iptman
SILVER Star
IFZFE
Pretty flat from 2500 to 3500.
Transfer case re-gearing
- Thread starter NielsC
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IFZFE
Pretty flat from 2500 to 3500.
IFZFE
Pretty flat from 2500 to 3500.
Can't be right. Torque and HP cross at 5250rpm. Always.
This has to be an obscure joke that I missed somewhere.
ppc
M Go Blue
That is true but when the graphs (torque/hp) are overlayed upon each other the crossing point is totally dependant on the relative scale used on each axis. The scales used may never show the lines crossing if that is the intent of the graph's author.
Googled 'Torque and HP cross at 5250rpm' and learned something new, thanks. Turns out it's usually graphed there, but only because 5252 RPM is used to calculate HP.... or torque, depending on who you ask. My brain started hurting so I left it at that. Bottom line is it's not a requirement, just a convenience.
You could separate the two graphs and move the torque line up, as long as you move the torque values with it nothing changes. It's completely irrelevant.
iptman
SILVER Star
FWIW this is where the graph came from. Certainly not where it came from originally but still....
Low-end torque - Another FJ80 vs FZJ80 Question
Low-end torque - Another FJ80 vs FZJ80 Question
That's AWESOME!
So, as I did when I was in HS a LONG time ago, I designed my gearing and tires based on where the HP and torque curves neared their high points. (69 Chevy K10, 350 bored 0.060")
Basically, I look to see what RPM that the engine would be just to the left of the peak on HP and torque.
Then, I chose that RPM as where I wanted to be when I was on the highway, at that time, driving 65 MPH. That would give me plenty of HP and torque remaining to stomp on the gas and get up and go to pass a car on the highway.
Also, since I had a 4 speed, I could check where my best RPM was for pulling, towing, depending on what gear I was in. It turned out on THAT truck, the RPM was about 2700 RPM at 65 MPH was where I wanted to be.
Therefore, My plan ended up at 33" tires and 4.10 gears.
When I ported and polished it, it improved the volumetric efficiency and made the flow out through the head and exhaust smooth. Balancing the engine made it smooth and easy start and capable of sustained higher RPM.
It still could have used another gear, as it was running bout 3100 RPM at 75 MPH. That's where we have the OD that gives us the extra advantage on the highway.
Looking at this graph, I would choose about 3000 RPM on the 1FZ-FE. It looks like torque spikes about 3500 RPM, so if I was pulling a load, or climbing a mountain, I would select whatever gear places me about 3500 RPM for that climb.
So, as I did when I was in HS a LONG time ago, I designed my gearing and tires based on where the HP and torque curves neared their high points. (69 Chevy K10, 350 bored 0.060")
Basically, I look to see what RPM that the engine would be just to the left of the peak on HP and torque.
Then, I chose that RPM as where I wanted to be when I was on the highway, at that time, driving 65 MPH. That would give me plenty of HP and torque remaining to stomp on the gas and get up and go to pass a car on the highway.
Also, since I had a 4 speed, I could check where my best RPM was for pulling, towing, depending on what gear I was in. It turned out on THAT truck, the RPM was about 2700 RPM at 65 MPH was where I wanted to be.
Therefore, My plan ended up at 33" tires and 4.10 gears.
When I ported and polished it, it improved the volumetric efficiency and made the flow out through the head and exhaust smooth. Balancing the engine made it smooth and easy start and capable of sustained higher RPM.
It still could have used another gear, as it was running bout 3100 RPM at 75 MPH. That's where we have the OD that gives us the extra advantage on the highway.
Looking at this graph, I would choose about 3000 RPM on the 1FZ-FE. It looks like torque spikes about 3500 RPM, so if I was pulling a load, or climbing a mountain, I would select whatever gear places me about 3500 RPM for that climb.
What is the 1FZ-FE RPM redline?
Mine is not home and I can't find anything online.
Mine is not home and I can't find anything online.
That's the reason I always insisted on the idea of having the OEM top gear at 0.753 in the eventuality that we will see a 5-speed auto swap (_______ place you favorite Unicorn picture here) instead of a longer one (as in A750 @ 0.716) especially when we all run larger tires on our rigs.
