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internal combustion gas or diesel engine clean sheet designing

internal combustion gas or diesel engine clean sheet designing

internal combustion gas or diesel engine clean sheet designing

ok I finally have a copy from John Manning’s book, Internal Combustion Engine Design, published by Ricardo, 2012. ISBN 978095732920-1

directly from Ricardo engineering :)

here's a few question that I still not fully understand especially concerning the "Cylinder Block and Cylinder head"

especially from the Sketch DRAWINGS to the Final detail BLUEPRINT DRAWINGS before the first procurement prototype engine

1) when designing an engine "cylinder block" DRAWINGS is there any parts of the engine assembly preliminary design DONE before the said cylinder block DRAFTTING Ex: Crankshaft, camshaft, ect .

2) the designing process of the cylinder block DRAWINGS generally does it start with "Bottom Up design" or "Top Down design".

3) in a cylinder block design preliminary DRAWINGS what are the block Features design DRAFTING sequences Ex: A) crankcase, B) cylinders layout, C) lower cylinder deck, D) water jacket, E) upper cylinder deck .

4) How does the interaction Between the different engineers and the draftsman Works? who will be in charge of the designed features?
of the specific engine part for a cylinder block DRAWINGS

5) at last all the above questions BUT for the "Cylinder Head" part

I am interested in the principle behind engine designing DRAWINGS only, not much in CAD or FEA and or CFD. I am just intrigue by the way they design major engine part like in the 50's, 60's and 70's drafting tables and slide rulers! BUT any computer related design subject still appreciated as a feedback :) casting and machining drawings both are in my field of interest

and if any GOOD publication of concern of the above subject and questions I'll be happy to source if I can get them

engine size mostly of my interest would be bellow 1000 CU-IN or about 17 liters in displacement gas or diesel ICE industrial or automotive from 1 to 8 cylinders either inline or v configuration

any reply appreciated


RE: internal combustion gas or diesel engine clean sheet designing

First some general overall-assembly illustrations to get the concept on paper. Then rotating/reciprocating parts. Then cross-sectional assembly views. Then details of the components. Then off to the pattern-maker/toolmaker/machinist/"shop". Then, probably, back to the detailer to correct any errors or missing information or improvements from the shop as they attempted to do their work and needed more information (or made corrections) in order to do it. Then back to the assembly drawing for detailing. And probably back and forth a few times. After the prototype engine was built and tested, most certainly there would be more rounds of revisions - probably several through the process, as issues were discovered and resolved.

I never designed engines, but did design other mechanisms, and the beginning of my career was before the common and relatively inexpensive availability of CAD, and the above is generally how it happened.

This would have been before finite-elements methods and simulation were used to optimise every conceivable aspect of engine operation, performance, and weight before committing any design to metal.

I have two examples of a motorcycle whose design would have been done in the early to mid 1980s, and upon disassembly, it's quite apparent where they eliminated one crankcase bolt from the design but couldn't be bothered to update the design of the casting, and where they added two more ... the two whose bolt heads can't be accessed without first dismantling the entire top end of the engine even if said dismantling is not otherwise necessary ... you still have to do it, JUST to be able to get to the heads of those two infernal bolts. Descendents of that design stayed in production into the late 1990s.

RE: internal combustion gas or diesel engine clean sheet designing

Greg is correct. Rotating and piston assemblies first.

Have the packaging requirements in mind. Engine design is all about packaging once you have in depth knowledge of the individual components (no small thing).

Pick a reasonable BMEP not something over the moon. Pick a reasonable piston speed and the bore and stroke.

It's just me, but I go for the easy part next, the piston pin. From the max predicted pressure and pin bearing pressure, design with bending bending and ovality limits in mind.

Then put a survivable top land and ring package on top the pin hole and begin on the skirt and rod design. (Gas engine pin diameters are about 1/4 of the bore and diesels about 1/3 give or take.)

