You gunna pay for the broken parts?
And you'll be waiting a few years before I need new tires I hope...
Woodrow's 97 Green TJ Moderate Build
- Thread starter Woodrow
- Start date
You gunna pay for the broken parts?
And you'll be waiting a few years before I need new tires I hope...
There are a lot of shortcomings with inertial dynamometers. In the racing world, we didn't use them much. Of course, pulling an engine and putting it on a brake dyno is an expensive way to go, so it's rarely done outside of racing. Mike, you probably already know this, but if you're using an inertial dynamometer to track changes in torque and power, you have to keep everything you possibly can the same between dyno runs. Same tires, at the same pressure, and same gear (preferably 4th on the AX-15 because it's 1:1, so there's no torque multiplier effect from the transmission). The dyno software corrects for atmospheric conditions, but that's not perfect, so if the dyno's not inside a climate-controlled building (that is capable of supplying climate-controlled air to the intake system), don't compare a winter run to a summer run.
And to geek out, here is why there's a big difference between an inertial dyno and a brake dyno. On a traditional brake dyno, the torque is almost measured directly and horsepower is calculated (it's very hard to ever measure power directly - even with electricity). The brake housing will freely rotate around the dyno shaft. There is a load cell at a measurable radius from the centerline of that shaft that prevents rotation of the brake under load. When the engine turns, the brake loads the load cell, and a reaction force is generated in the load cell as the brake is prevented from rotating by it. Due to heat buildup, most brakes use a fresh supply of water moving through vanes to generate the load.
The load cell reads force (pounds) and the computer multiplies it by that radius to get ft-lbs of torque. The horsepower is then a simple calculation of torque (in ft-lb) times engine speed (in RPM) divided by 5252 for units conversion. On motorcycle engines with integral transmissions, it was easier to connect the dyno to the countershaft (output shaft on the transmission), and with a brake dyno, the gear doesn't matter. Whatever that load cell sees, it measures instantaneous torque. The biggest benefit of this system is it's an instantaneous or steady-state system. You can hold it at a given point in the fuel map to calibrate the base map perfectly. At Harley-Davidson, a co-worker and I created an automated system to calibrate the VR 1000 engines that used an instrument-grade air-fuel ratio sensor as an input to the system and then adjusted the fuel map based on that reading at each point in the map. That made it very easy to calibrate each engine individually (a custom fuel map for each engine), and it was only possible with brake dyno.
An inertial dyno, on the other hand, is a different beast altogether. It measures the speed of the drum as the vehicle accelerates. By looking at the drum speed at two points in time during the run, the rotational acceleration of the drum is calculated, and then you can calculate torque by multiplying the rotational acceleration of the drum by the rotational inertia of the drum (this is a physical property of the drum) and then multiplying by a factor for units conversion. Once you have torque, you can then calculate power the same as for a brake dyno. The big drawback of the inertial dyno is that you can only measure torque while accelerating, meaning that you can't isolate points in the fuel map and test for those. You can only test points that get passed through when you do a run. Also, because inertia is involved in the measurement process, anything that will change the acceleration rate of the drum will affect the calculations.
I left the racing world over two decades ago now, and shortly before I left, I think Superflow had come out with a hybrid dyno that was mainly inertial, but also had a small electromagnetic brake that improved upon the usual inertia dyno. It was not good enough to do steady-state fuel mapping, but it was better than a simple inertia dyno. I never got to mess around with that, and I haven't paid much attention to the current state-of-the-art in chassis dyno technology. It's entirely possible that newer technology exists to address some of what I've written above, so keep in mind that I'm old and antiquated...
And to geek out, here is why there's a big difference between an inertial dyno and a brake dyno. On a traditional brake dyno, the torque is almost measured directly and horsepower is calculated (it's very hard to ever measure power directly - even with electricity). The brake housing will freely rotate around the dyno shaft. There is a load cell at a measurable radius from the centerline of that shaft that prevents rotation of the brake under load. When the engine turns, the brake loads the load cell, and a reaction force is generated in the load cell as the brake is prevented from rotating by it. Due to heat buildup, most brakes use a fresh supply of water moving through vanes to generate the load.
