OlderThanMe Posted June 29, 2007 Share Posted June 29, 2007 So I have this little idea for a motor... Take an LD28, turbo it, add go-fast goodies, put into lightweight Z car, have fun. There are a couple LD motors around here that are asking for a new life... What modifications would be necessary to setup an LD28 for a Z? Obviously it would need to be converted to rear sump. That is not too much of a big deal. I'm thinking what would be needed to upgrade the engine to make lots of power? The fuel system is a big restriction and could be sold off to the maxima guys. The stock system is a MFI with a big fuel pump where the alternator normally goes. This would need a lot of custom work. An increase in bore would also be helpful for more power as with any engine. As on our gas engines the cylinder head is a big restriction once you double the power. Porting on the cast iron head of the LD would be a pain. I'd like to find out if any Z car oversize valves could be used in the cast iron LD head. I doubt it as I think the LD head has almost no chamber and has longer valves than a Z aluminum head. Increasing RPM range, The LD is good for about 4500RPMs stock from what I have read. If that could be increased to 5500 or 6000 that would be great. The stock LD flywheel is REALLY heavy. Maybe swap it out for a lighter stock steel 240mm zxt flywheel? Exhaust The L28ET header will work with some modifications. Some bolt holes have to be elongated to fit but it will work. A weld-el log header may be a better solution for better turbo placement. Turbo, I'm thinking a slightly larger than stock T3 turbo would be fine (upgraded z31 turbo?). I'm figuring this is would be a 2.9-3.0 with a mild overbore. You could also run biodiesel if you can get it where you live... Any thoughts? Dan/OTM Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 29, 2007 Share Posted June 29, 2007 At the time the LD28s were in vogue, automotive diesels were not really built for power. I have a friend who built up a mid 80s Toyota turbo diesel for his truck, and most of the work he did revolved around porting the head, because the stock casting was so INCREDIBLY poopy. I mean really bad. They just weren't built for performance. He spent a lot of money and did all the headwork himself and was hoping for 150 hp. Now I haven't seen the LD28 ports or any of that, but I think looking to do anything other than get good mileaage out of an LD28 is going to be an exercise in frustration. Maybe I'm wrong, but it's a fairly expensive thing to try and find out. I did try to search google and find hp output. Stock auto LD28 was 80 hp I found, and in agricultural trim they put out 92 hp. If you could get one to turn out 150 hp with a turbo I think you'd be doing pretty damn well, and you'd be back to bone stock 240Z levels of power. I do not think the way to make more power with a diesel is to increase the rpm range, and that would not be the way I'd approach it. Find some tall gears and some tall tires, then work on making the head flow well and turning up the boost/intercooling/etc. If you decide to get into this I think you'll be into a lot of books on diesel fuel pumps, because that seems to be the other key to making power. I just think with diesels winning Le Mans and all kinds of endurance racing and F350's doing 12 second 1/4 mile times it's giving people the impression that every diesel is a highly capable piece of equipment, but just like gas engines there are good ones and bad ones to try and coax a lot of power from. I'm doubtful that the LD is a good choice for ultimate power output. Quote Link to comment Share on other sites More sharing options...
Noddle Posted June 29, 2007 Share Posted June 29, 2007 Increasing RPM range, The LD is good for about 4500RPMs stock from what I have read. If that could be increased to 5500 or 6000 that would be great. The stock LD flywheel is REALLY heavy. Maybe swap it out for a lighter stock steel 240mm zxt flywheel? Dan/OTM I would have though that a lighter flywheel would reduce the torque of the engine Nigel Quote Link to comment Share on other sites More sharing options...
Flexicoker Posted June 29, 2007 Share Posted June 29, 2007 I would have though that a lighter flywheel would reduce the torque of the engine Nigel No, lightening the flywheel, or any rotating component for that matter does not reduce torque. It reduces inertia, which can make it more likely to stall, and make launches a little bit slower. But it will also make you accelerate faster. And thats good. Quote Link to comment Share on other sites More sharing options...
gjc5500 Posted June 29, 2007 Share Posted June 29, 2007 Ive thot about this before. iw as thinking about getting a beater 280 and doing it Quote Link to comment Share on other sites More sharing options...
