Turbo Diesel Questions

[Chewievette]

I've been tinkering with a couple of ideas over the last few days. I had planned on swapping a BMW V12 into my 280ZX but recent events have got me looking more seriously into upgrading the motor that I already have, or swapping in something similar. I want to do something not entirely custom, like the v12 would be, but still something not many have seen before. Since this car will mostly be a showcar and weekend cruiser, Power isn't at the top of my list. Something around 300-400hp would be great.

 

The other day while looking at stroker motors I got to thinking why not just swap in the diesel LD28? I've been searching the forums because someone said the diesel swap has been done before but I havn't been able to find anyone that has done it. I am confident that I can make the mechanical aspect of the project work seeing how it is mostly bolt up. but I cant seem to find any info about the differences between Gas and Diesel fuel systems. What kind of mods would I have to do to the car's fuel system? I expect that I'll have to replace all the seals but what else? Will the pump be up to the job? How about the filter? Do I need a different one or would simply replacing with a new one be okay?

 

I also heard that the same people that have been putting diesels in also Turbo them. While the stock single turbo is great, I would really like to try a sequential twin turbo (one small turbo and one large turbo), mostly because I haven't done it before and it has always facinated me. But trying something like this has left me stumbling around in the dark. What will determine the size of the turbos, in relation to each other? One is obviously smaller but by how much? I have some more specific questions but I'll save those for when I start to refine the idea.

 

My other questions concern the engine. I've always heard that Turbo engines need lower compression but diesels require a rather high compression. On a turbo diesel does the high compression have priority or does the boost from the turbo make up for it blancing for more N/A range numbers? I'm also trying to decide if I should just swap in the LD28 and go from there or should I build up an L28 turbo block with LD28 parts? I hear the F54 turbo block is the strongest but would going to the hassle of all the parts matching be worth it in the long run for a medium power show car?

 

I'm also concerned about the car's ignition system and how it should be modified for diesel, I imagine I'll be replacing most of it with the system from the Maxima. Also the electronic controls for the engine might be a problem, should I plan on taking the whole harness out of the maxima? What else I'm I missing? I'd appreciate any help you can provide. Thanks

[Guest bastaad525]

I'd be very interested for someone to try and document this swap some day...

 

 

there was this crazy 240 on ebay quite a while back that had a LD28 turbo motor in it, supposedly made really big power, I don't recall the details, but I seem to remember mention that it ran on vegetable oil (!!!!).

[SHO-Z]

Check out this web link.

 

http://zhome.com/rnt/L28conversion/3031FAQ.html

 

It should answer most of your questions.

[jt1]

There's a guy here in NC who has swapped a maxima diesel into a 280. I saw it at a track event but don't recall his name. He said he got 30+ mpg and the performance was only slightly less than the gas engine. Pretty wild to see a 280 go by and hear the diesel sound.

 

John

[Chewievette]

Check out this web link.

 

http://zhome.com/rnt/L28conversion/3031FAQ.html

 

It should answer most of your questions.

Acctually it didn't answer any more questions than any of the other 2.8L' date=' 3.0L, or 3.1L buildup articles that I've read. Problem I'm finding is that no one addresses building up and installing a diesel engine. I'm going to keep looking for most of today but I still havn't found anything useful.

 

There's a guy here in NC who has swapped a maxima diesel into a 280. I saw it at a track event but don't recall his name. He said he got 30+ mpg and the performance was only slightly less than the gas engine. Pretty wild to see a 280 go by and hear the diesel sound.

Fuel economy is one of the big reasons why I want to use the diesel. I travel a lot and in the summer it stands a pretty good chance that the ZX will come with me, the better the economy the better my wallet feels! I also think it'll be cool seeing the reactions on people's faces when I start it up!

[rayaapp2]

I'm actually building one right now. Search here and zcar.com for my posts.

 

26psi of boost is possible with the diesel engine. It just needs new seals and good compression. The LD28 has lower compression than most diesels already, but that doesn't matter that much in the world of diesel. I am slowing finding out diesels are completely different that gas. Obviously you'll have to modify the A/F! This is also done through the stock fuel pump for the diesel. It has a adjuster screw that lines up through a specail window for adjustment. It can be turned up from what I hear to 5X the stock fuel delivery. There are also aftermarket pumps for industrial apps for this engine.

 

 

I am going to be starting out with a ceramic ball bearing turbo from a VG33 made in japan. I may find that this turbo does not meet the CFM requirements at higher boost though. I would stick with a single turbo setup. You total RPM range is 4600 rpms.