The load cell reads force (pounds) and the computer multiplies it by that radius to get ft-lbs of torque. The horsepower is then a simple calculation of torque (in ft-lb) times engine speed (in RPM) divided by 5252 for units conversion. On motorcycle engines with integral transmissions, it was easier to connect the dyno to the countershaft (output shaft on the transmission), and with a brake dyno, the gear doesn't matter. Whatever that load cell sees, it measures instantaneous torque. The biggest benefit of this system is it's an instantaneous or steady-state system. You can hold it at a given point in the fuel map to calibrate the base map perfectly. At Harley-Davidson, a co-worker and I created an automated system to calibrate the VR 1000 engines that used an instrument-grade air-fuel ratio sensor as an input to the system and then adjusted the fuel map based on that reading at each point in the map. That made it very easy to calibrate each engine individually (a custom fuel map for each engine), and it was only possible with brake dyno.
An inertial dyno, on the other hand, is a different beast altogether. It measures the speed of the drum as the vehicle accelerates. By looking at the drum speed at two points in time during the run, the rotational acceleration of the drum is calculated, and then you can calculate torque by multiplying the rotational acceleration of the drum by the rotational inertia of the drum (this is a physical property of the drum) and then multiplying by a factor for units conversion. Once you have torque, you can then calculate power the same as for a brake dyno. The big drawback of the inertial dyno is that you can only measure torque while accelerating, meaning that you can't isolate points in the fuel map and test for those. You can only test points that get passed through when you do a run. Also, because inertia is involved in the measurement process, anything that will change the acceleration rate of the drum will affect the calculations.
I left the racing world over two decades ago now, and shortly before I left, I think Superflow had come out with a hybrid dyno that was mainly inertial, but also had a small electromagnetic brake that improved upon the usual inertia dyno. It was not good enough to do steady-state fuel mapping, but it was better than a simple inertia dyno. I never got to mess around with that, and I haven't paid much attention to the current state-of-the-art in chassis dyno technology. It's entirely possible that newer technology exists to address some of what I've written above, so keep in mind that I'm old and antiquated...
If you started from a roll at idle it really shouldn't break anything. Dropping the clutch to launch or doing a hard shift will shock load and stress things hard.
There are a lot of shortcomings with inertial dynamometers. In the racing world, we didn't use them much. Of course, pulling an engine and putting it on a brake dyno is an expensive way to go, so it's rarely done outside of racing. Mike, you probably already know this, but if you're using an inertial dynamometer to track changes in torque and power, you have to keep everything you possibly can the same between dyno runs. Same tires, at the same pressure, and same gear (preferably 4th on the AX-15 because it's 1:1, so there's no torque multiplier effect from the transmission). The dyno software corrects for atmospheric conditions, but that's not perfect, so if the dyno's not inside a climate-controlled building (that is capable of supplying climate-controlled air to the intake system), don't compare a winter run to a summer run.
And to geek out, here is why there's a big difference between an inertial dyno and a brake dyno. On a traditional brake dyno, the torque is almost measured directly and horsepower is calculated (it's very hard to ever measure power directly - even with electricity). The brake housing will freely rotate around the dyno shaft. There is a load cell at a measurable radius from the centerline of that shaft that prevents rotation of the brake under load. When the engine turns, the brake loads the load cell, and a reaction force is generated in the load cell as the brake is prevented from rotating by it. Due to heat buildup, most brakes use a fresh supply of water moving through vanes to generate the load.
The load cell reads force (pounds) and the computer multiplies it by that radius to get ft-lbs of torque. The horsepower is then a simple calculation of torque (in ft-lb) times engine speed (in RPM) divided by 5252 for units conversion. On motorcycle engines with integral transmissions, it was easier to connect the dyno to the countershaft (output shaft on the transmission), and with a brake dyno, the gear doesn't matter. Whatever that load cell sees, it measures instantaneous torque. The biggest benefit of this system is it's an instantaneous or steady-state system. You can hold it at a given point in the fuel map to calibrate the base map perfectly. At Harley-Davidson, a co-worker and I created an automated system to calibrate the VR 1000 engines that used an instrument-grade air-fuel ratio sensor as an input to the system and then adjusted the fuel map based on that reading at each point in the map. That made it very easy to calibrate each engine individually (a custom fuel map for each engine), and it was only possible with brake dyno.
