What kind of reliable power can be made with the 1HDT

[wagonteeth]

I've seen many threads about changes to fuel, turbo, intercooler, nut not much on what the results of the change gave. In Australia videos, they upgrade and go to a tuner. We don't really have that in the US, so likely end up tuning ourselves. How has it resulted for anyone that went for mods?

My own is 219k kms on a 94. It has 3" straight exhaust and someone fiddled with the fuel screw. I am ready to add a boost and egt gauge and am looking at turbos and ICs.

I've seen number of 500ftlbs and 250 to 300whp. From a 12 valve?

 

[mudgudgeon]

I've seen number of 500ftlbs and 250 to 300whp. From a 12 valve?

Someone either spent a lot of money, or has their hand on it!

300whp is reasonably achievable with the 24 valve 1hd-fte. But, you're still gonna be spending a hefty chunk of change on turbos, intercooler, new air boxes, exhaust, injector and pump work, tuning etc

30-50% increase over stock power is fairly doable with the 1hd-t without huge layout.

 

[duece71]

Someone either spent a lot of money, or has their hand on it!

300whp is reasonably achievable with the 24 valve 1hd-fte. But, you're still gonna be spending a hefty chunk of change on turbos, intercooler, new air boxes, exhaust, injector and pump work, tuning etc

30-50% increase over stock power is fairly doable with the 1hd-t without huge layout.

That’s with a new turbo (how much psi) and an IC correct?

 

[mudgudgeon]

That’s with a new turbo (how much psi) and an IC correct?

Stock turbo, 3" exhaust, tuned, and boost bumped up to 15psi, you'll get maybe 20% more power.
But drivability is the biggest improvement. More low end torque, earlier boost really changes the way they drive.

Beyond that, an aftermarket turbo will be the biggest factor. An aftermarket turbo line Gturbo or equivelant is gonna bump airflow and boost a lot beyond what a stock turbo will do.

Then it becomes a question of what the limitations are and how much your prepared to spend to eliminate them.

Air intake restriction. ---> New 4" air box and snorkel.
Injection pump capacity and state of wear and tear. ---> Custom pump rebuild.
Injectors to match the pump. ---> New high capacity injectors.
Intercooler to keep intake air cool.
Boost limit of the turbo.
Cooling system state of repair.
Tuning.

There's lots of variables, and lots of corners that get cut

Depending on what you can do yourself, throw another $1-2k at most of those steps. Some things, that figure will be more like $4, 5, 6k
Turbos, pumps, custom air box etc are gonna be big ticket items.

Like anything, you gotta pay to play! Or do a much as possible yourself to keep costs down.

 

[wagonteeth]

Excellent info. And that's what I was getting at. Most new 1hdt owners I'm guessing see a new turbo as the next step with intercooler to follow. New pumps and custom injectors seem a step more and maybe a line drawn.

So 20%+/- increase by tuning what you have, yes?

With a good turbo and intercooler, but stock injectors amd pump, what can be expected?

Going whole hog and increasing fuel flow along with air processing is capable of? With a 12 valve?

 

[wagonteeth]

Gturbo lists the following on the g350 in the 1hdt

Standard, the HDJ81 1HD-T produces 290Nm of wheel torque and 76-80rwkw. With a Bad Boy turbo combined with a customised tune of the factory injection pump (while in car), you can expect 400-550Nm of wheel torque and 120rwkw to 135rwkw, with up to 150kW when used with an efficient intercooler. Boost should reach a minimum of 9psi at 1500rpm when tuned correctly without intercooler or 14psi with intercooler. Installations with a large intercooler, 3” exhaust, custom injection pump and an upgraded air box and feed to turbo have yielded results as high as 180rwkw and torque over 700Nm at the wheels.

400nm is 293ftlbs. 550 is over 400.

If I can get over 300 ftlbs to the ground, I would be astounded. Just trying to figure the path to het there and what it's gonna cost.

 

[mudgudgeon]

So 20%+/- increase by tuning what you have, yes?

Add a good 3" exhaust system, and 20% should be achievable for sure

EGT and boost gauges installed correctly are kind of mandatory if you're chasing maximum power.
Learn how they should be installed, and how to make sense of readings.

 

[mudgudgeon]

Just trying to figure the path to het there and what it's gonna cost.