Base the small end of the rod on pin bearing load and pin bosses in the piston and then base the width of the big end of the rod on the crankpin bearing limits and your estimated crankpin size. The crankpin is about 2/3'd of the bore diameter if you expect to slide the pistons in from the top with a straight cut rod cap. Is it a Vee or opposed engine? Make sure the bottom of the piston skirts don't hit one another in a Vee or the back of the opposite rod in an opposed layout. In line just need to clear crank bits and main bearing bosses.

Once you have a rod that seems to work put it in position every 10 degrees of crank rotation to generate an outline of the path the rod travels (banjo shape)so you can give it clearance to your block and cam if there is one in the block. Next decide on a bore spacing and layout a crankshaft. The preliminary crank design should take into account 1) bending stress 2) balance weights and 3) oil hole placement. Torsional stuff and oil film calculations come in later iterations.

Work out the main bearing caps and bolts next from the expected loads. You'll need a head bolt pattern. This may require a cylinder head design. It will surely require a good concept.

Next, I like to think about the core that will make the water jacket and how it will be supported in the foundry flasks. You will also have a water pump location in mind.

Maybe at this point you can pencil in your space claim for the block.

Don't expect your first try to be great. It takes practice but in time you'll get better.

RE: internal combustion gas or diesel engine clean sheet designing

it is interesting to see the ping pong ball effect between different engineering department trying to figure out how the hell are all those parts going to fit together I am sure that there was plenty of Advils in reach to control head aches :)

so from what I understand is that the rotation/reciprocating mass parts are calculated and drawn BEFORE the stationary parts, so they can have the whole assembly drawings done when they can get all the parts to fit together INTERESTING INDEED!

now I have an idea why an engine program could take years to be develop a reliable engine in the slide rules, pencil and paper era

as I understand it seams that most preliminary calculation are done before the first detail drawings and are bases on ratios, from either bore to feature ratio and/or stroke to feature ratio for dimensions and stress factors

By the way is there any publication that details those process of design like SAE papers or books or what search engine term that would highlight this subject especially 60's and 70's era


RE: internal combustion gas or diesel engine clean sheet designing

No world class manufacturer is going to divulge their trade secrets in detail in real time or shortly after the fact. And once their competitors have figured out what they're up to there's little point in either of them publishing such information. What you're left with are fairly vague publications that are rich with claims and qualitative comparisons, and relatively devoid of specific design criteria. For instance, "American Iron, A History of the OHV V8 1961-70", by STS Press, 1999, which is a collection of papers published in SAE Transactions describing the design and development of significant OEM V8 engines in the named period, by the designers themselves.
At the end of the day, the only recipe for competitive design is hard won experience coupled with judicious assessment, comprehension, and digestion of what has gone before.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: internal combustion gas or diesel engine clean sheet designing


here's a good link that is of interest I might buy the book when it will be available

in that web page there's some really good info but does it have most of the answer that I am seeking for ?

the above link is there as an example of what I am interested in :)

publication based on the above example

I am aware that many engineers wont disclose much knowledge about the subject from what I understand it is almost a black art no joke

there's quite a few legacy engine parts blueprints on the net but to understand the sequence of the process to the design itself is somewhat

of a mystery don't forget there is about a couple hundreds of ICE engine manufacturers in the world so the info is there just real hard to get

sadly people like Leo Goosen , Giotto Bizzarrini and Mike Costin/Keith Duckworth just to name a few are all gone by now so engine designers

of those days that work on engine project development are really scarce so does the info


RE: internal combustion gas or diesel engine clean sheet designing

If modern engine design is anything like modern vehicle design then you spend at least a year with spreadsheets and little what-if studies (or even, heaven forbid, literature studies), and teardowns of older designs, before you really get a decent spec hammered together. Then you'd do the product development V.


Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: internal combustion gas or diesel engine clean sheet designing

Engine design is like any other complex engineering design - incremental over time. If the goal is to create a new engine, a small research team is going to identify a few critical features/improvements for an existing engine size/family, design/model/prototype a few parts, put them on an existing mule, and flog that engine on dyno to fully understand the effect of your changes and correlate them back to a combustion model. Once they have a promising set of improved parts, research throws it over the wall to the production teams and those part/system-specific specialists to further analyze, improve, and test that iron. Once those handful of parts appear production ready, a much larger team of part/system-specific specialists are going to each design their new part/system to fit the new engine's requirements, build a few prototypes, test, complete pilot runs, etc through the production process. I have worked on OE engine research and production component teams and can attest its a very long and complex process, starting with a few engineers assigned and ending with dozens.