An inertial dyno, on the other hand, is a different beast altogether. It measures the speed of the drum as the vehicle accelerates. By looking at the drum speed at two points in time during the run, the rotational acceleration of the drum is calculated, and then you can calculate torque by multiplying the rotational acceleration of the drum by the rotational inertia of the drum (this is a physical property of the drum) and then multiplying by a factor for units conversion. Once you have torque, you can then calculate power the same as for a brake dyno. The big drawback of the inertial dyno is that you can only measure torque while accelerating, meaning that you can't isolate points in the fuel map and test for those. You can only test points that get passed through when you do a run. Also, because inertia is involved in the measurement process, anything that will change the acceleration rate of the drum will affect the calculations.
I left the racing world over two decades ago now, and shortly before I left, I think Superflow had come out with a hybrid dyno that was mainly inertial, but also had a small electromagnetic brake that improved upon the usual inertia dyno. It was not good enough to do steady-state fuel mapping, but it was better than a simple inertia dyno. I never got to mess around with that, and I haven't paid much attention to the current state-of-the-art in chassis dyno technology. It's entirely possible that newer technology exists to address some of what I've written above, so keep in mind that I'm old and antiquated...
Good explanation, Scott. I picked up some of that from this article earlier (https://www.hotrod.com/how-to/hrdp-0405-chassis-dyno-guide).
I also watched this video:
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There are a lot of shortcomings with inertial dynamometers. In the racing world, we didn't use them much. Of course, pulling an engine and putting it on a brake dyno is an expensive way to go, so it's rarely done outside of racing. Mike, you probably already know this, but if you're using an inertial dynamometer to track changes in torque and power, you have to keep everything you possibly can the same between dyno runs. Same tires, at the same pressure, and same gear (preferably 4th on the AX-15 because it's 1:1, so there's no torque multiplier effect from the transmission). The dyno software corrects for atmospheric conditions, but that's not perfect, so if the dyno's not inside a climate-controlled building (that is capable of supplying climate-controlled air to the intake system), don't compare a winter run to a summer run.
And to geek out, here is why there's a big difference between an inertial dyno and a brake dyno. On a traditional brake dyno, the torque is almost measured directly and horsepower is calculated (it's very hard to ever measure power directly - even with electricity). The brake housing will freely rotate around the dyno shaft. There is a load cell at a measurable radius from the centerline of that shaft that prevents rotation of the brake under load. When the engine turns, the brake loads the load cell, and a reaction force is generated in the load cell as the brake is prevented from rotating by it. Due to heat buildup, most brakes use a fresh supply of water moving through vanes to generate the load.
The load cell reads force (pounds) and the computer multiplies it by that radius to get ft-lbs of torque. The horsepower is then a simple calculation of torque (in ft-lb) times engine speed (in RPM) divided by 5252 for units conversion. On motorcycle engines with integral transmissions, it was easier to connect the dyno to the countershaft (output shaft on the transmission), and with a brake dyno, the gear doesn't matter. Whatever that load cell sees, it measures instantaneous torque. The biggest benefit of this system is it's an instantaneous or steady-state system. You can hold it at a given point in the fuel map to calibrate the base map perfectly. At Harley-Davidson, a co-worker and I created an automated system to calibrate the VR 1000 engines that used an instrument-grade air-fuel ratio sensor as an input to the system and then adjusted the fuel map based on that reading at each point in the map. That made it very easy to calibrate each engine individually (a custom fuel map for each engine), and it was only possible with brake dyno.
An inertial dyno, on the other hand, is a different beast altogether. It measures the speed of the drum as the vehicle accelerates. By looking at the drum speed at two points in time during the run, the rotational acceleration of the drum is calculated, and then you can calculate torque by multiplying the rotational acceleration of the drum by the rotational inertia of the drum (this is a physical property of the drum) and then multiplying by a factor for units conversion. Once you have torque, you can then calculate power the same as for a brake dyno. The big drawback of the inertial dyno is that you can only measure torque while accelerating, meaning that you can't isolate points in the fuel map and test for those. You can only test points that get passed through when you do a run. Also, because inertia is involved in the measurement process, anything that will change the acceleration rate of the drum will affect the calculations.
