RPM, spray angle, bowl design

[Fahlin Racing]

Just curious on how many have experimented or bench raced with the injection angle of our fuel and bowl configuration best suited for high rpm operation? Just something I have been day dreaming about lately.

[lenahan05]

I like this thread. Could turn into the most informative thread on here but i doubt anyone will chime in that has tested this on the dyno....people are very secretive. IMO.... If your wanting power in a pulling motor for example, with acceleration not being an issue then you want a wide shallow bowl with a wide pattern. try for low timing and higher boost for more efficiency. Example; injector pattern around 155-160* cone angle with as wide a bowl and shallow flat bottom. This has worked well with tractors. When you bring rpm into the situation with timing and wide patterns you obviously cant run the same timing. List more of what your setup is and what your doing with it. drag racing or sled pulling and maybe someone will chime in with a decent setup and a few ideas.

[Joesixpack]

From my research through SAE articles and no dyno or competition proven data your looking for the wide shallow bowl. The wider the bowl the more timing you can give it at the same crankshaft angular position.

A wide shallow bowl is a lower swirl bowl and that swirl can cost HP when you do not need the aggressive mixing especially high pressure common rail.

Same could be said with high intake pressure and temperature, simply less mixing is required.

I can say in my own testing a single injection event came out on top for the most power production on top. Seems like a bit of combustion lag can be advantageous when it comes to cramming fuel.

[cummin get it]

Watching

[Fahlin Racing]

I have no real application at the present moment Lenahan05, I am more or less continuing my combustion research until I can get a few guinea pig engines to modify crowns etc and hopefully run them on an engine dyno/vehicle to see the effect of what I am and many are interested in. Power and also acceleration rates, if the latter even will change noticeably.

Do you still happen to have those SAE paper titles Joe?

I should open up Charles Fayette Taylor's I.C.E. In theory & Practice and see if they had published any thing like this in there. Ricardo had to of researched this in his day since he specialized in combustion.

If a wide shallow bowl is more desirable, would you be speaking of something on the lines of the 4-53 Detroit piston dish?





or would we want to have a more pronounced center cone in the dish or even just a plain flat area across the crown dish?

[oldestof11]

Subscribing...

[DIESEL_POWER]

Impingement point is whats important. Get that straight, all else falls into place, and is easy to address.

[joefarmer]

Lots of work has been done in this area. If you want to get the good bowls, you'll need to call around and gain trust (read: spend on a performance engine) before any knowledge can be released.

[RonA]

Originally Posted by joefarmer

(read: spend on a performance engine) .

.

[Schrowang]

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[97rada]

Originally Posted by joefarmer

Lots of work has been done in this area. If you want to get the good bowls, you'll need to call around and gain trust (read: spend on a performance engine) before any knowledge can be released.

So true^^^ watching this one. I am planning to build a Dyno mule here soon to find some of this out. Should be interesting to test cams to

[Smokem]

Get rid of the flycuts.

[Chris Mallett]

Originally Posted by Smokem

Get rid of the flycuts.

I read this "because good swirl creates equal combustion and higher lift cams are not a cure to a poor flowing head". Am I close?

[Smokem]

No, 230/240* 0.360/0.360" cam could still be used.

[cummin get it]

Originally Posted by Smokem

No, 230/240* 0.360/0.360" cam could still be used.

But nine times out of ten it will need fly cuts correct?

[XLR8R]

No, we're getting ~.500" net with our Super Stock lobes - installed height of OEM valves is more of a brick wall than P-V interference... pocket & seat machining and different valves can return flycuts as the limiting factor.

[Fahlin Racing]

You can improve breathing of a poor head by using more cam duration as well. You also have to look at different valve designs/mods that allow better discharge coefficients, 1 valve design isn't optimum for all applications. Air entering our cylinder is important as well so we get the right mixing propagation and pressure rise for our peak power.

Now fixed injection timing and multi-point injection chamber I think are going to differ between chamber layouts. All I can say is there are no secrets, just people who don't share, may actualy be holding themselves back from advancing forward as fast as they would like.

Here is some from Charles F. Taylor's ICE Vol. 2

In the open-chambet type, the mixing of fuel and air depends entirely on spray characteristics and on air motion, and it is not vitally affected by the combustion process itself. In this type, once the compression ratio, maximum operating speed, and operating temperatures are selected, the delay angle is determined chiefly by fuel characteristics. Engines of this type are very sensative to to spray characteristics, which must be carefully worked out to secure rapid mixing.

This book was revised on 1985, taylor passed in 1996 I believe at 102 years of age. Granted we have advanced since then, I still think this is still relevant today.

[Tobin]

Also check what Haywood has to say:

Amazon.com: Internal Combustion Engine Fundamentals (9780070286375): John Heywood: Books

Amazon.com: Internal Combustion Engine Fundamentals (9780070286375): John Heywood: Books

[joefarmer]

Originally Posted by Tobin

Also check what Haywood has to say:

Amazon.com: Internal Combustion Engine Fundamentals (9780070286375): John Heywood: [email]Books

I need to just spend the money and get a copy of his book.

I have been curious to see some testing on dynamic cylinder pressure.

Tobin

The engine builders that I trust already have the actual cylinder pressures of these race engines. Some of this data is incredible, yet it lets you understand why some designs work.

[Fahlin Racing]

I was looking at haywood's book a while back, however I am not able to purchase his writing as of yet. On another forum, I had been involved in an engine thread that involved needing to know cylinder pressure and temperatures involving failures due to engine timing, I had collected part numbers from ISSPRO to assemble a testing tool, which I haven't been able to buy yet either.

Since there is less time at high rpms, would creating a slight lip going inward to the center of our bowl creating slight more turbulence hoping to influence a state where our atomized fuel turns into a equally spread mixture easier, albeit, squish action could be more benficial and just have the bowl wall meeting the piston crown top edge, with a radii be sufficient?

Our crown temps get fairly high, I sometimes think a lip would counteract combustion efficiency through acting as a heat-sink and overload the crown thermally. Hmmm ......