As to drafting and design, engines are like any other product today - top-down design, 3d models are master, engineers own the design, and drafties own the prints pursuant to both the engineer's and checker's approvals. OE engine prints tend to be VERY detail oriented with common layouts due to complexity, their drawing standards after often 1k+ pages to ensure that every detail of a 10-20 page block print is almost identical to every other block print corporate-wide.

RE: internal combustion gas or diesel engine clean sheet designing

I do understand the production side of an engine department with goals, objectives and criteria to meet before the homologations
for production that I am aware of those issues my question pertains more to the sequence of event from the initial sketch drawing to the final first detail sets of drawings before the first prototype evaluation engine the first new born and before the second iteration of the said prototype I am more interested in the process of finding the steps involved for each of the parts but mostly the cylinder block
and cylinder head

one of the mystery question I do have when the rotating and reciprocating mass studies are done
does the CYLINDER HEAD DESIGN come first BEFORE the CYLINDER BLOCK DESIGN or are BOTH done silmultaneously ?

like in the cylinder head does the layout of the of the CYLINDER HEAD DECK GEOMETRIC PROJECTION comes first OR the one from the CYLINDER BLOCK ?

I know that the casting pattern makers and tool makers are deeply involved in that process :) with the help of a lots of advils for the head aches LOL

like I have in mind that the cylinder head deck is define first before anything else THAN the combustion chambers including valve seat size are define as the next step ,THAN third the in and ex ports layout, THAN fourth the intake and exhaust port flange pad location
and so on all base on the initial drafted sketch and feedback from engineering, tools and casting department

each of these features of a cylinder head must be define in some sort of a sequence like a base layout to start with

I know that it is mostly related to DRAFTING and ENGINEERING as question wise it just seams to be real hard to find info on the process I just hope I am not to redundant in my request and the capital letters are only there to highlight the specific term of my questions!

P.S. I am not trying to reinvent the world BUT just trying to understand how the world was reinvented :)


RE: internal combustion gas or diesel engine clean sheet designing

You'd design much of the head before the block. In a large organisation they'd be designed more or less simultaneously but the block would lead.

Of course in a large organisation there are other constraints on the design and it is likely the block machining line would affect the eventual design.


Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: internal combustion gas or diesel engine clean sheet designing

Back in the days of Charles Kettering, clean sheet engine design was done wirh single cylinder proof of design engines. The combustion side of engines was not well understood and much experimentation was required. Once a well functioning cylinder was developed the cylinder block and crankshaft could be built around it. I see the same being true for modern concepts such as HCCI. Cylinder blocks are a relatively mature technology but combustion still has much development ahead. Then again, Ford's 2.7 Ecotec has a very unique cylinder block design.

RE: internal combustion gas or diesel engine clean sheet designing

and what about the cylinder head feature design in which sequence like A then B then C and so on ?

so I guess that the combustion chamber would be detail draw first then the ports positions then the cylinder block mounting bolt holes because the placement of the ports wont constraint with the mounting bolt and so on

it's sure that if you have an OHV design you have almost no choice to draw the block and head blueprints simultaneously
because than the valve-train assembly becomes a new constraint for designing the lifter box cavity location and head gasket

REALLY INTERESTING! :). Now I can see that there's just so much allowed into a package with multitude of parts and constraint like stress analysis, flow dynamics, heat rejection, and on and on. WOW that must be real stressful especially when you have to
meet a time table requirement for the project to be within the management goals rewarding when you succeed but brutal for your career if you fail! one tiny mistake in the design and the company could loose a lot, because of miss management like the infamous CHEVROLET VEGA in the 70's that had aluminum bore engine that failed to perform as expected and put GM between a rock and a hard place


RE: internal combustion gas or diesel engine clean sheet designing

The Vega engine itself was way ahead of it's time. Most of the big German manufactures started using Alusil blocks after the mid-1990's with good success. It seems the root cause of the Vega problems was a dysfunctional cooling system which exposed other weaknesses of the design.

