turbodiesel L6 build ideas.

[OlderThanMe]

Here are the exhaust ports...

 

 

 

They are pretty rough but not terrible.

BTW I'd like to use a pair of L28ETs for a work table...

[JMortensen]

It's really tough to see the shape of the ports in these pics. Like I said before, I think it'll be an expensive investigation to find out whether or not it's worthwhile. I would still venture a guess that it is not a good option from a performance standpoint.

[twoeightythreez]

stock L28ET, with proper tuning, makes some dang awesome torque, too, just my .02 (i can pull out in 4th without a problem, I could probably pull that stump out of your backyard with my gas L28et)

Mine spools up off idle and hits full boost at about 2200.....I can bark the tires shifting at 2500rpm in 2nd and third...but not at 4000rpm...like a diesel.

I can get people to think it's a diesel cuz it burns a LOT of oil (badly stuck oil rings but great compression)

..it's still slow because it won't rev above 5000...and makes power up to about 3800...I think it's an ignition problem..(well I guess it eventually is when the plugs foul).going to get some hotter plugs and keep tuning but I think the motor's screwed (uses a qt of oil every 100mi)

[Chewievette]

Is it just me or does that diesel cam look a Lot like a gas cam? acctually, the whole valve train looks pretty darn close. Why do I get the feeling that if you drilled and tapped the injector holes for plugs and had some lower compression pistons you could use that head on a gas L series? I see absolutely NO advantage in doing that but the fact that it could be done is an interesting thought.

[roger280zx]

Do you have any of these LD28's OTM? I've been looking for one.

[240hoke]

Excuss my ignorance but I have always wondered why the truck diesels are so easy to modify and can quadruple their HP output.... why not car diesels?

[Challenger]

Excuss my ignorance but I have always wondered why the truck diesels are so easy to modify and can quadruple their HP output.... why not car diesels?

 

My friend put a 100 dollar chip on his 98 Dodge Cummins 24v and got like 150 ftlb. And a couple other easy things with the intake/exhaust/turbo, hes probalby making over 200 ftlb over stock (with chip). Thats pretty awesome.

[JMortensen]

Excuss my ignorance but I have always wondered why the truck diesels are so easy to modify and can quadruple their HP output.... why not car diesels?

Here's my take on this question, and this may or may not be the case, but it's how it has been presented to me.

 

The newer diesels (car and truck) are built better. They might have DOHC in some cases, the ports flow better, I remember the Duramax had all sorts of hipo stuff like piston squirters to keep the pistons cool, a girder bottom end, I mean it's basically a hipo V8 that runs diesel instead of gas. The mid 80's diesels weren't built that way. They were built for low output and 300K mile durability.

 

Anecdote time--I went racing with a buddy who was just starting to trailer his car. He did not have a tow vehicle, so he borrowed his dad's tow rig which was a '76 F150. This truck wouldn't pull his car more than 35 mph up any hill. It had the worst emissions designed heads imaginable, and although it got a steady 9 mpg, it probably put out no more than 150 bhp. I mean seriously I think we could have hooked his trailer up to my little Toyota truck with a 22RE and it would have done a hell of a lot better. Later engines were just made to produce more power. A 1978 Vette with an L48 put out a whopping 175 bhp with a 4 barrel carb. But these are gas anecdotes...

 

I can also remember going fishing with my uncle. He had an 84 (approximately) K5 Blazer with the NA 6.2 liter diesel. Same story basically, we were pulling a 1000 lb boat at about 25 mph up every grade between the house and the lake. I mean incredibly slow. I also had a couple of friends with diesel rabbits. They'd put out a max of about 55hp and would do 65 mph with a tail wind downhill. The diesels of this era were made to sip fuel, not to make power.

 

There was a sea change in diesel design and I don't really know when it happened. I think it was the Cummins in the Dodge, but suddenly diesels didn't necessarily suck anymore, and from that point on they've been made increasingly powerful. But pulling one of those old ones out of the junkyard and trying to make power with it is like pulling the engine out of the 78 Vette with the knowledge that you can't change the heads or the induction and trying to make power with it. Yes, it's a 350 Chevy. That doesn't mean that it doesn't suck.

[OlderThanMe]

Do you have any of these LD28's OTM? I've been looking for one.

