Porting to reach high rpm breathing

[Magnus]

As far as what this head looks like on the floor with a flatter SSR, the Dmax head may just seem to be developed to work well in a mid-range operation range, but, the height of the runner-roof I would say limits this. If anyone would care to voice what they feel about the head flow, I am all ears to view your point of view. I think there is still something left, I won't be doing many major mods for more flow here. Albeit we must think of enhancement of swirl quality within out combustion space too so we can not neglect the chamber side of the valve seat not just for the purpose of swirl but for the purpose of relieving the upstream flow characteristics that appear to be a negative.

Are there any posted flow numbers for stocker heads here? I tried a search and nothing really dedicated to flow rates.

What about CC of the runners? Has anyone really thought about that in terms of overall flowing capacity of the runner within adequate flow velocities?

Swirl quality? In a diesel? Really? You think the air swirling makes a difference in how well the fuel burns at 25000psi injection pressures and pre-injection cylinder pressures well over 400psi? Do you think it's even possible for momentum induced laminar flow to continue under those conditions? Even if it did "swirl" wtf difference does it make when it's pure air and injection and combustion are simultaneous?

Im not trying to be offensive but you, sir, must not be an engineer and I suspect you're confusing people with your gas performance jargon.

 

[Magnus]

Also it's been mentioned, but many people have made serious power with stock heads and even stock cams... Like enough power that keeping a drivetrain in one piece and getting that torque to the pavement are much bigger concerns than port optimization.

Diesel performance is a unique animal from gassers. In fact I'd say thermodynamically, heavy fuel turbines are mathematically closer to a turbo-diesel at steady state than gassers are. It's entirely acceptable to just increase boost pressure in order to up mass flow, so long as you're not pressurized enough to break anything else in the motor.

The bottom line is you're optimizing a duramaxes strong point. The 32valve aluminum head was revolutionary in the small diesel market and still offers more performance stock than a lot of other older designs can muster with modifications.

I feel like others have been trying to hint at this already. If you insist on reinventing the wheel ill watch and see what your intake runner cross pulse theory produces in results, but I AM an engineer with a very good grasp on fluid mechanics and thermodynamics and I'm not too optimistic.

 

[Fahlin Racing]

If swirl initiation were to mean nothing than the ports would not be positioned in a diamond pattern, OR with the runner layout as they approach the cylinder. Regardless of heavy or light diesel engines. The injected streams of fuel will actually disrupt the swirl within the cylinder too.

If you are an engineer, AIR FLOW IS AIR FLOW SIR that should be a fundamental understanding With dry air flow you don't have to worry about suspension of fuel droplets which entails smaller runners, ALBEIT, the capacity of the runner in terms of CCs if you notice will I guess you can say control the flow rate maximum. I don't intend to run a toy hauler or sled puller with this here. If its so great than how come gains can be found?? I have no problem with people settling with what they have, I go for the stuff than can be achieved with the phrase outta the box thinking, I don't settle for stock performance. I WANT TO GO FAST!!

The injection pressures sure do atomize the fuel however with the right size orifices that in a sense dictates the evaporation rate of the fuel which is also tied into how volatile the fuel itself is. DIESEL is not very volatile WHICH in turn needs SWIRL or tumble or swumble to not just mix the air and fuel, but, to advance the evaporation rates and produce a fast, efficient burn cycle with in the usable burn angle to produce the torque needed. The stronger your flow is throughout from the intake manifold the easier it fills and the more dense it fills, which I am sure you know like the back of your hand.

If someone is reinventing the wheel I wouldn't be doing it with these LMM heads. I promise you that. All the geometry improvements than need to be done with cranks or valve trains will be done. I have no concern about improving traction problems etc that is the far less complex world of tuning, we worry about that at the track however that is very important and you can make big power and still lose due to that lack of quality there. Low power maker can beat a big power maker if its not going straight any day.

Thank you for posting. I enjoyed your posts :thumb:

 

[Fahlin Racing]

Your thoughts have kept me thinking most of the day on btw Magnus. Good thought provoking post.

What have you seen in terms of swirl or tumble motions disrupted by compression pressures alone from pressure building as the piston comes to TDC Magnus?

Could this be simulated by heating the air and turning the engine at certain rpm with a electrical motor and deliver wet-flow testing fluid and have cameras watching?

The reason I mention swirl quality, it ties into our flow. The convergent, tuned venturi and divergent sides of the valve are the most critical areas of the flow path. You can gain or lose flow with just the WIDTH of a valve seat angle within the valve job.

Whats your view on the SSR being so flat Magnus?

I am curious to what you have on the subject, if you have the time to post again.

I may not be an engineer by trade, however that does not regulate my viewpoint and thinking on innovation for speed. :thumb:

 

[jkholder09]

I always thought the diamond shaped valves layout was a function of rocker arm and bridge design.
The swirling air may help scavenge remaining exhaust gas from cylinder if there was a considerable amont of valve overlap and reasonable drive pressure.


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[jkholder09]

In a diesel there is minimal overlap and typically high drive pressure so overlap is counter productive unless you just have to have egr.



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[x MadMAX DIESEL]

I had heard a new term today about head flow today. I don't quite understand what this is but he said that "square" valves tested better for swirl. Does that mean intake and exhaust use the same size, or something about the valve angle cut? Forgive my ignorance but I think that question could be related to this thread.

 

[Dave c]

As far as what this head looks like on the floor with a flatter SSR, the Dmax head may just seem to be developed to work well in a mid-range operation range, but, the height of the runner-roof I would say limits this. If anyone would care to voice what they feel about the head flow, I am all ears to view your point of view. I think there is still something left, I won't be doing many major mods for more flow here. Albeit we must think of enhancement of swirl quality within out combustion space too so we can not neglect the chamber side of the valve seat not just for the purpose of swirl but for the purpose of relieving the upstream flow characteristics that appear to be a negative.

