Has there ever been a reason Porsche/VW speced L-jet injection for the 1.8 engines instead of D-jet like the 1.7 and 2.0 engines used?

Usually when manufactures do this there are financial reasons for the change. Either they have the same engine on other vehicles they produce, or its just cheaper to use whatever part is being used.

But Porsche didn't use the T4 motor on other cars at the time. And if it was cheaper, they would have done away with Djet on the 1.7 and 2.0. I don't think VW was using l-let at the time for the bus... but maybe?

There has to be a reason that Porsche wanted Ljet on the 1.8.

Zach

Bosch made them a deal they could not refuse

Djet came out 1970 or earlier

Ljet didn’t come out until 74
Volkswagen was going that direction
And it was the new technology
Plus the 1.8 was sourced from vw
Probably what vw was already going towards and what came on the motors when they contracted with vw

It was the guinea pig for the FI system that was to become the standard for many Porsche and VW cars through the 80's as well as many BMWs and Mercs.

74 was the pre cat and EGR version, 75 added those. It was then used on the 76 912E, followed by 924, 928, and 944 as well as serving as the base for K Jetronic

Progress...

The 1.8 was born AFTER Bosch created and de-bugged the L-jet.

The D-Jet was rare enough that I have never had to work on one and I believe that system did not go "World Wide".

The L-jet was the recipe that CREATED what we have today.

It went worldwide and although I have little Porsche experience, I have SHITLOADS of L-jet experience as Nissan jumped on the L-Jet bandwagon early.

If you're not constantly changing, you're stagnating, and the competition will leave you behind...

L-jet was the way forward IMO.

Also known as the Bosch 'Barn Door efi. N/Denso also adopted this style on to their market share of cars, trucks. Alfa and Fiat efi cars as well.
The Bosch units on 911 Carrera and 944 Turbos are larger than the 914 1.8L .

Thought I read someplace the 914-4 2.0's would also have received L-Jet, but D-Jet was still good enough for emissions until the 914's end of production. Sort of proof of this is the 912E having L-Jet and T2's etc.

I put L-Jet on a stock 1975 914 2.0 years back and it worked very well.

D-Jet was not the first EFI, but it was the first EFI that made it to mass production. Yes worldwide. VW beginning in 1968 on the T3, then T4. BMW E9 (3.0si). M Benz: 250E, 280, 300, 350, 450. Volvo 1800E, 142, 144, 164E. Citroen SM, DS. Jaguar XJ-S, XJ12. SAAB 99E. Cadlillac. Renault.

My understanding is that L-Jet came to be for lower emissions, fewer parts (but a more complicated harness!) and is a simpler system than D-Jet.

more modern, simpler and more emissions friendly

D-jet was on a TON of cars in the early 70s. Just not to many that people care about today.

BMW 3.0Si, 3.0CSi, 3.0 CSL
Citroen DS21, DS23, SM
Jaguar XJ12 XJ-S
Lancia 2000 HF Coupe, Berlina
Mercedes-Benz - To many to list
Opel Commodore GS/E, Admiral, Diplomat
Porsche 1.7, 2.0 (Of course)
Ranault 17 1.6 TS, Alpine A110 1.6, Alpine A310 1.6
Saab 99 E, 99 EA, 99 EMS
Volvo 142 2.0E 144 2.0 E 164 3.0 E, 1800 2.0E, 1800 2.0 ES
VW 411 1.7E, 412 1.7E, 1.8E 1600 1.8E

I would suspect @brant is correct and that it was a result of L-jet being a more modern system and VW updating their engine offerings.

D-jet "calculates" airflow by a Speed-Density calculation, that is it senses manifold pressure, air temperature, and RPM and applies those values to an ECU tuned to a specific engine configuration. Granted d-jet did this with very complicated analog circuits it is the same concept as Speed-Density base systems today. Basically a look up table that returns the predetermined amount of fuel based on the inputs. Some shortcomings of this sort of system ANY changes to the engine that impact airflow at a given RPM and load result in your mixture being off as the engine is flowing differently than the ECU was set to fuel. So displacement change, cam change, possibly exhaust changes and even engine wear over time will throw your mixture off.


L-jet actually measures the airflow via an early airflow meter so when conditions of the engine result in airflow changes at a given operating state you still have an accurate mixture as its measuring the airflow and not calculating it from a lookup table based on other factors.

I imagine Bosch and VW moved to it as a cleaner, more efficient way of fueling and the 914 got it as a result of the VW product offering changing.




Porsche did actually wind up eventually doing away with D-Jet on other variants of the Type 4. The 1976 912 E got L-jet on the 2.0 Type 4 (914 motor) Had the 914 survived longer I suspect all motors would have received L-Jet. Suspect it didnt in 76 as the 76 cars were basically Porsche clearing out the remaining parts from 75.

correct answer. way simpler. way cheaper. emissions emissions emissions.

D jet by Bosch (Germany) is Electrojet by Bendix (Chicago).
They bought the patents or the license when Bendix and Chrysler gave up.
L jet is the native german system. completely their own idea.

and.......it wasn't anything to do with Porsche. or Porsche's choice.
100% VW.
VW backed Bosch on D Jet even beore Mercedes Benz decided to dip their toe in the water, despite being asked first. VW never hesitated. And they got L jet first.
Primarily it was all about VW engines. The 914 had one of those.

