NWA 280ZXTD Posted January 29, 2012 Share Posted January 29, 2012 Well I've been doing alot of research on here about the L4N71B Transmission and figured that you guys would want to see what I'm workin on. It started out when I bought an 82 Maxima with the LD28 Diesel and the L3N71B, and I then found an 82 280ZXT with a bad ECU and was able to pick it up for $550. Here's a run down of what I'm doing: Pulling out the L28ET and replacing it with the LD28 and fitting it with the turbo setup, and tracking down a L4N71B to keep down the revs on the highway. A few more details on the swap can be found over here http://nissandiesel.dyndns.org/viewtopic.php?t=2850&sid=9ca988e437ad19222572e33fc5d29844 Comments and pointers are welcome let me know what you think! Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 29, 2012 Share Posted January 29, 2012 Just a thought, why the emphasis on 'keeping the revs down' as the Maxima didn't have the higher ratio afforded, and the rear end was comparable to the Z? The LD is good to 5400 rpms from what I recall, meaning an early 5 speed with .85 OD and a 3.9 gearset would be good at redline of 125mph (even though non-turbo it will only do 112.) Lowering them somewhat if the car is driven at higher speeds (80+) for extended periods may be an advantage... What is the plan for 'turbo' as if you lower the rpms too much you end up boosting to keep the speed at the rpms, defeating the purpose of the diesel in the first place. Unless you are planning on a non-corrected fueling setup to try to completely burn the already mapped fuel. That may work to your advantage but it may be better to keep the stock gearing as it sits as loading it up at lower rpms may not have enough fuel in the pump delivery to take advantage of the better burn afforded by the boost it will produce. If that makes any sense? Quote Link to comment Share on other sites More sharing options...
NWA 280ZXTD Posted January 29, 2012 Author Share Posted January 29, 2012 (edited) I understand your point, but I drove the Maxima for a month before tearing it down, and with the factory R180 3.55 diff, I was turning 3K rpms doing 60mph and burning lots of fuel at those revs, by going with the O/D I can drive 70mph and be doing around 2,100-2,300 rpms. Even though its a higher reving diesel barely getting 27-28mpg, your optimum fuel efeciency range is going to be under 3K which would mean driving it under 60mph all the time. O/D will primarily be for highway use to get the fuel consumption down. My Cummins diesel has a 3.55 rear with 31" tall tires and it gets its optimum fuel effiecency at 1,900 rpms at 65mph, its in and out on the turbo but still manages 24mpg in a 7,500lb truck with almost twice the engine. And if it bogs down or is burning more fuel boosting in O/D I can always kick it down to 3rd. But being in a lighter, more arrow-dynamic car and turboed, I don't see it being a problem with the experience I had with it in the Maxima, having plenty of power at those speeds, and really feeling the need for the extra gear and that's without a turbo. Also it won't have any provisions boost compensation, it will have a set fuel rate like without the turbo, I'll turn the fuel up a bit to compensate for the added air but not alot as my Fuel mix is thicker than diesel and will naturally run richer. Oh yeah and I forgot to mention in this thread that whole purpose behind me converting it to diesel is to run it off of my used engine oil fuel mix that I make. I've ran three trucks on it for years with zero problems in mechanical injected engines, its a 85% UMO and 15% gasoline mix and I can make it for $0.30 a gallon. Edited January 29, 2012 by NWA 280ZXTD Quote Link to comment Share on other sites More sharing options...
NWA 280ZXTD Posted January 30, 2012 Author Share Posted January 30, 2012 I've got the short block assembled, and most of the other parts ready to go together, just waiting on my headgasket to show up now. Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 30, 2012 Share Posted January 30, 2012 "Even though its a higher reving diesel barely getting 27-28mpg" Something is wrong with your pump or odometer. You should be getting mid 40's with that setup at that speed. An S30 running 80mph will return mid 40's, and with non-aneroid corrected fueling closer to low-mid 50's. The HP requirement for 65mph is around 25hp, and you can't run off that curve. The S130 will have slightly better aero at 75 and 80mph but you are still constrained by the HP rolling requirement. If you overgear it you will be boosting all the time meaning you will want a segmented turbo manifold and a .48AR, not the .68 like on the Gasoline engines. I've got three of those turbine setups for my LD28T, and it was some work finding them. It's like the old VW Rabbits with mechnaical FI, you can pump boost in them get a complete burn and have lower EGTS as well as more power with better fuel economy. But you don't have to really drop the rpms that much. The .67OD will drop you to 2000 rpms at that same speed. Same as if you ran a standard tranny from a late ZX and a 3.36 gearset. My Maxima donor had 275K on it with the late ZX Style Transmission, and the standard 3.54 rear gear, meaning 2500 rpms at that speed. I'd shoot for 2500, but not 2000. With teh .48 A/R turbine you will boost at 1500-1700 to the stock 5 psi. There is a boost aneroid, and a turbo fuel pump available. For my tastes, if I was going to do this again... I'd grab a Navara 2.7 or 3.0 Direct Injection setup where it's got electronic injectors and do an Essing Diesel Tuning chip upgrade and go to the races... Quote Link to comment Share on other sites More sharing options...