I left the racing world over two decades ago now, and shortly before I left, I think Superflow had come out with a hybrid dyno that was mainly inertial, but also had a small electromagnetic brake that improved upon the usual inertia dyno. It was not good enough to do steady-state fuel mapping, but it was better than a simple inertia dyno. I never got to mess around with that, and I haven't paid much attention to the current state-of-the-art in chassis dyno technology. It's entirely possible that newer technology exists to address some of what I've written above, so keep in mind that I'm old and antiquated...
How many keyboards to you go through in a year, Scott???
Great info as always. Thanks for taking the time.
What's this thing? Do you know if it is an inertial or brake dyno, or something else?
That's a form of the Brake Specific Fuel Consumption formula. The most basic version is BSPC = R/P, where R is the rate of flow of fuel and P is the power produced. In that case, it's re-arranged into P = R/BSPC. BSPC is about .5 for a normally-aspirated engine, and the inverse of .5 is 2, which is the 2 in your calculation. R is then the flow rate through a single injector times the number of injectors times the duty cycle. I'm not sure how the units work out though. It's typically used for sizing injectors, not actually to calculate your horsepower.
I'm a pretty proficient typist. Engineers write a lot of reports... And I only buy high-quality keyboards!
How many keyboards to you go through in a year, Scott???
Great info as always. Thanks for taking the time.
What's this thing? Do you know if it is an inertial or brake dyno, or something else?
View attachment 653315
View attachment 653316
That's a brake dyno that uses an eddy current brake. Remember the hybrid Superflow dyno I mentioned? It used a small eddy current brake, but it's load capacity was pretty low because it generated a ton of heat. Instead of using flowing water to create resistance, it uses electromagnets (I think). I never dived in to understand how they work. Assuming it's accurate, that's a much better dyno to do development on than an inertial dyno. As I said earlier, I'm about 20 years out of date with my dyno experience. It seems that eddy brakes have grown up. I don't know how they dissipate heat, and if I can find the time, I'm going to do some surfing to update myself.
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Thanks for sharing the updates applied to your tune. I'm trying to learn and improve and see some info I'd gotten on AFR was out of context and from what I see, my jeep rolled off the line running way to rich.
The other side of this is that most tuners are not looking at adding fuel under the assumption that you'd never keep your foot in it that long or you'd be going to jail. They've evidently never driven a loaded TJ up a mountain pass. I think that's why jeep setup the stock tune like that to drop lambda (run richer) as the rpm climbed as it often is a slow climb at high load.
If you do spend long pulls at heavy load around 3800-4500rpm for some reason, I think you might want want to ask them to add back in some power enrichment there. .88 lambda produces the highest heat and these motors can melt pistons and valves if pushed really hard. Bringing it back down to .85 would be a bit safer on the top end.
Really curious to hear what your experience is like with the tune.
I've been somewhat of an automotive enthusiast my whole life but I've never known anything about things like tuning or cam profiles or combustion chambers etc. I still don't but at least I'm beginning to know what I don't know and its so complicated and interesting.
With regard to the current tune's A:F, it is significantly richer than stock until 4000 RPM and I rarely exceed that engine speed for long. So I would assume it will run a little cooler most of the time. That may also translate to more CO output and soot. I'm curious to drive some before I dive into winter mods for next season.
When are you planning on starting your winter mods?
Same same for me on only starting to get a grasp on the more intricate parts of designing a engine or selecting the parts to make it better.
Soon. Lots to do. I'm still collecting parts.
You are definitely way ahead of me there.
The TJ isn’t the only rig I need to pay attention to. The “fire truck” had another issue. Its a 94 GMC 3500 4x4 chassis cab flat bed w/ a ‘88 Cummins 4BT swap.
Definitely rough but not rusty and perfect for it’s job which is standing fire watch in the summer with a 425 gal water tank, pump and hose. It got used for real this fall when a burn pile started going for a walk.
No pics or video of the actual event but it put out the slow moving grass fire in seconds.
