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I've collected all the bits to do a full swap of my US 4.7 for an 86 Euro 4.7. Wondering on a couple things and hoping someone might have advice. I've actually currently got euro heads/intake on my US motor and I have a modified euro TB that accepts the micro switches.
Few remaining questions regarding the full swap:
(1) Is the L-Jet system capable of managing the fuel system for the higher compression motor w/ stock injectors etc.? (2) Can I keep the twin dizzys w/ the L-Jet or am I going to need to modify the ignition system or go to a single? (3) Does it seem possible to modify the euro heads to accept the cold-start valve from my car?
So you are planning to move from the LH system with the hot wire MAF back to the LJet system with the "barndoor" AFM and the infamous green wire in lieu of the CPS?
About 15 or so years ago I converted my Supercharged Murf928 US 81 to LH/EZF from a 1985 EuroS.
Originally Posted by Setzer
(1) Is the L-Jet system capable of managing the fuel system for the higher compression motor w/ stock injectors etc.?
Other people have done it. There's no way to "tune" the fuel or ignition with these L-Jet systems. There are piggy back computers that can be installed to go between the "barn door" and the L-Jet computer to adjust fuel.
The 944 crowd has developed an L-Jet to MAF conversion. I haven't spent much time looking into what they use, but something similar could be done with a 928 L-Jet.
However, the 944 doesn't have a factory MAF system to convert to like our 928's do.
Originally Posted by Setzer
(2) Can I keep the twin dizzys w/ the L-Jet or am I going to need to modify the ignition system or go to a single?
Technically yes with the thought process "anything is possible". But by the time you get this working properly you will have completed the majority of the steps to make the LH system work too.
Back in the day I contemplated installing the LH side first, keep it simple & not change too many things at once. By the time I laid out the plan, it didn't make sense so I just installed the whole system.
Originally Posted by Setzer
(3) Does it seem possible to modify the euro heads to accept the cold-start valve from my car?
You're causing me to really dig deep in my memory banks as I pondered the same thing years ago. I recall my plan had I gone this route, was to simply copy the CIS system and install the 9th injector in the plenum. As explained above, I never got that far since I installed the LH system.
Should be noted, you can NOT use the L-Jet low impedance injectors with the LH computer, you will fry it. You must source high impedance injectors, 24lb if you plan to keep it stock. I installed 42lb injectors from the start from the Murf928 Supercharger system. In order to install these injectors I used fuel rails from an S4 that were modified for better hose routing with the 16V intake and distributor caps.
Few things to note from my install
1. Crank sensor needs to be added to the back of the engine if you want to keep it "stock" and some kind of mount to hold the sensor. Twin Turbo Todd made me a mount which also acted as a jig to drill the hole in the upper bellhousing
2. You need a flywheel with a timing ring. I don't know the current availability of these. Some may suggest adding a timing ring to the front of the engine instead (common method when adding a stand alone system to an older car). I'm not a big fan of this idea since the stock location is an option. My philosophy is keep as much as you can stock, you'll have less problems. Also, these are a 100 tooth timing ring, not very common. Not sure how that will work on the front.
3. Ignition harness - I made mine from scratch and used a donor LH harness. The connector that goes between the computers is rather unique, I opted to use it since that carries the shielded ignition signal. Colin aka Lizard sourced me a harness piece to make this.
4. In order to tune the ignition, you'll need a Shark Tuner version 1 and the breakout box: http://www.jdsporsche.com/NEW%20Mk%2...harktuner.html
While I was sourcing parts for my project, many very knowledge people suggested I would be better off going with a standalone 3rd party ECU instead of trying to get this to work. There are many supporting reasons why this is good advice to follow, I went with the LH/EZF anyway because:
1. I already had a Shark Tuner 1
2. I like a challenge
3. It's fun to see how much you an do with stock parts
4. If you've never fully tuned a standalone system from scratch, there's something to be said for having all the base maps (warm up, start-up, cruise etc..) already completed.
