I had a 1hzt it did not rev as fast as my rebuilt 12ht and I mine is pulling around a 2700kg 75 series ute goes better then my 80 series for shaw my next upgrade is an 3" exhaust then a turbo upgrade probably a G turbo
12HT improvements
- Thread starter Rocher
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True, also I suppose it comes down how involved a rebuild you do and also, how many here actually bought in 1986 a brand new 60 series with a 12HT as to compare what a new motor was like to the 350,000 to 600,000klm ones running around now?
We all know that the new spec of a 12HT is around 135hp but after 30 years they are probably lucky to have 100hp and then trying comparing it to a 1HZT?
My comparison to the 1hzt is a lot closer than your comparison with the bmw tri turbo 380hp 740nm motor. My 12ht has 30,000km since complete rebuild including ip and turbo
Comparisons:-
BMW full power is limited to the high rev end, its sweet spot is 3200 to 4500 revs under load, it finds the gear (8 speed box) to that power range on the beach. The new F15, locks the torque vectoring on the rear ( like a auto e-locker), front has 60% of the power so it pulls you thru the soft sand rather than push you.
Third turbo kicks in at high revs, high speed, Autobahn stuff, which is great if your cruising at 120kph and want overtake you hit 160kph before you know it. Cruise at 200kph all day but not here is AUS or the US, top speed is straight to 260kph.
On the beach at full tide at 60 t0 70kph+, has the tendency of nose up the sand dune, more than a normal vehicle due to the 60% power to front wheels, so your are rallying rather than driving, the faster the better with air adaptive drive suspension, the only problem is the coconuts rumbling underneath..
Now the 12Ht (coil suspension chassis) has its own sweet spot, choppy high tide is 45 - 65kph, just holding 3rd gear, powdery sand will hold 4th at 75kph+ in a straight line only if beach is not chopped up, but again you have that power rev band to stick too.
So it's a matter of power, suspension and clearance that dictates the speed you do on the beach at high tide when you have to drive in the powdery sand, the 2H is fine at 20kph, limits you to 2nd gear and the leaf suspension limits the speed anyway as it cannot handle the rough powdery chopped up surface. The problem worsens as the 2H cannot handle these conditions if dragging to much dead weight as at the lower crawl speed you just dig hole. A 12HT in a standard 40 under these conditions you may get 25kph but the suspension at higher speeds would be bone jarring, low tide & highway cruising is a different story.
My point being if your going to install a 12HT in a standard 40 for any other reason other than just cruising (as a DD would be great for hwy cruising) then don't, not unless your happy to go slow on rough surfaces, otherwise you need to alter the leaf suspension, then why put a 12Ht in and not stick to a 2H?
My reason, was I needed more power to pull a 470kg jet-ski thru 12" of powdery sand, the problem lies in momentum, pulling 470kg dead weight requires power, you need power to drive 4 locked wheels (at 100lbs each) but at low speed all you do is dig 4 holes?, so then you need speed to keep moving, but if the suspension cannot handle speed you cannot obtain it. The 12HT has the power, but speed requires a better suspension than what the 40 has as standard, so I changed the suspension to handle higher beach speeds. A V8 would do the same thing but economy comes into play plus I don't want to be sitting on 110ltr of petrol or storing that much petrol up at the beach house.
Now before you say it, "why don't you use the M50d", simple ground clearance, if I stop on 12" of powdery sand I am sitting on my belly, and with 470kg behind me I am not going anywhere, plus there is only so much coconut milk you can drink?
And finally, I wanted a simple diesel engine, no rubber timing belts, bit of extra boost, hoping for 150hp, economy, 300,000klm life span which it will never achieve on the beach, maybe do 6000klm per year max. The 12HT revs quickly so I can get the speed up to the rev power band and get momentum and hold, which was not achievable with the 2H, would it be achievable with a 1HZT I do not know, and would the 1HZT handle a 40klm run under these conditions?
I have owned a 80 & 100 series some 15 years ago but only for hwy use, but at full tide I do over take them as they waller in the deep tracks and toss from side to side as they do not have the power to pull themselves up onto the smoother sand between the tracks, but then again some are jacked up so high the must be a nightmare to drive anyway?