Gareth Posted June 29, 2007 Share Posted June 29, 2007 Even tough I'm not a Datsun purist, my vote goes agains the diesel engine, especially if it's the LD28. Why? As Jon has already pointed out, the LD28 isn't an engine that was built to make power. It's just a L-series based, naturally-aspirated economy engine that makes a lot of torque, which makes it a good engine for heavy cars (like the Patrol). Its main characteristics are typical for a diesel engine - lots of low end torque, low fuel consumption (plus diesel is cheaper than gas/petrol/whatever you call it, narrow range of usable RPM, and stronger construction than any other L-gata engine (hence the bigger weight). Now increasing the RPM range won't make a diesel faster. Why? Because it is made for lower revs, that's why. The fact that it doesn't spin too high is caused by a very strong crakshaft/flywheel combination, and this is where all the torque-friendly environment comes from. Toss the heavy flywheel, and you'll end up going agains one of the diesel's fundamental characteristics. Increase the rev range, and you'll get nothing. The only way to tune a diesel engine for better power (aside from internal tuning, which is usually mirror-polishing the pistons etc.) is to add LOTS of compressed air to the mix, with a bit of fuel to back that up. Trust me, forced induction aside, there are no ways of increasing the power seriously... If you don't think of increasing the diplacement, or simply putting a bigger engine in. Tuning it is just as difficult as tuning any other car engine. In the US it may be even more difficult, just because of the fact that only the pickup guys really tune the diesels there. Close ratio gears are also a helping factor, especially if combined with lots of low end torque and traction needed to hold everything in one place. Diesels in your typical bread-and-butter passenger cars are much more popular in Europe than in the USA, and this is why many guys tune their cars for much higher power. Mind you, most of the cars are powered by fresh, direct-injection engines controlled by advanced ECUs that are easily remapped, not like the ancient LD28. The most popular way to tune, say, a Volkswagen 1,9TDi diesel is to remap the engine, throw in front-mounted intercooler, a performance exhaust, and couple it with a close-ratio 6 speed transmission from sportier models. The result? A 200HP daily driver that can smoke some of the more powerful 1,8T variants, as long as it is driven properly. Some guys even throw in bigger turbos from other diesel engines, like the Garrett GT22 (they're different than gas engine turbos though - that's because of the lower heat range they operate in), or even nitrous oxide. It is proven to work - there is a team which makes 12s, 11s or even 10s with their cars on VERY rough airfield surface (we have no dragstrips here, the closest one is in Germany). Non of these cars have lightened flywheels or crankshafts. Throwing a lightweight crank in would give a comparable result to using a diesel crank in a B16B Honda, if you know what I mean. The fastest diesel in my country, an Audi 200 with a VW Touareg twin-turbo V10 diesel coupled to an automatic transmission, recently made a mid-10 second run, and has potential for much more (I'm going to the drags this weekend, I think it will be there). The same guys who built the Audi had earlier run a AWD, 6 speed, nitrous-oxide fed, 300+HP VW Lupo (something in a size of a Yugo), and they made regular 11 second passes with it. I remember it taking off VERY quickly (imagine a car smaller than a Civic with lots of low end torque and good traction), but because of the diesel's narrow powerband and close ratio gears he had to run in 5th a bit before the 1320 mark... Even tough it is possible to make a diesel engine go really fast, you'd have to make a LOT to make it as fast as untuned gas engines of the same displacement. A heavily tuned diesel will lose all its merits (except for the torque characteristics), and will surely be more difficult to further tune and maintain. OTM, if I were you, I'd just search for a good ole' gas engine with some power potential. Sorry for the long post, hope this helps. P.S. - Putting a diesel in a Z would be like taking a huge bomber aircraft engine and couple it with a lightweight fighter airframe - this is what the Czechs did with the Bf-109. They married Junkers Jumo 211 engines with Avia S-99 (Czech-built Bf-109) frames, and the result was a slow plane that was a pig in handling characteristics... Quote Link to comment Share on other sites More sharing options...
Chewievette Posted June 29, 2007 Share Posted June 29, 2007 So basically what you guys are saying is that putting an LD in a Z for fuel economy is a good idea and putting an LD in a Z for power is a bad one? On the other hand, take that 90hp LD and put boost on it and you would end up with 150hp (maybe?) but it would be making all kinds of torque. At the very least it could be a ton of fun to drive. Quote Link to comment Share on other sites More sharing options...