Porsche don't use L jet on their aircooled engines until the 964 comes along 15 years later. i think its on the 924. but thats a VW engine again. and i suppose its on the 928 or a version there of.
by then everybody was using L jet on everything pretty much.
or later versions of L jet.
yes - its on the 912E. but thats a VW engine. plain and simple. supplied to Porsche.

The VW 412 is numero uno for L jet. 3 months before the 914.
same 1.8 engine more or less. but the honour goes to the 412.
the California market VW bus is the 3rd car, about 3 months after the 914.

Production of the 1.8 in 74 is delayed by 3 months because the L jet components were new and in limited supply. a staged introduction.

thats not to say Porsche were sitting on the hands during all this.
no. they were developing this.
(finally found a decent image of one).


Click to view attachment


this would have been in the replacement for the 914.
intended for production in 1972/73.
its the engine (or one of the versions) for the aborted VW EA266 -Porsche Project 1966.
came in 3 cylinder and 4 cylinder laid flat version for what would have replaced the beetle. with power range from 50hp up to 110 hp. the 4 cylinder 914 would have got the 110 hp version along with a souped up version of the VW saloon. basically a Golf GTI before the GTI.

not sure what version of fuel injection this would have got. its hard to tell.
but it dates from 1967-1972 development period.

all under engineering direction of f. piech.
the idea was a modular engine family.
f piech was one hell of a evil genius.
but this project blew up in his face big time.

porsche were developing flat V versions of this for their own cars.
a flat 6 derived from the VW flat inline 3. and a flat V8 derived from the inline 4.

but it all got detonated.
so they battled on with the tail end of the aircooled cars while VW under a lot of pressure very quickly developed up the Golf and other water cooleds and cut Porsche adrift, terminating their development contract which had been in place since the end of WW2.

basically the 73 onwards 914s were never really intended to exist in f piechs masterplan for "world domination".

there is more to this too.
there was a rival proposal within Porsche engineering tor the VW beetle replacement.
piech won out.
i believe h. bott was behind the other one.
and guess what. the rival was a front engine inline with a rear transaxle.
for a beetle replacement.

what does that sound like. 924/928 anyone?

in common with both porsche engineering ideas was an absolute refusal to do front engine front wheel drive.

piech overcame his porsche rivals with his single minded edict that all cars, yes all cars had to be mid engined.

VW settled the argument savagely in 1972.
basically said you are all wrong.
and..........we are going front wheel drive front engined.
and by the way. bye bye.

VW does not get a lot of credit for what it was doing in the late 60s and 70s.
but it was really pushing it behind the scenes.

we all got L jet in cars thanks to VW. no thanks to Porsche.
VW did all the testing and proved its reliability in hand with Bosch.
and VW got first dibs as a result.

GM europe also put their money where their mouths were.
the Opel Kadet was #4 to get the system.

the rest of the USA battled on with strangled carbs and generally what is known as the maliase set ups until they got on the bandwagon.

Australia sat back like it usually does, waited until the american public had finished being used as guinea pigs and then just straight out applied the same regs to car design beginning in the 80s. by then it was japanese licensed versions of L jet on everything that came here.

no D jet was world wide techninja.

we had it down here. it was on the VW type 3 fastback top of the line model.
marketed as the "hot rod" engine. from around about 69 on.
pretty rare but basically first car with EFI in aus.
hardly any survive.

also a lot of the Lancias and Alfa saloons had D jet as an alternative to twin carb set ups.
again the D jet was more powerful. but expensive. on top of the line models.

a few other things floated around down here with D jet on them. I am pretty sure the big citroen DS also had it.

wasn't just the USA and was not about emissions at that stage in other parts of the world. it was more about high tech and power outputs.

L jet less so. all the VW models that had L jet in the USA were sold as twin carb versions of same engines down here.

i dont think we got the merc D jets down here that came out soon after the VW fastbacks. everything i have ever seen is dual carb set ups or mechanical injection during that era.

there is another reason for L jet and it being necessary in 1974.
i'd forgotten it but was a discovery in digging up all the "minutia" as steve calls it - for our L jet research.

VW could not get the 1.7 with D jet to work with automatic transmissions and pass CARB emissions regs (california) for 1974 calendar year. the D jet with auto could still pass USEPA regs for 74 but EPA was one year behind CARB.

that meant their big sedan/station wagon was a goner for 74 and they still wanted to sell it for one more year. the water cooleds were not ready.
and 99.9% of 4112/412s sold in the states were autos. thats what the customers wanted.

so.........L jet was absolutely the only way they could go with the type 4 engine.

only auto 412s as 4 door sedans and 2 door variants were sold in california in 1974.
no stickshift and no fastback version.

the 2 door fastback was sold in the rest of the USA with a D jet 1.7 in 1974 and only with a stick shift. very small numbers were sold. the rest were auto 1.8s as 4 doors and variants. there was some difference with california models i believe. no EGR in 49 states is think what happened.

so.......thats the big reason. the 1.8 low compression unleeaded fuel engine HAD to have L jet to get through california emissions with a slush box.

and.....that was it, VW just made the executive decision that all the 1.8s aircooled in the USA got L jet and committed to it.

