12H-T performance Build (1 Viewer)

Joined
Oct 6, 2008
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Perth, Australia
Hi Guy's,

I am building up a 12H-T for more performance over standard.

Thought some might be interested because 12H-T power threads are few and far between. Most owners don't dyno after mods like intercooler or extra boost or exhaust so it is hard to gauge how they compare to other excellent motors such as 1HD-T or FT/FTE.

So far, I have bought or done the following:

* Ported significantly the head, currently fitting larger valves (that I have, they are only slightly larger). Head looks real bad standard. TD42 by comparison looks like an old style racing head:eek:
* Bought the full build kit 1mm oversize, pistons have steel top ring land inserts, unlike original - (this makes a big difference)
* Block has been bored and decked, crank has been cleaned up and crack tested.
* Inlet manifold will be ported. I have started it and it wont take long - pretty **** standard. Having said that, I havent done flow tests so it is only what the eye tells me.
* Turbo - secrets here, but aiming for 21psi upwards with view to minimize pressure ratio difference between inlet and exhaust. I will be using a newer GT spec and may use a second turbo for compounding. In this way boost should top at 43psi, rising from 21psi at 1400rpm through to 43psi at 3800rpm. THis is to offset the worsening VE of the engine with revs. Will see how I go
* Intercooling Laminova type; I have the cores (only 4), now got to do the hard stuff. Currently in design stage.
* Lubrication/Cooling - fitting bigger piston collers - which I have
* Pump tune up to delivery whatever it is capable of. I am loathed to go over 150rwkw and even that might be optimistic because the conrods are not at the same level at the 1HD-T rods (nice motor by the way, this time I wanted inline pump though. My 1HD-T got 114rwkw at all 4 33" tyres 21psi boost. made heaps of torque early but suffered from excessive exhaust back pressure - I measured it. It was = to inlet up to ~ 2000rpm then it just got worse. At 3000rpm 25psi boost, backpressure was 37psi, so hardly worth the trouble of boost. This is due to turbine design and housing spec, but since it was auto and I was silly enough to lower the stall speed on the torque converter, I needed the small housing!

Anyway, there you have it. Will definately take 3 months to finish. Please nobody tell me that the motor will die with boost etc etc. It could die if delivering too much power, but that depends on whether the inline pump can flow enough as it is with just rack mods. Diesels die on fuel or power/torque related issues, not boost.

The only other thing I would like to do is bigger rods and head stud kit. I have had them priced up - ~ $1800 for a set rods. But if the pump cant flow the fuel, there is no point.

I will post the odd pic as things go along.

Cheers!
 
Joined
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I measured rack movement last night on spare injector pump. looks like 50% from std (ie: 21.5mm vs 13.5mm) is the limit, so long at rack movement/fuel flow is a linear relationship. so 470nm and 210hp looks the limit.

No need for compound turbocharging in this case, might still do it anyway for the fun of it.

By the way, the pump had done 540,000km and looks new inside!!!!

Cheers,
 
Joined
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Messages
796
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The highest power 12H-T that I could find anywhere on the net was 190HP and 462nm @ Flywheel. And I only found that with alot of searching and there was no dyno graph.

This is nice power, but not enough for me.

If anyone has a dyno of theres please post it, they are few and far between.

Even a serious intercooled 2H?? Anyone??

Surely someone out there has fitted a good turbo, intercooler and exhaust and maxed out the injector pump!!
 

kevin in okinawa

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from the title, i thought there might be some useful info in this thread, lol. this is definitely not applicable to most trucks, but good luck anyhow.:beer:

do you have plans for h2o/meth injection?
 

Tapage

Club 4X4 Panamá
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did you gonna keep the factory engine compresion ratio . ?

I'm running and intercooler but nothing compared to your plans .. :frown:
 
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Actually, there should be plenty of info transferrable to 12H-T owners who do not want to go to the trouble I am; for instance, using a single GT2860RS turbo or even a high flowed CT26 (16G6 Compressor, slightly back cut turbine) + intercooler will likely yield very similar results to mine anyway......

I think it would be good to know the limits of the std fuel pump and the inherent strength of the motor. I honestly think that the pump will be the limiting factor; not the motor strength - but I will find out and let you all know my findings.

When I dyno the LC, I will video it and it will be very interesting (to me anyway) whether I can get significant power with almost zero smoke and low EGT's.

I will have the ability to effectively bypass the second turbo anyway, so you will be able to compare directly to a signle setup.

I am using 1HD-T oil squirters for the pistons to increase cooling; they are twice the flow of the 12H-T std fitment.

I did the head porting myself, anyone handy can do it if I can do it.