 

The diesel block is the strongest. It is different from the gas block. You'll see once you get a diesel engine. Very obvious.

 

As far as ignition goes use the maximas. It's just a fuel cut. Build your own...

doesn't matter all that much just make sure that all fuel can be cut in the event that your diesel runs away!

[JMortensen]

I think you'll find that smaller turbo is better. You'll want to stay LOW in the rpm range, so you want a small turbo that spools at those low rpms. Get a large turbo and it won't spool until close to redline. I'm not an expert on turbos or diesels but I wouldn't think you'd want anything bigger than a T3, maybe even smaller would be better.

 

That's why you occasionally hear about people putting the Cummins/PowerStroke/Duramax turbos on their 4 or 6 cylinders.

[savageskaterkid]

idk, i work in an quicky lube shop, and those Garrett Turbos in the duramax, cummins, and powerstrokes are HUGE-compared to a Z turbo, and a Supra turbo.

 

(edit)

NVM, i relized that u meant the ones they put in are TOO BIG for the application. I thought u meant that they r small and that they should only b used on 4 cylinder cars...........my mistake.

[JMortensen]

No, you read it right the first time. Again, I'm not a diesel OR turbo guy, but I think diesels run small turbos. Think about it this way, if you have a 6 liter that spins 3500 rpm or a 3 liter that spins 7K rpm, they'll both need the same amount of volume (in a perfect world). Here's what I'm talking about: http://forums.hybridz.org/showthread.php?t=90177

[Chewievette]

I think you'll find that smaller turbo is better. You'll want to stay LOW in the rpm range' date=' so you want a small turbo that spools at those low rpms. Get a large turbo and it won't spool until close to redline. I'm not an expert on turbos or diesels but I wouldn't think you'd want anything bigger than a T3, maybe even smaller would be better.

 

That's why you occasionally hear about people putting the Cummins/PowerStroke/Duramax turbos on their 4 or 6 cylinders.[/quote']

If I'm understanding the theory of sequential turbos correctly, Exhaust passes through the smaller turbo and spools it up at low rpm and then the larger turbo spools up providing more boost higher up in the revs so you have a smoother power curve. It also helps reduce turbo lag, you only have to wait for the smaller turbo to spool up. I was thinking, just as an initial ballpark guess that I could use the stock T3 turbo bolted to the stock manifold, then run the exhaust from that to a T4 turbo and then out the back. Giving me the sequential setup while retaining the bolt on simplicity of the T3.

[JMortensen]

You just don't need that much volume IMO. But don't take my word for it. Try asking around on diesel forums.

[cheftrd]

If I'm understanding the theory of sequential turbos correctly, Exhaust passes through the smaller turbo and spools it up at low rpm and then the larger turbo spools up providing more boost higher up in the revs so you have a smoother power curve. It also helps reduce turbo lag, you only have to wait for the smaller turbo to spool up. I was thinking, just as an initial ballpark guess that I could use the stock T3 turbo bolted to the stock manifold, then run the exhaust from that to a T4 turbo and then out the back. Giving me the sequential setup while retaining the bolt on simplicity of the T3.

 

No. All the exhaust has to go through one turbo. Then as boost builds up, a valve opens, letting the exhaust into a second turbo. As the boost from the second turbo comes on line, another valve on the compressor side opens to let the air from the second turbo enter the piping. When it's fully on-line, it operates just like a regular twin turbo, with both turbos working. For the sequential to see any bennifit, the exhaust on the first turbo has to be quite small. This will create a severe restriction in the exhaust flow as rpm's climb, and the engine won't make any power unless the excess pressure is fed to the second turbo. It's very complicated and hard to get all the valve timing and pressures right.

A better option is to use a VATN turbo like the ones on the Ford Power Stroke. You can have a large turbo and lots of power. With proper sizing, full boost can be achieved by 1500-1800 rpm.

[rayaapp2]

diesels move MORE volume than gas! Read up on it. Also look at the HUGE intake for the diesel motor. It flows more because the engine consumes more. The T-3 turbo will spool fast on the diesel because of the volume! BUT it may spool up to fast and become ineffieciant before you get anywhere near redline.

 

This is where having a larger second turbo would be great. But having a single turbo that covers the exact range you want would save you a few headaches.

 

I work on Power Strokes, Cummins, and Duramax trucks everyday. I dare you to get one of those to spool up on you L series engine before redline! VOLUME.

Not only are all those engines approx 6.0L engines but they are diesels. My 7.4 L 454 CI stocker doesn't flow as much as those engines.