RE: internal combustion gas or diesel engine clean sheet designing

yep the famous ford ECOBOOST with the oil pan covering half the cylinder block yep and interesting design no doubt

or the STYER M14 and M16 engine are Monoblock and quite an unusual but interesting design no less

here's a description






RE: internal combustion gas or diesel engine clean sheet designing

yep those special developement engines are called "Mono-cylinder Test Rig" these engine are use for evaluation purpose only for updating emission certification on diesel or gas industrial engines General Electric use to have one at its R&D center in Nyskayuna NY
for evaluation homologation EMD has one too like caterpillar or any other engine manufacturer around the world F1 engine like Ferrari
used to have one to for there development of there 90's v12 and v10 F1 engines even the venerable 2 stroke Detroit diesel use to have a 1-71 engine ( made by the Cleveland diesel company a division of GM ) pretty uncommon these days but if you type it on google you will get pic and specs for it I have seen probably 4 or 5 of those at engine shows in running condition :)


RE: internal combustion gas or diesel engine clean sheet designing

Going back to my previous post, engine design starts with a small group developing the core combustion hardware - combustion chamber/piston, valvetrain, and boost for a given bore, stroke, and rod length. Much of that work is still done with single cylinder research engines bc they're easy to remachine/relocate and replace major components, and you can easily control temperature and pressure of every fluid throughout the system. Once complete, translating that work into block and head castings is a lot of fairly straightforward design work as the previous team provides most of the necessary interfaces. The head and block guy fills in the blank around the previous team's hardware, shells it in CAD, runs a CFD on the resultant oil, cooling, and fuel passages, tweaks as necessary, analyzes the necessary joints, then runs a casting sim and reviews with the foundry to ensure castability/manufacturability. Like most engineering today, there really isn't nor does there need to be much/any interaction with the trades until you begin building prototypes.

RE: internal combustion gas or diesel engine clean sheet designing

Agreed - in the case of diesel engines, the design starts with the combustion system and works outwards from there. Today, there are numerous subtle tweaks to the combustion chamber shape and proportions that are evaluated in the single cylinder engine to meet your pre-aftertreatment engine-out emission targets , since without the confidence of meeting emissions the engine will never be sold. In the pre-emissions era, the focus was just on power, fuel efficiency and manufacturing cost.

Once the combustion system has been settled, you now know the peak cylinder pressures that you have to design for, the location of the fuel injector (on-axis or side entry), the induction port shapes to get the required in-cylinder air motion, and the peak injection pressures which may impact your camshaft design and location if unit pumps/injectors are specified. Another early stage decision is whether to go with a slab cylinder head or individual unit heads as used by, for instance, Scania and MAN.

RE: internal combustion gas or diesel engine clean sheet designing

so from what I understand for the cylinder head model drawings is first you start by modeling the combustion chamber and sparkplug location second you model the ports design(length, cross section and locations for both in and ex ) third you model the valves fourth you model the valve guides fifth the upper oil deck with all the features related to the valve train and so on till the last step
is the close all the external surfaces ( cylinder head external feature like valve cover pad the intake and exhaust ports pad flange
than the external surfaces ends. I think I begging to understand the sequence that leads to the finished part


RE: internal combustion gas or diesel engine clean sheet designing

Essentially yes. Engine design is like any other complex design today - parametrically driven. For the rough initial design, in CAD I would float all of the internal components into position as well as some external bounding planes/surfaces based on the space-claim/package limitations, then just solidify the space in between to form the block and head.

