L-Jet on Euro Motor

Stuartc

True Classic
Hi, first post on here so hello everyonešŸ‘‹ . . Done a lot of reading here and elsewhere on the subject matter but nothing really specific.
First off 1988 Bertone X1/9 UK Euro motor with 24/66/64/28 Cam, Weber 34 DATR 85 BHP so completely stock.
What Iā€™d like to do is put the L-Jet FI on the car that US cars came out with.
Again a few things, Iā€™m aware of all the differences regarding head design so I know I will need to change thermostat housing to accommodate water temp sender and probably the thermo time switch and add aux air valve, O2 sensor etc.
Iā€™ve also read that Matt from Midwest Bayless said that on the US spec cars that if you raised the compression added either a set of headers or euro exhaust and cam that the motor would produce about 100bhp.
As the Euro motor already has the exhaust & camshaft & compression lift would it be logical that I would see the same power output and also will the std L-jetronic be able to accommodate for the cam, exhaust and compression of the Euro motor.
Iā€™m not looking for a race car just drivability gains primarily as Iā€™m fitting factory air conditioning.
Any feedback will be appreciated.
 
Hi and Welcome! Iā€™d read Steveā€™s Ultimate SOHC thread and take it from there. Seems a complex and potentially expensive way to get 15bhp by fitting injection IMHO.
 
Here:

 
Yes on all those.

As you will be doing a fair amount of fabrication, have you considered going to a MicroSquirt system rather than LJet?
Do you have all the parts for an LJet system? Both the ignition and fuel injection components, mechanical and electric?
LJet was ā€˜stand aloneā€™ meaning most of the rest of the car is untouched by its addition. For example the electrical side added one circuit to power all the injection components.

One subtlety that may be a bit more difficult is the fuel tank. Normally the injection fuel tank draws from the bottom through a 12mm orifice, as you know new fuel tanks are available which can be used for either carb or FI use.

If you went with a MicroSquirt system you would be able to use more modern components with elements which might be easier to source. For example one could use a DCNF or IDF manifold with associated throttle bodies from Jenvey or similar. Modern sensors could be used.

Yes there will be a lot of other work for a MS system but getting a ā€™goodā€™ LJet set up could be rather challenging as well. The advantage for the LJet is there is plenty of existing collateral information around debugging and so on.

MicroSquirt info here:
 
Here:
 
Iā€™ve also read that Matt from Midwest Bayless said that on the US spec cars that if you raised the compression added either a set of headers or euro exhaust and cam that the motor would produce about 100bhp.

I would say that would be pretty optimistic to think you're going to gain almost 20% increase by fitting standard factory EFI to a standard euro spec engine... but by all means do it and dyno it before and afterwards and let us all know.

SteveC
 
Thanks for replies.
Iā€™d be happy with the extra 15bhp if L-Jet will get me to 100bhp....will it thatā€™s what I would really like to know? Iā€™ve had advice from an engineer who said it may cause a loss of power!
The plan would be to fit the L-Jetronic System in itā€™s entirety and then maybe at a later stage transition to Microsquirt using the semi-sequential option available with microsquirt. But in reality Iā€™d be happy to stay with L-Jet if it works sufficiently well.
As Iā€™m fitting factory air (itā€™s hot here in Australia) the FI system will provide a better idle control.
Whilst Iā€™m not looking for a street racer Iā€™ve owned a ā€˜81 1500 which had twin IDFā€™s and I have fond memories of that combination very much suited the vehicles character.
 
I would say that would be pretty optimistic to think you're going to gain almost 20% increase by fitting standard factory EFI to a standard euro spec engine... but by all means do it and dyno it before and afterwards and let us all know.

SteveC
šŸ˜‚ Hi Steve!
So, question is ā€œI put the OE L-jet system on the Euro motor what will happenā€?
With your knowledge and experience can you give me the likely outcome?
 
šŸ˜‚ Hi Steve!
So, question is ā€œI put the OE L-jet system on the Euro motor what will happenā€?
With your knowledge and experience can you give me the likely outcome?
I've never bothered to do it, so I couldn't say.

But the OE EFI manifolding certainly looks to leave a lot to be desired from a flow perspective, I have one to test on my flow bench but havent got around to it yet, so I don't have hard data on the standard part to share. Pay me to test one of each and I could tell you.

