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Ultimate v8 ?

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2K views 26 replies 8 participants last post by  Hans 
#1 · (Edited)
I have always considered the V8 EFI more problematic in the long haul than straight carburation. The other problem
with the NAS V8 as I see it, is it's dependance on the ECU. Is it possible to convert the NAS to straight carburation such as the Weber 500 (as per RPI ), go to mallory distributor, retain the cats, and still pass emissions? Would love to get away from all this computer controlled cr*p that really shouldn't have a place in offroading IMO.
According to RPI, their 4.6 engine via Weber gets up to 23mpg, 30% power increase, instant throttle response, and no flat spots.. they also claim that the Weber 500 float positioning prevents stalling at extreme angles when offroading. What disadvantage would it be for NAS owners in the US?
 
#3 ·
I can't speak about the RPI claims, but I can tell you the 3.5s and 3.9 we have set up with the Weber (Edelbrock) 4bbl on an Edelbrock intake don't get anywhere near 23 mpg... more like 16 mpg. Our fuel is a lot crappier over here than in the UK, so I think they would get better MPG in the UK even in the same vehicle.

and they do have a pretty good flat spot, even after re-jetting.
 
#5 ·
Hi Eric, don't have problems with the efi or ecu yet. My question is geared towards finding out what fellow D90 source members think on the subject. I for one dread the notion of either unit failing, as I would be stuck with no clear capability of field repair. Carburation to me seems more viable in that area. It seems that one of the incentives to convert to a diesel engine has also been no ecu and all the associated sensors, among the other clear advantages of diesels such as MPG, simple ignition, and water resistance. Wouldn't a carbed V8 address some of those issues?

ECR
I think RPI's claim of 23mpg is for the 4.6L stage 3 (whatever that means) with the 500 Weber.
I'm sure you guys know the details on the subject. Is our gas that bad??
 
#6 ·
Look up Megasquirt. Although it is EFI it is totally customizable, uses fewer sensors, rock-solid American ignition system, DIY, cheap and quite a few are running it n Rover motors - so the hard work is already done for you.

With such a system there is really no need for carbs.
 
#7 ·
When I owned a ECU controled 3.9L 90 I hated that engine with a passion. Everything was fine and dandy except for the MAF, distrubuter, O2 sensors, stepper, ECU, and the pile of other doo-dads that caused hours upon hours of frustration. I had to replace the ECU twice, the MAF once, o2 sensers and I switched to a mallory and never looked back on that one.
The problem wasn;t that things broke (well mabye)... things are bound to need repair, it is just the diagnosis and expence of the components that is a PITA. Plus as you mentioned... my ECU crapped out on the trail it was a HUGE PITA. I now have a 300tdi and love it, simple and effective. If I where to build a new rig for the trail (please?) I have considered a 350 due to the cost avaliability and simplicity and power, but it would suck down the gas.
 
#8 · (Edited)
I have both, carbed 3.5 in my 130 and EFI 3.9 in my Disco. Aside from the 130 being a better family camping vehicle it is the vehicle of choice now when I am going to be out in the middle of BFE. I like the idea of the simplicity of the carb system and being able to do fixes on the trail. EFI is better for extreme angle 4 wheeling but I have had my truck on some pretty good angles and it did OK. Fuel economy sucks but the motor has almost 200k on it. Power is fine especially torque, seems much better than the Disco.

There is a post on another Land Rover board right now about a guy who is looking for help to get his EFI Disco out of the mountains because of some computer glitch. I may get stuck in the mountains but it wont be because of a computer glitch.

There are pros and cons to both. I don't know why some feel the need to defend EFI so passionately? After all, people have been running some of the toughest trails in the country for decades with carbs.

Follow-up Post:



BTW I am using the Edelbrock manifold #2198 and 500cfm carb #1404
I believe there is a new carb out by Edelbrock that addresses some of the flooding issues, I think it is there AVI Series or something like that. Dont buy overseas for the parts, there is no reason to. All parts can be bought much cheaper here in the states. I found a Intake manifold on Ebay for $35.
 