RE: internal combustion gas or diesel engine clean sheet designing

AWESOME! finally I have a basic understanding of the process in sequence. so you rough the model by using a baseline parametric data

of your internal ( rotating, reciprocating with stress analysis, flow dynamics and thermal analysis for the combustion including moving parts ) THAN you build the SHELL around it :0)

SWEET :) now what I have to find is a publication with example of initial baseline parametric ICE concept so I can start from there to fully understand the whole process

and what I need is literature in the 20's all the way to the 70's with baseline parametric ICE concept

all I am interested now is how they parametrically design the first iteration detail drawings of say an old 1950's Waukesha ICE engine as an example that's the info I need to seek now ! not necessarily brand or model specific data

now can you take a say old existing engine design and extract parametric data to conceive another engine variant of that design ( almost reverse engineering in a way )?


RE: internal combustion gas or diesel engine clean sheet designing


Why do you need literature about engines long ago abandoned for superior designs?

RE: internal combustion gas or diesel engine clean sheet designing

It wasn't done parametrically if you go back a few decades. The technology to do it, didn't exist back then. 'Course, they didn't have to conform to emission standards back then, and consumer expectations for reliability, durability, etc weren't what they are now.

RE: internal combustion gas or diesel engine clean sheet designing

if you take Keith Duckworth who design numerous racing engines for Cosworth I always wonder how he design them. today with all computer technologies and no slide rules or drawing boards, it is a kind of mystery on how they manage to design reliable engines that lasted under tough conditions. I know that many and many prototypes have been tested for the same engine model before success but they still manage to get most everything up to spec and be reliable

one last question is ( the rough initial model design) , is there any mathematical formulas like (feature ratio) you have to apply
before building the initial model in CAD , do you start with a previous existing model or is it done just by experience like making a basic crankshaft with summary of the first agreed sketch ex: engine requirement length is 550mm so crankshaft length would need to be about 530mm for the floating model?

by the way I don't need the newer design because I want to understand the basics of an ICE modeling done on paper and slide rules FIRST like the old timers draftsman use to do, that's the fascinating part to me by doing so, it is way easier to build CAD model afterward!

it is like in electronics you don't design circuits WITHOUT understanding the basic of a resistor or capacitor FIRST

it is the same thing with ICE engines design if you know your proportions THAN you have a real good starting point for your model :)


RE: internal combustion gas or diesel engine clean sheet designing


It wasn't done parametrically if you go back a few decades.

Yes and no. In the sense that 3d CAD wasnt available modern parametric design wasn't, but I would argue that good design has been done parametrically since forever. One of the first things we all should have learned about engineering is basic process starting with listing your knowns and unknowns, once you have the knowns you can start to resolve the unknowns which is the basis of parametric design. In 3d CAD I can constrain the individual components and fill in the block/head between them. Done in 2d that just requires careful drafting of multiple views and a bit of careful consideration/imagination. Paper "motion models" with the max throw of a crank as a dashed circle were common then before we moved into 3d CAD with the same part modeled in multiple positions, and then developed the modern animated models.

RE: internal combustion gas or diesel engine clean sheet designing

is there someone here in this thread answering my questions that actually design engine BEFORE the computer age, in slide rules , pencil and paper era ?

just wondering because I am sure that major ICE engine have been design on a monitor screen since the mid 70's at least ?

RE: internal combustion gas or diesel engine clean sheet designing

The first time I was involved in engine design was 1992, and it was in the transition from Mylar to a proprietary CAD system. The block for that engine was designed in 1985-1989 and would have been ink or pencil on Mylar, and most of it was hand calculated, by my boss. There may have been some modelling of the combustion forces in that timeframe, there certainly were some balancing programs for crankshafts.


Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: internal combustion gas or diesel engine clean sheet designing

I should have posted this earlier.


A little humor from the text:

"None of the plain bearing variations was made to run with any success until along about 1940
when somebody who did not know that bronze bearings would not work tried them
again in a 567 engine. When this attempt was made the person used two cycle
brains instead of four cycle. He simply made the bushing so that it would not be
pressed in the rod, but would float in the rod and he gave the bushing a great deal
of clearance on both the inside diameter and the outside diameter."