Hindsight it might have been better to go with LH / EZK system from an 87+ 928. I recall I opted not to go this route for a few reasons like mounting the knock sensors and HAL sensor. You wouldn't have to install these, to make it work, but you'd lose the knock detection system. However the LH/EZK system is easier to tune since you can use the Shark Tuner version 2, which is less expensive and has additional tuning options.
My next project is my stock US 80. For this one I'm going with a 3rd party standalone ECU, most likely AEM Infinity from Beyond Redline in Green Bay. Why this system? Because my tuner friend knows this system like the back of his hand.
If you ponder the 3rd party route, you could still use the EZF ignition parts (twin dizzy, coils, twin dizzy) just make sure your choice of ECU can control those Bosch ignition amplifiers. I may do this just because I like the way the twin dizzy looks. Many will say "go with coil on plug", that is another option, but I don't feel that's 100% necessary.
Are you planning on swapping an entire LH Euro 4.7 into a US car that is currently L-Jet?
Or are you just planning on swapping the 'motor' part over, leaving the L-Jet in the car?
Those are two very different projects.
I've got a US 4.7 that is L-Jet and it has a lot of the euro goodies already grafted on. I'm trying to gauge whether it might be worth going the full monty and swapping over the whole euro block. Trying to get a sense if I can do that without major modification to harness, i.e. whether I can keep the L-jet instead of going to LH-jet
For instance, I am thinking that I may try to use a single distirbutor from the US car which the L-jet can run. I could also modify a 4.7 US head w/ bigger valves and use the euro cams. That would allow me to keep the cold start rather than using the euro heads where I would lose it. I already have a modified euro TB which takes the microswitches. Just wondering if there is anything else I am missing in this calculus and whether this plan is optimal from a HP perspective.
About 15 or so years ago I converted my Supercharged Murf928 US 81 to LH/EZF from a 1985 EuroS.
Other people have done it. There's no way to "tune" the fuel or ignition with these L-Jet systems. There are piggy back computers that can be installed to go between the "barn door" and the L-Jet computer to adjust fuel.
The 944 crowd has developed an L-Jet to MAF conversion. I haven't spent much time looking into what they use, but something similar could be done with a 928 L-Jet.
However, the 944 doesn't have a factory MAF system to convert to like our 928's do.
Technically yes with the thought process "anything is possible". But by the time you get this working properly you will have completed the majority of the steps to make the LH system work too.
Back in the day I contemplated installing the LH side first, keep it simple & not change too many things at once. By the time I laid out the plan, it didn't make sense so I just installed the whole system.
You're causing me to really dig deep in my memory banks as I pondered the same thing years ago. I recall my plan had I gone this route, was to simply copy the CIS system and install the 9th injector in the plenum. As explained above, I never got that far since I installed the LH system.
Should be noted, you can NOT use the L-Jet low impedance injectors with the LH computer, you will fry it. You must source high impedance injectors, 24lb if you plan to keep it stock. I installed 42lb injectors from the start from the Murf928 Supercharger system. In order to install these injectors I used fuel rails from an S4 that were modified for better hose routing with the 16V intake and distributor caps.
Few things to note from my install
1. Crank sensor needs to be added to the back of the engine if you want to keep it "stock" and some kind of mount to hold the sensor. Twin Turbo Todd made me a mount which also acted as a jig to drill the hole in the upper bellhousing
2. You need a flywheel with a timing ring. I don't know the current availability of these. Some may suggest adding a timing ring to the front of the engine instead (common method when adding a stand alone system to an older car). I'm not a big fan of this idea since the stock location is an option. My philosophy is keep as much as you can stock, you'll have less problems. Also, these are a 100 tooth timing ring, not very common. Not sure how that will work on the front.
3. Ignition harness - I made mine from scratch and used a donor LH harness. The connector that goes between the computers is rather unique, I opted to use it since that carries the shielded ignition signal. Colin aka Lizard sourced me a harness piece to make this.
