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.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?
I used Nm (metric), you used ft-lb (imperial). 590Nm is 435 ft-lb.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 😁
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.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’m 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 ‘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.
Which numbers are you looking at?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.