NWA 280ZXTD Posted January 30, 2012 Author Share Posted January 30, 2012 "Even though its a higher reving diesel barely getting 27-28mpg" Something is wrong with your pump or odometer. You should be getting mid 40's with that setup at that speed. An S30 running 80mph will return mid 40's, and with non-aneroid corrected fueling closer to low-mid 50's. The LD28 engines in the Maxima's were epa rated for high 20's low 30's with no O/D, and if you can get 40+ MPG's out of one you need to tell the guys over at nissandiesel.org what they're missing. The highest one over there I've seen is mid 30's that's with a 5spd non-turbo setup, I have no idea where you're getting your numbers from any diesel running high rpms will not return good fuel milage under any circumstance. 2500rpm's is probably a better RPM to shoot for, but I can fine tune it with tire size. The way it is now with out an overdrive I would have to run a 31" tall tire to hit 2,500rpm's @65mph, where as with an O/D and 215 65 R14 tires I can run 70mph @ 2,500. Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 30, 2012 Share Posted January 30, 2012 In a Maxima or a Z? Actually, there is a guy who was posting at Nissan Diesel Forums about a retrofit turbo. I would have never considered doing a non anneroid-corrected fuel pump setup save that this guy did it and got results a lot like the old Rabbits. I forgot to mention the Maxima five speed was a .74OD with the 3.54 and they should get much better economy in a 2400# 240Z than in a 3000#+ Maxima. The old Mechanical Pumps just don't do that great when it comes to trying to go fast and get good fuel economy. The new electronically controlled engines do a lot better in that respect. After Essing worked the BMW M3 we took there, we not only got more power (when we wanted) the fuel economy increased dramatically. The Z's with a 24-25" tall tire will turn 2000rpms at 50mph with the 3.36 rear gear and that latex .74od transmission. Roughly translated that means 500 rpms less than what you get now. Meaning all you need to turn 23-2500 rpms at the same speed is put the .74 OD standard trans in there (if you are turning 3000 now...but I think you have some slip in the tranny or something.) The earlier tranny with the .85 O.D. will be closer to a straight 500 rpm drop from direct drive 4th. If you have a live axle car, swapping the differential is a bit harder... but the easy way to get your rpm point is to swap differentials. There are plenty of 3.36 R180 differentials out there to drop the R's well into the low rpm range you want. Easy swap. That 4speed autobox into a ZX is easeir than into an S30, but not as easy as a diffy swap and playing with the different 5 speed boxes out there. Quote Link to comment Share on other sites More sharing options...
NWA 280ZXTD Posted January 30, 2012 Author Share Posted January 30, 2012 (edited) double post Edited January 30, 2012 by NWA 280ZXTD Quote Link to comment Share on other sites More sharing options...
NWA 280ZXTD Posted January 30, 2012 Author Share Posted January 30, 2012 Going with the L4N71B transmission, over any other O/D transmissions including 5spds, was simplicity of the swap. If going 5spd I have to get all of the associated pieces for the car(pedals, console, driveline, etc.) its near impossible to find a LD28 flywheel being that they're near double the wieght of a factory gas version, but also getting a 5spd that's not going to go through bearing ever other year. I can find L4N71B's locally and build them with the guts of the turbo tranny and I've got a transmission that would more than meet my needs. The 280zx that all of this is going into has a r200 3.55 diff, which is about the best I can see going with, unless my revs do drop to where I'm out of my power band I'll look at stepping up to a lower gear ratio. If you know how to work with the Mechanical injection diesels you can fine tune them to get as good if not better mpg #'s, All I've done with my cummins is a fuel plate, tuned the smoke screw, and bumped up the timing and I have a heavy truck with a big motor getting almost as good a milage as most 4cyl or 6cyl cars. The Maxima's don't have tachometers so the rpms I was referring too are purely off of a gear ratio calculator and from other maxima diesel owners, and at those speeds the engine is really humming There are guys that will stuff a 215/75/r14 in the back with out an over drive and can get their rpms down to 2700 @ 60mph, but I drive all interstate to work and back and you get run over at those speeds. Also if you look at the LD28's power #'s its peak hp is made at 4,400rpm's but its peak torque is made at 2,000rpm's, so this engine should be right at home between 2-2,500rpms. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted January 30, 2012 Share Posted January 30, 2012 Getting the l28et manifold fitted up is not very easy as the intake ports are much lower in the LD28. Quote Link to comment Share on other sites More sharing options...