 

should have one by wednesday. Once I sell off all the parts I'll buy another one that is also nearby. It is a way better option to buy the whole LD motor and sell off the parts to the Diesel maxima guys.

In the morning I'm going to go pick up a L28 that the local yard got yesterday. Probably going to do a rebuild, raise compression with a maxima head, and then sell it on Ebay. Who knows I may even get the parts and build a high compression N/A stroker out of it to sell.

 

Jmortenson,

Aren't the stock L28 motors the same idea? good gas mileage and live forever? I don't see why you can't modify the head to use aftermarket injectors, put a big(for a diesel) turbo on there, and run boost up at like 30+ psi...

We know the Nissan internals can take the abuse since they are all forged. Just some forged pistons and add boost.

With the gas motors we are taking an "economy" L28 that got 25mpg well tuned back i the 70's and now some guys are making 600+ hp on the stock crank (albiet modified, but came in a production car).

What is needed in the fire triangle to go faster with a diesel?

 

heat: Glow plugs (will stock work? probably not.)/compression ratio

fuel: bigger injectors/fuel pump

oxygen: big turbo, ported runners, bigger valves

 

 

With a diesel you don't have to worry about spraying fuel around the valves as it is injected directly into the combustion chamber.

 

 

Just some thoughts...

[BLKMGK]

You guys might want to read up on the new Banks salt racer. One of the KEYS to making more power on that motor was raising the RPMs. HP is torque factored with RPM, make the same torque and raise the RPMs and you get more HP. They had to significantly lighten the rotating assembly in order to do this. As for the flywheel, I'll bet they made it that heavy to dampen vibrations and store some energy. I dunno' if this motor is a good one to mod or not but getting more power from new motors is usually accomplished by bumping up boost a good bit. Diesel will run incredible amounts of boost setup correctly - till they fail

 

Yeah, I'm driving a TDI diesel these days. REAL tempted to chip it! Redline is like 4K. (lol)

[nbesheer]

there was a video somewhere on here (a youtube video) of a LD28 S30 and it was pretty quick, I don't know if It was turbo or not but I don't think it was. as previously mentioned you don't need a huge HP number to have fun, we had a S10 with a 4 banger but it had a stick shift so it was all good.

[JMortensen]

Jmortenson,

Aren't the stock L28 motors the same idea? good gas mileage and live forever? I don't see why you can't modify the head to use aftermarket injectors, put a big(for a diesel) turbo on there, and run boost up at like 30+ psi...

We know the Nissan internals can take the abuse since they are all forged. Just some forged pistons and add boost.

With the gas motors we are taking an "economy" L28 that got 25mpg well tuned back i the 70's and now some guys are making 600+ hp on the stock crank (albiet modified, but came in a production car).

I bet you if you asked 1000 engine builders what engine they would want to start with to produce a reliable 600 hp not one of them would choose an L. I think that is right at the root of why this site exists, really. The L is not the best engine to start with, and I don't think you'll find too many (any?) who argue that it is the pinnacle of internal combustion engine design. I'm not trying to tell you not to do it. If trying to build a hipo L diesel gets you out of bed in the morning, fine. I'm just saying that like the gas L series, I suspect that making big power with the diesel L is going to be like squeezing blood from a stone.

 

If you want to prove to me that I'm wrong, that's great. I'll follow the buildup and I'll be happy to be wrong if you post having just dynoed your diesel at 300 hp and 600 lb/ft of torque.

[BRAAP]

Excuss my ignorance but I have always wondered why the truck diesels are so easy to modify and can quadruple their HP output.... why not car diesels?

 

I don’t know why Diesel tuners aren’t revving them higher as more RPM is more horse power, though I’m sure there is a very GOOD reason why they aren’t, (I have a few theories, but I honestly don’t know). AND the cars, I guess in Europe there are Diesel tuners getting impressive HP from the cars.