4. In order to tune the ignition, you'll need a Shark Tuner version 1 and the breakout box: http://www.jdsporsche.com/NEW%20Mk%2...harktuner.html
While I was sourcing parts for my project, many very knowledge people suggested I would be better off going with a standalone 3rd party ECU instead of trying to get this to work. There are many supporting reasons why this is good advice to follow, I went with the LH/EZF anyway because:
1. I already had a Shark Tuner 1
2. I like a challenge
3. It's fun to see how much you an do with stock parts
4. If you've never fully tuned a standalone system from scratch, there's something to be said for having all the base maps (warm up, start-up, cruise etc..) already completed.
Hindsight it might have been better to go with LH / EZK system from an 87+ 928. I recall I opted not to go this route for a few reasons like mounting the knock sensors and HAL sensor. You wouldn't have to install these, to make it work, but you'd lose the knock detection system. However the LH/EZK system is easier to tune since you can use the Shark Tuner version 2, which is less expensive and has additional tuning options.
My next project is my stock US 80. For this one I'm going with a 3rd party standalone ECU, most likely AEM Infinity from Beyond Redline in Green Bay. Why this system? Because my tuner friend knows this system like the back of his hand.
If you ponder the 3rd party route, you could still use the EZF ignition parts (twin dizzy, coils, twin dizzy) just make sure your choice of ECU can control those Bosch ignition amplifiers. I may do this just because I like the way the twin dizzy looks. Many will say "go with coil on plug", that is another option, but I don't feel that's 100% necessary.
This is super helpful, thanks! I am actually wanting to keep things as simple as possible. Actually thinking I may try to use a single distributor so I can maintain my L-jet harness and even thinking I might modify US heads w/ 944 vales, rather than using the Euro heads, so I can keep the cold start. I know this isnt the route to the highest possible HP but I think should be a big a substantial gain about the standard US 4.7. Maybe I am wrong though.
Why not just put a supercharger on what yiu have that already works? If the end result is HP and Torque increases, I think a SC will net you more than any of these alternatives with a lot less work and complexity. Plus, with forced induction, a lot of those other gains from the Euro differences will be marginal. Cams are good, but intake runner size and other things make marginal differences when supercharged because the intake air velocity goes up so much. Also, for forced induction, the lower compression motor you may already have is a better candidate than a high compression motor.
I have a 4.7 with 4,5 cams that's supercharged on a k-jet system.
This is super helpful, thanks! I am actually wanting to keep things as simple as possible. Actually thinking I may try to use a single distributor so I can maintain my L-jet harness and even thinking I might modify US heads w/ 944 vales, rather than using the Euro heads, so I can keep the cold start. I know this isnt the route to the highest possible HP but I think should be a big a substantial gain about the standard US 4.7. Maybe I am wrong though.
Questions like this pop up from time to time, I kinda of went into auto-pilot with my response, I didn't realize you had the block too. Do you have any of the LH / EZF parts or harness or the proper flywheel with the trigger wheel? Camshafts?
My motivation to switch computers was better fuel / ignition control with the Murf928 Supercharger system.
It sounds like you're in the middle of this project, you have not fired up the engine with the EuroS bits installed yet, correct?
I seem to recall the throttle position switch can be used with L-Jet, the closed idle works the same and the WOT activates similar to the L-Jet micro switch.
Since you already have the EuroS heads I'd be inclined to use them versus trying to modify the US heads. There are other ways around the cold start function. Years ago @PorKen eliminated that circuit on his car, maybe he could chime in here. The CIS cars simply mounted the cold start injector on the front of the plenum, so there are other options to ponder.
Another random idea that has been discussed before, wiring in a manual button to simply fire the injectors on demand as needed.