Slightly more torque possibly due to the longer runner lengths, but I doubt it would allow the engne to rev as well (as the carb manifold) due to it's obvious flow restrictions .

SteveC
 
šŸ˜‚ Hi Steve!
So, question is ā€œI put the OE L-jet system on the Euro motor what will happenā€?
With your knowledge and experience can you give me the likely outcome?
I wouldnā€™t expect 15 hp. I would at most expect 5-10. Likely closer to the 5hp.

The biggest value of making this change would be better all around driveability. It will be quite a lot of work for a relatively small gain. US cars with carb and a 1500 went from 67 strangled hp with tons of ugly emissions equipment to 75 with the fuel injected version and much less extraneous stuff.

As a EU carb car had none of that other stuff you will likely see a somewhat similar improvement but not neccessarily as the Bosch ECU is tuned for economy and emissions versus outright power.

If you are interested in improving your cars output a pair of DCNFs would likely be a good place to start along with electronic ignition. Yes much more fiddly in day to day use.

Could you get to 100hp with FI? Yes but not likely with the stock US EFI system due to inherent limitations in the intake manifold, the vane type air metering system and so on.

Hussein and a few others have leaned pretty heavily into their EFI systems and achieved good gains but at significant effort. TonyK did a custom FI system which included a custom intake and engine mods on his ā€˜79 1500 carb car. It is an unusual install but one that is still running. Hussein has since moved on to a Honda K24 install. The documentation of what he did is still on the forum.
 
US cars with carb and a 1500 went from 67 strangled hp with tons of ugly emissions equipment to 75 with the fuel injected version
1979 carb usa spec used a 30/32 DHTA carb, pretty woeful as a prefomance carb, and going to efi on the same engine/cam/exhaust netts 8hp.

Euro spec already uses a much better inlet manifold and better flowing 34DATR, so the improvement in inlet flow would be significantly less than 8hp (if anything at all)

If your interest is to get better idle control for A/C, then you need a 34DATR(A) ... the second A is for Avviamento, which is the vacuum operated idle speed device - as found on australian spec 34DATRA carbs, but in that instance it's for idle speed increase for emission check, but the same device is can be used to increase idle speed for air conditioned cars (like a lancia or regata)

a lot simpler to mod or replace the carb than it is to retro fit EFI.

SteveC
 
1979 carb usa spec used a 30/32 DHTA carb, pretty woeful as a prefomance carb, and going to efi on the same engine/cam/exhaust netts 8hp.

Euro spec already uses a much better inlet manifold and better flowing 34DATR, so the improvement in inlet flow would be significantly less than 8hp (if anything at all)

If your interest is to get better idle control for A/C, then you need a 34DATR(A) ... the second A is for Avviamento, which is the vacuum operated idle speed device - as found on australian spec 34DATRA carbs, but in that instance it's for idle speed increase for emission check, but the same device is can be used to increase idle speed for air conditioned cars (like a lancia or regata)

a lot simpler to mod or replace the carb than it is to retro fit EFI.

SteveC
Yes I noticed you had a DATRA from a Lancia available but looks sold now?

Idle control is part of what Iā€™m trying to achieve for the A/C and if I have to fit a DATRA or instal the fast idle device onto my existing DATR (if possible not looked into that as yet) as the part is listed p/n 9936515, then will do that in the short term.

So Iā€™m deducting that the FI induction system will not give me the ā€œRev off the dialā€ my last twin carb setup gave me on my ā€˜81 with same engine I currently have but I still like the idea of having FI if it gives me a modest improvement on the 85bhp I have std.
The retrofitting doesnā€™t phase me as Iā€™m going to have it all apart anyhow. Iā€™ve already run the extra wiring from the junction box to the spare tyre well for the multi relay as it was easier to do it now whilst I was running the extra wiring for the A/C & new Trinary Safety switch.

I only know of one person whose done this on an early 1500 in the UK but he never really gave a thorough assessment of the resultšŸ¤·ā€ā™‚ļø
One further question Steve, you say the induction manifold is restricted but doesnā€™t the Uno Turbo mk1 run the same induction plenum & runners?
 