rest of the world lost D jet on aircooled type 4 engines and they all reverted to twin carbs. no L jet in rest of the world. only in the USA.
i have a feeling that the 2.0L 914 engine in europe might have been it for type 4s with D jet from 74 on. not 100% but it appears D jet just stops around that time for the rest of VW range in ROW.

in europe the opel manta was released with L jet and became first car in europe market to be sold with it.

time line is
AUG 73 VW 412 (usa model).
NOV 73 Porsche 914 (usa model)
JAN 74 VW bus with 1.8 engine and auto box for california only.
MARCH 74 OPEL manta (german domestic market).

the member here who cracked all this open was @L-Jet914 .
he had the keys to the info vault and threw me a set.

thats when you realise a porsche 914 really was a marketing exercise as a porsche in north america.

behind the scenes VW-North America are handling the whole thing.
all the documentation for USEPA and CARB certification is handled by VW NA.
the 914s are lumped in with other VW models.
the documentation is not handled by car models but rather by engine types.
then the various models utilising the engine type are listed as subsets.
the documentation applies to engine by engine listings.'

and porsche are off on their own with the 911 models.
and all the documentation for their cars is submitted and processed by Dr. Ing Porsche Stuttgart etc. they have absolutely zero to do with US certification of the 914s.

so anything to do with those VW engines is VW doing it and making the calls.
and the other interesting thing is its ultimately VW handling all the warranty matters to do with the cars. like if your engine blew up. VW handled the new engine etc.
sure you went to a Porsche-Audi dealer but in the USA that was a subsidiary of VW North America.

this is despite or slightly against the idea that porsche take over responsibility for control of the 914 project from 1973/74 onwards. i think its a little more complex than that.
its more like VW pull out of it, and start to become more the builders of the cars and the suppliers of all its components. they still call shots because essentially they tell porsche what they can have for the cars from an available pool of components and secondly what they will certify and warranty in various markets in terms of those components.

@wonkipop I have no idea what your talking about

he he he.
those secret files explained it all.
quite clever those 1.8 engines.
all done by just taking a hose off and leaving it disconnected and slapping a different sticker on.

i got to the bottom of the auto box problem for VW.
they couldn't make their double vac distributor retarded idle work with a torque converter at the lights without it blowing the gauges down at the EPA when they stuck the hose up its backside. D Jet didn't have a hope in hell.

they just managed to do it with the 412 engine by deleting double vac and then going full tilt on NOX clean up at cruise with an EGR. dirty as hell at the lights though standing still. in between L jet cleaned it up just enough to scrape through.

wasn't really such a big deal for 914s. but they got the whole deal anyway in slightly less compromised form. at least for 74.

the top pick is either a 74 49 states 1.8 or a 75 california 1.8 (believe it or not).
the 74 cals and the 75 49 states ran hot at cruise (at least if you left them the way tney came from the factory without the advance can hooked up).

I can see why they left the vacuum hose on the advance side of the vacuum advance/retard unit on the distributor and tucked away for CA certified vehicles because as the ignition curve advances it increases NOx. Being in CA their emissions standards are nuts so 1st thing to go after would be NOx and then HC and CO. So I don't know why mine was reconnected by whoever connected it onto the second port on the t.body.

so that it only did the NOX reduction thing at idle at lights/standstill - but behaved like VWs were expected to at cruise. run cool. run economically. and run a bit smoother on and off the throttle at cruise. someone in the know did the obvious thing. i think back then the VW dealers understood what was going on with that hose and "on the QT" probably advised - here do this.

all you would had to do was disconnect it again for annual smog. and afterwards re-connect it.

the problem with the 75 state engine (which was identical to 74 cal) was the throttle body appeared to have a vacuum port delete - at least from factory. so you had no choice. i think the 74 calis had a cap over the port you could remove and connect hose.
but again anyone in the know could have just installed a 75 Cal TB or a 74 49 state TB and problem solved.

the 75 cali had an EGR. so even though ignition retarded for NOX reduction at cruise it had the TB port like the 74s and it was connected to EGR. EGR helped the engine to run cooler and cancelled out effects of retarded ignition a little. also restored some fuel economy.

i think what has happened over the years is the knowledge has been lost as to just what that double vac can dizzy and the two hoses did. of course in aus 30 years ago it was completely esoteric. all the cars here just had the single advance can dizzy.

-------

when i posted above i said that no L jet VW aircooled type 4s ever came to australia.
i'm not sure if its true but i do now remember a story from back in the 90s from a VW bus guy i met from time to time. and he told the story as we was looking over the engine of my 914 at some historic races thing i went to. he claimed a small batch of 1.8 L jet buses came into Aus in the mid 70s sometime. he said they were fully imported from germany unlike the more usual CKD buses (complete knock down) that were being brought in at that time after local production had ceased. if that was true i have never seen any of them. must have been a very small batch of cars. most all i see of the later buses are the 2.0 twin carb ones.

@technicalninja

here you go for some "world wide" D jet.
sorry to side track off L jet.

a mate of mine's lancia saloon.
neat little car.
still running its original D jet.
think its a 72 but don't quote me on that.
(has a 5 speed box with identical dog leg shift pattern to a 914).
there were quite a few of these in aus.
i believe they were preferred to the twin carbs. did not go out of tune.
but kind of intimidating to your average fix it again tony mechanics.
you had to find a rational german to look after it because the italians got hysterical.


