Build FZJ80 6.5TD diesel swap build thread
- Thread starter 6840
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- Thread starter
- #42
wrong. Diesel EXHAUST temps run hotter when rich and cooler when lean. Diesel internal cylinder temps (and thus water temps) are hotter when the engine is running lean and cooler when running rich.
Let me see if i can help, the leaner a diesel runs the cooler it runs. Remember you lean a diesel out to make it idle. The reason it runs hot with low fuel pressure is because the pump needs the pressure to advance the timing, instead it is retarded to much. When in doubt remember a diesel engine is opposite of a gas engine when it come to fueling.
How does it magically go from really hot inside the cylinder to really cool in the exhaust?
At what point does it switch from hot inside cool outside to cool inside and hot outside?
Think about it some more. How can a small diesel fire in a room make it hotter than a large diesel fire in the same room with the same amount of air?
- Thread starter
- #45
Gee, I guess you are right... I must be imagining the whole thing. How could I be so stupid as to trust TWO temperature gauges, and a handful of master diesel mechanics when I should be trusting some mystery post on Ih8mud. What was I thinking??
So, Yoda of automotive knowledge - tell me why the engine magically runs cooler when the ONLY thing I changed was the fuel restriction at the tank??
So, Yoda of automotive knowledge - tell me why the engine magically runs cooler when the ONLY thing I changed was the fuel restriction at the tank??
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I told you. The goat.
It's not just IH8MUD, pick any website, any diesel mechanic, anyone who understands anything about diesel combustion.
The world is indeed against you on this one.
Because you've got more boost and driving faster.
Neat swap, keep up the good work!
I might suggest that there could be a link between injection timing and internal pump fuel pressure like there is in the VE pump. Inefficiency due to incorrect timing can cause overheating. Too much advance for example = overheating and lower than usual EGT's
More fuel = higher cylinder temps = more heat to cooling system and higher EGT's. Remember combustion occurs in the cylinder first and the gas gets cooler from that point on.
More fuel = higher cylinder temps = more heat to cooling system and higher EGT's. Remember combustion occurs in the cylinder first and the gas gets cooler from that point on.
- Thread starter
- #50
Dougal,
Please find another thread to post in. you aren't adding anything constructive to my thread. Maybe go over to mudbay and shop around for wax or carpet cleaner - something you are able to understand.
Sent from my ADR6300
Please find another thread to post in. you aren't adding anything constructive to my thread. Maybe go over to mudbay and shop around for wax or carpet cleaner - something you are able to understand.
Sent from my ADR6300
Great swap! Should be really nice once you get all the bugs sorted out.
I'm not sure that trying to insult someone who knows more than pretty much anyone on the diesel forum is wise, though. He was trying to help, if it wasn't obvious, and he's 100% correct.....
I'm not sure that trying to insult someone who knows more than pretty much anyone on the diesel forum is wise, though. He was trying to help, if it wasn't obvious, and he's 100% correct.....
- Thread starter
- #52
He may have been trying to help, but he is quite insulting in his posts. Also, he is not 100% correct. I started this thread to share info with the group about a fairly unusual swap. Have tried to give detailed info as I progress. Now, having sorted out one of the major problems encountered, Dougal has decided that he doesn't believe the facts as presented. There is NO argument to be had. The water overheat problem stopped when the fuel restriction was eliminated. Simple as that.
I think your build post is really good, but I'm sad to see it go to this back and forth crap. Maybe another post should be created for what happens to engine temps on a diesel when it's lean or not.
Keep up the good work 6840, I'm happy that your engine now runs cool. The last 6.5 I swapped had the 4l80e transmission, and I will build one with a NV4500 next ( I used that trans in my previous previous 6.2 swap )
Keep up the good work 6840, I'm happy that your engine now runs cool. The last 6.5 I swapped had the 4l80e transmission, and I will build one with a NV4500 next ( I used that trans in my previous previous 6.2 swap )
I had that issue at first, but it was due to the throwout bearing. I replaced it with a different kind from Advanced Adapters, and it worked great. The stock bearing tends to rattle around inside...
Let me see if I can summarize: the engine ran hot, other fixes did not work. Then when you fixed a crimped line, the problem went away. Simple input/output kind of observation, but since it doesn't fit within spectator's understanding, you must be wrong or imagining the whole thing. Or the world is indeed against you and/or back to school for you. Huh?
With that aside, what was ballpark budget for your swap? Torfab has me enchanted with the concept of a 6.5 & NV4500 in my 97 LX450 in about 20K more miles. Danged if I'm not also entertaining the thought of an Atlas case to boot.
Can't spend it when I'm dead.
Managing Coolant Temperatures on Modified Vehicles
I thought I would provide some input on the matter. When you modify a vehicle—such as converting over to a larger diesel engine—it can overtax the original coolant system, and in the case of the GM 6.2L and 6.5L turbo diesels, there is an issue with the rear cylinders getting too hot even in factory vehicles.