What I have found is that these Turbo Diesel guys are cramming AH MAH GAWD amounts of boost down these things. They are honestly cramming 60+ PSI! My brother in law, Bryan Compton, (owns BC Offroad, a 4 wheel drive ATV aftermarket parts supplier http://bc-offroad.com/shop/ ), and a couple years back he was bragging about running 35 PSI of boost on his then new ¾ ton Dodge Turbo Diesel 6 speed 4x4. He had installed a new Turbo, complete exhaust system, super whiz bang clutch, and some fuel adjuster made by “Edge”. I was like "Chyea right". I honeslty didn’t believe he was boosting to 35 PSI, so he took me for a ride. Sure enough, 35 PSI of boost on the Auto meter boost gauge and his 7000 lbs 4x4 was leaving two strips of rubber from the Super Swampers all the way through 3rd gear! That truck I believe would run at least a low 14 ET, he claimed high 13’s.. He sold it so I guess we’ll never really know, but none the less, it was very impressive, for what it was.

 

Here is one of those aftermarket suppliers selling Turbos for 60+ PSI!!!!

 

http://www.atsdiesel.com/ATSWebsite/ProductsDodge/TurboSystems.asp

[76s30]

ok the cummins is a med duty truck engine so is the 7.3 ford (built by IHC)

they are bulit alot heavier. and can take punishment accordingly.

 

Glow plugs have one prupose to preheat the air so after it is compressed it is at 1000 degrees or more. Glow plugs hang out in a little precombustion camber a small cup in the piston or in the head that the fuel is injected into. Not all diesel have glowplugs, the cummins B,C and N seires just have a flat head and a dished piston.

 

If you were set on making power with a L I would work on adapting an injection pump from a larger (higher hp) engine. maybe even a p7100 bosch from a cummins.

Making power in a diesel is about flowing fuel.

We port heads on the big diesels when egt's get to high. Air flow is nesscesary of course. but when your runing 80-100 lbs of boost you can cram alot of air through a tiny port. Not that some care shouldn't be taken to open up the flow some since the richest a diesel runs is 15:1 A/F and thats the piont were you see black smoke and egt's start climing above 1400 which mean piston meltdown is close at hand.

 

Tractor pull guys run in excess of 250 psi with turbos feeding turbos the enigne disapears under a mass of exhaust tube. Its common to find any where from 5 to 8 turbos on a competion rig. there are at least 2 stages, almost always 3 sometimes 4.

A diesel can spool a very large turbo at relativly low rpms as long as its under load.The more load the more boost. your average semi truck will boost 2 psi when you give it with no trailer. Put a full trailer behind it and watch that 30psi gauge peg.

 

The biggest problem I see with making power (not making it hold the power) is getting the fuel, its not like gas efi or carb and you can just swap out for bigger stuff I.E. bigger injectors remap the computer and maybe a bigger fuel pump. The heart and soul of a diesel IS the fuel injection unit. Tunning is not terribly difficult though. Getting the timming right and add fuel untill you can keep egts below 1400 under full load.

 

Diesel injection pumps have "torque backup" built in the amount varies between pumps. But 25% is generaly the case. Torque backup is what allows the engine to built torque when the rpms drop becuase of load.

 

I.E. an engine is held WOT and is spining 2000 rpm no load, A 300 ft/lb load is placed on it. The rpms drop untill the eninge is making 300ft/lb of torque.

 

Gas engines have this to but not in the same way. I.E. an industrial gas engine is grossly under rated from its max hp. say an l28 for example in an industrial application would be rated for about 50 hp maybe 60. Its how much power it can make at what rpm with out losing rpm.

 

 

 

sorry for the long post hope this info is a little helpful.

[BRAAP]

Hmm.. Looks like the LD28 head is shorter in height overall as compared to the L series, and the cam towers look as though the bases of the towers themselves are thicker. Maybe the cam centerline to head deck surface is the same as L-series? If you look at the water outlet, (thermostat housing area), it looks as though Nissan shaved the top of the head down and lowered then intake ports considerably. At any rate, being as the ports, in particular the intakes, are so low, that means the port has a sharp 90 degree turn, (tighter centerline radius), as the air makes the transition from the manifold to the valve seat. High velocity air flow will suffer because of the sharper turn, (as compared to the L-series). But if the velocities are slow enough, (these things don’t rev that high), it wont be as much of an issue. Hmmm… A little larger port diameter, optimize the port shape both intake and exhaust, see what it would take to install larger valves if possible, I’ve’ got nothing against porting iron heads, (ported MANY a SBC and SBF head), Hmm…