Click to view attachment
Click to view attachment

he had a pile of swedish rust under a tree a few feet away from it.
under the faded paint and oxidation also lurked an intact D jet system.
74 SAAB.
i scored a fuel pump off it as a spare for my 914 before it went to the graveyard in the sky.

Click to view attachment

most of the SAABs that came here in early to mid 70s ran D jet standard.
and there were lots of these SAABS.
they sold like hot cakes. great cars actually.
very sad that SAAB keeled over.

D Jet was more common than you think. on a lot of euro cars of that era.

@wonkipop

Thank you for all of your knowledge!

The early history of German fuel injection is very interesting.

Even more so that Bosch bought Bendix patents.

I thought Bosch was OG on all of their stuff.

World-wide to me means more than Europe.

Seeing D-Jet across Europe doesn't surprise me at all.

I "lump" Australia in with Europe due to the "English" component.

This is probably unfair as the USA had that same component (till we chucked them out!).

I see L-Jet as the ancestor of all modern port injection.

What would be VERY interesting is the "number of units made" of each style.

I'm not sure of the "death date" of L-jet. I see Motronic as a modern digital version of L-jet. I am probably wrong.

I, also, cannot pinpoint an American car that used the first version of L-Jet so even L-jet is not "World Wide" using my designators (actually manufactured on all continents).

By the time L-Jet added computer control of the ignition, MAP and MAF sensors, potentiometer on the throttle, and O2 sensors it went mainstream on American stuff as well.

I don't know if it was still considered L-Jet at that time.

I cannot remember a single American car with an AFM...

Maybe there is one!



Now, impress me!

I'd love to know all about the earlier stuff...

I'm speaking of the mechanical injection on the 300SL Gullwings/roadsters

Was that the same (I believe Bendix) as the early FI in American stuff (57 FI Corvette)?

I don't think it is. I think the early Mercedes stuff is more like diesel injection (or Spica) but have never heard a good explanation.

The above might be better in another thread.

Sorry if I've ruffled feathers...

Didn't mean to.

What was the first FI actually made in Australia?

The first American stuff has the word "Bosch" imprinted on most of the components...

No ruffled feathers here...we are here in part to learn from each other.

From the great Wikipedia:

"The Electrojector was first offered by American Motors Corporation (AMC) in 1957.[3][4] The Rambler Rebel was used to promote AMC's new 327 cu in (5 L) engine.[5] The Electrojector-injected engine was an option and rated at 288 bhp (215 kW).[6] It produced peak torque 500 rpm lower than the equivalent carburetor engine[7] The cost of the EFI option was US$395 and it was available on 15 June 1957.[8] According to AMC, the price would be significantly less than Chevrolet's mechanical fuel injection option.[9] Initial problems with the Electrojector meant only pre-production cars had it installed so very few cars were sold[10] and none were made available to the public.[11] The EFI system in the Rambler worked well in warm weather, but was difficult to start in cooler temperatures.[8]

Chrysler offered Electrojector on the 1958 Chrysler 300D, DeSoto Adventurer, Dodge D-500, and Plymouth Fury.[9] The early electronic components were not reliable in an underhood environment and were not easily modified as engine control requirements advanced. Most of the 35 vehicles originally equipped with Electrojector were retrofitted with 4-barrel carburetors. The Electrojector patents were subsequently sold to Bosch.

Bosch developed their D-Jetronic (D for Druckfühlergesteuert, German for "pressure-sensor-controlled"), from the Electrojector, which was first used on the VW 1600TL/E in 1967. This was a speed/density system, using engine speed and intake manifold air density to calculate "air mass" flow rate and thus fuel requirements. This system was adopted by VW, Mercedes-Benz, Porsche, Citroën, Saab, and Volvo. Lucas licensed the system for production in Jaguar cars, initially in D-Jetronic form, before switching to L-Jetronic in 1978 on the XK6 engine."

Druckfühlergesteuert...

Now, there's a mouthful!

I've got one of your L-Jet harnesses that I bought from another member with a "complete L-jet system". Your harness is the MAIN reason I purchased it.

Truely WORLD CLASS.

You KICK ASS on harnesses, Sir!

You could probably sell the same basic critter to the Z car world as well...

Thanks!

Then there was also Rochester Ramjet for certain American muscle but it was a mechanical-based injection that died on the vine:

"The Rochester Ramjet is an automotive fuel injection system developed by the Rochester Products Division of General Motors and first offered as a high-performance option on the Corvette and GM passenger cars in 1957. It was discontinued partway through 1965 in favor of the Chevrolet Big Block as a performance option.[1][2] Unlike electronic fuel injection systems that would become common decades later, the Ramjet is purely mechanical and relies on vacuum and pressure signals to measure airflow and meter fuel.[3]"

And here's the REALLY sad part...

Just before I was born my dad was SCCA racing a 1957 Corvette "Sebring Special".
This was the car you ordered from Chevrolet to go racing...
It had ALL of the performance RPO and NONE of the luxury RPO.
FI, super T10, LSD, sinter-metallic brakes, soft top, ram air intake.
Radio delete plate, no chrome, even the "cove" was body color.

The baddest of the bad...

Hard to say what that car would be worth today. I'd guess 7 figures

He sold that and replaced it with a Convertible D (which he aslo raced W-W) right about the time I was born.

The D was special as well...