I would first suggest modifying the engine’s coolant system with a coolant crossover kit. You can purchase them, but they are expensive, and if you have some basic fabrication skills, you can build your own for less than $50.00 (see first image below). The modification utilizes the coolant passage openings, which are normally blocked-off at the rear, to draw coolant from the rear of the engine to the front of the coolant crossover and into the radiator.
If you live in a warmer climate, drive on hilly or mountainous terrain, or haul trailers and heavy equipment, then the factory radiator from Toyota may not be up to the task. An aluminum radiator can be expensive, and not guarantee the results you are looking for. It isn’t that the radiators aren’t efficient enough, but that the system doesn’t carry enough capacity to meet the needs of a larger engine that generates more heat than a petrol motor.
I ran into this problem when I moved back to Texas and started driving in the Hill Country. What I decided to do was to increase my coolant capacity by expanding the system.
By modifying the lower radiator to water pump hose, and adding another connector to the rear cylinder coolant crossover kit, I was able to add an expansion tank to increase the overall volume of the coolant system. It can be fabricate using basic plumbing supplies and steel square tubing. Aluminum is more efficient and doesn’t rust, but requires access to a TIG. By treating the metal with POR chassis paint, I was able to build it with materials that are easily available and less costly.
The tank was made from a piece of 5”x5”x16” square tubing 3/16” thick. I acquired a castoff as metal scrap purchased for $5.00, which gave me about 28” of usable material. I tapered the ends so that I could mount the tank high up on the frame, under the driver’s seat well where the factory exhaust system would cross over the frame (’91-’92 FJ80s with the 3FE engine), and fabricated brackets which took advantage of the original mounting locations for the exhaust hanger (frame) and heat shield (raised floor pan).
The tank’s volume is just over 1.5 gallons. Consideration of fluid dynamics was made in designing the system. The hot connector, where coolant enters the tank, is located at the top, and the coolant system return is located at the bottom. Brass 5/8” hose connectors are threaded through the outside wall of the tank and joined by copper threaded fittings. The top connector empties directly into the front of the tank, whereas the lower return has a 12” copper tube sweated on to draw fluid from the back of the tank. This ensures effective circulation within the tank itself.
The high-volume water pump maintains a good flow rate. With this system now in place, I no longer have to worry about overheating. In town, at lower speeds, during the cooler months, my coolant temperature is about 172-degrees (190-degrees is optimal), but at highway speeds, when my exhaust temperatures are between 550- and 950-degrees or higher, my coolant stays between 191- and 217-degrees. Even with my fans cut off, I have only been able to get the coolant to rise up to 227-degrees with this system.
If I were still driving up North, in sub-zero temperatures, I would still perform this modification. However, I would suggest adding cutoff valves to the system to bypass it during the winter.
I thought I would provide some input on the matter. When you modify a vehicle—such as converting over to a larger diesel engine—it can overtax the original coolant system, and in the case of the GM 6.2L and 6.5L turbo diesels, there is an issue with the rear cylinders getting too hot even in factory vehicles.
I would first suggest modifying the engine’s coolant system with a coolant crossover kit. You can purchase them, but they are expensive, and if you have some basic fabrication skills, you can build your own for less than $50.00 (see first image below). The modification utilizes the coolant passage openings, which are normally blocked-off at the rear, to draw coolant from the rear of the engine to the front of the coolant crossover and into the radiator.
If you live in a warmer climate, drive on hilly or mountainous terrain, or haul trailers and heavy equipment, then the factory radiator from Toyota may not be up to the task. An aluminum radiator can be expensive, and not guarantee the results you are looking for. It isn’t that the radiators aren’t efficient enough, but that the system doesn’t carry enough capacity to meet the needs of a larger engine that generates more heat than a petrol motor.
I ran into this problem when I moved back to Texas and started driving in the Hill Country. What I decided to do was to increase my coolant capacity by expanding the system.
By modifying the lower radiator to water pump hose, and adding another connector to the rear cylinder coolant crossover kit, I was able to add an expansion tank to increase the overall volume of the coolant system. It can be fabricate using basic plumbing supplies and steel square tubing. Aluminum is more efficient and doesn’t rust, but requires access to a TIG. By treating the metal with POR chassis paint, I was able to build it with materials that are easily available and less costly.
The tank was made from a piece of 5”x5”x16” square tubing 3/16” thick. I acquired a castoff as metal scrap purchased for $5.00, which gave me about 28” of usable material. I tapered the ends so that I could mount the tank high up on the frame, under the driver’s seat well where the factory exhaust system would cross over the frame (’91-’92 FJ80s with the 3FE engine), and fabricated brackets which took advantage of the original mounting locations for the exhaust hanger (frame) and heat shield (raised floor pan).
The tank’s volume is just over 1.5 gallons. Consideration of fluid dynamics was made in designing the system. The hot connector, where coolant enters the tank, is located at the top, and the coolant system return is located at the bottom. Brass 5/8” hose connectors are threaded through the outside wall of the tank and joined by copper threaded fittings. The top connector empties directly into the front of the tank, whereas the lower return has a 12” copper tube sweated on to draw fluid from the back of the tank. This ensures effective circulation within the tank itself.
