1HDT Cylinder Head Performance Modifications (6 Viewers)

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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.
I am curious as to why the guys at riverena changed the bowel design they removed the lip. One thing I did think about was injection timing.
I noticed that with stock 1HDT injection timing the spray pattern on the piston top is almost all in the bowl with only a very small wash pattern on piston top.
When you advance the timing the injector cracks earlier in the piston stroke before TDC and sprays fuel on the piston top or squish face. I suspect some of this fuel on the crown doesnt burn because of quenching with the cooler head and piston. Or it burns at the wrong time producing soot and wasted fuel.
Is Riverena making the bowl opening larger to allow for advanced pump timing so all the fuel sprays in the bowel?????
The first pic is stock timing the second poor pic is advanced timing. Notice the spray pattern on the advanced pic. It is way outside of the bowl washing carbon off.
Stock the pattern is capured in the bowl.

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Now that is a very interesting observation. The spray pattern from memory is suppose to be partially split on the bowl edge itself but not equally split. If they have had good results it would support what your saying. This is pretty cool stuff I must say. Timing the split of the injection spray on the edge of the bowl is doable but you'd have to measure particulate, egt and nox to determine a positive change. Cool thing is once you do the machining it's all just timing adjustments after that .you could do a dyno each time but dyno results can vary wildly between each run.
 
Sorry I'm doing this on my phone and basically repeated what you just posted . So I guess in short I would agree. Finding a good way to measure results might be a challenge .
 
Sorry I'm doing this on my phone and basically repeated what you just posted . So I guess in short I would agree. Finweding a good way to measure results might be a challenge .
I wonder if this is the reason the newer engines had larger bowls after 8/92. There injectors have different thickness of washers too. Is the nozzle angle similar.
Could we run advanced timing with thinner washers under the injectors and larger bowls and get the pattern of wash all in the bowel.
Do we need more advance???
Squish velocities would be slower too... which seems to be a trend. Slower swirl less heat loss to head., piston, and cylinder.
It gets mind bending for sure.
I am going to be boring out .020 very soon. Be a good time for tinkering.

:worms:
 
You don't ever want to spray on the piston. It's cold and will delay combustion and make smoke.

The picture below is from a MAN V8 diesel at the Deutsch Museum in Munich. It's a four valve commonrail so the injector is centred and that's why the four reliefs exist on the piston edge.

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I did 240rwhp and 744rwnm on 35s. With 35psi at 1800rpm with peak torque and power before 2000rpm. Afrs at 22.1. With the bowl work you want to get as much fuel in as 15 to 16.1 then lean it off hard and that really helps with smoke.

The only down side i have found is they love a good smoke when cold. I'm also running the larger washers on the early pistons.
 
I did 240rwhp and 744rwnm on 35s. With 35psi at 1800rpm with peak torque and power before 2000rpm. Afrs at 22.1. With the bowl work you want to get as much fuel in as 15 to 16.1 then lean it off hard and that really helps with smoke.

The only down side i have found is they love a good smoke when cold. I'm also running the larger washers on the early pistons.
That is great! It is nice to see some really positive results and quality work. Did Riverena do some head work too... or stock ports and seats.
Also Are your pump and injectors stock? Early type.
 
I drive diesel locos for work and the modern EMD (now Cat) and GE engines are pretty well engineered and like most designs often being improved but much of that is not mechanical design changes because all modern diesels depend on a computer to manage them to gain the required efficiencies and emissions targets for certification. Compare that to the much older (but still very much used) EMD 567's and 645's and Alco 251's (and 244's). 645 powered locos are pretty much the main ones I'm on at work but still get 60+ yr old units with Alco 251 in-line 6 cyl engines showing up.

Whether Toyota's gone done that some road is probably true since automotive diesels sort of went ahead of railway and marine diesels for 'trending' towards using electronic controls vs better mechanical design to achieve improvements. Hardest thing would be that there's a limit on what can be done mechanically within the limits of materials available. I've never (yet) had a turbo diesel motor so only have my very old and tired 1hz to go on.