The RPM in top gear will just drop too much (this is what the majority of the people want unknowingly when thinking about better MPG).
You would be lugging your engine at lower than 2000RPM with 35" and kill your fuel economy. No passing (perceived) power either.
These engines were made to be happy at what we today consider high RPM 2000-4000.
Remember what Landcruiserphil always said about dropping it in 2nd gear and floor it going up on a hill running at high RPM. It's simply how this engine runs better.
The RPM in top gear will just drop too much (this is what the majority of the people want unknowingly when thinking about better MPG).
You would be lugging your engine at lower than 2000RPM with 35" and kill your fuel economy. No passing (perceived) power either.
These engines were made to be happy at what we today consider high RPM 2000-4000.
Remember what Landcruiserphil always said about dropping it in 2nd gear and floor it going up on a hill running at high RPM. It's simply how this engine runs better.
I'm still holding out and saying that graph is wrong. You can't move something on a graph when it relates to something else on the graph. They don't cross at the correct RPM.
There are many graphs online of many engine of different makes and models. Most of them are not seeing the 5252RPM relationship because they are overlapped manually. Skewed or whatever term you want to use.
Just move the HP curve to the right in your mind.
Most maps come separate in terms of HP and torque. People just overlap them afterwards.
Just move the HP curve to the right in your mind.
Most maps come separate in terms of HP and torque. People just overlap them afterwards.
Ok, I'll try this another way. Can the torque be graphed without the HP? HP graphed without the torque? The two are separate graphs, overlaid so they take up less space. If you take only the left side and bottom data, you have the torque curve. Only the right side and bottom and you have the HP curve. The two don't relate to each other through anything other than the RPM. Newton metres and foot pounds are the same measurement in metric and imperial, just as HP and kilowatts are the same things. Separate the two graphs, move the torque curve up so the lines cross at 5252 RPM, move the corresponding data on the left side up as well, and you'd have what you want.
Redline is at 5000 RPM
I watched a video about this and the 5252 number is due to Imperial units. If done in metric, the magic number is like 9454 RPM.
What you need to do is run a vertical line straight up from the RPM that you want to look at and see where it intersects each line. You want it to the LEFT of the highest peak on the torque curve. This is how you set the goal of what RPM you want it to operate for a given application.
You want it where the HP is still climbing or at least not dropping off.
Each engine (particularly camshaft) chart will give different results. It's knowing what to do with those results and how to interpret them.
A guy running a Mud Racer wants HIGH RPM so he can stand on it and keep his wheel speed high. His optimum RPM location will be more like 5000 to 8000 RPM. Then he has to build the engine to accommodate that as well as the gearing and tire size.
A guy doing rock crawling will want his RPM in the 3500 range, but wants very SLOW wheel speed. So he will adjust his engine and gear /tire combo to be running 3500 RPM when he is in first gear, you can walk around the truck while it's in gear at 3500 RPM. Hi torque on the axles through gearing. It keeps the engine in its optimum range for doing the most work.
Watch the video, then you'll understand the math better.
Why Horsepower and Torque Always Seem to Cross at 5252 RPM
My old 69 Chevy K10 with the 350, bored, ported, polished, balanced, a Saginaw SM465 granny-low transmission, and a Rockwell T-221 gear driven T-Case, with roll bar, rack of lights, was about a 6200 LB truck with nothing in it, got 14 MPG on the open highway at 75 MPH. It never got less than 12 MPG pulling a 20,000 LB loaded trailer...(yes, that's too much....different story and working it on a farm) and I had 375 HP to work with.
I get disappointed many days at the 12-13 MPG with 210 HP (or whatevr it is) out of my 6000 LB Land Cruiser. But, I can ride in style, with air conditioning and I can actually hear the radio.
Don't forget "ride in comfort". One of the greatest thing about the Landcruiser is that you can take a long trip and not be physically ruined from the effort. Most vehicles that can hold a candle to an 80 series have seats that will kill you after a few hours of wheeling!
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Kinda, one consideration is driveshaft speed, turning them faster can increase vibration, wear, etc. So diff gears increase the speed, transfer gears don't.