@technicalninja

mr. b (Jeff Bowlsby) knows everything there is to know about D jet.
i've never owned a D jet i only know the history in a typically skim the surface way.
though digging out precise times and dates from obscure documents is something i have enjoyed regarding L jet. i've got an emotional stake in L jet and even 30 odd years ago when i got the car i knew it was significant for being the first car with the system.
(or so i thought until 3 or 4 years ago when i discovered it was actually the VW 412 - but if we say its the 1.8 air cooled engine in both cars then its true it was the first).

yes - basically D jet is an american home grown invention you might say.
D jet owes a tremendous amount to the schematic layout and elements of the Electrojet system.

I believe somewhere in the USA a person owns the only surviving intact specimen of this system. it was fitted to a certain low production chrysler model.

as to mercedes benz and their mechanical fuel injection systems.
as for instance applied to the gullwings, or stirling moss's famous racer.
straight from WW2. virtually the same system that went in the BF 109 fighter plane.
why....germany relied on artificial synthetic fuels made from coal processing.
very low octane. the engines needed mechanical fuel injection and superchargers to match the performance of british spitfires etc. the engines were also inverted in 109s so they could run the destructive 20mm cannon straight through the centre of the crankshaft. i think fuel injection was almost necessary to run the engine upside down so to speak. if you were in a 109 and you wanted to escape a spitfire you put it into a negative g at the top of the curve dive. the spitfire would stall trying to chase the 109.
until there was some kind of mrs shillings orifice or something like that to fix the problem of the carbies on the english engines.

but i digress. none of that stuff is electronic fuel injection. purely mechanical.

porsche were the same about injection. everything had to be for racing. at least during f. piechs time there during the 60s. so it was mechanical mechanical mechanical, even in the road cars.

i guess the point about L jet and its been made a million times is it was simple simple simple and cheap cheap cheap(er) than anything that had come before it.
still more expensive than a carby or two but.........if you are making a mass market car in huge numbers with a tiny engine that is going to be massively crippled by emissions laws you know its the only way you can go.
VW had its backs to the wall when it came to the USA market after the Nixon Clean Air Act of 1970. when bosch engineers rocked up with a fastback clandestinely fitted with a prototype system in the mid sixties, VW did not even hesitate. straight into it. lets go sort of thing. its a well known and often told story. about the merc sedan and the VW type 3 that were driven straight to the VW and Merc engineering departments with the keys tossed to them for a drive. birth of D jet.

i might add @technicalninja
there is very little written about the history of Ljet and its development.
even by bosch themselves.

its possible texts exist in german and are held in technical universities in germany.
but i have not found anything in searches.

i don't even know who the main mind behind it was.

but its a classic bit of avant garde modernist thinking.
its called inversion.
you rigorously observe the opposite principle.
you force yourself to think the opposite way from the way it is.

thats basically what they did.
thought of it as the opposite of D jet.
thats a very smart way to go about things.

regarding australia and lumping it in with the rest of the world.
very american attitude. no offense taken.
post WW2 australia is riven politically and economically by two tensions.
the establishment tied to the british upper ruling class and the aftermath of its origins as a colony and their interests in the "mother" country.
and a new emergent group allied to the United States and its vision for the pacific post WW2. despite the awfulness of WW2 and the aftermath of the Japanese being the enemy Australia was one of the first countries to really open itself culturally and economically wit Japan. we supplied them with iron ore etc etc.
we got all their cars before you guys.
we were the guinea pigs for the japanese export car market.
it all came here and got tried out before it was sent in big numbers to you guys.

i believe some of the earliest datsun 240Zs ever made came to australia before they even hit the domestic J market. it helps to be right hand drive when it comes to japanese product.

secondly a massive immigrant population post WW2 of greeks, italians, germans. lithuanians, russian jews. you name it fostered the import industry of european cars.
alfas, fiats, lancias, VWs, Porsche, Mercs, Citroens, Panhards, on and on.

the only carmakers to suffer defeat were you guessed it. the mother countries rolling junk piles. morris, austin, shaguars, etc.

@technicalninja - re first fuel injection made in australia?

well the australian auto industry (home grown sort of but not) was as the industrial outposts of FORD, GM and CHRYSLER.

Leyland was a player in the 60s and early 70s. a better word though would be loser.

FORD tended after the 60s to allign itself with Ford Europe.

GM similarly so.

Chrysler did not. and local Chrysler folded first.

all the gear on the Fords and Holdens is bosch.
it starts being fitted in the 80s and 90s.
bosch had a local operation too, but not sure to what extent exotic components such as ECUs etc were made here. doubt they were. but don't really know.

all irrelevant now.
the industry folded in the early 21st century.
a tragedy i might add in my view.

Two ways to measure load on an engine.
Manifold vacuum- D-jet, also MAP sensor. Can calculate load
Weight of air- maybe more accurate in operation than MAP, L-jet K-jet also MAF sensor.
This actually measures the amount of air being consumed.

All modern stuff I work on has BOTH now...

It's helps to get all of the available data.

This is a NICE quick read regarding Bosch Jetronic overall. I have learned the "death date" of L-jet and it happened exactly as I described...

I also learned that "Mono-Jetronic" exists.