#9 ·
Yeah, the edelbrock 500 carb should be fine. In fact, on this size engine a 600cfm will probably be too much. the 'Thunder Series' already included the spring loaded needles and seats, which prevent flooding at crazy angles.

However, there will be more changes than just a new manifold and distributor. You will also need to change the fuel system over to a low pressure pump, the one in there for the EFI system won't work.

If it will pass emissions, I honestly don't know. It all depends on the shop and local laws. No dealership or other strict shop would pass it because of all the components that have been removed, and I am not sure if the carb will run clean enough to pass the tailpipe test. Down here on Long Island, you would never get it passed. I don't know what the rules are for upstate NY where you are.

-Hans
 
#10 ·
Good info to know about the fuel pump pressure. I wonder if anyone has run a carbed Rover or D90 with Catalytic converters? It would be interesting to see dyno results.. Both of my previous Rovers were carbed. Both ran on extreme angles no problems. Seems that I worried less then. Yes the diesel is the cream no doubt about it. But the cream is very costly. Checking out carbed option in the future when and if an engine replacement is called for, would be great info to have as far as comparison to a diesel money wise, viability, performance, and efficiency is concerned.
 
#11 ·
The cost of the conversion should be pretty cheap if you do it yourself, the job is pretty easy. Just about any low pressure fuel pump will work. The distributor on mine is a no points distributor, same as my Disco. I am in the proscess right now of running a back up manuel fuel pump that will be flush mounted on the seat box and have a line routed into the tank. This set up will allow me to pressurize the tank incase of a fuel pump failure. I could just buy a spare fuel pump but it just wouldnt be as cool :D

There was a guy on Dweb who recently converted his Disco to a carb. I think he was from NY also.
 
#12 ·
Actually, you may not have to change the distributor either. It is a self contained unit, and doesn't require any type of signal from the ECU at all. In fact, the only extra connector on it is a tach feed running to the ECU, but that has nothing to do with the spark output at all, it only has to do with sending the RPM signal to the EFI system.

-Hans
 
#13 ·
thewap said:
Hi Eric, don't have problems with the efi or ecu yet. My question is geared towards finding out what fellow D90 source members think on the subject. I for one dread the notion of either unit failing, as I would be stuck with no clear capability of field repair. Carburation to me seems more viable in that area. It seems that one of the incentives to convert to a diesel engine has also been no ecu and all the associated sensors, among the other clear advantages of diesels such as MPG, simple ignition, and water resistance. Wouldn't a carbed V8 address some of those issues?

ECR
I think RPI's claim of 23mpg is for the 4.6L stage 3 (whatever that means) with the 500 Weber.
I'm sure you guys know the details on the subject. Is our gas that bad??

I don't like relying so heavily on electronics either but I like the way the EFI performs over a carburator especially at high elevations.

When my vehicles were carburators, points, condenser, and distributer I could almost always find a way to limp home if something went wrong. If my EFI electronics fail I am totally lost.

Funny thing is though, when I had the carb, points and stuff I often did have to work on it to get home. So far with the EFI I have not been forced to walk. But maybe it's because I can afford better cars than in the past?

I'll stick with the EFI but I do take extra food, water, and warm clothes when I wheel alone.
 
#14 ·
I like the hand pump idea, good back up series style. Yeah the mallory has also been on my mind.

I hear you about limping home with carbs. There was always a way. The only time I got stuck is with that little condenser sucker frying out. It leaves you stranded like a dead duck. But after that I always carried an extra condenser.

So far so good with the EFI. But after reaching 73K mileage, I'm starting preplanning for future likely scenarios.
 
#15 ·
Just got back from a trip where I was above 10k feet for 4 days. I was very pleased with the carb performance, although I was not cruising at highway speeds just crawling. At higher speeds I would notice it more but for creeping it was fine. I just checked the alternator and it is the same as the disco.
 
#16 ·
Coincidentally DFoc_t7 's recent thread on replacing his failed ECU relates well to my concerns. If we cannot source an OEM ECU for our D90's, we are forced anyway to find alternative solutions.. I am not sold on converting to megasquirt
type of set up.. Any thoughts?
 