Back when I was autocrossing my 1300 '74 X1/9, I fitted an aftermarket FI system using the US L-Jet spec manifold. There are a few things to note about using this manifold and the L-Jet system.

First, the L-Jet's biggest limitations are the air flow meter and its crude controller. I have tried to makes gains on FI cars using the L-Jet system and found the effort to be mostly wasted. The L-Jet system is really only good for improving reliability and drivability. There is little to be had in the way of performance improvement over the proven carb upgrades.

Second, the L-Jet manifold isn't as bad as you might think. With the air flow meter removed the manifold will respond well to modest porting. You can't make the manifold breath like a DCNF manifold because the runner OD is to small to accommodate much porting but you can open it up enough to generate reasonable flow.

My 1300 was a very carefully built unit. It was bored .040 over and fitted with Malhe OE spec pistons. The head was milled to the factory service limit, a service manual spec valve job and port match completed the work. I used an OE cam and pulleys and the entire engine was carefully blueprinted and balanced. This build was to the full extent permitted by the rules package the car competed under. I used a custom header and exhaust along with the ported FI manifold and a DFI (Digital Fuel Injection) ECU.

I should note that much of the gains I realized were from time spent on the dyno programming the fuel and ignition maps. The motor made about 80 wheel HP at 7000 rpm. Remember, this is on a stock cam with a small increase in compression.

I later built a 1500 to similar specs; balanced-blueprinted, head milled to service limit, port match, etc... It had a greatly improved header/exhaust system and a carefully designed individual runner (slide throttle) intake manifold, both tuned to make maximum torque. The engine made just under 90 HP (4500 to 6200 rpm) with just under 100 lbs/ft of torque (at 4250 rpm).

I never ran the L-Jet Manifold on the 1500 so I don't have that data.

My conclusion from my experience, given your questions, would be; I would only bother using the L-Jet manifold is it was ported and fitted with the MicroSquirt control system. And then tuned by an experienced tuner. I think you would be quite happy with the results.
 
but doesnā€™t the Uno Turbo mk1 run the same induction plenum & runners?
yes it does, but pushing the air thru a port is totally different to drawing the air thru, so I don't see your point?

there are certainly benefits to be had from porting the OE EFI manifold, but you're not saying you're going to do that....

if you're after a performance increase, there would be far more to be had via properly porting the head, as per published results, that's no cam change, no compression increase, no valve size increase, no carby change, no exhaust change and it goes from 62 wheel HP to 84 wheel hp from a euro / UK spec 1500 carb.
headflow.jpg

SteveC
 
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First, welcome to the forum. :)

It cannot be argued that pretty much any fuel injection technology is superior to pretty much any carb technology. The biggest gains will come from better drivability (especially for a road car), more reliability, improved fuel efficiency, lowered emissions, and higher torque. That last item is the big winner here; torque is what makes a road car go, not HP. So all of the references to HP figures are only telling part of the story. The drivability/reliability factors are things like improved starting and warm up in all conditions, better control of idle speed - particularly with AC, better off idle and low end response, smoother running across the RPM range, increased efficiency, etc. Just ask yourself why every modern car in the world has FI instead of a carb? šŸ¤·ā€ā™‚ļø

As for the original stock FI on the US spec X1/9's, there are limitations. It was a early version of electronic injection. While it works beautifully (when properly sorted), there is more to be gained by upgrading it with some newer technology.

Taking bits of the comments already posted, I'd say the best option is to use the factory US spec (or similar) FI manifold, throttle body, fuel rail/injectors, and a few other related components, but ditch the air flow meter and stock ECU in favor of a aftermarket ECU...for all of the reasons already discussed by others. If it is more readily available for your location, then you can use the manifold/throttle body/fuel rail from pretty much any early Punto/Uno or similar Fiat, as they fit the same as the X1/9's (I'm using a Uno manifold on one of my X's). A later Punto item should offer a bit better airflow that the earlier versions. The fuel tank does not really need to be replaced, Bosch FI pumps are very capable of drawing the fuel up the short inlet tube in the carb tank with no issues - there are factory systems that do that reliability. You already have the primary wiring in place. A aftermarket ECU will have its own harness for everything else needed. Another major advantage to a aftermarket ECU is it will control the spark in addition to the fuel...a huge benefit. So the stock distributor/electronic ignition from a US spec FI engine will not be needed. However you will need to add a front crank pulley trigger wheel. There are a few options for doing that, as has been discussed in other threads. Yet another benefit to using a aftermarket ECU is it will offer a much better idle control system, eliminating the need for the Aux Air Valve, etc. Therefore the whole swap will be very easy, and frankly no more money (possibly less) than dual carbs...but with much better results. ;)

I can go into much more detail if you decide to go FI.

