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- #21
Engineers always have a better idea. Dogs won’t pee on that tree!
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1HDT Cylinder Head Performance Modifications
- Thread starter Wildnlost
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- 1hdt cylinder head performance
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I hope I never meet the dog that does!
That tree is in a mall next to where I'm working. There got to be at least 2 or 3t or more hanging in a public mall by two ratchet straps
Ps, hijack over
I don't think you've got a bad turbo, it's just a turbine swap which really isn't a big deal overall. I Can say that cus Im not the one unbolting it which I've heard is a bit of a crappy job for you guys. I buy parts from both mamba and kinugawa but never a whole turbo though. Quality has been ok so far.
I have to ask....why strap a tree to that kind of pole? I'm sure several Aussies just did a facepalm and wonder right now why I would ask such a silly question when the answer is right in front of me but....it's not a telephone pole. Not a light pole. No banners. Not a power pole. Is it a tree specific pole? Like engineered for this kind if stuff. It would have to be to handle any kind of wind I'm thinking. We don't have those tree poles up here in Canada. We Have these cute ones with like baskets filled with flowers and stuff which I thought use to be kind of cool, but now seem sort of lame when compared to the tree pole.
I have to ask....why strap a tree to that kind of pole? I'm sure several Aussies just did a facepalm and wonder right now why I would ask such a silly question when the answer is right in front of me but....it's not a telephone pole. Not a light pole. No banners. Not a power pole. Is it a tree specific pole? Like engineered for this kind if stuff. It would have to be to handle any kind of wind I'm thinking. We don't have those tree poles up here in Canada. We Have these cute ones with like baskets filled with flowers and stuff which I thought use to be kind of cool, but now seem sort of lame when compared to the tree pole.
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Plenty of facepalm action going on here coz it's just so ridiculous.
It's some tosser's idea of art.
The pole is about 10-12metres tall.
Nothing but ratchet straps holding the palm tree! Just looks like a random pole. It was windy here yesterday and the palm was taking a beating.
I'm sure I'll open the newspaper in a few weeks and see that some poor family has been squashed by a palm tree.
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- #26
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- #27
So I am pulling my 1HDT engine to machine the block as it is warped on the cylinder head surface about .005". I found this problem the last time the head was off but I was short on cash to fix
The question I have is what is an optimal piston to cylinder head clearance. Squish clearance is important on 2 and 4 stroke engines. I assume it is important on diesels too.
Things To Consider
Squish clearance
Rod Stretch
Squish Velocty
My software program for calculating 2 stroke squish velocities does not like the shape of our combustion chambers.
I suspect squish velocities are important for proper combustion. Not to high (no mach velocities) and not too slow ....poor mixing and combustion.
Any info would be great.
The question I have is what is an optimal piston to cylinder head clearance. Squish clearance is important on 2 and 4 stroke engines. I assume it is important on diesels too.
Things To Consider
Squish clearance
Rod Stretch
Squish Velocty
My software program for calculating 2 stroke squish velocities does not like the shape of our combustion chambers.
I suspect squish velocities are important for proper combustion. Not to high (no mach velocities) and not too slow ....poor mixing and combustion.
Any info would be great.
The head is essentially flat, so the squish ring won't be modified by machining it. Squish will only change when the block is machined, and this is set by measuring the piston protrusion and selecting the proper thickness of head gasket.
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- #29
Yes exactly. The closer the piston is to the head at TDC the velocity of the gases being squished is higher. In a gas engine usually higher squish velocities promote better combustion.
To a point anyway.... if you reduce the piston to head clearance too much you can have velocities that exceed the speed of sound. This causes a sonic shock wave that can cause preignition.
Also when you are adjusting piston to head clearance you have to allow for conrod stretch which at redline with heavy rotating assembly could be significant. This would reduce the clearance at redline and increase squish velocity.
I know from experience that getting it right on a gas engine can improve driveability and efficiency.
The default seems to be use a 5 notch gasket as it is safe. I suspect getting this tuned properly could be very satisfing.
Squish Velocity info
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- #30
Found some info on Toyota site about modern diesel engine design. As normal engineers can complicate things.
Toyota used 5 different head gaskets in the factory to get piston to head clearance correct.
Aftermarket head gaskets are available in thickness 1, 3, 5.
It may be possible to get others from Toyota?
Aftermarket head gaskets are available in thickness 1, 3, 5.
It may be possible to get others from Toyota?
Found some info on Toyota site about modern diesel engine design. As normal engineers can complicate things.
Interesting read. I wonder how much of that would be relevant to a 1HD-T with bigger bore and higher compression ratio?
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- #33
The same design considerations and mechanical/chemical processes are taking place irregardless of engine size. Modern technology has improved combustion chamber design which has led to efficiency improvements and reduced emissions.
For my current project because I am decking the block to get it flat again an oppurtunity exsists to tune the combustion chamber design.
On racing snowmobile 2 stroke engines getting the proper combustion chamber design and squish velocities makes the differance between fast and first. I have attached an interesting read below.
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How much R&D and trial and error goes into "first"?
There's a huge number of variables for stuff like this. A single change often has unexpected results and/or consequences.
The paper you linked to uses a test engine with 83mm bore, vs 94mm for 1HD-T. That alone changes things. A combustion chamber design that works for 83mm, may be way off the mark for 94mm. They discussed changes in bowl diameter of a few mm making big differences, but made no mention of bowl shapes.
They used injection pressures of 130Mpa, ~19000psi vs ~2200psi for 1HD-T.
There's also ythings like injector placement, nozzle orifice size, injection spray angle, injection timing and duration, valve placement, port angle. All play a part.
I'm interested to see what other info you can dig up
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- #35
Sorry for any confusion. I only posted the links to show some of the parameters that are considered for combustion chamber and squish design. They were not intended to show what needs to be done to a 1HDT.
So back to my original question what is the optimal piston to cylinder head clearance? Is toyotas chart for gasket choice the best for our modified engines? Maybe. The chart for gasket choice based on piston protrusion gives a clearance of aproximately .025” to .030”
Being that a number of modifications have already been done to my motor away from the factory spec with a bigger turbo, porting, intercooler, etc. Are there gains to be had by tuning in this area as well. At what point is there interferance with the head?
As stated earlier on gas engines this is an important area on modified motors ........is it the same for diesels?
Link for related info with gas engine
TECH ESSAY: Not Hitting The Head
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- #36
how can delete this duplicate oops
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Pual st riverina did my head work and it really picks up to torque and stops the dt's chocking ar 250hp. Also did a little piston work when she was open
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- #38
Looks like the overhang of the top lip of the bowel is machined off . I think 12HTs have a similar bowel shape. Riverena does great looking work.
Did you need to change injectors and pump for the new combustion chamber shape? I
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If you can retain the lip it's very beneficial to keep the flame front away from the cylinder walls and head . Without it the flame front cools as it hits cold surfaces and you get more soot and less power . Those lips are also designed to increase bowl tumble to improve Aur fuel mixing . I'm so interested in bowl geometry and improving combustion but holy cow that is a major trial and error game .Even when you read articles in improving it you get 70% chance of reducing effeciency. Very slight chance of improving it with the most subtle changes in bowl geometry. It would be incredibly easy to get it wrong.
Found some info on Toyota site about modern diesel engine design. As normal engineers can complicate things.
So why are Toyota Hilux utes burning ~15% more fuel than other utes?
The 2.8L current Hilux burns more than the 3.2L Ranger and 3.0 Isuzu.