[RCWhite]

Bram- I am looking at doing a swap into my 55. I have found a 4b2tc locally and I don't want to change the drive line from what it is. Let me know if you need any help with CNCing I have access to one and would love to get to work on the project. Thanks for taking the initiative on the adapter. Let me know what I can do to make this happen. Ryan

[RHINO]

ryan and everyone else,, i think you'll be disappointed w/o OD unless you rarely travel the hiway. to put into perspective i have 4:10 and 37" tires, on the hiway i have played around with what a four speed would be like for you guys to avoid the expense. anything above 60mph and its vibrating and buzzing ready for the upshift a couple hundred RPM's ago. with something like 31" tires it'll prolly start buzzing around 50mph, with 33's prolly about 53mph. its definitenately doable, i have cruised it a bit in 4th gear like that just to see, that turbo is really screamin' at those rpms, sounds cool, but its just beggin for me to shift, when i do its like a little piece of heaven, turbo whines nicely, exhaust hums a little ditty and my smile can be seen for miles.

BTW, this past w/e marked my 3rd road trip now, this time it was just shy of 190 miles and included an afternoon of wheelin, the whole trip including half a day of loping along a trail claimed a whopping 1/3 tank of fuel, my wallet gets lonely on these trips nowadays.

[Dougal]

I changed to a higher ratio transfer box in my 4BD1T powered truck, dropping the rpm at 100km/h from 2500 to 2000.

Fuel economy picked up by over 10% (to be expected if you see the fuel consumption curves), noise dropped off dramatically and I could also then use 4th gear for passing (2800rpm at 100km/h, not far off max power).

With 118mm stroke these engines don't like screaming.

[rtarh2o]

What are the fuel consumption curves (not what are they but what are the numbers) Also what are my transmission/transfer case options for a 94 FZJ80? The best I can find is a 700R4 with overdrive at .70. I can't remember the exact numbers but it seems like the rpm with 33" tires would be about 2200 at 70? Where does this fit into the fuel curve?
Rusty
94 FZJ80 waiting for engine

[rtarh2o]

What are the fuel consumption curves (not what are they but what are the numbers) Also what are my transmission/transfer case options for a 94 FZJ80? The best I can find is a 700R4 with overdrive at .70. I can't remember the exact numbers but it seems like the rpm with 33" tires would be about 2200 at 70? Where does this fit into the fuel curve?
Rusty
94 FZJ80 waiting for engine

[Dougal]

Originally Posted by rtarh2o

What are the fuel consumption curves (not what are they but what are the numbers) Also what are my transmission/transfer case options for a 94 FZJ80? The best I can find is a 700R4 with overdrive at .70. I can't remember the exact numbers but it seems like the rpm with 33" tires would be about 2200 at 70? Where does this fit into the fuel curve?
Rusty
94 FZJ80 waiting for engine

This is the closest you'll find online. It's for the 4BG1T but the trend is similar
http://www.isuzu.co.jp/world/product...l/b_per02.html

I have the NA 4BD1 curves at home, I'm post it tonight.
2200rpm at 70mph would be about right. Higher gearing will drop the noise and revs but you'll have less power available which may frustrate you.

[Dougal]

Here're the 4BD1 power/torque/fuel curves.
The stock turbo version has a smoother torque curve which peaks around 330Nm around the 2000rpm mark. The fuel consumption curve bottoms out at the same point.
Very similar to the 4BG1T curve in the link I provided above but the figures are a little different.

[Dougal]

I'll throw in another 2c.

If you've got a dead truck you want to get on the road ASAP, then I'd go the chev 6.2 conversion.
Once you've got the chev in, start looking for parts for a better conversion. When the MkII is ready to go, you'll be able to flick the chev as a bolt in kit for someone elses's cruiser.

Yes it'll be more work (doing things twice), but the advantage of not having a dead truck and the luxury of time to get the conversion properly planned out will be worth it.

[rtarh2o]

What is the MkII conversion? I may do what you are saying about build the 6.2 first until the Isuzu is all sorted out. It would be nice to have a kit for the Isuzu, or at least a list of parts that will make it work and some help with brackets etc. All of that work has been done with the 6.2, although I am sure there will still be a fair amount of fab work to be done. I would also really like to talk to someone who has driven the Isuzu in an 80.
Decisions, decisions!
Rusty
94 FZJ80 Still waiting

[Dougal]

Originally Posted by rtarh2o

What is the MkII conversion?

Mk II conversion being your second (first would be installing the chev).