Anyhow, I drive it every week or two to keep the fluids circulating and pay attention to it. I actually driving enjoy it. Something about beat up old trucks
After a recent trip to town, I smelled coolant and saw saw a wisp of steam. Upon opening the hood, coolant was coming out of the weep hole on the water pump pretty quickly:
I found an OEM Cummins pump and seal and OEM belt tensioner on eBay and got a new belt at NAPA. This was also an opportunity to replace the alternator which has been struggling for years. The old 4BT takes literally 3 wires to run, the truck has no electronics and doesn’t get driven at night so the alternator is almost unnecessary as long as the battery has a trickle charger when parked. But it was time for a new one. With the help of Romaine Electric in Portland, I figured out what was in there and they sent me a new 160amp unit built by them (they also built the custom 240 amp unit in my TJ). It took 10 days to collect the parts and about 90 leisurely minutes to put it all back together and put new coolant in.
This is the first time I have seen over 14v on the voltmeter.
Good to go until next time:
Definitely rough but not rusty and perfect for it’s job which is standing fire watch in the summer with a 425 gal water tank, pump and hose. It got used for real this fall when a burn pile started going for a walk.
No pics or video of the actual event but it put out the slow moving grass fire in seconds.
Anyhow, I drive it every week or two to keep the fluids circulating and pay attention to it. I actually driving enjoy it. Something about beat up old trucks
After a recent trip to town, I smelled coolant and saw saw a wisp of steam. Upon opening the hood, coolant was coming out of the weep hole on the water pump pretty quickly:
I found an OEM Cummins pump and seal and OEM belt tensioner on eBay and got a new belt at NAPA. This was also an opportunity to replace the alternator which has been struggling for years. The old 4BT takes literally 3 wires to run, the truck has no electronics and doesn’t get driven at night so the alternator is almost unnecessary as long as the battery has a trickle charger when parked. But it was time for a new one. With the help of Romaine Electric in Portland, I figured out what was in there and they sent me a new 160amp unit built by them (they also built the custom 240 amp unit in my TJ). It took 10 days to collect the parts and about 90 leisurely minutes to put it all back together and put new coolant in.
This is the first time I have seen over 14v on the voltmeter.
Good to go until next time:
The TJ isn’t the only rig I need to pay attention to. The “fire truck” had another issue. Its a 94 GMC 3500 4x4 chassis cab flat bed w/ a ‘88 Cummins 4BT swap.
View attachment 653529
Definitely rough but not rusty and perfect for it’s job which is standing fire watch in the summer with a 425 gal water tank, pump and hose. It got used for real this fall when a burn pile started going for a walk.
View attachment 653528View attachment 653527
No pics or video of the actual event but it put out the slow moving grass fire in seconds.
Anyhow, I drive it every week or two to keep the fluids circulating and pay attention to it. I actually driving enjoy it. Something about beat up old trucks
After a recent trip to town, I smelled coolant and saw saw a wisp of steam. Upon opening the hood, coolant was coming out of the weep hole on the water pump pretty quickly:
View attachment 653530
I found an OEM Cummins pump and seal and OEM belt tensioner on eBay and got a new belt at NAPA. This was also an opportunity to replace the alternator which has been struggling for years. The old 4BT takes literally 3 wires to run, the truck has no electronics and doesn’t get driven at night so the alternator is almost unnecessary as long as the battery has a trickle charger when parked. But it was time for a new one. With the help of Romaine Electric in Portland, I figured out what was in there and they sent me a new 160amp unit built by them (they also built the custom 240 amp unit in my TJ). It took 10 days to collect the parts and about 90 leisurely minutes to put it all back together and put new coolant in.
View attachment 653534View attachment 653533
This is the first time I have seen over 14v on the voltmeter.
View attachment 653526
Good to go until next time:
If you can find a disc plow for the back of your tractor it is worth getting to cut fire line. Just in case!
That would be smart. This one surprised me. It was a month or so ago. The fire ban had been lifted for weeks and recent rains had put a lot of moisture in the ground. Damp clumps of dead grass from mowing in the spring were what was burning (slowly with lots of smoke which how I noticed it from two fields away).
Collecting parts for the next project(s):
@macleanflood helped with this part which had to be harvested:
@macleanflood helped with this part which had to be harvested:
What do you need a second frame for?
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