Lowandslow Posted January 25, 2013 Report Share Posted January 25, 2013 So this is my first time on this forum and my first time with a Datsun. I have a 1980 Datsun 720 with the original l20b. I have done some research on this truck but I still need some more help. First off, it takes 20 seconds to get from 0 - 60. I know this truck is no race car or anything but it becomes an issue when I try to get into the freeway. Is this a normal 0 - 60 time? It still has the stock hitachi carb so I don't know if that's hindering the performance of the truck or not. Secondly, is it worth swapping in a Z24 engine? Or is it about the same as the l20b in terms of reliability. I have changed the intake/exhaust manifold gasket, cleaned the carb, put in a new down pipe from the exhaust manifold back, and a new generic flowmaster type exhaust. Quote Link to comment
flatcat19 Posted January 25, 2013 Report Share Posted January 25, 2013 Welcome to Ratsun. Your pictures are too small. Quote Link to comment
Lowandslow Posted January 25, 2013 Author Report Share Posted January 25, 2013 Thanks!! I have not posted any pictures tho. Quote Link to comment
wayno Posted January 25, 2013 Report Share Posted January 25, 2013 Welcome to Ratsun B) It's a 720 with an L20b, be happy it is not a 4X4 :lol:, I actually cannot tell you how fast they are supposed to be, as I have only owned 720 diesels, and they likely take even longer to get to hiway speed, I myself would have to be in it to tell you if it is gutless. The reason flatcat19 said what he said is that you did not post any photos, so they are to small for him to see. :lol: :lol: :lol: It's a Ratsun thing, we like photos a lot. You would likely have to change everything to put a Z24 in your truck, I beleave that the actual frame mounts are differant for the engine, and your best bet would be to change the wiring harness also, as I think the napZ also has a ECU. If your looking for more power, and you have the resources/knowledge, you will would get a lot of feedback/help/encouragement going with a VG30 of some type, as we all want more power, well and moar loar also. :lol: Quote Link to comment
flatcat19 Posted January 25, 2013 Report Share Posted January 25, 2013 My last truck(LZ22) got up to speed pretty fast. Broken speedo-so I can not verify. The truck prior(L16) also had a broken speedo. So I'm even more lost on an actual 0-60 time. I will say though, neither one of them took 20 seconds. And an L20B should reach 60 faster than an L16, stock to stock. (Oh shit! 5,000th post!!!) Quote Link to comment
Lowandslow Posted January 25, 2013 Author Report Share Posted January 25, 2013 Ah, I get the comment now haha I just found out how to post pictures so I will upload what I have right now. I have started looking into swaps and I'm kinda weary about engine swaps as of right now, but I plan on getting into them. As for right now I just want to get to 60 mph in 10 seconds or less haha getting passed by semi trucks going up hills is no fun. I posted a picture of my truck when I got it and what it's like now. I will post more pictures when I get home!! (Hopefully I used the img code correctly) Quote Link to comment
Lowandslow Posted January 25, 2013 Author Report Share Posted January 25, 2013 20 seconds seemed a little bit too long for me. Maybe it's just my shifting points? I don't have a tach so I go off of the sound of the engine. I shift at 20 mph, 30 mph, 55 mph, and 65. Quote Link to comment
wayno Posted January 25, 2013 Report Share Posted January 25, 2013 It's a heavy truck, they only used the L20b in it for 1 year, I bought a 1980 4X4 for parts and drove it home, it was fairly gutless compared to my L20b powered 521. Quote Link to comment
ggzilla Posted January 25, 2013 Report Share Posted January 25, 2013 Stock 0-60 was 12 to 16 seconds depending on year, engine, emissions, etc. Stock 510 was 0-60 in 12 seconds. But the 720 weighs about 600 lbs more. To make it acclerate faster: 1. Rev the engine higher before shifting. The L20B redline is 7000, but makes best power if shifted around 5000 RPM. 2. Change the rear end gear ratio. Higher numbers make for quicker accleration. If it has 3.889 now, change to 4.375 and it will accelerate qucker and still do 80 mph. 1 Quote Link to comment
Lowandslow Posted January 25, 2013 Author Report Share Posted January 25, 2013 Would a swap to the z24 be a better idea? Rather than rebuilding the l20b? 12 to 16 seconds is still pretty slow haha I'm going to have to get a tach to know what RPM's I'm shifting at. So the redline is 7000? That's way higher than I thought it would be! I'm trying to make it better on the highway as well, so a higher rear end gear ratio isn't something I wanna do at this moment. At 70 it sounds like the engine is screaming!! It might just be me not being used to the louder engine. Quote Link to comment
ggzilla Posted January 25, 2013 Report Share Posted January 25, 2013 No a swap to Z24 is not really better, it's only 6 HP difference. Just learn to drive the L20B. If you don't wnnt to drive it like it was designed (rev it up!), swap in the KA24DE it is 40 HP more. Quote Link to comment
Lowandslow Posted January 25, 2013 Author Report Share Posted January 25, 2013 I'll get a tach and start revving it up I guess. Like I said as of right now I'm just going off of the engine sound. If revving it up doesn't get me a little faster I will definitely start looking into a ka24 Quote Link to comment