I realize there are a lot of die hard carburetor fans in the vintage car world who will soon post rebuttals to much of what I've said. After all, for a long time I was one of them. But like the cockroach I have evolved and therefore survived longer than the dinosaurs. :p
 
* Not mentioned yet, the cylinder head itself will need to be modified for the fuel injectors; the ports have 'scallops', making the gasket surface more teardrop-shaped than round. Easy modification, but will involve grinding.

Period Ferraris and Lambos (among others) used both K-jet and later, L-jet injection (separate airflow meters on each side of their V12s!) so these systems can't be all that bad...
 
I did a lot of the things mentioned in this thread when swapping the carbed 1500 with an UT engine.
I would go for an aftermarket ECU if converting to FI. Personally I like the MaxxECU. That will remove the need of (the flow restrictive) AFM and will make the build and tuning much easier. It will also remove a lot of obstacles such as idle control with AC. However, modern ECUs require modern sensors so prepare for extra costs.
Keeping existing tank is not a problem together with an aftermarket external electric fuel pump and pressure regulator.
I am convinced that going FI is the best way to modernize this engine and would make the car more reliable, quicker, cleaner and more fun to drive.
 
Well, you've got a lot of feedback.
I've done the swap on a warmed over USA version '79 1500 (mild cam, compression, header, 34 DMTR). I didn't notice any increase in power, but the drivability was much better. I think it was an upgrade for sure. One plus, with FI I was able to modify the air/fuel ratio at will, on the fly, with a rheostat wired into the water temp sensor circuit. On the downside FI added a bit of weight, and complexity. I didn't use the AUX air valve - didn't need it because I didn't drive the car in freezing weather. I DID try to use the AC idle up solenoid to increase idle speed at will, but it didn't work for me. Not sure why, but I didn't really need it anyway - I didn't have AC.
I had a donor car, so the swap was very easy, I could see where to mount everything, and I had all the parts. I was amazed at how may FI components mounted in locations that were already on the '79 body. I did have to drill a pretty good sized hole in the firewall to get the wiring into the spare tire compartment. I mounted the ECU on the distributer access panel, which I mounted inside the spare tire compartment. I found that it gave more room in the engine compartment and was easier to remove.
IMHO an FI 1500 w/AC is a relatively simple and worthwhile mod for any early (1300/4spd) car. I think adding AC would be harder than adding FI. I think that if you have access to all the stock FI bits you should make the swap.
 
I have done this exact conversion, with higher conpression pistons, euro cam and retro fitted all factory ljet components

I am very happy with it but the improvements i was after was mainly the drive ability and smoothness in a FI system not sure there was any outright horsepower compared to running an equivalent carb setup my goal also was as the car is not used everyday to get away from carb issues going out of tune, blocked jets etc so its more set and forget system

i have noticed cold start as a dramatic improvement, i can leave the car for weeks and car will start right up

happy to help document the process i went through for converting
 
One more thought on converting to FI. If your cam, compression, exhaust system, and/or other performance mods are significantly improved from a stock US spec 1500, then the bone stock factory FI may not be able to fully cope with the air:fuel ratio needs. That is due to the stock ECU not being programmable or adjustable. However utilizing a aftermarket ECU will allow the AFR to be dialed in to match any/all mods. It can even compensate for some components that might be slightly marginal for those mods. For example the stock fuel injectors do not have a huge flow rate, and if you modify the engine to the point that the stock injectors are struggling a little, then the ECU can be set to help compensate for that (to a degree). But if you go really big on the performance mods then you may need bigger injectors, and direct replacements for the stock ones are readily available.

And speaking of performance mods, that is another wonderful aspect to a programmable EFI system. With it you can do whatever you want down the road to increase performance - turbo system, nitrous injection, blower, 15:1 compression, radical head and cam mods, whatever.
 
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