Gareth Posted June 29, 2007 Share Posted June 29, 2007 So basically what you guys are saying is that putting an LD in a Z for fuel economy is a good idea and putting an LD in a Z for power is a bad one? Exactly... Who cares about the fuel economy anyway? At the very least it could be a ton of fun to drive. Well, it depends if you like revving your engine to a ~4500-5000 maximum, with a possibility to spin it to its death if you do more (thank you mr. Diesel for all the heavy internals)... Quote Link to comment Share on other sites More sharing options...
randy 77zt Posted June 29, 2007 Share Posted June 29, 2007 you will need more fuel to make it go.back in the day i used to work on vw diesel rabbits with mechanical injection.the local diesel injection pump shop will be your friend-they have machinery to dyno the pump and the injectors.they can change the nozzles on the injectors.plus a good exhaust temp gauge.probably a standard 280zxt turbo would work-but it wouldnt spool soon enough-a small garrett t25 might work. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted June 29, 2007 Author Share Posted June 29, 2007 Thanks for the replies guys. I wasen't really thinking about building one of these now... I'm going to do a turbo gas L6... I have just seen it mentioned a couple times and was wondering about if it could be built up to be fast. Increasing the RPM range doesn't help power but it does make you go faster to stay in gear longer. if you had a Z with a 140hp N/A 2 liter that could spin to 15k RPMs and had a REALLY wide gear ratio tranny you could be faster than a much higher power car that was wasting a lot of time shifting... Weight.. The LD shortblock doesn't weight ALL that muc more than an L28. It is the cast iron cylinder head that weighs a ton. I guess the LD shortblock probably weighs 20 pounds more than an L28. The extra 20mm of deck height and then a LITTLE more weight from the crank and slightly heavier rods. The cylinder head is probably twice what a Z car head weighs. Stripped it is probably 60 pounds! Lightening the flywheel, The LD flywheel is a heavy beast. Like, well just look 35lbs Well to learn about things sometimes it hurts. This was a learning experience that hurt a little but it was good to know. Thank you all for your replies! OTM Quote Link to comment Share on other sites More sharing options...
Chewievette Posted June 29, 2007 Share Posted June 29, 2007 Well, it depends if you like revving your engine to a ~4500-5000 maximum, with a possibility to spin it to its death if you do more (thank you mr. Diesel for all the heavy internals)... I used to drive an 87 ford mustang with a 2.3L four cylinder and a five speed. I only reved it to 5K, and it had no power at all but it was a blast to drive! I think an LD powered Z would have a similar fun to drive factor. It wouldnt rev as quickly but it could pull that stump out of your back yard. At the very least it would be an interesting experiment, something to try just to see what happens. I'm still not understanding this impending doom theory. If weight of the internals is the problem, that can be fixed by any competant performance engine builder. So yes you could get it to spin higher without destroying it. But its been mentioned that even if you could there is no power to be had up there. That might be true if you kept the stock fuel system but if your going to get all buddy buddy with the diesel shop down the street and all their cool gadgets why cant you change the fuel curves to meet the need for more power up top? and regrinding the cam is no big deal, any performance rebuild would have one anyways. So what is the limiting factor? Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted June 29, 2007 Author Share Posted June 29, 2007 BTW there are lots of guys putting these "heavy" internals in their gas motors and going way fast. The crank isn't that much more than a L28 crank, the rods aren't that much heavier, and the pistons have a 2mm taller pin height... It is the darn 90+ pound cylinder head and 35lb flywheel that start the weight problem. Not the actual internals... Quote Link to comment Share on other sites More sharing options...