Niffa, the impression I get is the 12HT in 60 series with it's weight is probably like a owner with a worn 2H in a HJ47, your looking for that little bit extra, is it not the case all the time you are thinking if only I had 35hp more? what if I put headers on will it give me 20hp, will I get another 10hp with 2 & 1/2" exhaust? I will turn the boost up? So if a 12HT in a 40 is the holy grail, what's the holy grail engine for a 60?
BMW full power is limited to the high rev end, its sweet spot is 3200 to 4500 revs under load, it finds the gear (8 speed box) to that power range on the beach. The new F15, locks the torque vectoring on the rear ( like a auto e-locker), front has 60% of the power so it pulls you thru the soft sand rather than push you.
Third turbo kicks in at high revs, high speed, Autobahn stuff, which is great if your cruising at 120kph and want overtake you hit 160kph before you know it. Cruise at 200kph all day but not here is AUS or the US, top speed is straight to 260kph.
On the beach at full tide at 60 t0 70kph+, has the tendency of nose up the sand dune, more than a normal vehicle due to the 60% power to front wheels, so your are rallying rather than driving, the faster the better with air adaptive drive suspension, the only problem is the coconuts rumbling underneath..
Now the 12Ht (coil suspension chassis) has its own sweet spot, choppy high tide is 45 - 65kph, just holding 3rd gear, powdery sand will hold 4th at 75kph+ in a straight line only if beach is not chopped up, but again you have that power rev band to stick too.
So it's a matter of power, suspension and clearance that dictates the speed you do on the beach at high tide when you have to drive in the powdery sand, the 2H is fine at 20kph, limits you to 2nd gear and the leaf suspension limits the speed anyway as it cannot handle the rough powdery chopped up surface. The problem worsens as the 2H cannot handle these conditions if dragging to much dead weight as at the lower crawl speed you just dig hole. A 12HT in a standard 40 under these conditions you may get 25kph but the suspension at higher speeds would be bone jarring, low tide & highway cruising is a different story.
My point being if your going to install a 12HT in a standard 40 for any other reason other than just cruising (as a DD would be great for hwy cruising) then don't, not unless your happy to go slow on rough surfaces, otherwise you need to alter the leaf suspension, then why put a 12Ht in and not stick to a 2H?
My reason, was I needed more power to pull a 470kg jet-ski thru 12" of powdery sand, the problem lies in momentum, pulling 470kg dead weight requires power, you need power to drive 4 locked wheels (at 100lbs each) but at low speed all you do is dig 4 holes?, so then you need speed to keep moving, but if the suspension cannot handle speed you cannot obtain it. The 12HT has the power, but speed requires a better suspension than what the 40 has as standard, so I changed the suspension to handle higher beach speeds. A V8 would do the same thing but economy comes into play plus I don't want to be sitting on 110ltr of petrol or storing that much petrol up at the beach house.
Now before you say it, "why don't you use the M50d", simple ground clearance, if I stop on 12" of powdery sand I am sitting on my belly, and with 470kg behind me I am not going anywhere, plus there is only so much coconut milk you can drink?
And finally, I wanted a simple diesel engine, no rubber timing belts, bit of extra boost, hoping for 150hp, economy, 300,000klm life span which it will never achieve on the beach, maybe do 6000klm per year max. The 12HT revs quickly so I can get the speed up to the rev power band and get momentum and hold, which was not achievable with the 2H, would it be achievable with a 1HZT I do not know, and would the 1HZT handle a 40klm run under these conditions?
I have owned a 80 & 100 series some 15 years ago but only for hwy use, but at full tide I do over take them as they waller in the deep tracks and toss from side to side as they do not have the power to pull themselves up onto the smoother sand between the tracks, but then again some are jacked up so high the must be a nightmare to drive anyway?
Niffa, the impression I get is the 12HT in 60 series with it's weight is probably like a owner with a worn 2H in a HJ47, your looking for that little bit extra, is it not the case all the time you are thinking if only I had 35hp more? what if I put headers on will it give me 20hp, will I get another 10hp with 2 & 1/2" exhaust? I will turn the boost up? So if a 12HT in a 40 is the holy grail, what's the holy grail engine for a 60?
