rebuilding my 12ht

[rideglobally]

finally found a place in Los Angeles that will rebuild my 12ht, i have to provide all the parts. they will do the machining and labor. the good thing is that the shop will allow me to help or work on it. i have the 12ht engine manual with all the specs. i am making it clear to the shop i want all the specs followed perfectly. i intend to inspect the specs myself as the engine gets rebuild. i think this is referred to as "blue printing".

my question are; is there anything i can do to the inside of the engine that will make it more efficient, increase power without compromising reliability? is it possible to rebuild the engine better than when it came out of the toyota assembly line?

here are some of the list of things i intend to do;
1. i am purchasing an overhaul kit from Australia
2. the head gasket will be Japanese made (i am told that gaskets made else where have problem)
3. i will replace the all valves and springs.
4. replace push rods and lifters
5. the pistons will have steal inserts (alfin)
6. make sure that all the pistons weigh the same
7. balance the crankshaft
8. balance the camshaft
9. cylinders houn

Am i leaving anything out? if you have done this before, any wisdom you can offer will be greatly appreciated.

i plan to begin this work in a couple of months.

 

[blis]

I envy you, im too damn poor to do anything to my 12ht engine wise :E

But yeah, that seems like a good plan, especially those pistons with steel insert since they are in most cases the weakest link in 12ht. I'd imagine with fully rebuilt engine there is alot of potential for power increase too by increasing boost (maybe some 1,5bar or so) and crank up the fuel... Also if you have time and skills then smoothing all the transitions in head and stuff like that is always worth the while...


ps. just dont ruin the engine with improper break-in when your done....

 

[goldchaser]

I'll be watching this
last trip outback my 12ht used about 4ltrs of oil in 3000klms,heavily loaded.Im off again in 4-5 days,making room for 4ltr oil tin
Still running good and temps are good but... needs to be done next 12months for sure.
My plans RG are along yours,try to improve power without losing reliability.
Im planning on full balance,renew as much as possible in the valve train.

she's done about 460,000klms and getting tired
mahle have some nice looking pistons,sizes im not sure on.

 

[Red Rattler]

I have just built my 2H myself to date it has cost me $12,000 and I'm still not finished. I have had the head port and polished, custom pistons to suit a higher compression, injectors and pump repaired and wound up. I have made the engine so when I get some more money I can fit a supercharger to it. I have had the engine dynoed and at the flywheel I'm getting 167Hp. For the turbo the best thing to fit is a catch can and run the breather to atmosphre I done it to my Toyota Surf and everything started to improve. One thing I have learnt is don't skimp on things it will only cost you more later.

 

[Red Rattler]

I'll be watching this
last trip outback my 12ht used about 4ltrs of oil in 3000klms,heavily loaded.Im off again in 4-5 days,making room for 4ltr oil tin
Still running good and temps are good but... needs to be done next 12months for sure.
My plans RG are along yours,try to improve power without losing reliability.
Im planning on full balance,renew as much as possible in the valve train.

she's done about 460,000klms and getting tired
mahle have some nice looking pistons,sizes im not sure on.

What oil are you using? I have found that makes a big difference. I only use Castrol RX Super and I also recommend it to my customers. I was using valvoline but I was better off putting it in the fuel tank.

 

[Tim-HJ61]

As bils said, smoothing the transitions in the head will make you feel you've made a difference.

Ensure your new pistons have steel ring inserts too.

Gbentink has put bigger Nissan valves but they also stroke the crank and do things I don't think you will want to consider.

Tim

 

[prado t]

I would consider machine in or sleeving the block.

 

[rideglobally]

thanks blis, what do you mean by "smoothing out the transitions in the head" i will make sure i do that, i have lot's of time and will not take short cuts.

when this is done i will tell you the total cost, it may surprise you.

I envy you, im too damn poor to do anything to my 12ht engine wise :E

But yeah, that seems like a good plan, especially those pistons with steel insert since they are in most cases the weakest link in 12ht. I'd imagine with fully rebuilt engine there is alot of potential for power increase too by increasing boost (maybe some 1,5bar or so) and crank up the fuel... Also if you have time and skills then smoothing all the transitions in head and stuff like that is always worth the while...


ps. just dont ruin the engine with improper break-in when your done....

Hi Tim, maybe after this overhaul i will have enough guts to turn up the fuel, that 10mm and the allen wrench is still under my pillow. thanks all for your help, Gbentink, Brian you all got me this far.

As bils said, smoothing the transitions in the head will make you feel you've made a difference.

Ensure your new pistons have steel ring inserts too.

Gbentink has put bigger Nissan valves but they also stroke the crank and do things I don't think you will want to consider.

Tim

 

[IH8Wood]

Can you share the name of the shop?

 

[Tapage]

custom pistons to suit a higher compression

why .. if the 2H already come with more than enough compresion for NA engine .. and you are going turbo ?

I would consider machine in or sleeving the block.

sleeving IMOP ..

 

[PERUVIAN]

If you are weighing the pistons.. you should be weighing the rods as well.. if there are heavier pistons.. balance them out with a lighter rod.. or vice versa.. will aid in a smoother running unit-

 

[goldchaser]

What oil are you using? I have found that makes a big difference. I only use Castrol RX Super and I also recommend it to my customers. I was using valvoline but I was better off putting it in the fuel tank.

I think the last change was valvoline,different oil may help a little but she's just tired.