Chewievette Posted June 29, 2007 Share Posted June 29, 2007 Well even if the engine physically weighs more it should still be able to make power. Obviously certain design features limit this, like head flow, but even gas L engines are getting 400hp, so the flow cant be too terrible. esp since a LD has basically the same head flow as a gas L. idk, maybe its my lack of knowledge about diesels but it just seems like there is no reason to limit the rpm that low, other than how deep your wallet is. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 29, 2007 Share Posted June 29, 2007 Well even if the engine physically weighs more it should still be able to make power. Obviously certain design features limit this, like head flow, but even gas L engines are getting 400hp, so the flow cant be too terrible. esp since a LD has basically the same head flow as a gas L. idk, maybe its my lack of knowledge about diesels but it just seems like there is no reason to limit the rpm that low, other than how deep your wallet is. The heads are completely different. The diesel head is cast iron. Like I said, you may want to look at one before you write the idea off, but the mid 80's diesel heads that I've seen up close had nothing at all to do with performance. The short side radius was literally a right angle, the ports were high and so there was not much area to smooth it out, they were just about as crappy as you could possibly get for airflow. Made my 22RE head which I always thought was a real crappy design look like an AFR head or something. Quote Link to comment Share on other sites More sharing options...
TravRMK Posted June 29, 2007 Share Posted June 29, 2007 Well even if the engine physically weighs more it should still be able to make power. Obviously certain design features limit this, like head flow, but even gas L engines are getting 400hp, so the flow cant be too terrible. esp since a LD has basically the same head flow as a gas L. idk, maybe its my lack of knowledge about diesels but it just seems like there is no reason to limit the rpm that low, other than how deep your wallet is. Diesels are a totaly different animal. Just go look at all the high tech new turbodiesel pickup truck tachs. You will see the redline at 3000-4500 Max. Typically they are generating full boost at 1000-1500 RPM's. They are also making huge torque, and good HP. The power output over the last 10 years has gone way up, but the RPM range has stayed the same. If the key to making more power ot of them was to turn Higher RPM's. Then why hasn't that been done? IMO they way to make power is more air (boost) and more fuel, not higher revs. JMO Quote Link to comment Share on other sites More sharing options...
Challenger Posted June 29, 2007 Share Posted June 29, 2007 Has anyone seen the LD28 Z in the classified? Did someone mention it already? Quote Link to comment Share on other sites More sharing options...
Chewievette Posted June 29, 2007 Share Posted June 29, 2007 Thats all fine and dandy I was just trying to discover why people are obsessed with rpm and the associated Ka Boom of this engine after 5,000rpm. I dont understand, if the engine isnt designed to operate above 5K and it wont make any power above 5K Why would it need to be mentioned that it will die when you try to rev it that high? Your totally right, I've never looked at the ports on an LD before, I just know that both the intake and exhaust from a L could be made to fit which means they are close in port dimension. Plus they are both two valve and SOHC which means they should be similar. I did know its a cast iron head but what does that have to do with flow? either way, if you are correct about the sharp angle of the flow that would not be good, if its possible to smooth that out I'm sure it wouldnt hurt. Even if I was going to attept this project (not possible at this time) I wouldnt be after the power numbers of the new diesels just something reasonable for the street. I'm all about fun to drive odd ball stuff, this certainly would fit the bill. Maybe when I blow the engine thats in my car now and the one I'm starting to build up now ...it might be a while. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted June 29, 2007 Author Share Posted June 29, 2007 Here are some pics of the LD ports with a ZXT manifold. A good website to look at: http://datsunmotorsports.selfip.com/Diesel%20Experiment.htm Uhh... are those rocker arms on the opposite side as on a gas motor? Weird... Chewie... I think the problem is that fuel cuts off at those high RPMs on a stock LD motor. Can't physically rev any higher. Unlike our gas motors where it can rev to 8k+ on stock carbs. (not that you would want to but it can) Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 29, 2007 Share Posted June 29, 2007 Those intake ports look pretty good. What do the exhaust ports look like? Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted June 29, 2007 Author Share Posted June 29, 2007 obviously this guy doesn't know his stuff but is spreading bad information. http://datsunmotorsports.selfip.com/Engine.htm from the site: "The V07 block is from the Diesel family(The Dark Side). It has a 1/2" taller deck height than the petrol version. It also has a far thicker cylinder wall than any of the other blocks. I have sources that claim to be able to get a 104mm bore from this engine, though I have gotten a 95mm bore from one safely. This block is also reinforced with more internal webbing." Umm...the bore spacing on a L6 block is 96mm and 98mm in the middle. There is no possible way to have a 95mm bore and have any amount of cylinder wall. Maybe he got an 85mm bore and forgot a centimeter? and somehow the MN47 head in his engine calculator is not 39 or 39.5cc... It is 42.4cc??? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.