It's still the 12ht for the 60 series.
In my opinion it is the holy grail toyota motor, as you said it's pure no BS machinery that's made to last and produces the right amount of power.
It's because it's not computer managed and it performs as good as it does stock that makes it such a great motor.
So in keeping with the OP question, I still think the answer is nothing and don't mess with something that isn't broken. (That's not an easy phrase for me to say)
In my opinion it is the holy grail toyota motor, as you said it's pure no BS machinery that's made to last and produces the right amount of power.
It's because it's not computer managed and it performs as good as it does stock that makes it such a great motor.
So in keeping with the OP question, I still think the answer is nothing and don't mess with something that isn't broken. (That's not an easy phrase for me to say)
He is itching to put something into that 40 when he buys it and specially if he buys a FJ model it will be a big task going from petrol to diesel, whether its a 12HT or a 1HZT its going to be a big job and its a tight squeeze and won't happen over night either? will be watching this thread?
big front mount intercooler could do something also
I saw the thread on someone who retro fitted a throttle damper to the 12ht but was wondering if anyone in this thread has done a similar modification. The 12ht is hands down my favourite diesel I have ever driven (compared to a 1HZ turbo, TD42 turbo... havent had a go in a HD series). Just the touchy throttle gives me the s***s real bad offroad!
I've ported a couple 3b heads John and noticed the exact same casting band on the exhaust port as well. It encroaches several mm and really chokes fow, but is only like a bump that is extremely easy to grind off as there is no material past it. The valves on these engines are also very shrouded.
I install a dampener off a early model Mazda onto the throttle linkage of the 12HT, fixed it.
Will take a photo over this coming weekend, I just made a bracket and replaced the adjusting idle screw/bolt with the dampener. Its a bit of a fiddly job and you are better off doing it before you install the engine because of the confined space around the throttle linkage area. but its doable.
Also interested in how you set that damper up... as a "resting point" for the idle position?
Will try to remember to take a photo next weekend when back up at the beach house of the dampener.
- Thread starter
- #37
I have been thinking some more about the 12HT motor a bit more now that the re-wire and power steering are done on my '40 and I remembered coming across asymmetrical pistons when looking to upgrade my race cars motor.
I know that a diesel engine piston is designed differently to a petrol motor (higher compression, higher heat, more shock loading, etc), but was wondering if this could work in a 12HT, using a single piece steel piston with the ALFIN around the ring grooves.
The reduction in friction as opposed to full piston skirt should reduce friction (improved efficiency) and the reduction in weight would allow for knife edging the crank (well more like slightly rounding the counter weights) to assist in cutting through oil (again increasing efficiency).
Seeing as part of a rebuild of a 12HT would normally include upgrading to ALFIN pistons (and ideally re-balancing the rotating assembly) it seems like a bit of an increase in cost for a potential increase in efficiency and reliability (or power without decreasing reliability if you are that way inclined)
I know that a diesel engine piston is designed differently to a petrol motor (higher compression, higher heat, more shock loading, etc), but was wondering if this could work in a 12HT, using a single piece steel piston with the ALFIN around the ring grooves.
The reduction in friction as opposed to full piston skirt should reduce friction (improved efficiency) and the reduction in weight would allow for knife edging the crank (well more like slightly rounding the counter weights) to assist in cutting through oil (again increasing efficiency).
Seeing as part of a rebuild of a 12HT would normally include upgrading to ALFIN pistons (and ideally re-balancing the rotating assembly) it seems like a bit of an increase in cost for a potential increase in efficiency and reliability (or power without decreasing reliability if you are that way inclined)
A fully rebuilt 12HT produces a fair bit more power than 2H, it revs quicker and has a better torque range than the 2H. The fuel economy is good also, I pulled a 16ft tiny with outboard motor on a trailer over the long weekend, up & down the beach at full tide for 3 days and averaged just over 13L/100klm, which I thought was pretty good running a locked rear diff and in 4 wheel drive.