#17 ·
For most people, Megasquirt is not a valid option. It's a VERY D.I.Y. type system, where you have to adapt the ECU to the engine you are using. In our case it's not as complex as most, since the majority of the existing parts can be used. But you do have to change the O2 sensors to standard types and adapt the wiring harness to the new connector. Then, you still have to tune the computer, which can take a while.

I do want to run the Megasquirt on mine because of the cost of replacement in some components that wouldn't be needed. Specifically the Mass Air sensor and ECU which are just really expensive. But I'm still waiting to hear if they are going to stop emissions testing on pre OBD-II cars down here, which has been rumored for a while. Either that, or if I finally move to Colorado Springs where they are halting emissions testing on January 1st. When that happens, I have a THOR manifold that I want to put on with a Megasquirt II computer.

-Hans
 
#18 ·
I just found out that in Upstate NY (Ulster) I only need the visual inspection (low emissions inspection). I guess that means to check if cats are tampered with. That and the basic safety inspection. Here is how the low emiss. reads:

What does the low-enhanced emissions inspection include?

The low-enhanced emissions inspection includes a gas cap check and a visual inspection to find evidence of tampering and to prevent malfunctions in the air pollution control devices. The test is done annually at the same time as the safety inspection..




Better check my gas cap:)
 
#19 ·
The gas cap check is just to make sure the venting is working properly.

The visual inspection, that would all depend on the shop you bring it to. Some of them might notice the carburetor on a vehicle listed as MPI.... and some might just honk the horn, blink the lights and send you on your way.

-Hans
 
#20 ·
I also looked at Magasquirt as a high learning curve mod - initially. After considerable research the hardest part is mostly solved - the fuel mapping. There are several success stories which I'll rely on to get 90% there. The final steps are to fine tune things but you get a lot of support from the community.

With version 3 due out it is ver tempting - if I wasn't stuck in OBDII hell.

Considering the current dilemna with ECU replacement, I would think you OBDI guys would be jumping on the MS wagon.

Do the research, you'll be pleasantly surprised.
 
#21 ·
Well, not many guys are willing to take a bag full of resistors, chips and transistors to solder together their own ECU. Personally, I didn't have much trouble with it until the engine in my CJ failed from age and oil issues. But it did run great.

Though I would highly suggest going with the MS-II system as opposed to the MS-I, since it offers support for the stepper motor and idle control. And later on, the Lucas distibutor can be converted to take a GM HEI module, including the 7 and 8 pin versions for full electronic spark control too.

-Hans
 
#23 ·
Is that for the 2.2 or the 3.0 board set? Most places I've seen selling the 3.0 set assembled are around $330 or so for MS-I and $400 for MS-II. The more robust flyback circuitry in the 3.0 as well as the IAC controll in the MS-II chipset really do make it a better system, as well as the expanded fuel mapping.

But then again, selling the old Lucas ECU and Mass Air sensor should pay for the Megasquirt and possibly even a wide band O2 sensor setup if you're lucky :)

That reminds me, I really need to order the MS-II daughterboard for my old 2.2 MS-I. I really want to get that IAC motor going in my CJ.

-Hans
 
#24 ·
low emissions check list

Here is the list from DMV for low emissions visual test in the Upstate area. I guess it rules out converting
to a carb:(:


  • Positive crankcase ventilation system (PCV) - 1968 and newer.
  • Catalytic converter (CAT) - 1975 and newer.
  • Fuel inlet restrictor (FIR) - 1984 and newer.
  • Exhaust gas recirculation valve (EGR) - 1973 and newer.
  • Thermostatic air cleaner (TAC) - 1984 and newer.
  • Air injection system (AIS) - 1984 and newer.
  • Evaporative emission control (EVAP) - 1984 and newer.
 
#25 ·
Interestingly, the EFI Defenders do NOT have most of that equipment installed.

The PCV valve, no problem
CATs, no problem
Fuel Inlet Restrictor, no problem..... it's at the gas cap.
Thermostatic air cleaner, we never had
Air Injection System, we never had
Evaporative system, easy to convert to use with carbs.

-Hans
 
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