The recipe is pretty much in your post above

 

[AussieHJCruza]

Stock (healthy) injectors and pump will facilitate about 200 whp and 600 nm at ~25 psi boost, 20:1 AFR assuming enough turbo, intercooler, intake and exhaust to facilitate, etc.

 

[jurassic cruiser]

I’m selling mine sadly but I have a 1990 1hdt hdj81 I did the g turbo grunter the pdi intercooler with custom air box and snorkel from moonlight fabrication. I did sea performance exhaust. I rebuilt the injection pump and did new injectors and custom fuel pin. I have about 23psi and did very little smoke and OH MY GOD this is not a gas powered 80 series. I have a chop top 1997 on 35’s with bumpers and a regear and my diesel fully loaded with a 38 gallon fuel tank and roof top tent plus 4 arb drawers is way faster. The tired will break loose on wet pavement and around corners if I give it gas either 1 or both rear tires will break loose depending on the type of terrain. That being said i personally feel that it lost the reliability I had with my gas 80 series. Also I upgraded the transmission with a billet torque converter from wholesale automatics cuz the stock auto could not handle the power. Hope this helps I am likely going to do a build thread on this rig before I sell it if nothing else to save someone else all the headaches I went through

 

[wagonteeth]

@jurrasic cruiser that's why I asked the question- at some point reliability decrease as performance increases. I'm still getting to know my truck and as I consider expensive upgrades to gain more juice, the cost is on both ends.

There are some signs of jdm fiddling as there was some electric turbo blanket on the turbo and at the least, the fuel had been turned up. I turned it down to reduce smoke amd that's about all I've added to the fiddling.

I pulled the fuel pin yesterday. This is aftermarket, right? I didn't think the oem had a recess for the pin to compress when reinstalling.

 

[wagonteeth]

I dialed the star wheel down a few clicks to try to drop the pin out of the defueling angle a bit. UT gave it more range in the throttle and acceleration through the rpms happens where it did just climb to an rpm and hold.

 

[wagonteeth]

I have the egt gauge in a pillar mount (which kinda sucks in fitment) so just need to drill the manifold and then I can fiddle a little with what's there and decide if anything more than an intercooler is worth it.

 

[jurassic cruiser]

that’s definitely aftermarket. Seems like it was running at full fuel a lot and even moving into overfueking where it turned the fuel back. I can’t exactly remember why but I had to make a shim from a housing if a plastic bic pen to fit over the pin and stop it from moving to overfueking if I remember correctly. I need to open it up again and look i honestly got it right and never touched it again.

 

[mudgudgeon]

@jurrasic cruiser that's why I asked the question- at some point reliability decrease as performance increases. I'm still getting to know my truck and as I consider expensive upgrades to gain more juice, the cost is on both ends.

There are some signs of jdm fiddling as there was some electric turbo blanket on the turbo and at the least, the fuel had been turned up. I turned it down to reduce smoke amd that's about all I've added to the fiddling.

I pulled the fuel pin yesterday. This is aftermarket, right? I didn't think the oem had a recess for the pin to compress when reinstalling.

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Definitely aftermarket, and not properly hardened.
You can see a groove in that first pic where the following pin has rubbed a trench into that.

OEM is more polished

 

[TheBussman]

I’m selling mine sadly but I have a 1990 1hdt hdj81 I did the g turbo grunter the pdi intercooler with custom air box and snorkel from moonlight fabrication. I did sea performance exhaust. I rebuilt the injection pump and did new injectors and custom fuel pin. I have about 23psi and did very little smoke and OH MY GOD this is not a gas powered 80 series. I have a chop top 1997 on 35’s with bumpers and a regear and my diesel fully loaded with a 38 gallon fuel tank and roof top tent plus 4 arb drawers is way faster. The tired will break loose on wet pavement and around corners if I give it gas either 1 or both rear tires will break loose depending on the type of terrain. That being said i personally feel that it lost the reliability I had with my gas 80 series. Also I upgraded the transmission with a billet torque converter from wholesale automatics cuz the stock auto could not handle the power. Hope this helps I am likely going to do a build thread on this rig before I sell it if nothing else to save someone else all the headaches I went through

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would love to see the thread, other then the torque converter what broke?