9/32" drill bit to drill a hole at the marked location. Then I used a M8x1 tap to make threads in the newly drilled hole. This allowed the throttle cable end to screw into the adapter and eliminated the need for a nut on the pully side of the adapter. The other nut on the back side now acts as a jamb nut.

I got to looking at the Throttle Position Sensor closer, and though that it might be reversable. So, I took it apart and sure enough it can be installed 180 degrees. This puts the plug facing downward rather than upward. Also, this puts the plugs for the TPS and the IAC pretty close to each other and will make for cleaner wiring.  

I assume I can't post pictures to the forum so here is a link to some pictures of the project. 

https://imgur.com/GAdLiz6