The EuroS engine has a combination of higher compression ratio, larger valves, more aggressive cams, larger intake runners, larger throttle body and no "barn door", all combined to give the extra power. The early EuroS engine with CIS made only slightly less power than the later LH/EZF EuroS. Those CIS cars have the same ignition system as your car, unless those distributors have a different ignition curve. So IMO that should be fine with the current plan. The biggest air flow resistance that could hurt power is the "barn door".
I'm assuming you are still using the lower intake piece the throttle body bolts to from the L-Jet system? Did you grind out the area so that opening matches the EuroS TB?
Regardless of your engine management choice, it would be advantageous to find some EuroS camshafts. If those prove difficult or too expensive to find, a common stop gap is the 78/79 camshafts. More aggressive than what you have now and typically easier to find than EuroS units.
Another idea to ponder to go "all in" is what we call a "EuroS Hybrid" which uses a shortblock from an 85/86 for even higher compression and 5 liters. A few of those have been built starting with an early EuroS engine, retaining the stock ignition and CIS fuel injection.
Now that I think were are all on the same page, to answer the initial question: Yes, you can use L-Jet & stock ignition on a EuroS engine (or any combination of said parts). If anything I'd install an adjustable fuel pressure regulator in case you need to add a bit more fuel upstairs. Cannot get too crazy here or you'll be flooding out the engine at idle / cruise.
There are some other "tricks" using the coolant temp sensor to manipulate fuel delivery levels.
What about exhaust? The stock exhaust on the 16V cars is quite restrictive. At the very least find some stock manifolds off an 85/86 32V and eliminate the stock CAT in favor of a Y-pipe with your choice of high flow CAT (or leave it off).
I have run a lot of the components that the OP is mentioning, all with the L-Jet barn door and ECU, single distributor. I made a bracket to mount the microswitches on the Euro throttle body as well. I am using the L-Jet "U" below the throttle body ground out to match the bigger throttle body. I have used Euro cams onto U.S. heads, Euro cams onto two different Euro head types, I have used U.S. 4.7 block and pistons, I have used Euro 4.7 block and pistons, I have used 85/86 5L block and pistons (with valve reliefs cut). I am using Euro throttle body and plenum, but U.S. runners since the runners I got were CIS and don't hold the L-Jet injectors.
It is possible to adjust the fuelling with L-Jet. What you do is to unglue the lid on the AFM and there is a toothed wheel in there that can adjust the spring tension on the barn door; this has the effect of changing how much fuel you get for how much air. I have it written down somewhere which direction is tighter and which is looser, but I think it is somewhat obvious when you're in there. You have to seal the AFM lid up again well, since it is an air leak if you don't. I use a TechEdge Wideband O2 setup to monitor AFR, and am happy with it. I use it to get the barn door spring set properly as well. I use the narrowband O2 simulation output from the TechEdge as the input to the ECU and it works well. There is only the wideband O2 sensor present, with no physical narrowband.
For cold start there is both air and fuel to get fixed/adapted. For fuel I bought the plastic piece that mounts on the front of the plenum and moved the "9th" cold start injector there. I made an extension harness with parts I bought from eagleday.com to extend the original connector and power the injector in the new location. For air I kept the cold start Auxiliary Air Valve in the original L-Jet location near the back of the engine and ran a long hose, with size adapter, to the plastic piece on the plenum with the 9th cold start injector. Without this cold start cranking was very long, and I tried various other things. With this setup the cold start crank until running is very consistently under 2 seconds.
I have run a lot of the components that the OP is mentioning, all with the L-Jet barn door and ECU, single distributor. I made a bracket to mount the microswitches on the Euro throttle body as well. I am using the L-Jet "U" below the throttle body ground out to match the bigger throttle body. I have used Euro cams onto U.S. heads, Euro cams onto two different Euro head types, I have used U.S. 4.7 block and pistons, I have used Euro 4.7 block and pistons, I have used 85/86 5L block and pistons (with valve reliefs cut). I am using Euro throttle body and plenum, but U.S. runners since the runners I got were CIS and don't hold the L-Jet injectors.