RE: internal combustion gas or diesel engine clean sheet designing

I was challenged to design a four stroke engine that would fit under the cowl of an existing two stroke. The design was done on paper but I used a calculator not a slide rule. (yes, I have them).

The crank, block, head, piston, rod, flywheel, cam and valve gear were clean sheet. First line to running sand cast prototype took 22 weeks.

There is no advantage to using paper and pencil over a computer aided drafting program. I prefer and own cadkey 19. It is a non-parametric program. I judge it to be faster than parametric programs because there is no time spent re-dimensioning and re-positioning features. That said there are some nice features in newer CAD programs like FEA that make them attractive. (Join the EAA($40)and get Solidworks free! or get FreeCad for, surprise, Free)

Designing a terrific building or engine on the first try is unlikely. Architects draw lots of plans to develop an understanding of building layout and form. They need to learn about materials and construction techniques and arranging things in a given space. Engine design is similar. Quit worrying about the magic of drawing boards or slide rules and embrace what is available. Like the wannabe architect, you need experience and knowledge. Copy an existing engine design but change one thing. The copy another and change something else. Learn about cam lobes from both Michael Turkish and modern polynomial equations. Learn about time-areas for two strokes. Then design a cam lobe and some two stroke ports. Learn how to calculate bolt stretch and the compression of the part that the bolt clamps. Figure out the ratio of head bolt clamping force to gas pressure force on the head of your favorite engine. If you don't know something, you can copy an existing design.

Good Luck

RE: internal combustion gas or diesel engine clean sheet designing

Those floating bearings were the width of two connecting rod big ends on the V8 Ford crank. The components (rods and bearings)were also used in a refrigeration compressor at least through the 70's.

Floating bearings are not dead. Today you will find floating bearings on turbocharger shafts.

Bonus question: How many have seen a cast steel piston from a Ford 60? Steel pistons are back too.

RE: internal combustion gas or diesel engine clean sheet designing

The steel pistons were reintroduced by Mahle under the Monotherm name. Here is one from a Cat:

RE: internal combustion gas or diesel engine clean sheet designing

so now what I need is a non parametric engine design info than ill be able to understand the whole basic picture and yes I agree making a clean sheet engine on a drawing board is a pain BUT they manage to do it in the old days! not perfectly but in reliable
way afterward

by the way using a calculator and paper where do you get all the proportion ( the stress counterbalance and oil film formulas ) to go with it, any source of info still available these days in the era of CAD FEA and CFD ?


RE: internal combustion gas or diesel engine clean sheet designing

TugboatEng - Nice picture illustrating the teepee shaped small end of the connecting rod. The lower half of the pin bearing bore has more area for combustion gas loading compared to the inertia loading on the top half. The piston bosses are moved in at the top for additional bearing area and reduced pin bending. The strength to weight ratio of steel is better than aluminum especially at high temperature.

Steve - In the old pre-computer days we went to the library. Start with Taylor as suggested by GregLocock.

RE: internal combustion gas or diesel engine clean sheet designing

yep I think I found a copy on the net :)

RE: internal combustion gas or diesel engine clean sheet designing

I always wondered why the ends of the rods were tapered. I just assumed it was for weight savings.

RE: internal combustion gas or diesel engine clean sheet designing

The net effect is a weight savings by allowing a shorter pin with a larger I.D. to carry the loads piston loads. Diesel allowable pin bore pressures have more than doubled in the last 60 - 70 years from perhaps 60 ksi to 140 ksi. Fit, finish and some design tricks account for much of the increase in bearing surface loading but the bending stress limits of steel have remained pretty stagnant. So moving the firing load areas closer together really helps to reduce the bending stress and the amount of steel needed to cope.

Another interesting steel piston was phased into the Series 60 Detroit. There was an evolution from the original aluminum piston skirt through a couple of steel designs.

RE: internal combustion gas or diesel engine clean sheet designing

The 71 series had some interest pistons as well. It was a steel crown with an iron skit but the connecting rod bolted to the wrist pin.