The valves are only 43.5mm IN instead of 42mm and 36.5mm EX instead of 35mm. I only increased the valve size because when cleaning up around the valve seat, the casting matching to the machining/seat inserts was really rubbish and I had to machine away some of the inner diameter of the seat to have a smooth transition from the casting to the insert; thus the bigger valves are required to seat correctly. I also deshrouded the inlet and exhaust since that looks to be a bad area as well and bellmouthed the inlets. The valves I used are 117mm long instead of factory 120.5mm and are 8mm stem instead of factory 9mm, so I am obviously fitting different guides. I am dealing with the difference in valve length by shaving 1mm from the top of the head and 0.5mm from the head gasket surface. Since the rocker geometry is 1.7:1, shaving the top 1mm drops the rocker fulcrum 1mm closer to the valve, so 1 + 1.7*1 = 2.7mm. Since the head is dropped 0.5mm, that adds another 1.7*0.5mm = 0.85mm. So it follows that 0.85mm + 2.7mm = 3.55mm which is effectively the difference between the two valves lengths.

The valve springs are being replaced from those of another diesel engine to increase the valve seating pressure - same source as the valves. The seating pressure increase is significant. The whole process of fitting the new valves and springs is inexpensive.

Will the porting and bigger valves and stronger seating pressure be worth it???? I am gonna find out!

Anyway, as I mentioned, I will show dyno results and video and get some photos uploaded of the engine build for those interested
 
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The valve springs are being replaced from those of another diesel engine
what engine is that? 1-HD?

Also, do you plan on "ringing" (don´t know what it´s called exactly.) the Head or block, won´t the head gasket blow under 18+ psi?

O-ringed head, put a metal ring in the groove to better clamp the head gasket.


this thread will be interesting :) always wanted to see how much the old 12H can withstand (IMHO: a LOT!)
 
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So what type of inline pump? Is it a kiki/zexel/bosch A type or something different?

The kiki/zexel/bosch A type fitted to my Isuzu tops out around 120 cc/1000 shots, but there are several different plunger diameters. 120cc/1000 shots is enough for 550Nm on a decent 4 cyl direct injection engine.

Do you have any mods to help hold the head down?
 

Tapage

Club 4X4 Panamá
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I thought only based in my apreciation on field off course that the inline from the 2H are not enought ( or at least not as same as the 1HD-T IP would be ) to deliver real amount of diesel .. at least not mine.

I turned mine 6 complete turn to increas the diesel and yes .. I got a lot more, but are not as fast as a rotative ..

Other thing that I got it's after aprox 2 years of turboing my 2H and running it at 14PSI it loose compresion ..

I don't measure it yet .. ( don't think I will do anycase ) but I feel it in the cold starts ..

Anycase thanks for share all info .. I'm more than happy with my engine right now .. not a rocket but it do the job ..
 
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The porting to what looks OK can be a bit of a trap, you really should be using a flow bench... I have done numerous v8 petrols and some of the things I have seen done and done myself (unfortunately), can be very detrimental to flow.

From my experience, porting turbo motors doesn't have as big an effect/improvement as on an n/a motor.. I'm not saying it won't help, but just not as much, tho the reverse is true also, that is, if you stuff it up, it probably won't hurt as much either..

Also while you have machined your head in an effort to maintain the relationship between various parts within the head, you should technically, shorten the pushrod as well and take more off the rocker post, to preserve the true (theoretical) geometry between the cam and valve.. but this is being picky/blueprintish.

Should be an interesting project, everyone will be calling for fotos , me included, so get clicking... :cool::cool:
 
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ozwallaby, you are absolutely right and I would like to flowbench the head... but I wont because I cant put the metal back now.....

Essentially what I have done is to widen the ID of the valve seat as little as possible to ensure a linear transition from seat to head casting and I did this on the inlet and exhaust sides hence the ~ 1.5mm increase in valve diameters. It is not a perfect job, but in my estimation (yet to have the seats cut...) I have taken out as much as possible without having to put in new inserts.

The casting in the exhaust side is really bad - at least it was on mine. The casting jutted out at least 3mm directly under the exhaust valve seat into the port area behind the valve on the outside radius. I cleaned it up ensuring that I did not increase the diameter behind the seat.

On the inlet side the reverse is true, the casting was somewhat more in diameter immediately behind the seat in the form of a groove. I did what I could to get a smooth transition, but bigger inserts are needed to get it perfect. In my thinking (which as you say may be incorrect), I have improved it where it matters.

For the inlets to the head, I bell mouthed them - took out heaps here to try and improve laminar flow.

For the exhaust ports, they are cleaned up and de dagged. I could have done more, but they seemed OK to me. Some big dags came out though!! I certainly wouldnt have wanted one to come off and go through the turbine!!

