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Discussion Starter · #22 ·
I'm curious, where do you get your numbers of; 130 hp at 1800 with only 225 lbs twist? Or 130 at 1800 with 325 twist? What formula do you use to get those numbers? Is the formula different for different engines? If the formula is different, why is it different?

I want to stay open minded, I'm not saying those numbers are wrong by any means, I just curious to know how you got them.

The formula I use is; rpm x torque / 5252 = hp.... if that is wrong it would be nice to know and be corrected 馃榿
 

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150hp (110kw) at 1800rpm is 590Nm. The 200hp recipie will do that: 200hp 4BT Recipie
Dougal, will that Cummins recipe work the same on the Isuzu. Those 2 engines have different power curves. While the Cummins reaches peak 130 HP at 2500 RPM the Isuzu is 3000 RPM. So to reach 150 [email protected] 1800 RPM the Isuzu would need around 230 HP @ 3000 RPM. The Isuzu has the same bore and a .07" shorter stroke so the 2 engines are essentially the same. Their power curve is totally different. At 1800 RPM the 130 HP 4bd1t has 225 lb ft of torque. The 130 HP 4bt has 325 lb ft of torque. That is a huge difference. Not totally sure what is causing that difference but I assume it must be camshaft design and maybe some timing. At the same power level, the Isuzu may out rev the Cummins but the Cummins will out pull it. If he already has an HX30W, what turbo do you use to get more air at lower RPM? Would the HE221W be a better turbo? It will boost a little faster than the HX30W. The Super HX30W may flow a bit more air so could that be a possible?
Yes, at those lower rpm's they are basically identical for fuel/boost/power/torque. Above 2500rpm they diverge with the Isuzu continuing to build power until about 3000rpm depending on airflow.
HE221 is a great low rpm high boost option. TD04HL-19T is more efficient but can't do as much boost. HX30 and Super HX30 I expect to be a few hundred rpm behind.

IMO the Isuzu was tuned for lower torque for gearbox longevity. Isuzu saved weight on the gearbox and flywheel.

I'm curious, where do you get your numbers of; 130 hp at 1800 with only 225 lbs twist? Or 130 at 1800 with 325 twist? What formula do you use to get those numbers? Is the formula different for different engines? If the formula is different, why is it different?

I want to stay open minded, I'm not saying those numbers are wrong by any means, I just curious to know how you got them.

The formula I use is; rpm x torque / 5252 = hp.... if that is wrong it would be nice to know and be corrected 馃榿
I used Nm (metric), you used ft-lb (imperial). 590Nm is 435 ft-lb.
 

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As the owner of two 4BD2TCs (one inop due to headgasket then fricking thieves taking the accessories and the other daily driver flatbed / drug head driver intimidator / Junkman hauler) I have a curiosity about some of this stuff. I was told the head and block of the 4BD1 series did poorly with a big turbo unless head studs are used instead of headbolts. I lost track of the guy in BC, Canada just as Covid19 hit who has the same as mine in a Toyota 4x4.
Twice now I have lost out on getting a decent flatdeck for my truck (one had the 5 lug brake drums that are unobtainium to replace but my box truck is now just backup parts with a new Jatco transmission and radiator for spare)
I鈥檓 still planning to get an AW4 or AW6 automatic behind my motor because 3000 rpm on the freeway concerns me without another overdrive to upshift to and engine temps climb fast. Once my home here is sold, the wife is finalizing retirement before needing more surgery and the last of our bills will be paid off so Grandma and Grandpa get little kid time before they start school and great grandkids start popping out.
Back to the question. Which turbo would the 鈥94 NPR Boxtruck have stock compared to these? The daily was a Seattle city tow truck for alleys that I removed the fixed Beavertail off of.
 

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Sunny48, those torque numbers are published by Isuzu and Cummins. Isuzu lists peak torque on the 4bd1t of 243 lb ft @ around 2000 RPM. The peak varies somewhat depending on engine application. HP also varies on that engine. See numbers of 116 HP up to 135 HP. The Cummins 130 HP 4bt is the CPL1839 and that one has 325 lb ft right around 1700-1800 RPM. All standard 4bt road engines have torque that is 2.5 times HP in stock form. Same is pretty much true for the B series Dodge 6bt engines. The 160 HP engine has 400 lb ft of torque. Cummins is famous for their torque.
 