RE: internal combustion gas or diesel engine clean sheet designing

All EMD's engine 567, 645, 710 series uses cast steel piston and are floating trunk piston design with only one internal snap ring at the base of the skirt, these 2 cycle diesel engine don't have a intake suction phase like 4 cycles engines does so there's no almost tension on the piston and the rod itself only compression so the snap ring to hold the piston on the trunk free to spin on its own axis

here's a cutaway with temp gradient in this link


RE: internal combustion gas or diesel engine clean sheet designing

Those monotherms aren't cast, they're forgings like most modern steel pistons, hence the cooling gallery having separate stamped/welded cover plates. Like most forgings, they are a nice product for high combustion pressures and extreme durability, but pricey and somewhat limited for new development. Typically they are forged thin for a specific bowl so there isn't much meat left to work with unlike aluminum castings which are cast thick and blank/flat topped, readily accepting of whatever bowl you'd like to machine in.

RE: internal combustion gas or diesel engine clean sheet designing

just an update on the subject I started up about 3 weeks ago here's a few examples of what I was looking for

are those proportion a form or parameterization

if so what is the terms used so i can search more info on the subject

i am looking for proportions in relation to the bore size ( bore to ratio features sizes ) for the "cylinder block" and "cylinder head" features and dimensions

any publication with those kinds of formula!

i got lucky and found those pics by looking for something else and these came up

P.S. if i am a pain let me know as i don't want this subject to stretch for ever just want to get as much info as i can on this thread


RE: internal combustion gas or diesel engine clean sheet designing

While it will be found that certain of those dimensions may fall within certain relationships to other dimensions, an attempt to design an engine strictly by rule of thumb is sure to end in failure.

Changes to certain engine parameters (e.g. compression ratio, whether the engine has forced-induction or not, rev limit, piston speed and acceleration at redline, etc) will shift those relationships, for example.

You HAVE to crunch the numbers, and even in the old days, they crunched the numbers. They may not have had modern analysis tools available, which meant they had to allow for bigger margins of safety, but they did indeed crunch the numbers the best they knew how to do at the time.

I can tell you for sure that the crankpin journals in the last motorcycle engine that I had apart are not 0.65 times the bore diameter, and the main journals are certainly not 0.35 times the bore diameter in width. And the piston skirts nowadays in such an engine are much, much shorter and do not form a complete circle at the bottom - the unnecessary weight is cut away.

I'm guessing that the sketch you found is for a heavy-duty engine designed for higher cylinder pressure, and much, much lower revs. And perhaps those dimensional relationships are appropriate for an engine with that service. But ... you have to crunch the numbers.

RE: internal combustion gas or diesel engine clean sheet designing

I think I found what I was looking for and it is a really interesting book about cylinder head modeling


book title

Parametric Design of
Diesel Engine Inlet Ports

author Michael C Bates

there a lot of nice delicious juicy info and details about cylinder head designing that I was seeking for :)


RE: internal combustion gas or diesel engine clean sheet designing

This post is probably useless but maybe worth a read.

Over the past 15yrs I have cut up and measured approx 60 engines from 1L budget things from yonks back to new F1 engines.

Heres what I found in terms of lets say the 150-170hp 2L inline four bracket... ranging from about 1985 to 2000.

They all had 4 valves per cylinder.
Some had nice combustion chambers, some had not.
Some had 81mm pistons, others hand 90mm ones...
All had aluminium pistons.
Some had lovely port shapes, others had awful shapes and entry angles.
Some had piston squirters others did not
Some had alloy blocks others had ci blocks.
Some had cast cranks others had forged, one or two had billet items.
Some had 3mm head casting thicknesses others I saw walls 6-8mm thick.
Some had a head coolant volume 3 times of many of the others.
Most had same waterpump L/per/Min rate.
All had same thermostat opening temp.
Some had carbs, others Kjet, rest EFI.
Some had ci rings, others steel, others uber bimetal types.
Some had ladder style sump girdles, others 2 bolt conventional main caps, others 4 bolt.
Some had long rods, others short, some with drillings to small end others not.