Chevrolet TBI! Ford CFI!
Millions of them...
Only uses a TPS to determine load but totally dependent on O2 control.
Super simple.

https://en.wikipedia.org/wiki/Jetronic

yes @technicalninja

the old 02 sensor.
the next big thing.
and a massive investment by bosch.
bigger in someways than the whole development behind the earlier efi systems of D jet and L jet.
bosch controlled the patents on that after they finally succeeded.
its made them a fortune.

the lack of a suitable 02 sensor stalled the timeline of the Nixon Clean Air Act.
they were meant to get to a point in 1975 that they did not achieve until the early 80s.
the carmakers and (even bosch) simply could not deliver the technology to make the standards in the time span. The USEPA worked with the carmakers to amend the plan realistically. the 02 sensor was the critical bit needed.

the difference between CARB and USEPA was an agreement reached between the USEPA and carmakers as well to assist with the introduction of technology. more of less split the domestic car market in half and meant in any one year USA and foreign car companies only had to address 50% of the volume of sales to the new standards. the remaining 50% would use the californian stuff the year after in the other 49 states.

L jet evolves. quickly becomes L jet with added suffixes as the 02 sensor kicks in.

not sure when the last airflow meter is done. but i know that 964s had AFMs in the very late 80s. and some domestic sales australian stuff still had them in the 90s on new cars.

in the absence of an 02 sensor L jet is assuming load but its got no feedback.

it was able to do a better (more accurate) job guessing (or assuming) what that was than D jet could. but it still could not make the standards that were aimed for in 1970 for 1975. no one could.

ps @technicalninja

one of the cars that did have L jet here early on that i remember was the fiat x/19.
that was from the early 80s.
and i think all the third generation VW buses had it. they were called VW caravelles here.
the later ones had the water cooled boxer engines with L jet from memory.

there is no real enforcement of emissions standards in australia.
we don't have to smog the cars.
its more an informal thing where service shops are meant to ensure the car is tuned to the factory specifications each time it is taken in for regular maintenance.

the manufactureres are required to guarantee a warranty on emissions for a statutory period. i think its 5 years.
it is however illegal to tamper with the emissions equipment on cars and there have been cases where workshops have been fined if it can be proved they have removed or altered emissions equipment.

if anything was ever enforced in relation to historic cars my 914 would be so far in front of the aus standards in 1974 it would walk through it. assuming of course engine internals in good condition. but nothing is enforced in that regard. apart from your car cannot blow oil smoke. the cops will pull you over for that and give you a canary.
(yellow unroadworthy sticker). once its got a canary you cannot drive it on the road.

side track I know Toyota adopted the L-Jet system and improved on the system with their Denso versions and O2 sensors. My 1990 Toyota Corolla LE 5 speed with the 4A-FE engine had a vane air flow meter just like our 1.8L 914s. Toyota used that system up until 1992 on the corollas, 1994 on the Toyota pickup (US) 3VZ and 22R-E, Celica Supra with the 5M-GE, Toyota Supra with the 7M-GE and I can't remember what other models utilized that system.

@L-Jet914
yeah - in a similar vane (no pun intended) our workshop 1994 ford falcon ute (aussie ford) that i restored during lockdowns has a straight six with LE-Jetronic fuel injection.
pretty sure its a vane type AFM on it as well. have to check but i seem to recall its there.
fairly contorted plumbing on the fords of that era as they converted and adapted a very old design from the 70s first to cross flow and then to LE fuel injection. the model before it still had a carby with emission strangling. the commercials were the last to get the EFI system.

@technicalninja

and anyone else vaguely interested.
the original SAE paper written by the development engineers at Bendix behind the system. paper dates from the late 1950s.

for those of you with D jet you will recognise all the components.
including the operation of the lower half of the ignition distributor.

some of you probably already have this paper.
i would imagine mr b. ( @JeffBowlsby )has it stashed away in his files.
i found it in an obscure section of junk i had filed away on origins of L jet.



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never been able to find any contemporary papers or such on L jet dating from the time of its development.
i guess it was all ho hum by that point in time and no big deal?
all part of the general horror of emission controls negativity.

in the main bendix got done in by external electronic interference of the electronic control unit. vulnerable to electric fields etc. at least understand that appeared to be what caused huge problems and was not detected during factory testing. or as some stories go bendix did not get done in but chrysler perhaps failed to execute to the necessary high standards for components. (bean counters at work?)

bosch cracked it. made a better shielded control unit. took them a lot of hard work though. i believe bendix made money out of every bosch unit sold. good way to make coin. like printing money?

So L-jet was on VW buses and 412s starting in 1974.
So there it is. I thought VW was using D-jet on the late busses. But that's the business case for it.
I am very surprised that L-jet did not replace D-jet across the range if it was cheaper and better, but I suppose that the D-jet components had already been purchased and it made more sense to use them up.

Loving this thread on the 914s weird middle child.

Zach

the answer to that one is not too difficult Vacca.

USA Fuel regulations. easy to forget but USA is introducing unleaded fuel way in front of other countries. The 2.0 L porsche tweaked 2.0 had already been developed with that in mind. it comes way after the VW 1.7 engine which dates from 1969.

there was always two versions of the 2.0
euro with 8.0:1 compression - ran on 95 RON.
USA with 7.6:1 compression - ran on 91 RON
the USA 2.0 was able to run on unleaded fuel from the get go.
unleaded when first introduced could only be formulated with a low octane rating.
compression ratios had to come down.
no need to rethink the 2.0L, they could just leave it alone until the end of its production run. it was a 914 only engine anyway. the numbers were not there to bother with deveioping a special engine with new injection. at best 10,000 engines in 73/74.