It is possible to adjust the fuelling with L-Jet. What you do is to unglue the lid on the AFM and there is a toothed wheel in there that can adjust the spring tension on the barn door; this has the effect of changing how much fuel you get for how much air. I have it written down somewhere which direction is tighter and which is looser, but I think it is somewhat obvious when you're in there. You have to seal the AFM lid up again well, since it is an air leak if you don't. I use a TechEdge Wideband O2 setup to monitor AFR, and am happy with it. I use it to get the barn door spring set properly as well. I use the narrowband O2 simulation output from the TechEdge as the input to the ECU and it works well. There is only the wideband O2 sensor present, with no physical narrowband.
For cold start there is both air and fuel to get fixed/adapted. For fuel I bought the plastic piece that mounts on the front of the plenum and moved the "9th" cold start injector there. I made an extension harness with parts I bought from eagleday.com to extend the original connector and power the injector in the new location. For air I kept the cold start Auxiliary Air Valve in the original L-Jet location near the back of the engine and ran a long hose, with size adapter, to the plastic piece on the plenum with the 9th cold start injector. Without this cold start cranking was very long, and I tried various other things. With this setup the cold start crank until running is very consistently under 2 seconds.
This is exactly this kind of information that I was looking for- thank! Right now, I am thinking that I will run the Euro 4.7 block, plennum, TB, and runners. But then I'll modify a U.S. 4.7 head to take 951 valves and swap over the Euro cam so that I can just leave the coldstart exactly where it is. I'm sure I'll lose a little HP by not just using the euro heads but I'd rather simplify things as much as possible and it'll look cleaner vs. inserting in the plenum.
On the distirbutor, glad you can confirm I can just use the US single- hadnt gotten confirmation until now that anyone had actually done that.
I've actually already got the euro plenum/runners and a modified euro TB w/ micro switch bracket on my car. I've got the wideband bung that I plug into when tuning and have a rising rate AFPR but havent needed to play with the AFM spring yet.
But your comments give me confidence I can accomplish.
Anything else that I need to consider with this plan??? Nothing with the flywheel since I am not running a knock sensor, right?
The U.S. style cold start does look more tidy. This is what my cold start for Euro Heads with L-Jet looks like:
You can see that the required extension harness is quite short. The fuel is extended from the same place on the fuel plumbing the 9th injector used to mount, using a banjo connector.
You don't do anything with the flywheel because you don't need the CPS (the mounting hole for this is at the top rear of the LH block, above the flywheel). The green wire from the distributor tells the L-Jet ECU about engine position instead of the CPS for LH.
For exhaust I am using 85/86 32V tubular manifolds connected to a 928 Specialists Y-pipe, no cats. Stock from there back. Sounds goods but not crazy loud.
For exhaust I am using 85/86 32V tubular manifolds connected to a 928 Specialists Y-pipe, no cats. Stock from there back. Sounds goods but not crazy loud.
Yep, same as me. Round tube stainless exhaust manifolds I had powdercoated with hi-temp cerakote and then a stainless Y-Pipe and no cats, then a Borla cat back exhaust. My Y-Pipe is from 928MS though and to make the early car Y-pipe work with the later exhaust manifolds, have a gap filling connector piece from Motorsports in Utah (Dave).
I basically have the same set-up as you guys on there already. I dont have a good pic but I have the 85/86 manifolds as well. I have them going into a black Cerakote to a custom Y-pipe to 3inch since with two inline Moroso spiral resonators. I thought the Moroso’s would be way too loud but they’re actually a fantastic sound and they don’t drone at all on the highway. Moving out to California so I’ll have to stick a Cat back on there soon.
Pics for good measure. If my need for speed wasn’t so insatiable, I wouldn’t tear back into that beautiful engine bay again.
05-15-2020, 09:13 AM
Euro 4.7 LH-Jet into US 4.7 L-Jet