In 5th gear boost sits at around 10lbs at 80kph and around 12lbs at 100kph, at idle its around 2-3lbs, the boost light/switch is set at around 5lbs and at 1000revs goes out, at around 1200rev it sits at about 8lbs and 1600revs is 10lbs. Have seen at 135kph about 17lbs and the pyro was sitting at 500. Even towing the boat at high tide in soft wet beach sand does not bring the pyro temps up much passed 400 if I push the engine hard. Pyro is situated in the exhaust right where the dump pipe connects to the exhaust, so even if I add a 100 degs to the numbers its still cool.
I am running a 3" exhaust SS, 4 core full brass radiator and water temps don't go passed the first mark on the temp gauge, there is no smoke out of the exhaust while driving, only a puff of black when you first start the engine.
The only thing I am still trying to sort out is the oil. Temperature here this summer has averaged something like 30c, have noticed the oil pressure dropping off as the engine has been working at operating temp over an extended period, water temps and pyro temps are fine so l believe the oil is breaking down, the viscosity cannot handle the temperature its running at. My reasoning for this is at engine start there is no noise of loose, worn, rattling or valve train or lifters etc, but when run over a period of time and the oil gets hot, the oil pressure drops, you sense the engine is becoming noisey.
Am running Penrite Classic Light Mineral 20w-60 and the engine has now done around 700klm, so I will change it out for a Penrite Classic Medium 25w-70 which is suited more for our tropical climate.
In 5th gear boost sits at around 10lbs at 80kph and around 12lbs at 100kph, at idle its around 2-3lbs, the boost light/switch is set at around 5lbs and at 1000revs goes out, at around 1200rev it sits at about 8lbs and 1600revs is 10lbs. Have seen at 135kph about 17lbs and the pyro was sitting at 500. Even towing the boat at high tide in soft wet beach sand does not bring the pyro temps up much passed 400 if I push the engine hard. Pyro is situated in the exhaust right where the dump pipe connects to the exhaust, so even if I add a 100 degs to the numbers its still cool.
I am running a 3" exhaust SS, 4 core full brass radiator and water temps don't go passed the first mark on the temp gauge, there is no smoke out of the exhaust while driving, only a puff of black when you first start the engine.
The only thing I am still trying to sort out is the oil. Temperature here this summer has averaged something like 30c, have noticed the oil pressure dropping off as the engine has been working at operating temp over an extended period, water temps and pyro temps are fine so l believe the oil is breaking down, the viscosity cannot handle the temperature its running at. My reasoning for this is at engine start there is no noise of loose, worn, rattling or valve train or lifters etc, but when run over a period of time and the oil gets hot, the oil pressure drops, you sense the engine is becoming noisey.
Am running Penrite Classic Light Mineral 20w-60 and the engine has now done around 700klm, so I will change it out for a Penrite Classic Medium 25w-70 which is suited more for our tropical climate.
I assume you have a mechanical oil pressure gauge, is pressure within spec or does sit below spec on hot engine.
Viscosity breaking down, I would doubt that, don't over think it, 20-60 is at the over and above the top end of viscosity for warm climates.
If your engine temps are good, I wouldn't get too hung up on it.
Viscosity breaking down, I would doubt that, don't over think it, 20-60 is at the over and above the top end of viscosity for warm climates.
If your engine temps are good, I wouldn't get too hung up on it.
- Thread starter
- #40
Seeing as it's kind of related to my old thread...
U guys have suggested that the stock (ish) power of the 12ht is adequate in a 40. Is there any reason not to fit a 4cyl diesel with similar power torque to get improved fuel economy?
Oh and I currently have a 12ht 60 series ATM, which I'm hoping should give me a pretty good idea of fuel economy of the 12ht with my driving style.
U guys have suggested that the stock (ish) power of the 12ht is adequate in a 40. Is there any reason not to fit a 4cyl diesel with similar power torque to get improved fuel economy?
Oh and I currently have a 12ht 60 series ATM, which I'm hoping should give me a pretty good idea of fuel economy of the 12ht with my driving style.