Can you tell us what has been done to your 2H.
I don't understand how you could spend $12,000 on a 2H.
For that money i would have bought one of the new V8's, or a rebuilt 12HT,1HDT.

 

[rideglobally]

12,000 dollars WOW i had to look at that twice, i hope to speed less than half of that. that is way over my budget. i will look into getting the head port polished, i will be replacing the valves and springs. polishing the head port should not be that much more. i will be getting the steal sleeved piston from alfin to address the higher compression issue

I have just built my 2H myself to date it has cost me $12,000 and I'm still not finished. I have had the head port and polished, custom pistons to suit a higher compression, injectors and pump repaired and wound up. I have made the engine so when I get some more money I can fit a supercharger to it. I have had the engine dynoed and at the flywheel I'm getting 167Hp. For the turbo the best thing to fit is a catch can and run the breather to atmosphre I done it to my Toyota Surf and everything started to improve. One thing I have learnt is don't skimp on things it will only cost you more later.

can you tell me why i would need to sleeve the block? unless they are really in bad shape

I would consider machine in or sleeving the block.

i will share the name of the shop after or during the build, i just want to make sure that they will do a good job before i share the info.

Can you share the name of the shop?

 

[Red Rattler]

12,000 dollars WOW i had to look at that twice, i hope to speed less than half of that. that is way over my budget. i will look into getting the head port polished, i will be replacing the valves and springs. polishing the head port should not be that much more. i will be getting the steal sleeved piston from alfin to address the higher compression issue

I wouldn't sleeve the block I would just hone it if it's not to bad. Otherwise I would just get it machined to suit an oversize piston. I was going to replace the sleeves but it was just easier to get it machined to suit an oversize piston.

 

[Red Rattler]

I think the last change was valvoline,different oil may help a little but she's just tired.

Can you tell us what has been done to your 2H.
I don't understand how you could spend $12,000 on a 2H.
For that money i would have bought one of the new V8's, or a rebuilt 12HT,1HDT.

Try morey's oil treatment I use it in all the old trucks I service. I was going to update the engine but I want to keep everthing as is. A rebuild kit and block machining cost me $4500 alone. I had to get a new oil cooler element and that alone cost $1500. Fuel pump cost $2500 to be rebuilt. New alternator direct from factory $480, cylinder head $1200. New crank $1000. Custome clutch $650. Injectors $160ea. Rods $200 ea.

I had my oil pump fail which destroyed a bit in the engine I had to buy a second engine to make one good one. Atleast tho it has made me start the off chassis restore, thats why I'm spending the money to make it how I want it.

 

[goldchaser]

Try morey's oil treatment I use it in all the old trucks I service. I was going to update the engine but I want to keep everthing as is. A rebuild kit and block machining cost me $4500 alone. I had to get a new oil cooler element and that alone cost $1500. Fuel pump cost $2500 to be rebuilt. New alternator direct from factory $480, cylinder head $1200. New crank $1000. Custome clutch $650. Injectors $160ea. Rods $200 ea.

I had my oil pump fail which destroyed a bit in the engine I had to buy a second engine to make one good one. Atleast tho it has made me start the off chassis restore, thats why I'm spending the money to make it how I want it.

I'll get some and try it on this trip and report back.
Your definetly not cutting corners on the rebuild.

 

[Red Rattler]

I'll get some and try it on this trip and report back.
Your definetly not cutting corners on the rebuild.

I have seen so many people cut corners when getting repairs done. It always costs more later on. It's how I make my money.

 

[prado t]

12,000 dollars WOW i had to look at that twice, i hope to speed less than half of that. that is way over my budget. i will look into getting the head port polished, i will be replacing the valves and springs. polishing the head port should not be that much more. i will be getting the steal sleeved piston from alfin to address the higher compression issue

I wouldn't sleeve the block I would just hone it if it's not to bad. Otherwise I would just get it machined to suit an oversize piston. I was going to replace the sleeves but it was just easier to get it machined to suit an oversize piston.

How about this, if it is bad then sleeve it, you are going to have to hone it anyways. Pay abit more and machine it for sleeves, so you dont have to fxxx with oversize pistons, you can keep the stock bore. I think this motor lasted RIDGEGLOBALLY like a year. That way if it is sleeved it will be much easier to rebuild next time. Anyhow it is not my motor.

 

[blis]

thanks blis, what do you mean by "smoothing out the transitions in the head" i will make sure i do that, i have lot's of time and will not take short cuts.

when this is done i will tell you the total cost, it may surprise you.

Usually there are shard edges and gaps between transitions, such as between head and intake and also between head and exhaust... Also there may be rough edges inside the ports...

Smoothing them out will improve the flow a little bit and make your engine just a bit happier, it also gives bragging rights at local pub and garage especially if you can prove it by enfulging pedestrians in black smoke cloud when you leave for home

 

[rideglobally]

thanks, i will absolutely smooth out the transition, that is free and will not cost anymore. i will have to think about the black smoke, i don't think the smog in los angeles will not look good in black smoke.

Usually there are shard edges and gaps between transitions, such as between head and intake and also between head and exhaust... Also there may be rough edges inside the ports...

Smoothing them out will improve the flow a little bit and make your engine just a bit happier, it also gives bragging rights at local pub and garage especially if you can prove it by enfulging pedestrians in black smoke cloud when you leave for home