1HDT Cylinder Head Performance Modifications (1 Viewer)

[Wildnlost]

I tryed blending the rough die grinder finish with a flap wheel . Contour is much better.
Posted a couple of early pics of port progress.....with any luck more power too.

 

[Wildnlost]

Before bolting on the cylinder head I decided to make sure my head is still straight. Cylinder head that is, we all know that my head is warped. Turns out that my head is warped again about .003". Within spec but I am not taking any chances. I dissassembled the head expecting valves and seats to be fine with only 15,000km since valve job. Intake valves and seats looked perfect exhaust seat was good but the exhaust valves were extremely pitted. FML.
Not sure of the cause.

Heat has been sited as a possible cause from a couple of different people. I do monitor EGT.s and have never been over 1200F. To much EMP? Bad sender on egt?
I think possibly the problem is too narrow of a valve seat. Spec is 1.8mm to 2.2mm my seats were about 1.2mm wide.
The valve gets cooled by seat to valve contact when closed. So I recut seats to 2.0mm.

Narrow on left.
Head is planed again valves done. Diesels Unlimited has some porting notes on there facebook page to improve the 1HDT exhaust port flow which is quite poor.
To port or not to port, that is the question....
Where is the die grinder???

 

[gerg]

When I ported my 3B head there was some casting that was totally in the way a super easy to get. I did end up polishing everything and spent alot of time but I suspect the bulk of the bennifit came from the easy stuff. Go for the easy stuff!

 

[Wildnlost]

Ported the exhaust port a little bit more as you can see from the pic below there is a significant restriction from the valve guide boss protruding into the top of the port.

The valve guide is sticking out past that about 2
mm.

So I trimmed the guide off and reshaped around guide. Widen around where the valve stem runs thru and tapered it alittle.

 

[gerg]

Cool. You haven't wasted any time!

 

[Wildnlost]

Exhaust manifold has been cleaned up as well. Matched the exhaust ports to the gaskets. Also matched the turbo to the manifold. One place that was particularly restricted was the rear portion of the exhaust manifold where it joins to the front part.

I often put thegasket in place and then spray paint the opening to show where material needs to be removed.

Turbo has a big step where it meets the manifold.

Die grinder takes care of that.

Matching manifold to turbo and trying to improve the flow out of the manifold by trying to increase the short side radius at the dump into the turbo.

 

[mudgudgeon]

Cool.
How much does die grinding suck!? Worst shavings ever.

When I've done this in the past, I would also put a smear of paint on the manifold, and mate it up to the head so your matching head to manifold and visa versa, not just ppmatching to a gasket.
You want the exhaust manifold port to be 1/2 mm larger all round than the head port so if there's a slight misalignment you don't get a lip that impedes gas flow. Opposite on the intake.

 

[gerg]

Nice work. I hate steps, they totally destroy flow. Nice thing is they are often the easiest to identify and correct.

 

[Wildnlost]

I am using ARP direct fit studs from Diesels Unlimited in Glen Forrest, Austrailia. Recommended at 24 psi at turbo. I was running 24 psi at the intake manifold so probably about 27 psi at the turbo.

That's what a $1000.00 CAN. looks like.

 

[Magic Spool Bus]

I am using ARP direct fit studs from Diesels Unlimited in Glen Forrest, Austrailia. Recommended at 24 psi at turbo. I was running 24 psi at the intake manifold so probably about 27 psi at the turbo.
View attachment 2066374
That's what a $1000.00 CAN. looks like.
View attachment 2066557

Any updates on this?! I really enjoyed reading through this post.

 

[Wildnlost]

Any updates on this?! I really enjoyed reading through this post.

Good day. I have put about 5000km on the truck since getting back together in winter. I havent had alot of time to play around with it since getting things back together.
The motor runs very strong pre boost compared to the last build and rips on boost. I have not adjusted fueling or boost settings from my last build.
I attribute the new found low end power to getting the squish set at the tight end of the spec. Thats the clearance from the piston to the head at TDC. I am running a little closer than the recomended clearance.
I am assuming the squish velocites are much higher than my previous build as I used the thickest head gasket " to be safe" when in fact I needed a 3 notch gasket.
The motor runs cleaner for sure too.
I just oredered a new pyro probe I must have damaged mine during rebuild. Hopefully have some time after the snow flies.
Trying build a shop and finish some land scaping before winter.
Pulled a trailer with weighing 11,000lbs about 2 hours with cement blocks on it.

 

[Magic Spool Bus]

Good day. I have put about 5000km on the truck since getting back together in winter. I havent had alot of time to play around with it since getting things back together.
The motor runs very strong pre boost compared to the last build and rips on boost. I have not adjusted fueling or boost settings from my last build.
I attribute the new found low end power to getting the squish set at the tight end of the spec. Thats the clearance from the piston to the head at TDC. I am running a little closer than the recomended clearance.
I am assuming the squish velocites are much higher than my previous build as I used the thickest head gasket " to be safe" when in fact I needed a 3 notch gasket.
The motor runs cleaner for sure too.
I just oredered a new pyro probe I must have damaged mine during rebuild. Hopefully have some time after the snow flies.
Trying build a shop and finish some land scaping before winter.
Pulled a trailer with weighing 11,000lbs about 2 hours with cement blocks on it.
View attachment 2445996

This really makes me want to do some head work to my HDT. Recently been going through as much calculating as possible to find a near perfect single turbo. The head would be my last piece of the puzzle. I really wish someone with the know how could do some cam development as well. Everyone always says working the head isn’t worth it but when it comes to improving Volumetric Efficiency getting the engine breathing properly is a big factor. Of course it’s a 12v with not the best designed head but there is room for improvement wether it be small or large I guess it’s up to the opinion of the owner.