 

Ok, so if you guys are SERIOUS about doing one of these Diesels, and if you are attempting to coax more umph from it, I’ll offer my porting services for free, (gives me the opportunity to play with the LD28 head). You will have to cover any and all parts, but labor would be free. Also, keep in mind that our current work load of custom L-series cylinder heads is VERY heavy, so this project will not be a priority, i.e. as time allows we will tinker with it. For this offer, I would want 2 of these heads. One good one that will be finished product and one scrap head, (as long as it is somewhat complete), so that I can mutilate it to get an idea of just how far I can take the ports, valve sizes etc.

 

I can see it now. Watching Speed TV one Sunday afternoon… The Diesel Car Drag Nats in Pamona, HybridZ’s own monster Diesel Z car in the finals with Garret Maddox at the helm of the LD-28 powered 280ZX 2+2, blowing black clouds through the traps in 17.547 seconds @ 82.567 MPH….

[76s30]

The other porblem I see..... say you do make 550 ft/lbs from one of these. good luck on the tranny.

the torque comes in hard and fast. would you put a big block in front of your little nissan tranny... probably not.

 

When juging power of a diesel its best to look at the torque not the hp.

since you don't rev to the moon anyway. now how many rpms can you make 450ft/lbs of torque? if you could do it from 1500 to 4500 and had some tall gearing you would be very fast indeed. I see 12's possible in a z car though major structural renforcement would be needed.

[BRAAP]

The other porblem I see..... say you do make 550 ft/lbs from one of these. good luck on the tranny.

the torque comes in hard and fast. would you put a big block in front of your little nissan tranny... probably not.

 

When juging power of a diesel its best to look at the torque not the hp.

since you don't rev to the moon anyway. now how many rpms can you make 450ft/lbs of torque? if you could do it from 1500 to 4500 and had some tall gearing you would be very fast indeed. I see 12's possible in a z car though major structural renforcement would be needed.

 

 

 

 

Yes the trans would be an issue. Adapting the Z-32 5 speed to the L-series has been done and it appears to be holding up to low 11’second ET, (Hopefully soon to be in the 10’s). Also, a T-56 could be adapted if need be.

 

Now as for the chassis stiffening. If the Diesel car could run 12’s, it shouldn’t need any other reinforcing over what a Gas engine Z car of the same weight that runs 12’s would require. (I am not taking into account torque under the curve here and I do realize that does play role. It is a small role and not in context with the overall point I’m trying to convey). As you mentioned, the Diesel variant would be taller geared vs a gas equivalent. The purpose of a Transmission, (transmissions are torque multipliers), is to trade Torque for RPM, and vice versa. Taller gears mean more RPM and less torque, or less RPM and more torque, depends on the ratio between the input vs output, i.e gear ratio.

 

In short, the torque produced AT the wheels from the diesel car and Gas car that are GEARED to both run the same ET and MPH, ultimately would be the similar.

[djz]

I think the timing marks for the LD are on the flywheel, so if you want to time it correctly you have to stick with the stock one.

[ww]

Hey, I just think it would be cool to tow my 240Z to the track with a diesel LD28 turbo powered 240Z...

[76s30]

well yes the ultimate torque (at the wheels with correct gearing for the diesel) would be the same as a gas. I was refering to the torque that the drive shaft and the body would experience. with tall gears the transmission and drivshaft are put under much higher torque loads than before. So I would think that the body would twist more. especialy between the trans and rear.

I'm also used to big trucks which are under a higher loads every where because of the weight they must pull/haul no matter what the gearing.

 

But the main objective would be to increase the gearing ( lower number) untill e.t.s start to rise.

Other wise you will not see the potential output of the diesel.

 

On the subject of the head it is my opinion that nissan cut or cast the head with a shorter deck to cam center distance, as an easy way to increase compression. since I have only see one of these and it was in a 4 dorr stanza I can only speculate.

What if a gas head was adapted and injectors placed in the spark plug holes? yes a custom piston would be required to get the compression back and adapt to the differnt combustion camber design. but not as much compression would be needed or wanted if turbocharing was used.

There are quite a few porduction diesels with aluminum heads. this would also help fix the port problem.