The 1.7 engine had higher compression than the 2.0
8.2:1 - ran on 98 RON. world wide.
and once they dropped the compression ratio for california in 73 it was a disaster.
horsepower dropped from half respectable 80hp to 73hp.

time line on fuel was -
in 73 all new cars in california had to be able to run on 91 RON unleaded.
rest of USA in 74.
and worse - in 75 california by law had restrictor in filler and would take only unleaded 91. (Suspect thats part of the reason for later plastic expansion tank on fuel tank - its designed with the restrictor in mind).

and VW production needs on the 1.7 (smaller engine) were much larger numbers. 412/914 + Bus for first time.
so that engine got reworked.
had to be bigger to compensate for lower compression for 91 RON.
+ the engine was going to go on in the bus at a minimum so they gave it the new EFI system.

gradually everything VW got the new system bit by bit including the beetle.

you can see the quandry for the last of the 412s in 1974.
the high compression 1.7 soldiers on with a 8.2:1 and will only take 98 RON.
could not be sold in california on fuel requirements alone.
and technically ought not to have been sold in rest of USA.
i suspect VW pulled the same trick as they did with the 76 914.
they probably only made it up until the end of calendar year 1973 which meant 1973 standards could be applied. technically it was likely a 73 for certification purposes but sold in showrooms as a 74 while stocks lasted.


here are the specs for the 74 412 from owners manual.

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i suspect that no matter what D jet hit the wall emissions wise by 75.
the 76s never met 76 emissions standards and certification.
were sold as 76 model year but under the certification regime were classed as 75s if manufacture ceased by end of calendar year 1975 - which they did.

hence the 912E gets L jet. would probably have been too strangled dowb with D jet.
it is a certification standard 76 MY car.
as it was the L jet on the 912 copped a lot more gear on it than the last of the 1.8s.
smog pump for instance. no 914 L jet had a smog pump.


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and one last thing to bear in mind. L jet did not require payment of a royalty stream to bendix. not as far as i know. so bosch could turn that drip off once they finished with D jet.

far as i can work out last car to ever have D jet was the Jag V12. finished up in 1979.
probably went on that far because it was a specially developed developed system for 12 cylinders and they milked it for as long as they could. there was something funny about d jet that meant it worked in multiples of 4.
4 cylinders. 8 cylinders. 12 cylinders etc. jeff bowlsby would know exactly why that was.

So if this was the case:

i suspect that no matter what D jet hit the wall emissions wise by 75.
the 76s never met 76 emissions standards and certification.
were sold as 76 model year but under the certification regime were classed as 75s if manufacture ceased by end of calendar year 1975 - which they did.


Why are 76 914s subject to smog testing in CA? I mean, they should only have to meet the 1975 standards which is no smogging.

your logic makes sense...
but I would guess the state didn't want to have to consider each and every different manufacturer... who was a grandfathered car from 1975 and who had built an entirely new model that needed to be certified...

so they just chose a year for the cut off without the extra work of deciphering which cars had 75 equipment and which did not.

Djet is bank fire. 2 banks. For the 914, it’s 2 banks x 2 cyl. The 6cyl BMW E9 is 2banks x 3. MB V8 is 2 banks x 4. I can only guess what the jag is.

All the L-jet I am familiar with is batch in the same breakdowns.

L-jet touched OBD2 and maybe was sequential, but I'd expect the sequential shift with Motronic...

The L-Jet fires all the injectors together at the same time, but half the pulse width of a batch or sequential injection system.

VW and Porsche dropped electronic injection in favor of CIS until the 3.2 Carrera, so development of the L-Jet system was never present on any Porsche.

Motronic did not go to sequential until the 964. The 911 3.2 Carrera was just a more refined L-Jet system with ignition control.

L-Jet is a definite improvement over D-Jet. Adding a hot wire MAF instead of the Vane air meter was a substantial improvement. While VW and Porsche were building CIS cars, Volvo implemented the LH-Jetronic in the 80s on the turbo bricks.

VW, Audi, and Porsche went down the CIS rabbit hole and it was a dead end. So they lost a lot of ground on L-Jet/Motronic.

i knew there was something weird about it.
old f piech would have had trouble with his odd cylinder engines he liked so much.

got no clue as to the jags.
never even seen a jag V12 in the flesh from that time.

yes

this was gone over in another thread.
apparently some time back in the past (like 20 years ago?) some owners of 76s did manage to get their 76s exempted. on that very basis. i


you could probably do it now too, but its a fight with a dumb bureaucracy.
so good luck.
you would be fighting the technicality that though the 76 was certified on the basis that it complied with 75 emissions standards (legal under definition of when emissions standards apply per calendar year) they are also technically 76 MY cars. a classic grey area that bureaucrats can see one way or the other way.

i could try and dig up the topic and thread with a search when i get a bit of time.

its got the documents in it that define what standards were applied and when.

the 1970&1/2 ford mustang is another example of it.
rather than ford trying to make that mustang comply with 1970 epa standards that came in on the 1st of jan 1970 they stopped production on the last day of 1969. still sold it as a 1970 MY car and it was an update of the 1968 model year car.