 

I'll be back with some prof later

[JMortensen]

Please bring back your proof Ray.

 

Diesels don't have a TB either, is that because the TB is too restrictive? No, it is because they don't restrict the air coming into the engine to control the acceleration of the engine. They only change the amount of fuel going to the engine to change the rpm.

 

As I understand it diesels can't have ANY overlap, so essentially they have a VERY VERY small cam. How you can push MORE volume through an equivalent sized motor with an extremely small cam and 1/2 the rpm range is beyond me. I'd love to learn.

 

What about the other thread where Jamie took apart a 6.5 liter turbo and MEASURED the impellers? Why did that come out to be approximately a T3/T4 in size?

 

One more time. I'm not a diesel expert. I'm not a turbo expert. But I'm not going to change my mind because someone says I'm obviously wrong when it isn't anything like obvious to me.

[Chewievette]

Well maybe I'm getting the name wrong of something. but THIS is what I'm talking about...

 

This is a Caterpillar C15, I know my engine is no where near the same in size or volume, but this is the turbo setup I'd like to run. Air comes into turbo 1, then is ported directly into turbo 2 then into the intake manifold. Exhaust comes out of the manifold and goes into turbo 2, then the exhaust is directed into turbo 1 and out the downpipe. I cant really tell if one is bigger than the other from this pic or any of the other ones on Cat's website but I know this is a fairly common setup on Big Rigs. I havn't a clue if this setup is practical for my little 2.8L but just so we're all on the same page, This is what I'M thinking of.

[Bernardd]

I use a stock turbo off of a 7.3 IDI turbo diesel. I get full boost at 4200rpm. The compressor is a to4b 60-1 hifi, exhaust is a stage 3 .82 a/r. Turbo ford guys with 2.3l use the holset off a dodge cummins, and like mentioned above the gm 6.5 is a t04b with an exhaust turbine wheel that measures a bit smaller than a stage 3.

[Guest DoTheDrew888]

Why don't you run two turbos on seperate exhaust manifolds? For example: have a smaller, faster spooling turbo on a manifold running from cylinders 1, 2, and 3. Then have larger turbo for higher rpm power on a seperate exhaust manifold on cylinders 4, 5, and 6. Wouldn't that work and prevent the restrictions of having two turbos inline with each other?

 

Disclaimer: I know almost nothing about turbo setups and just wanted to put my idea out there.

[randy 77zt]

ignition is easy-there is a solonoid on the diesel injection pump.the hot wire from the coil goes there.if you drain the tank and change the fuel filter you can put diesel in.this swap would be easier than l28et.a stock l28 turbo might be worth a try.if you worked hard you might be able to swap a stock engine in a day.

[cheftrd]

diesels move MORE volume than gas! Read up on it. Also look at the HUGE intake for the diesel motor. It flows more because the engine consumes more. The T-3 turbo will spool fast on the diesel because of the volume! BUT it may spool up to fast and become ineffieciant before you get anywhere near redline.

 

This is where having a larger second turbo would be great. But having a single turbo that covers the exact range you want would save you a few headaches.

 

I work on Power Strokes' date=' Cummins, and Duramax trucks everyday. I dare you to get one of those to spool up on you L series engine before redline! VOLUME.

Not only are all those engines approx 6.0L engines but they are diesels. My 7.4 L 454 CI stocker doesn't flow as much as those engines.

 

I'll be back with some prof later[/quote']

 

 

rayaapp2, if you read my post a little closer, it says to use a VATN turbo LIKE the ones used on the Ford Power Stroke. They come in all different sizes...A properly sized VATN turbo will get 8-10 psi by 1500-1800rpm.

 

The Cat dual turbo setup is for super-high boost, not for quick response. Some Detroit Diesels are like this too, with the turbo boost going into a roots supercharger. Because the Detroit is a 2 stroke, it requires boost to even run.

[Chewievette]

So basically what this is coming down to is either go single turbo, independant twin turbo, or leave to turbo out of the picture all together (at least until more R&D can be done) Personally I REALLY like the idea of twin turbos on a diesel, aka totally unique, even if it has to be independant. The whole reason I wanted to do the sequential twin turbo was so I could use the bolt on exhaust manfold but if it's going to be a major pain and I have to use a custom manifold anyways then I might as well run independant for simplicity.

 

On a side note, would it be wise to run an intercooler on a turbocharged diesel? I always thought that the added heat would help combustion, but now that I think about it, too much heat is also bad.