[ozwallaby]

Wouldn't the fuel curves shown be taken at WOT ( wide open throttle) and therefore change as load changes. So these figures may be different from what actually happens "driving down the road".

[Dougal]

Originally Posted by ozwallaby

Wouldn't the fuel curves shown be taken at WOT ( wide open throttle) and therefore change as load changes. So these figures may be different from what actually happens "driving down the road".

Yes they are.
You can find the occasional one showing every little island in the BSFC map. But not for engines we're interested in.

But the trend still seems to hold. Get your cruise rpm close to max torque (min BSFC) and you'll hit the best operating conditions more often than any other rpm.

[ozwallaby]

Originally Posted by Dougal

Yes they are.
You can find the occasional one showing every little island in the BSFC map. But not for engines we're interested in.

But the trend still seems to hold. Get your cruise rpm close to max torque (min BSFC) and you'll hit the best operating conditions more often than any other rpm.

Yep, that's my understanding too. Get your most used (usually cruise) rpm close to torque peak, then you get best mpg/driveability. I didn't know if it stayed that constant. Thnks

[rtarh2o]

I just recalculated the numbers for an 80 with 33" tires, 4.11 final drive, and a .70 trans ratio from a 700r4 transmission that I plan to use. The rpm was about 2100 at 70 mph, it looks like that is a little higher than it shoud be according to the maximum torque being 1900 rpm? Is there any way to further change my gearing? Are there are any ring & pinion sets available lower than 4.11?
Rusty
94 FZJ80

[tntoyota]

Yeah the gear was 4:11 with factory size ? tire, your off a little.


I know 80's didn't come with 33's and 4:11's

[Dougal]

Originally Posted by rtarh2o

The rpm was about 2100 at 70 mph, it looks like that is a little higher than it shoud be according to the maximum torque being 1900 rpm?

That's about right where you want it. You're not really going to screw with different diff ratios to try and get the last few % rpm difference are you?

There are much bigger dragons to slay in an engine conversion. Diff ratios are probably the last thing to worry about (unless they're soo far off you can't drive it properly).

[rtarh2o]

Originally Posted by tntoyota

Yeah the gear was 4:11 with factory size ? tire, your off a little.


I know 80's didn't come with 33's and 4:11's

I was calculating for the way the car is going to be set up after the conversion. I could go to 35's if I really wanted to bring the rpm's down a little more but I prefer not to go that big. I read somewhere the decrease in economy for every 100 rpm's (above the most efficient) was pretty dramatic, like 10%, that could make the difference between 24 mpg at 2000 rpm, or 20 mpg at 2200 rpm. To me that would be worth messing with the gearing if that is in fact true, although I will still be very happy with an 80 that gets 20 mpg!
Rusty
94 FZJ80 waiting

[Dougal]

Originally Posted by rtarh2o

I was calculating for the way the car is going to be set up after the conversion. I could go to 35's if I really wanted to bring the rpm's down a little more but I prefer not to go that big. I read somewhere the decrease in economy for every 100 rpm's (above the most efficient) was pretty dramatic, like 10%, that could make the difference between 24 mpg at 2000 rpm, or 20 mpg at 2200 rpm. To me that would be worth messing with the gearing if that is in fact true, although I will still be very happy with an 80 that gets 20 mpg!
Rusty
94 FZJ80 waiting

I don't think you'll see 10% fuel consumption difference with 10% rpm difference.
I saw just over 10% consumption change with a 500rpm (20% down or 25% up) change in gearing.

[tntoyota]

Originally Posted by tntoyota

Yeah the gear was 4:11 with factory size ? tire, your off a little.


I know 80's didn't come with 33's and 4:11's

Originally Posted by rtarh2o

I was calculating for the way the car is going to be set up after the conversion. I could go to 35's if I really wanted to bring the rpm's down a little more but I prefer not to go that big. I read somewhere the decrease in economy for every 100 rpm's (above the most efficient) was pretty dramatic, like 10%, that could make the difference between 24 mpg at 2000 rpm, or 20 mpg at 2200 rpm. To me that would be worth messing with the gearing if that is in fact true, although I will still be very happy with an 80 that gets 20 mpg!
Rusty
94 FZJ80 waiting

If the factory tire size is 30" your gear is off by 3/10th's



REcalculate w/ 3:90 gears (act 3:91)

[astr]

785 pounds for a 1986 4BD1T if you knock off a couple pounds for the yard stick and the load cell display. Included on the engine:

Alternator w/vacuum pump
12V geared starter
A/C compressor
Power steering pump
FI pump and plumbing
Manual transmission flywheel
Intake & exhaust manifolds
Wastegated turbo (older style)
Fuel & Oil Filters
Oil in the crankcase
Everything else that you see in the photos.