I never seen much about lifting heads at 25-27psi on these engines until reading some of your post. I’m currently at 25 on the gauge with no issues for 15k miles or so but now I’m worried I need some head studs. I’ll need them anyways for this next turbo that is going on.

 

[Wildnlost]

This really makes me want to do some head work to my HDT. Recently been going through as much calculating as possible to find a near perfect single turbo. The head would be my last piece of the puzzle. I really wish someone with the know how could do some cam development as well. Everyone always says working the head isn’t worth it but when it comes to improving Volumetric Efficiency getting the engine breathing properly is a big factor. Of course it’s a 12v with not the best designed head but there is room for improvement wether it be small or large I guess it’s up to the opinion of the owner.

I never seen much about lifting heads at 25-27psi on these engines until reading some of your post. I’m currently at 25 on the gauge with no issues for 15k miles or so but now I’m worried I need some head studs. I’ll need them anyways for this next turbo that is going on.

I spent alot of time on the exhaust manifold and ports. This made a noticable differance to overall performance.
Getting the squish correct I think is critical too.
Overall response

 

[Magic Spool Bus]

I wanted to ask this hear as a lot of bright minds in this thread involving head work. When I originally got my new short block 1hdt from Toyota in Japan the guy measured my protrusion and his findings were .40mm and .50mm and selected the 5 notch gasket. As per the FSM for a 1hdt .525 or less is a notch 1. Notch 5 seems to be way overkill.

I bring this up because I am soon to be removing the head and installing head studs. Not because I am having issues but because I plan to be running around 27psi and just want peace of mind. Knowing the importance of squish I reckon if when I measure protrusion and find the same number should I run the notch 1 or 3 as it seems even 3 may be overkill. But I also can't pretend I know exactly what goes on in an engine over time or the danger of running it too close to the cutoff as per the FSM other than the piston contactin the valves which is obviously bad.

Any feedback is appreciated.

 

[Wildnlost]

Your measurements of protrusion is .4 and .5 mm correct? According to the pic of the FSM that would indicate a "1 notch" gasket.
That is the correct gasket. Putting the 5 notch gasket in place " to be safe" is a waste.
It results in.....slower squish velocites, poor fuel air bowl mixing, smoke and reduced off boost power. Follow the manual. Toyota knows better than most of us.
I am running less squish clearance than the FSM with no problems. I also run premium fuel.

Cheers from THE GREAT WHITE NORTH.

 

[Magic Spool Bus]

Your measurements of protrusion is .4 and .5 mm correct? According to the pic of the FSM that would indicate a "1 notch" gasket.
That is the correct gasket. Putting the 5 notch gasket in place " to be safe" is a waste.
It results in.....slower squish velocites, poor fuel air bowl mixing, smoke and reduced off boost power. Follow the manual. Toyota knows better than most of us.
I am running less squish clearance than the FSM with no problems. I also run premium fuel.

Cheers from THE GREAT WHITE NORTH.

Looking for a little feedback or logic about the direct fit studs vs the 1/2in studs that need tapping the head to fit....

Is the 1/2in even worth the trouble? I’m only wanting to run 30psi “safely”ish in terms of lifting a head. I know many other variable go into lifting a head like a improper tune.

I finally got my jet of a turbo on and the head is my next project. I want to go to the notch 1 after verifying the notch 5 is too large. Depending on what I find in protrusion. Might as well port it too

 

[Wildnlost]

Nice work on the manifold. The split pulse manifold should help spool too. Porting definatly aided off boost performance.

 

[Wildnlost]

Looking for a little feedback or logic about the direct fit studs vs the 1/2in studs that need tapping the head to fit....

Is the 1/2in even worth the trouble? I’m only wanting to run 30psi “safely”ish in terms of lifting a head. I know many other variable go into lifting a head like a improper tune.

I finally got my jet of a turbo on and the head is my next project. I want to go to the notch 1 after verifying the notch 5 is too large. Depending on what I find in protrusion. Might as well port it too View attachment 2593219

Regarding the studs. The drop in ARP studs I used were recomended over 24psi. I thought they told me good for 35psi Max. But I cant find the email that detailed the ratings

 

[Magic Spool Bus]

Back again!!! The day has finally came and now I cant wait any longer to pull my head off the old 12V. I have some leaking valve stem seals that need replacing if I am to keep the old girl on the road. Tossing around the idea of buying a new complete head or a new casting doing some port work too that head, and finally selecting the correct head gasket for that precision squish we all love .

The biggest question I have is about resurfacing the block while its in the truck. Being so many people have dramas after removing a head with it leaking and what not I am apprehensive. What would be the absolute best method to clean the block surface for best possible outcome?