Are there any posted flow numbers for stocker heads here? I tried a search and nothing really dedicated to flow rates.

What about CC of the runners? Has anyone really thought about that in terms of overall flowing capacity of the runner within adequate flow velocities?

Swirl is very important in a diesel reguardless what others say. Many top shops have proven it. However i have some flow #'s for you.

Stock @ 28" intake

.100-80
.200-146
.300-175
.400-177
.500-175
.600-179


Stock @ 28" exhaust

.100-60
.200-120
.300-137
.400-138
.500-138
.600-139


Ported stock#'s are about 50-70 more CFM peak depending on what valve lift and port in/ex

Hope this helps.

 

[Fahlin Racing]

I had heard a new term today about head flow today. I don't quite understand what this is but he said that "square" valves tested better for swirl. Does that mean intake and exhaust use the same size, or something about the valve angle cut?

First thing that comes to mind would be the intake and exhausts matched IMO, much like a squared engine with bore/stroke matched. As far as the tested squared valve arrangement, diamond or straight cross-flow, I couldn't say. Would be an interesting subject to read though!

Dave, thank you for the generosity on flow numbers sir. Many appreciate not just yours but other's posts as well throughout. Say, whats your take on the flattened SSR?

 

[Fahlin Racing]

I always thought the diamond shaped valves layout was a function of rocker arm and bridge design.

Could be more than one reason the design exists within many engines. JKholder, you have a very interesting thought on evacuation of the cylinder, would a swirl action help with emptying the bore? One thing we must consider always is the floor of the chamber is moving away from TDC and we also have the valves opening allowing pressure to drive the turbine wheel so I guess you can say there is a two-front pressure reduction, how much? who knows. All we know is once the blow-down phase has finished we have the rest of the exhaust to flow, which we utilize the runner design more after the blow-down has taken place. The blow-down efficiency is more influenced by valve job angles than the runner.

One thing about swirl is we are traveling a longer route to leave or come in. Could this help of hurt is what can be hovering around the brain waves now. It would be an interesting test to observe if, on a wet-flow if possible that a swirling exit would be more beneficial or not.

More great thoughts.....

 

[jkholder09]

Isn't the ultimate goal to make our pump as efficient as possible?

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[Fahlin Racing]

Indeed, making our engine efficient in every aspect of operation

 

[Dave c]

First thing that comes to mind would be the intake and exhausts matched IMO, much like a squared engine with bore/stroke matched. As far as the tested squared valve arrangement, diamond or straight cross-flow, I couldn't say. Would be an interesting subject to read though!

Dave, thank you for the generosity on flow numbers sir. Many appreciate not just yours but other's posts as well throughout. Say, whats your take on the flattened SSR?

Dont mean to sound dumb, its early. SSR???

 

[Fahlin Racing]

No problem, SSR just stands for Short Side Radius. This connects the floor to the valve throat area.

 

[Dave c]

No problem, SSR just stands for Short Side Radius. This connects the floor to the valve throat area.

Got ya. I really dont have a clue about that area of the port.

 

[Fahlin Racing]

Ok, thought I would ask. Thanks!

Going back in the thread Blk mentioned this

The intake on mine only picked up 30 cfm Russ,theres 60 cfm to be had on exhaust side atleast gasket match and manifold match.

As far as this (gasket matching) goes I think should have a little caution, just to make sure you don't enlarge something and cause thin areas. I am not sure how the gaskets are, but, I would port match more than gasket match IMO. You can trim gaskets too,though there are limitations as well.

 

[x MadMAX DIESEL]

You were correct on the squared thing.

 

[Fahlin Racing]

Picture of how flat that SSR is on the left intake runner on a different cylinder. The throat area is obvious with oxidation. Sorry it is a bit blurry on this one.

 

[blk smoke lb7]

Jim the guy that does my porting said he found the most flow reworking the valve pocket im sure you probably know this but just passing it on.

 

[Magnus]

I didn't mean to be attacking you, I just thought you were suggesting swirl played a key role such as in a gas engine atomizing fuel and holding it in suspension. I promise you whatever swirling is going on in a dmax cylinder it may help with initial cylinder filling from the intake ports (you're definitely right there and I apologize) but it's irrelevant as far as combustion efficiency once the injection event occurs. I'd especially stand by that analysis since reaching serious high rpm (5000+?) you'd want injectors the size of fire hose nozzles to really control the timing and peak cylinder pressures.

Effectiveness of any intake runner contours is dictated by thermal boundary layer behavior, which is determined by calculating a reynold's number based on the fluid characteristics. Boundary layer behavior in a highly pressurized competition diesel intake or exhaust might surprise you by how different it can be from a low pressure or atmospheric pressure gas system. Odds are pretty good that the intake air hugs to that SSR a lot more than you might believe just eye balling it. Perhaps the extreme SSR provides turbulence or "swirl" into the cylinder optimizing cylinder fill at 29psi boost and 3000rpm...

Your best bet if you're truly trying to do an "everyman's home builder port job" is to ensure cross sectional area, interior surface area, and surface finish quality remain as constant as possible throughout the length of each runner. Round edges entering the runners and leaving the valve seats with optimized parabolic radii, reuse stock intake manifolds with 3" y bridge, then pressurize the s*** out of it and measure flow under approximated race intake and exhaust pressures. If you're chasing the ultimate high rpm dmax performance with extensive port work, that's cool too and I'm sure you have your own ideas on how to get there.

What were the conditions for the measured port flow rates?