As far as o-ringing the block is concerned, I won't be doing it. I would like to do a stud kit, but will not be for my first build. If I do another, then it will be stud kit and big rods and massive boost (50 plus psi) and massive fuel (for 800+nm) - massive for a Toyota anyway, maybe not a 6BT!

Now, an area that I would appreciate anyones help:

Injector pump. It is a Nippon Denso and I do not know how big the plungers are or what other engines injector elements may fit etc. I also do not know how many cc's per cylinder the std fuel pump can deliver when maxed out.

This is a critical area of course, because without fuel there is no power.

Tapage - regarding the 2H, given there are no oil squirters or intercooling, I would expect low compression/cracked precoms being a problem after a while. So your 1HD-T easily has more fuel supply potential?? Mine could supply way more fuel than I could get air into it. I sold it before changing the turbo again.
 
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Dougal; - it is a nippon denso type. Any advice in the injector pump area is greatly appreciated. For example, how many cc per cyl required for 600nm.

If you say 120cc/cyl for 550nm so this would be 87.3cc/cyl for 6cyl 600nm??

Cheers, GB
 
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Dougal; - it is a nippon denso type. Any advice in the injector pump area is greatly appreciated. For example, how many cc per cyl required for 600nm.

If you say 120cc/cyl for 550nm so this would be 87.3cc/cyl for 6cyl 600nm??

Cheers, GB
Can you post up and pics and/or numbers from it? I know a few wizards I can run numbers past but I might be able to identify at least the type by photo.

120cc/cyl was for a four cyl (my bad), for a 6 cyl would give up over 800Nm, but I can't see the stock pump having that much spare capacity.
 
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Hi, I see you are online. Thanks for the response

No bad; I could see you say 120cc = 550nm for 4cyl, so if I shoot for 600nm, 6cyl, then I need ~ 90cc/cyl....if I understand correctly...

I will get the part numbers - I have an auto and manula pump, will give both.

For 120cc, are you referring to "1000 strokes" ? How is tghis measured?

I am looking at the toyota manual at the moment. Std is measured at 200 strokes and is listed at up to 11.3cc, so based on your numbers and assuming yours are based on 1000 strokes, lets do some maths:

[(11.3cc * 6cyl * 1000/200)/(120cc * 4cyl)] * 550nm = 388nm


Hmmm, close, but std the 12H-T is rated at only 312nm

I note that the "cold Weather Spec" lets the cold start see up to 18cc @ 200 pump rpm instead of std 9-13cc. This would indicate around 18cc per cyl @ 200 pump rpm may be possible.

So, again and allowing for the difference noted above, we might conclude that 18/11.3 * std torque 312nm = 497nm.......

Anyway, am really guessing now............
 
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Hi, I see you are online. Thanks for the response

No bad; I could see you say 120cc = 550nm for 4cyl, so if I shoot for 600nm, 6cyl, then I need ~ 90cc/cyl....if I understand correctly...

I will get the part numbers - I have an auto and manula pump, will give both.

For 120cc, are you referring to "1000 strokes" ? How is tghis measured?

I am looking at the toyota manual at the moment. Std is measured at 200 strokes and is listed at up to 11.3cc, so based on your numbers and assuming yours are based on 1000 strokes, lets do some maths:

[(11.3cc * 6cyl * 1000/200)/(120cc * 4cyl)] * 550nm = 388nm


Hmmm, close, but std the 12H-T is rated at only 312nm

I note that the "cold Weather Spec" lets the cold start see up to 18cc @ 200 pump rpm instead of std 9-13cc. This would indicate around 18cc per cyl @ 200 pump rpm may be possible.

So, again and allowing for the difference noted above, we might conclude that 18/11.3 * std torque 312nm = 497nm.......

Anyway, am really guessing now............
So yeah, from the 11.3 for 200 strokes we get 56.5 cc/1000.
The reason for the 1000 strokes is to bring it back to an every day measuring unit. Actual injection of 56.5mm^3 is tricky to measure.

From the stock fuelling of 56.5 and stock torque of 312Nm we can work out the BSFC.
It comes out at 265 g/kwh, which is pretty poor for a DI diesel. My Isuzu needs under 220 g of diesel to produce each kilowatt-hour at peak torque. Basically your engine will produce less torque from the same fuel.

I also worked back through the boost requirements (stock) to see if it made sense, how does about 11psi boost sound?

But now we have the BSFC, we can better predict actual torque levels. If you can get 90cc/1000 shots (that's the 18 cc/1000) then it'll be just under 500Nm.
You'll need about 25psi with a good intercooler to get enough air in for that.
 
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Dougal, thanks and you are right, 220gm/kwh is what I was aiming for and I was of the understanding that these trucks must get about that since the tall geared autos often get 9l/100km......

I will do some more research, and check the density of diesel to back calc......
 

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