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i'm guessing the way california looks at it is - the 76 is a 76 MY car and thats where they define the limit for smog test compliance on historic cars. and when it does it smog testing it must still comply with the standards it was built with. those standards are on the CARB certification on their records and files. which are 1975 standards. i have all the CARB docs for all the 914 MY years.

By now
All the forms have changed likely
Ha…. I work in a state bureaucracy

Here's the REAL kicker...

High end aftermarket ECU like the Megasquirt Pro that Clay is employing on his Godzilla car can not only do sequential but timed sequential...

You can time it from start of pulse, end of pulse, or, most interesting to me, center of pulse.

I'll tie center of pulse to LCA intake (intake valve fully open) and end up with the pulse firing INTO an open intake valve during its highest airflow point.

If you use a large enough injector, you can have as near to "direct injection" as possible without having to re-design the injector through the cylinder head.

Sequential injection that only fires when the intake valve is open is my goal here.

This is possible today!

The Megasquirt is not stupid expensive either.

nope.
still on file with CARB (California Air Resources Board).
it is what you and they refer to in establishing what equipment cars are fitted with originally and C0 etc levels.
you and i can go get them if you ask @L-Jet914 nicely -

its how they check a 76 complies.

ps
ii have a feeling that what might have hung up 76s for years might be lack of a cat and egr pipe exhaust system once the parts fell into unobtanium territory. but just say you had a 76 in intact condition with good internals, be no reason it would not sail through a smog check. everything on a 75 is exactly the same as a 76 and all same C0 levels etc.
so thats the parts pool. anything 75 cal spec.

different matter for a 912E. because they start producing it after jan01 76 its the world of 76 cal emissions standards. hence the L -Jet fitted and smog pump etc. but it does not have a CAT. instead it has the tin pot thermal reactor style exhausts that are supposed to do same thing as a CAT. again probably close to unobtanium.

All things considered how is direct injection beneficial to our aircooled cars given how it cakes up the valves? I doubt our injectors could tolerate that piston chamber exposure either.

Not a fan of DI.

neither am i. sh#t idea. i inherited a 2008 Audi A3 with a 1.8 turbo direct injection engine. fortunately one month before the dog engines with the dud oil rings.
i do double frequency oil changes on it to combat timing chain "stretch" syndrome.
its low mileage so i have kept it. 64.000 km total.

the direct injection was such a dud idea that VW put in two injectors in the third gen of these engines. one direct and one port, the port one being to clean the back of the intake valves. thats 8 injectors for a 4 cylinder engine.

we have given mine the subaru cocktail cleanser that you force down its throat and make it run for 30 minutes. known to work. and a whole lot cheaper than stripping off the intakes and walnut blasting as audi will do for you while shaking every last penny out of your bank account.

It's NOT economically possible to add true DI to a VW or Porsche engine that didn't come with it originally. (or ANY other manufacture)

The very best DI is now incorporating a secondary port injection system.
Mercedes is doing it with their 400hp 4 cylinder and Ford is doing it with the Coyote.
Mercedes and Ford are currently opposite as to when they fire the port system.

The "caking" up the valves problem is more excessive blow by reaching the intake over a direct problem with the injection. Having fuel washing over the intakes HELPS clean the valves better than anything else hence the addition of port. I think many will add some type of port injection to help with this problem.

A good catch-can can work wonders as well. I believe the most recent Eco-boost Fords come with a catch can like set up.

Now, IMO DI is a SHITLOAD better for one simple reason...

The fuel component of the air charge takes up approximately 9% of the total intake volume. If you remove the fuel from the intake track you get approximately 9% MORE air and an equivalent increase in power.
ALL ICE engines are oxygen starved. The number of oxygen molecules is the deciding factor regarding power, not fuel as many might think.
This is why when they change to DI it's ALWAYS a power bump.

They can do exotic crap with DI as well. Some system pulse the injection to make multiple squirts per combustion event. They have better control of the combustion event and run "lean-burn" strategies better.

I see the additional control that DI gives will allow 1 full point of compression to be added to the static compression ratio.

I'm a fan of DI.
It's forward progress for ICE.

I WOULD NOT try to install DI on something that didn't have it originally...

I'm going to cheat a port set up so I get SOME of the benefits of DI.

The biggest thing I'm going to change is the injectors spraying fuel into a closed intake. Just dumping fuel on the valve is NOT the way to make power.

Now, I wouldn't try to add it to an engine that didn't have it but...

I will, most likely, add an engine to a 914 that ALREADY has DI.

The engine in question makes 335 hp/285lbs.ft (stock with a restrictive intake and exhaust) and has a torque curve that makes over 250lbs ft over a 4K range.

It's a 3.6l 6 cylinder that weighs about what a 964 motor weighs.

It is 1/20 the cost however...

They are "dime a dozen" engines that have 11.5-1 compression ratios and can drink 85 octane fuel.

You can fuel it with mule piss in Mexico and it won't hurt it.

It gets good mileage in 4k lb cars. I'd bet it can equal the original mileage that a 4 cylinder 914 had in a 914 application.

The ONLY reason it can do this shit is the DI that it comes with...

Another engine I would LOVE to stick in the 914 is the late Cayman/Boxster 4 cylinders which are all DI.
A PDK would be a nice addition as well.