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As the owner of two 4BD2TCs (one inop due to headgasket then fricking thieves taking the accessories and the other daily driver flatbed / drug head driver intimidator / Junkman hauler) I have a curiosity about some of this stuff. I was told the head and block of the 4BD1 series did poorly with a big turbo unless head studs are used instead of headbolts. I lost track of the guy in BC, Canada just as Covid19 hit who has the same as mine in a Toyota 4x4.
Twice now I have lost out on getting a decent flatdeck for my truck (one had the 5 lug brake drums that are unobtainium to replace but my box truck is now just backup parts with a new Jatco transmission and radiator for spare)
I鈥檓 still planning to get an AW4 or AW6 automatic behind my motor because 3000 rpm on the freeway concerns me without another overdrive to upshift to and engine temps climb fast. Once my home here is sold, the wife is finalizing retirement before needing more surgery and the last of our bills will be paid off so Grandma and Grandpa get little kid time before they start school and great grandkids start popping out.
Back to the question. Which turbo would the 鈥94 NPR Boxtruck have stock compared to these? The daily was a Seattle city tow truck for alleys that I removed the fixed Beavertail off of.
The 4BD1T does fine with more boost. Bigger turbos aren't better, turbos need to be sized correctly. Randy (carcrafter22) hit 60psi boost on his 4BD1T before the standard head gasket let go.

Last of the 4BD1T/2T had a wastegated Garrett T25 turbo. It's okay but nothing to write home about and not worthy buying. Manifold is T3 pattern and the HX30 bolts up to it.
 

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Discussion Starter · #27 ·
On Saturday I was testing the Isuzu again, this little engine has quite a bit of spunk, it handed over [email protected] which is 525 ft lb twist. (711nm)

A friend of mine has a John Deere turbo he let me try before I actually buy one.I tried the John Deere 4.5 (Borg Warner 318615 ) industrial turbo, for my application at 1800 rpm it was 2 big. Like you said Dougal bigger isn't always better. The engine just smoked black till it hit 2500+ rpm. That turbo would be a great fit for someone who is running higher rpm, it has great positive crossover on the drive and boost. I got around 5 lbs boost till I saw any drive pressure.

The turbo that I have on there at the moment is the Cummins TB3404 which is pretty good, the engine still smokes under load but pulls quite well, this turbo has great positive crossover as well around the 5 to 8 lbs less drive than boost.

Before I decide to move onto other stuff I would like to try 2 more turbos, the TD04H I believe it is and a genuine HX30.

So my question, does anyone have one of those 2 turbos not in use I could borrow / buy to try on this engine.
 

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Never heard of an Isuzu that can put out that much torque to HP. You have a torque number that is 2.9 times HP. Even a Cummins doesn't sport numbers that high and they produce more torque than the Isuzu. Something doesn't sound right there.
 

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Discussion Starter · #29 ·
LOL well those are the number we got. I'm not kidding, and I'm not surprised you don't believe me either. A buddy of mine and I have been making high power at lower rpm on engines others never believed possible. The key is to find the right turbo for the job. Just like Dougal said bigger isn't always better it all depends on the application. If I could find the right turbo, I could easily beat those current numbers.

Below are pictures of the type of dyno we use. At 1800rpm we made 180 hp which = 525 torque, using the rpm x torque / 5252 = hp formula. Any engine gas / diesel whatever, will show the exact same torque number at 1800 using that formula.

I use the spicerparts online calculator to find my numbers, like I have stated previously if I'm doing something wrong I wouldn't mind being corrected. I've been wrong before, this wouldn't be the first time and I don't mind. For me it's the best way to learn it seems.

I helped build a C15 cat engine about a year ago, by the time everything was said and done it was putting down 700 hp at 1200 rpm which converts to around 3063 (4152 nm) torque. Making high hp at low rpm will produce some pretty crazy torque numbers.

131213


131214
 

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Discussion Starter · #30 ·
Anyway lets forget the numbers for now, what I really want / need is a TD04H turbo for the 4BD1, does anyone have a genuine used unit in good / reasonable condition they would sell?
 

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Never heard of an Isuzu that can put out that much torque to HP. You have a torque number that is 2.9 times HP. Even a Cummins doesn't sport numbers that high and they produce more torque than the Isuzu. Something doesn't sound right there.
Which numbers are you looking at?

If it's the 180hp @1800 with 525ft-lb, that's showing high torque and low power because the engine is at low rpm. It will produce more power but less torque at higher rpm. By 2500rpm it should be doing like 240hp.

On Saturday I was testing the Isuzu again, this little engine has quite a bit of spunk, it handed over [email protected] which is 525 ft lb twist. (711nm)
 
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