NWA 280ZXTD Posted January 30, 2012 Author Share Posted January 30, 2012 Getting the l28et manifold fitted up is not very easy as the intake ports are much lower in the LD28. There's a couple of guys over on nissan diesel that have done it and have a small wright up about it. To use the L28ET exhaust manifold is nothing more than port matching and relocating a couple of holes. A few guys say its easier to build your own "kit" with the factory LD manifold, rather than to go out and buy one that you'll have to manipulate to get to work, but I have it, so I'm going to make it work. All else fails I'll make my LD manifold work and use all the rest of the turbo set up. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted January 30, 2012 Share Posted January 30, 2012 Fun project. I love diesels, I still haven't recovered from the trauma of seeing a friend tearing down an LD28 just for the crank. Quote Link to comment Share on other sites More sharing options...
NWA 280ZXTD Posted January 31, 2012 Author Share Posted January 31, 2012 Fun project. I love diesels, I still haven't recovered from the trauma of seeing a friend tearing down an LD28 just for the crank. Yeah I'm a huge diesel fan, so that would be hard to see a perfectly good diesel engine tore apart for its crank. I'm really excited about this project I've always wanted a Z car, and once I found the possibility of a easy diesel swap it seemed like a perfect daily driver for me to keep the miles off of my two 1-tons since I'm not always needing the diesel for pulling but for running my fuel mix. I'll beable to build this for a third of what I could buy a Mercedes diesel(or equivelant), and have a killer looking one of a kind car that'll be fun to drive and save money at the same time. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted January 31, 2012 Share Posted January 31, 2012 I've got the entire setup but am having second thoughts at swapping the LD28t for the current L28et in my Infiniti M30. I feel the setup needs a car with better aero than what I have so maybe a 240sx will have to do. Quote Link to comment Share on other sites More sharing options...
NWA 280ZXTD Posted January 31, 2012 Author Share Posted January 31, 2012 I've got the entire setup but am having second thoughts at swapping the LD28t for the current L28et in my Infiniti M30. I feel the setup needs a car with better aero than what I have so maybe a 240sx will have to do. LD28T in a 240sx, that would be nice. Quote Link to comment Share on other sites More sharing options...
S30Mark Posted January 31, 2012 Share Posted January 31, 2012 Nice. I like the idea of a diesel Z with decent power. It's surprising how high the LD28 revs. My little 1.9 TDI red lines around 4500RPM. I love how a diesel will pull a vehicle up an incline without touching the accelerator pedal. Oh, the mileage is nice too I like your ideas, can't wait to see how this one turns out. Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 31, 2012 Share Posted January 31, 2012 Any turbocharged car pulls an incline in identical fashion... I oft commented the Jatta TDI would be the perfect engine for the majority of US Owners: shift before or at 3K, and when really getting on it, pulling to 5000+ reaching 140KPH (90mph) at the top if 3rd gear... Back in the late 70's we had a Crisco Rabbit, guy ran on filtered fry oil from Mc Donaldson. Big aluminum tank in the back with a heater loop through it-from September to April it never stopped idling to keep the shortening from coagulating in the tank. When he installed his turbo kit it was similar: power and fuel economy went up. It's a different fueling situation than in a gas engine, if you have the air to burn the fuel, it burns... If not it goes out the pipe. Boost on these old mechanicals burns ALL the fuel it was putting in there before anyway, giving more power and your most efficient burn. Crisco Rabbit ran many a mile on that oil...and showed up every Tuesday evening for his free fillip of hot drained vat oil! Hard to beat free!!! Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted January 31, 2012 Share Posted January 31, 2012 I do similar fueling with biodiesel made from used Chinese fryer oil, on both daily drivers. Hard to beat fuel for less than $1 a gallon, especially when the VW gets better than 40mpg city, and the SUV gets 25mpg city. Quote Link to comment Share on other sites More sharing options...
buddabeast Posted February 1, 2012 Share Posted February 1, 2012 Hi NWA 280ZXTD, I was wondering what turbo you were putting on your LD28? The one from L28et? You have any specs on this turb? I am doing a similar thing with my LD28 Laurel. Cheers! Quote Link to comment Share on other sites More sharing options...
NWA 280ZXTD Posted February 2, 2012 Author Share Posted February 2, 2012 Hi NWA 280ZXTD, I was wondering what turbo you were putting on your LD28? The one from L28et? You have any specs on this turb? I am doing a similar thing with my LD28 Laurel. Cheers! I'm not sure of the specs on the internals, but its the stock tb03(i believe) turbo from the L28ET. I got my gasket set finally the day I took the head in to get reworked. I wasn't going to and was just waiting to put it together when my headgasket finally showed, but I decided to go ahead and get the head re-worked since I had done everything else. Quote Link to comment Share on other sites More sharing options...
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