The biggest change might have been going from pushrod motors to OHC motors and subsequent changes have incrementally added better performance.
 
It's APART

Got things in pieces finally
Will doing some measuring and figure out the plan.
Crank may need a grind. Some wierd marks. Boring .020 os with Arco pistons.
This is my first diesel rebuild. Parts are big compared to gas stuff.

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You don't ever want to spray on the piston. It's cold and will delay combustion and make smoke.

The picture below is from a MAN V8 diesel at the Deutsch Museum in Munich. It's a four valve commonrail so the injector is centred and that's why the four reliefs exist on the piston edge.

View attachment 1770654
There is a very large bowl on these pistons for sure and very little squish. I would guess inlet velocity plays a role too. I Assume porting and multiangle valve seats speed up gas flow. A Bigger bowl with less squish would slow down the swirl. Is Riverena balancing the swirl velocities?
 
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So why is a stock 1hdt head *not* considered 'good'? Is it a case of it being 'good' as a commercial design compromise but just not 'good enough' in terms of highest possible performance within safe operating parameters? I get that modern motors with electronic control can all be 'chipped' to a degree, so with a non-electronic controlled motor it's all got to be mechanical changes.
 
Your intake port has a design to create swirl, the piston bowl creates tumble. Now not to tempt you but I've seen modifications to the piston bowl edge to exaggerate the swirl in the bowl but too much and the fuel is thrown against the bowl edge and too little and it does very little. It's something to do if your retired and take engines apart every week as a hobby .
 
:hmm::hmm:
Your intake port has a design to create swirl, the piston bowl creates tumble. Now not to tempt you but I've seen modifications to the piston bowl edge to exaggerate the swirl in the bowl but too much and the fuel is thrown against the bowl edge and too little and it does very little. It's something to do if your retired and take engines apart every week as a hobby .
Are the Riverena modified bowels done to reduce compression ratio to allow for 35psi booost? Sounds too simple.
I am always tempted to modify things .....trying to figure out why the mods are done and then seeif it meets with my target can be the hard part.
I am going to run my squish clearance at the small end of the Toyota spec and a little more porting on the head.
:hmm:
 
I did 240rwhp and 744rwnm on 35s. With 35psi at 1800rpm with peak torque and power before 2000rpm. Afrs at 22.1. With the bowl work you want to get as much fuel in as 15 to 16.1 then lean it off hard and that really helps with smoke.

The only down side i have found is they love a good smoke when cold. I'm also running the larger washers on the early pistons.


You have a spec sheet or build thread I can read about your engine?
 
Are the Riverena modified bowel

does the modified bowel happen due to the customer not lubng up?



You do know a bowel is 25ft from your lips at the stinky end of your intestines?


Sorry, carry on :lol:


I am always tempted to modify things .....trying to figure out why the mods are done and then seeif it meets with my target can be the hard part.

I'm a bit the same, but with some mods, you'll never know if it achieved anything. Particularly if there's no way to measure the result, or it's been done along with other things (like an engine rebuild) that could have contributed to overall improvements.
I've done mods that I have put a lot of effort into with no clear gain. Some i thought made a difference, but sometimes they "make a difference" because we want then to
 
I would go with what is proven. I too am tempted to modify combusyioncdynamics but the odds are really not in your favor . One study I read used a nox sensor and evt probe ti determine improvements. nox is directly linked to incylinder temps. Higher incylinder temps usually mean more effeciency combustion when egts are lower. So having all parameters remain the same on an engine and increase NOx and simultaneously lower egts should mean a more effeciency combustion cycle. If you can measure soot(particulate) that's even better.
 
Well is the 1hdft head design any better? Besides Toyota changing to the 24v design without shims, etc. what other benefits does that head give over a std 1hdt tried-and-proven design?
 
does the modified bowel happen due to the customer not lubng up?



You do know a bowel is 25ft from your lips at the stinky end of your /QUOTE]

Too funny... being lazy and using talk to text. Must be my Canadian accent. EH!:beaver:
 

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