Toyota CT26 Upgrade - 13BT/12HT/1HDT/1HDFT

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G

gbentink

Joined
Oct 5, 2008
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Location
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People want to know what parts its made from and prices,photos may help you too.
Im interested in the bored block etc,just bored out to 95mm without stroking what size does it end up?
 
Hi, not all, but alot of people always want the information for free after alot work is done to get it. Just plain lazy.

Why ask me such a basic calc? You must know the std bore and stoke of your engine. It is ~4.34L with 95mm bores. Nice option but requires custom rods if the other pistons are used - thats not a bad thing in itself......

95mm bore also allows oversize valves. Depends what people want. A nice high flowed CT26 without intercooler would be great with a 4.7-5L 12HT and would max out the fuel pump as they come std. The company I get to weld up the crank has over 25yrs experience in doing them for drag cars (petrols mind you) and havent had a single failure.

So, for ultimate power, I would go to just overbore with custom rods and MLS head gasket. But to really make it worthwhile $/kw requires the fuel pump to be stripped and adjusted to allow more rack travel. Currently the max you can get from external adjustments is ~ 13mm and that is good for ~ 170hp@ wheels, but the rack can move 21mm!!

It would be interesting, but if the 5L big bore was done and the current CT26 turbo mod was offered, you should get 21psi boost at 1400rpm. Now that would be something - especially in a manual. You would probably get away without having an intercooler too which really simplifies things.

The welded up crank does make me abit nervous. There is an option to get it shot peened which they do sometimes around the weld area. The journals ar built up then offset ground. As a result probably 80% of the original metal is there still. I drove in the 80 series only yesterday with the 12HT/4.76L and it is very smooth, builds boost very early (easy 10psi @ 1400rpm - it does have a high flowed CT26 to my spec, but not the new version which is entirely different). Perhaps my concerns on the crank are unfounded.

Cheers
 
Hi Graeme

Do these toyota 6's need any extra flywheel mass with lots of boost down low?
My Isuzu gets a bit rough with 20psi at 1400rpm, but it's flywheel is already very light. I'd like to double the mass someday.
 
Dougal said:
Hi Graeme

Do these toyota 6's need any extra flywheel mass with lots of boost down low?
My Isuzu gets a bit rough with 20psi at 1400rpm, but it's flywheel is already very light. I'd like to double the mass someday.
Click to expand...


Dougal are you able to expand on it being rough, like why? Torsional vibrations or something else because of the boost at that rpm ?
 
Hulsty said:
Dougal are you able to expand on it being rough, like why? Torsional vibrations or something else because of the boost at that rpm ?
Click to expand...

Simply torsional vibrations from lots of torque at very low rpm. My Isuzu has a very light flywheel for it's engine size, a 4BT cummins flywheel is about double the weight.
 
Hulsty said:
Dougal are you able to expand on it being rough, like why? Torsional vibrations or something else because of the boost at that rpm ?
Click to expand...

I'd take a guess and say it's because of the increased cylinder pressure.
 
Hulsty said:
Would a heavier harmonic balancer at the front also help your situation? How heavy is the standard flywheel?
Click to expand...

No a harmonic balancer won't help, a heavier flywheel will. Current one is only 16kg.
I'm currently running a slightly bigger turbo which side-steps the problem.
 
Dougal said:
Hi Graeme

Do these toyota 6's need any extra flywheel mass with lots of boost down low?
My Isuzu gets a bit rough with 20psi at 1400rpm, but it's flywheel is already very light. I'd like to double the mass someday.
Click to expand...

Hi Dougal,

I doesnt seem so. But I havent seent 20psi @ 1400rpm yet LOL!

Having a power stroke during the last stage of compression helps!

I would not like to get OT, but would be interested to hear if your twin turbo setup has seen any work yet?
 
gbentink said:
I would not like to get OT, but would be interested to hear if your twin turbo setup has seen any work yet?
Click to expand...

Sorry to say none at all. My garage is filled with a decapitated people mover. When the new gasket arrives, head back on and van sold I will have one less distraction.
 
Reports of dyno are over in the 60 series area.

Basically excellent results without smoke at full load considering these get 67rwkw standard at 3400rpm.

After fitting new turbo:

65/75/83/97/100rwkw @ 1600-17psi/1800-21psi,2000-21psi,3000-18psi,3400rpm,-18psi respectively

Torque peak appeared between 1700 and 1800rpm and was ~ 450nm back calculated to flywheel. Still had ~440nm at 1600rpm.

I have the video which shows in cabin whats happenening. Will post link to youtube shortly.

High temps during the day (35-36 when done) and engine had been in traffic for 40 mins, so no cheating here.

Pre turbo exhaust temps got to but didnt exceed ~ 600 deg C

Intake manifold crossover got to 105 deg C and was rising, so intercooler would make a huge difference here.

I am sure 60 series owners will notice that the overboost light is on at 1600rpm in the video. It would have done a bit better if the aneroid spring had less tension. No smoke at all and it seems that the fuel pump didnt juice up much until 12psi onwards - not what you want.

My 1HDT had no hope of getting 17psi at 1600rpm. I could get it by 1800rpm with a modded turbo and intercooler but at 1600rpm it was smoking and coming off boost quickly.
 
Last edited:
Hulsty,

Main fuel screw was unwound completely, so pump is producing maximum volume.

High flow turbo dealt with all the fuel the pump could produce, and the EGT with no smoke proves the engine can handle this high fuel load.

Tim
 
A vendor getting upset on a forum. Never seen that before.;)
 
Hi John,

Thanks for teaching me two things

1. the new phrase to me TROLL. Wikipedia definition here.

I hardly think what I am posting is "irrelevant or extraneous" as per the definition, but you're entitled to your view of course. I figure I'm pretty much like many others on forums around the place. New comers to start off with, who know nothing, or who know enough to be a nuisance. Then over time, with the information we gain from the forum, learn more and become more confident to modify and improve our vehicles.

As you're classing me only as GB's sidekick, you may not have searched my previous postings, nor checked my website where I have posted as much details in the past on what I have done as physically possible. I like to share what I learn in a way that is going to be helpful - probably much like you do.

It's pretty obvious that whilst many people rave about how good the 12h-t is, not many are actually doing much about some of the basic mods that can unleash the potential. I'd like to think that what I have posted has been useful to others understanding and building their confidence to make some of these minor mods themselves. Living where we do, we have access to a few of these to work on and play with. It's a nice hobby for me.

2. That I can buy a little star to show support for the forum. Interesting. Didn't know about that option. Will go and search it out now.


Have a good day John.

Tim

[EDIT] Link to little silver star is at https://forum.ih8mud.com/payments.php
 
Last edited:
Hulsty said:
was all this on standard fuel settings or were they optimised?
Click to expand...

As my sidekick (LOL!) Tim said, the aneroid screw was wound out so that it delivered the maximum that the standard pump can do. You still max out at 13mm of rack travel. We dont know what the rack travel is, I will be less than 13, maybein the 11-13mm range anyway. The rack can move 21mm and "one day" I would like to modify the rack control to allow full movement.

Key thing here is that at the full load it is clean. At idle, this engine smokes a bit, its not super clean as far as an engine goes - old tech, 230kkm and stock 1988. But when underl load, a situation where you would expect it to dirty up, it is clean.

I will upload another few vids over the weekend that show exhaust and the numbers on the dyno controller.
 
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