The high-volume water pump maintains a good flow rate. With this system now in place, I no longer have to worry about overheating. In town, at lower speeds, during the cooler months, my coolant temperature is about 172-degrees (190-degrees is optimal), but at highway speeds, when my exhaust temperatures are between 550- and 950-degrees or higher, my coolant stays between 191- and 217-degrees. Even with my fans cut off, I have only been able to get the coolant to rise up to 227-degrees with this system.
If I were still driving up North, in sub-zero temperatures, I would still perform this modification. However, I would suggest adding cutoff valves to the system to bypass it during the winter.
- Thread starter
- #59
One year later - an update
In no particular order, responses to questions and comments:
1. Yep, a factory toyota diesel swap would be cool, and require much less fabrication... But, THIS project was to swap the 6.5 in there. I've got access to 6.5 parts and data through my business, the engine was already sitting here begging for work, and the fabrication part is my "wrench therapy" after a hard day dealing with federal contracting officers. Might do a Toyota diesel swap in the next project... who knows.
2. Manifolds - this engine is fitted with a vintage aftermarket ATS turbo kit (originally for the 6.2 motor). By coincidence, the manifolds clear everything in the FZJ80 engine bay.
3. Fuel economy - very close to 20mpg cruising at highway speeds. 15-16 around town and climbing my mountain every day. Sure, my Audi A4 gets better mileage, but the 80 commands RESPECT in traffic...
4. Cooling - chased engine temps for quite awhile and eventually stumbled on the problem. The hose adapter that I used to fit a 1-3/4" radiator hose to the 1-1/2" Toyota radiator fitting was about 1" longer than the fitting, and had created a "flap" that was blocking most of the water flow - especially at higher flow rates. trimmed off the excess rubber and she runs MUCH cooler. But, the toyota radiator still can't keep up with full power bonzai runs in the mountains. Have got an aftermarket aluminum radiator ready to go in there as soon as summer returns and I can get some high ambient temp test data.
5. Torque - more than you can imagine. Amazing rock crawl at 900 rpms.
6. Transmission - NV4500 is cool and unusual. But, next time I will use an automatic. Simpler install, and even more important - every time you lift you foot to shift gears, you lose boost pressure and it takes time to build it back again. A good automatic will keep the engine spooled at max boost/power continuously. Probably a diesel spec 700R4 or 4L60E would be fine. At work, we have also been experimenting with a 4L85E in our high performance HMMWV. Spendy, but great performance.
7 Alternative fuels - haven't gone the veggie fuel route. But, I dump my used motor oil in the fuel tank and it works fine. Trying to keep the oil/diesel ratio to no more than 1:5 - but I might try straight motor oil at some point just for s***s and giggles. Biggest concern is that it will clog the fuel filter due to viscosity.
Have talked to several Mud members about their 6.5 swaps. Hoping to see your build threads here soon...
Will
In no particular order, responses to questions and comments:
1. Yep, a factory toyota diesel swap would be cool, and require much less fabrication... But, THIS project was to swap the 6.5 in there. I've got access to 6.5 parts and data through my business, the engine was already sitting here begging for work, and the fabrication part is my "wrench therapy" after a hard day dealing with federal contracting officers. Might do a Toyota diesel swap in the next project... who knows.
2. Manifolds - this engine is fitted with a vintage aftermarket ATS turbo kit (originally for the 6.2 motor). By coincidence, the manifolds clear everything in the FZJ80 engine bay.
3. Fuel economy - very close to 20mpg cruising at highway speeds. 15-16 around town and climbing my mountain every day. Sure, my Audi A4 gets better mileage, but the 80 commands RESPECT in traffic...
4. Cooling - chased engine temps for quite awhile and eventually stumbled on the problem. The hose adapter that I used to fit a 1-3/4" radiator hose to the 1-1/2" Toyota radiator fitting was about 1" longer than the fitting, and had created a "flap" that was blocking most of the water flow - especially at higher flow rates. trimmed off the excess rubber and she runs MUCH cooler. But, the toyota radiator still can't keep up with full power bonzai runs in the mountains. Have got an aftermarket aluminum radiator ready to go in there as soon as summer returns and I can get some high ambient temp test data.
5. Torque - more than you can imagine. Amazing rock crawl at 900 rpms.
6. Transmission - NV4500 is cool and unusual. But, next time I will use an automatic. Simpler install, and even more important - every time you lift you foot to shift gears, you lose boost pressure and it takes time to build it back again. A good automatic will keep the engine spooled at max boost/power continuously. Probably a diesel spec 700R4 or 4L60E would be fine. At work, we have also been experimenting with a 4L85E in our high performance HMMWV. Spendy, but great performance.
7 Alternative fuels - haven't gone the veggie fuel route. But, I dump my used motor oil in the fuel tank and it works fine. Trying to keep the oil/diesel ratio to no more than 1:5 - but I might try straight motor oil at some point just for s***s and giggles. Biggest concern is that it will clog the fuel filter due to viscosity.
Have talked to several Mud members about their 6.5 swaps. Hoping to see your build threads here soon...
Will
