match porting and polishing a 12th (1 Viewer)

[rideglobally]

i am getting ready to port and polish the cylinder head of my 12th this weekend. i have read a lot about porting and polishing but i did not see anything on a 12ht so I though it would be good to post here and get some ideas from those of you who have ported and polished a 12th cylinder head. would like to hear any tips on the dos and don'ts and mostly how to maximize the efficiency on the intake and exhaust. i have read something that say don't make it too smooth because it will create turbulence and this will have a negative effect. is that true?...... thank you

 

[BEE-JAY42]

I don't think you'll see much benefit from porting & polishing a 12HT head, due to the low RPMS the engine runs at there isn't really a need for massive airflow. Even at the redline the stock head should be able flow enough air to keep up. If your chasing a performance increase i'd be looking at an intercooler (if you haven't got one) or a turbo upgrade would be where I would be pitting my dollars.

 

[77cruiser77]

I agree. Besides I think you might want to go for longevity instead of a rockstompin powerhouse. if you do too much to that engine you're going to be asking more out of it and if it breaks down in 5 years it's only going to be that much harder to get parts to fix it. I'd upgrade the turbo and intercooler as stated before. not knowing the 12HT inside and out perhaps anything you can do to help the cooling and oiling would be beneficial too.

If you have done these things I am sorry but I have not read your thread for a while

 

[baxter650]

If you are going to do any work i would keep it to a minimum and don't remove any more material than need be.
Just knock off the big lumps in the ports and leave it at that.
Blending the transitions from the valve seats into the bowls will net more improvement than any porting you may do.

 

[DieselFumes]

I agreed with Baxter. Keep it simple.

Porting/polishing/extrude hone has been done very successfully for many years under extreme racing conditions. Yes, if you take too much from one side you may compromise strength... however I believe there only to be benefits from this if done properly, with that said, if you have no prior port and polish experience and especially with a motor that does not have that many performance references for this type job, I would look towards a professional port/polish match or send it to extrude hone.

 

[rideglobally]

thanks you, you all have been very helpful. here is what i plan to do:

1. i will take the exhaust gasket and port the cylinder head exhaust and the exhaust manifold so that the both are matching the inner opening of the gasket. i will be grinding off at the most 1/8 inches of material. in most places i will be grinding very little to get the exhaust holes to match up.

2. on the intake and all other areas i will be doing basically what Baxter is suggesting blending transitions especially under the valve seats to the bowl.

3. smoothing out the casting burrs to about 80 grid but not polishing it.

what do you all think?

 

[1tontoy]

General question: is this a DIY type job or should a machine shop do it?

 

[baxter650]

For general cleanup and blending the seats into the bowls it is very doable at home.

 

[DieselFumes]

for general clean up I have done it myself and also had it professionally done, it all depended on budget, project, time etc. Did I notice a difference pro vs. joe? not really, different applications. But there is more than one way to skin it!

Sorry I haven't read your build, did you drive the setup before porting? Would like to know a "seat" feel from you on before and after, I'll bet she will be more efficient if anything.

 

[rideglobally]

thanks again. here are picture of the port matching of the exhaust manifold and cylinder head port you can see by the lines how much i need to cut to match up the two ports. i am using carbide bit to do the first cut then rotary sand paper. the tool i am using is a die grinder i bought for 30. dollars, the whole thing will cost me 100 dollars plus my weekend. i have started on it just to get the initial idea of what it take to cut the metal. it is not that difficult. after matching the ports i am basically gonna smooth out transitions and smooth out casting burrs.

yes i have driven the set up prior to the engine rebuild. to answer earlier questions; yes i have a top mounted intercooler with a fan. also i will be installing a new turbo build by Graeme, the turbo is design to spool at 1,600 rpm. the engine is being completely balanced. so there should be a difference but i am not sure i can be able to distinguish the difference that the porting will produce.

 

[DieselFumes]

RideGlobally..... doing it right! That will be one sweet setup!

 

[Tim-HJ61]

This will be nice to have done.

Although many regard the 12h-t as 'the best Toyota ever made' you can see how with a bit of care and attention it, such as you are giving your motor, it can be improved little by little and the end result will be very nice.

Well done for persevering it's been a long work in progress.

Tim

 

[rideglobally]

update - picture

one day work match porting and removing cylinder head intake and exhaust burrs

 

[bigbrowndog]

I don't think you'll see much benefit from porting & polishing a 12HT head, due to the low RPMS the engine runs at there isn't really a need for massive airflow. Even at the redline the stock head should be able flow enough air to keep up. If your chasing a performance increase i'd be looking at an intercooler (if you haven't got one) or a turbo upgrade would be where I would be pitting my dollars.

X2, If you get it dyno tuned before and after you will find no difference in HP or torque.
At least you won't need to worry about taking too much metal away from where the pre cups are:whoops: on the 2H.

 

[gerg]

Diesel don't port for hp or torque necessarily. They do it to lower EGTs. I read that on the intraweb.
g

 

[cody c]

porting for lower egt's is porting for durability in my perspective. Although with lower egt's you can add more fuel/power as well...

 

[gerg]

Exactly. Its all about air in and exhaust out. Porting does apply to diesels.
g

 

[rideglobally]

lower EGT would be great. the Graeme turbo i am installing is also suppose to lower EGT. in addition i have a 3.5 inch down pipe, 3.5 pipes, inter cooler and a Donaldson air filter with over 1000 cfm. this 12ht should be able to breath easily. taking the cylinder head to the engine rebuilder tomorrow i am hoping that my engine will be done in a couple of weeks. i will find out for sure if all of this up grade works............ thanks

 

[BEE-JAY42]

It's not a question of does it apply to diesels, it's a question of how much benefit and at what cost? The higher the intake air velocity the more an engine will benefit from porting, the 12H-T is not an engine with high intake air velocity.

 

[gerg]

The term porting I think can be misleading. Although we use it for lack of a better word. Bigger is not better for low RPM diesels. You are right about intake velocity. Smoothing transitions and rounding out turns will all help increase the intake velocity and thus cylinder filling. This is actually for the same reason you add a turbo; to get more air. Although I wouldn't compare this with the benefits of a turbo. To what degree this helps... who knows. I guess you have to run it to find out.

I have read that formula 1 engines boast 130% VE with N/A engines, which is out of this world amazing. However, slap a 50$ turbo on your diesel and you can have that gain for the cost of a weekend and a case of beer..

The more I have read, the more conservative my plans become. Gasket matching and removing obvious casting slag is pretty straight forward. All the other stuff is pretty much a black art as far as I have read, and none of the magicians give out their secrets for free. That being said I have to redo my head gasket next week so an amateur magician soon I will be.

De-shroud valves, blend valve seat transitions, round out the short side on each runner, radise the exhaust valves, blend all the valve grinds, maybe even narrow up the intake runner with epoxy... but that sounds dodgy.
g