I couldn't resist playing with my new toy - the load cell with digital display

[RHINO]

astr, thats brilliant !! i knew it was real close to the 2F i pulled out.

[rtarh2o]

Originally Posted by tntoyota

If the factory tire size is 30" your gear is off by 3/10th's



REcalculate w/ 3:90 gears (act 3:91)

Huh? I am not exactly sure what you are talking about. I used an online gearing calculator and input the following:
Final drive - 4.11, trans ratio - .70 (gm 700r4 overdrive) and tire size of 33".
Am I missing something?

[tntoyota]

Originally Posted by rtarh2o

Huh? I am not exactly sure what you are talking about. I used an online gearing calculator and input the following:
Final drive - 4.11, trans ratio - .70 (gm 700r4 overdrive) and tire size of 33".
Am I missing something?

Going for four!!!


I DO NOT KNOW THE FACTORY TIRE SIZE!!!!



I DO KNOW THE FJ80 DID NOT COME WITH 33'S


I DO KNOW THEY CAME WITH 4:11'S


WHEN YOU ALTER THE O.D OF THE TIRE SIZE YOU EFFECTIVELY CHANGE IT'S FINAL DRIVE!!!!


THE FORMULA I USE IS .10 PER 1" IT WORKS AS TIRE SIZES ARE NOT EXACT!!!!!


AGAIN, INCREASE IN TIRE = DECREASE IN GEAR RATIO.



YES IT HAS 4:11 BUT NOT ACCURATE WITH 33'S WAS FOR FACTORY TIRE THOUGH....................

[rtarh2o]

Sorry, didn't mean to upset you. I don't have a formula for calculating the engine speed (apparently not as smart as you). I found a site in which you enter the variables (tire size, final drive and trans) and it gives you the engine speed at a given mph (it doesn't know your factory tire size). I understand that changing the O.D. of the tire effectively changes the final drive ratio. I am pretty sure the calculator I used takes it all into account. The 1/10 per 1" is good to know though.
Rusty
By the way, what does "going for four" refer to?

[88tlc]

Originally Posted by Dougal

It's not complete, possibly it never will as there'll always be something to add or improve.
But functionally it's almost there. I just need to put in the front timing gear cover and water pump.

I've been busy doing nothing lately. Mid winter holiday.

it looks like you have a plate modeled up to connect to the isuzu engine? I am working on laying up the isuzu/a440f adapter plate, and make a mock up of this in wood or something.

any chance you can reveal that plate geometry for the isuzu? one hole patterns worth of guessing taken care of!

[Dougal]

Originally Posted by 88tlc

it looks like you have a plate modeled up to connect to the isuzu engine? I am working on laying up the isuzu/a440f adapter plate, and make a mock up of this in wood or something.

any chance you can reveal that plate geometry for the isuzu? one hole patterns worth of guessing taken care of!

You want bellhousing bolt pattern?
No problem, I'll post something up from home tonight.

[Dougal]

Bellhousing as requested.

Please note, these are my best measurements but haven't been verified by anyone else.

http://users.actrix.co.nz/dougal.ell...ellhousing.PDF

[ozwallaby]

Dougal, you've measured this stuff yourself from an actual motor no doubt. What I wanna know is, is there a site on the web somwhere that has this type of dimensioning for common motors. I also realise there are probably specialist sites that have specific info that that site is interested in, but what I'm after is 1 site that covers numerous common motors. Any ideas........

[astr]

Originally Posted by Dougal

Bellhousing as requested.

Please note, these are my best measurements but haven't been verified by anyone else.

http://users.actrix.co.nz/dougal.ell...ellhousing.PDF

That is nice work! I can appreciate how much effort went into creating that drawing.

[Dougal]

Originally Posted by ozwallaby

Dougal, you've measured this stuff yourself from an actual motor no doubt. What I wanna know is, is there a site on the web somwhere that has this type of dimensioning for common motors. I also realise there are probably specialist sites that have specific info that that site is interested in, but what I'm after is 1 site that covers numerous common motors. Any ideas........

The SAE standard bellhousing dimensions are available somewhere online.
Otherwise you're looking into specific manufacturers data. They usually only publish mounting drawings for industrial engines, which in the case of the 4BD1 has a different bellhousing.