wayno Posted January 25, 2013 Report Share Posted January 25, 2013 I don't care what anyone says on here, the only way you are going to get 7000rpms out of a stock L20b is to floor it in neutral, it starts to lose power/acceleration slows at about 4500rpms, and 5000rpms is just about it, unless you like listening to it howling in defiance. An L16 or L18 might like going that high, but a stock L20b, forget it, now if you put an aftermarket cam in it, that would be differant, but when you do put a radical cam in it, you lose torque(starting out power). Quote Link to comment
Lowandslow Posted January 25, 2013 Author Report Share Posted January 25, 2013 I'm not trying to go 7000 RPM's at all haha that seems way to high for my taste. I think I'm going to get a tach, shift at 5000 RPM's and see what I get. If its still as slow as it is now then I will start to figure out if I want to do a swap or rebuild/build up the l20b. Quote Link to comment
wayno Posted January 25, 2013 Report Share Posted January 25, 2013 I'm not trying to go 7000 RPM's at all haha that seems way to high for my taste. I think I'm going to get a tach, shift at 5000 RPM's and see what I get. If its still as slow as it is now then I will start to figure out if I want to do a swap or rebuild/build up the l20b. I had a 521 with an L20b/5 speed, it now has a LZ23, anyway I haul debris in the truck as well as pull a trailer, I used that L20b for over 15 years, I had a tach the whole time, I may have run it up to 5000rpms a few times in first gear going up a steep hill because the engine did not have the power to do it in second and I just wanted to get to the top of the hill, I had a passenger one time, when I got to 5000rpms, the guy looked at me like I was crazy. The Z24 has way more power, but for what you get out of that conversion, it doesn't seem worth it, as there are better engines out there that take the same effort with a better result. Quote Link to comment
Lowandslow Posted January 25, 2013 Author Report Share Posted January 25, 2013 I can't even imagine driving for that long at that high of RPM's, specially in first haha I'm definitely trying to get used to the hum/loudness of this engine. It is y daily driver so I'm trying to get some days off in a row so I can go forward with a swap. Is there any website or anywhere I can find the hybrid engines? Like the L series and Z series combos. Quote Link to comment
flatcat19 Posted January 25, 2013 Report Share Posted January 25, 2013 KA, 5 speed, and a 4.11 gear set from a '79 620. BAM! Oh. And a tach. Quote Link to comment
Lowandslow Posted January 25, 2013 Author Report Share Posted January 25, 2013 The KA seems like its the best swap for this truck. Would I just get it out of a Hardbody? Quote Link to comment
JoeCool Posted January 25, 2013 Report Share Posted January 25, 2013 I have the same truck in a regular cab. It does seem to take off slow, but once it gets going it moves! It's just way it was designed I guess. America was still in the smog a vehicle to death stage, and a fuel crisis. While it was made in Japan, they still had to comply with our standards. Hell, compared to my first car, a 76 Chevy Monte Carlo with auto and a heavily smogged 305 this truck goes "ludicrous speed!" Quote Link to comment
ggzilla Posted January 25, 2013 Report Share Posted January 25, 2013 It's like a fine european sports car. The L-series engine is happiest when revved up. It won't hurt it to run at 5000 RPM all day long. Quote Link to comment
Lowandslow Posted January 25, 2013 Author Report Share Posted January 25, 2013 I feel the same way about the truck, the acceleration is slow but once it's going it picks up pretty good. I just feel like my 3rd gear is where it slows down immensly until the engine gets up in the RPM range. I'm getting more comfortable with getting the engine up in the RPM's. I got a tach today so this will add some peace of mind to my driving. Quote Link to comment
Lowandslow Posted January 25, 2013 Author Report Share Posted January 25, 2013 BTW Here's more pictures of my truck now that I got on a laptop Quote Link to comment
wayno Posted January 26, 2013 Report Share Posted January 26, 2013 Why two radio antennas? The type on the pillar looks the best in my opinion. Looks fairly straight for an 80, except for under the passenger door, or is that just shadows in the photo? Quote Link to comment
Lowandslow Posted January 26, 2013 Author Report Share Posted January 26, 2013 The truck just came with 2 antenna's. I have no clue why, and yes there is a dent under the passenger door. The previous owner didn't know how it had that dent, and I have no clue either. It's in a weird spot so the best guess I have is someone must of tried to jack the truck up from there. Quote Link to comment
wayno Posted January 26, 2013 Report Share Posted January 26, 2013 It's a nice looking truck anyway, I have taken some really ugly trucks and made them look decent, and you are ahead of where I was starting out. Delete the fender ant. ASAP, at least that is what I would do. This is my 80 after a whole bunch of modifications. Quote Link to comment
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