None of the above ''good bits'' were seen on any one engine, but each was a mix and match of all/some of the above.

All engines made about 160hp... with similar curves.

I cant answer all of your points above in op but in terms of engine design, a lot of it is ''follow what works''.

I have more experience in F1 and I will say that the Formula to follow comes first, then where the engine block has to fit in terms of space and aero, then the rest gets designed.

The only big decision I would be making in the morning if I was to design an engine with 2 cams and 16valves would be if I wanted to be able to get at the head bolts with cams in place, or...go for a more favorable valve separation angle which may see the cams sit over the head bolts and require a 2 piece head or the head bolt counterbores eating into the lower cam journals which is no harm either within reason.


RE: internal combustion gas or diesel engine clean sheet designing

what I was meaning is you start with proportions based on feature to bore size ratio, if it is done on cad you float the model with these baselines numbers for each features proportions EX:( like a 3d model of a piston base on a preliminary sketch ) and THEN you crunch the numbers and lock the constraint one features at a time

from what I read in the book

Parametric Design of
Diesel Engine Inlet Ports

is that there's rules you have to follow in some orders

like example the cylinder head bolt pattern is define by the 3D model of the cylinder head and not NECESSARILY by the engine block because the constraint of port design will dictate the bolt holes locations ( aside of other related cylinder head features ) the bolt size and the bolt length ( with the proper stress, total load clamping and port, cooling flow analysis )

my assumption was that the cylinder block head bolt location WAS ALWAYS DEFINE FIRST by the cylinder block so I was WRONG assuming this

the above book title really explain that process really well!


RE: internal combustion gas or diesel engine clean sheet designing

Chrysler found a work around for this on the Gen 2 hemi, that is still practiced today on top fuel engines, if I'm not mistaken wink

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: internal combustion gas or diesel engine clean sheet designing

Pahl & Beitz was first written in the era you're interested in, and I think was written to capture and teach 'best practices' of german general engineering design at the time, and on revision.


RE: internal combustion gas or diesel engine clean sheet designing

Engine design starts with what is its application is going to be. What machine or vehicle will it be powering? Next would be what power it is supposed to produce for the application. All that should help the design team or designer determine what the size of said engine will be. Remember an engine for a granny car to run to the store will be way different than one used for a locomotive, container ship, or a KC-97 airplane.
Once you have the application and HP power requirements, and any weight restrictions for the application, then the engine design can start. In the old days and I would think now as well all the chosen design of major components of the engine, if for a multi cylinder engine, is all first tested as a single cylinder engine. That means at that particular point none of the parts are the correct size of what the final engine design will be.
This is where all the components are checked and tested and tweaked so the final parts to be used will be some what proved for the particular design. The internal rotating parts and the case that will contain them, will all be an integrated design process, your not going to design say the crankshaft first and ignore how it will be fitted and held in the containment vessel, and in say the old large piston aircraft engine days
the most important thing to design would be the cylinder locations for the best cooling effect then the rotating member (crankshaft) would be designed to accommodate that particular crankcase design.
So unlike some say that the first items to design are the rotating internals, that would not be true in the particular large aircraft engine I'm writing about. The crankcase and cylinders arrangement would be first
then everything else made to fit.

RE: internal combustion gas or diesel engine clean sheet designing

somehow the crankshaft will define the displacement of a specific engine because of its stroke , but if you can't have an accurate LOCUS or BANGO interference fit how you will be able to assess the crankcase volume if you don't have the crankshaft modelled
FIRST because the crankshaft dynamics will have to be sorted out before the crankcase is modelled ( bending analysis, torsional, stresses ,oil film loading and balancing) now I understand why the crankshaft needs to be modelled first because it will define the stroke of the engine with its dynamics model

it is technically the same principle for designing a transmission if you know the torque rating, the rpm range the layout
first you need a gear analysis of all your internal component BEFORE making the transmission case because if you do it the other way you will never know how big and wide the gears need to fit that case the same goes for designing an engine!

by the way I found quite a few articles on crankshaft modeling online and all I can say it is really a fascinating subject to read :)

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