I'm desiging a "multi-cylinder" Engine

[Dragoon119]

I am in the middle designing a "multi-cylinder" engine simultaneously more powerful and smoother than any hitherto available. For this I am implementing SolidEdge as my media of choice for conceptualizing the design before I get it milled out. I understand the basic workings of the four stroke combustion engine and spend many days designing V8 and V10 engines of basic architecture and angles in my head. However I wish to make this engine as production-ready as I can which is why I have come to you all here.

This tutorial is a great way to help beginners design their own engine using 3D cad software but I feel it is lacking in structure rigidity.

The link is here: http://grabcad.com/questions/tutorial-h ... ine-part-1

My design calls for a similar layout to the engine presented however my V angle will be far wider. I have many questions, can anyone give me flaws in this design so I can work it out on the computer first, also any tips or hints on increasing block rigidity would be greatly appreciated. I want to make it clear that for right now I am working on the block and have already completed the cylinder bank, cooling jackets, headbolts, connecting rods ( Which will either be Chevy connecting rods or VW made.) Pistons (Which I have already sourced from Keith Black.) So for now I really need you expertise on the engine block.

Thank you in advance for reading my post and for any suggestions and or advice you deliver.

[Lycoming]

You're going to mill out the block, not cast it? especially if it's water cooled, seems like that could be difficult to impossible to do on a mill. Where do you want to improve block rigidity? why? What material do you plan to make the block out of? What sort of technical background do you have?

[Dragoon119]

Yes, the first prototype I wish to mill out of commercial alloys such as AA319 or AA356. I initially decided on iron cylinder liners but the thermal expansion of the pistons during load reduced my anticipation on implementing that aspect into the engine. I want tight tolerances but not insane ones

Yes, it's liquid cooled engine and I have seen it done quite a few times on 3D mills across the country. I want to improve block rigidity along the length of the block especially along in the inner valley of the V. I also wish to improve rigidity along the cylinder bank to reduce flexing under load just encase if I wish to use the engine as a structural member later on in it's production life. Technical background? Non really, besides tinkering with various engines here and there, helpping friends on various automotive projects, and studying Aeronautical engineering I don't have much background to be proud of. Oh well, this engine isn't gonna be milled out forever. I only intend the first three to be milled the rest will be cast. The milling is only so I can work out inherent quirks in the design before casting molds are made and then put into use.

[Tommy Cookers]

I am in the middle designing a "multi-cylinder" engine simultaneously more powerful and smoother than any hitherto available.
My design calls for a similar layout to the engine presented however my V angle will be far wider.

that's a noble goal !

have you settled on the capacity, number of cylinders, and V angle ?

[mep]

What is the reason for doing this?
Is this just a CAD design exercise?

I am in the middle designing a "multi-cylinder" engine simultaneously more powerful and smoother than any hitherto available.

Hahaha….. ah no!
The only reason I can see for building a own engine is when an engine of that size is not available on the market.

I have many questions, can anyone give me flaws in this design so I can work it out on the computer first, also any tips or hints on increasing block rigidity would be greatly appreciated.

You will not come around doing a series of FEM iterations on most of the parts. Also it requires posting of some pictures if you want any advice here.
Honestly, don’t underestimate the required knowledge for designing and building a complete engine. It goes far beyond some CAD tutorials. There is a reason why companies have +500 employees to create only the F1 engines.

[coaster]

Check out Alan Millyard, he is the guru of custom bike engines.
http://www.youtube.com/watch?v=TkggvRjk0eE

[Dragoon119]

I am in the middle designing a "multi-cylinder" engine simultaneously more powerful and smoother than any hitherto available.
My design calls for a similar layout to the engine presented however my V angle will be far wider.

that's a noble goal !

have you settled on the capacity, number of cylinders, and V angle ?

Thank you, Yes the capacity is going to be in and around 7 liters with a number of 16 cylinders and 135 degree V angle. I choose this instead of 45 in order to keep a low hood line at the cost of wider track and increased spark plug access difficulty.

What is the reason for doing this?
Is this just a CAD design exercise?

The reason is to develop my own engine that I hope to one day install into a car completely designed by me. At the moment I am designing the engine in cad to be milled out once completed but I want the engine block to be as structural strong as possible for it's intended role in the future.

Hahaha….. ah no!
The only reason I can see for building a own engine is when an engine of that size is not available on the market.

As far as I know, no engine is commercially available on the market that delivers the characteristics that I desire out of the engine I'm currently designing.

You will not come around doing a series of FEM iterations on most of the parts. Also it requires posting of some pictures if you want any advice here.
Honestly, don’t underestimate the required knowledge for designing and building a complete engine. It goes far beyond some CAD tutorials. There is a reason why companies have +500 employees to create only the F1 engines.

I am not underestimating the challenge. But I will not overestimate it either. In the early 30's to late 40's companies where designing engines that were decades ahead of their time with less men and experience than what we have now.

But anyway back onto the discussion.

As you look at the Ford Coyote 5.0L V8 you can see diffiant webbing being utilized within the V angle of the block. Supposedly this was improvised in order to increase the blocks strength for forced induction but I'm wondering if this could be used to strength the block to be used as a torsional member of the chassis.





Now in the tutorial the designer did not use webbing on the V12 block as you can see below.


Wouldn't webbing increase the rigidty of this block? Mercedes uses it but not as exstensivly as the Coyote block or in the same lattice structure.


I can't seem to find a F50 V12 torn down so I can't see what Ferrari did to get the engine to be a strong structural support.

Does anyone have any ideas, suggestions, or concepts that have been used or practiced to strengthen up the engine block on road or race cars with long engine banks such as Inline 5, 6, or 8's? Or any information on the their V equivalents?

[flynfrog]

yes webbing can increase the stiffness of the block the question is how much do you need.

[xxChrisxx]

I'm slightly concerned that all my posts on here are of a negative nature. But it's threads like this that spur me on to post.

I have an an issue with the usage of the word design in this thread. Those solidworks tutorials are not doing design, they are drawing a picture of an engine

[Tommy Cookers]

I want to make it clear that for right now I am working on the block and have already completed the cylinder bank, cooling jackets, headbolts, connecting rods ( Which will either be Chevy connecting rods or VW made.) Pistons (Which I have already sourced from Keith Black.) So for now I really need you expertise on the engine block.

is the crankcase intended to be seperate from what you have called the cylinder bank/cooling jackets ???

also, some relatively modern motorcycle engines can 'easily' form the basis of a seperate crankcase V16 around 5-6 litres
somewhat like the Powertec V8, but you can avoid making anything above the crankcase mouth

I think you should look at the Ferrari flat 12 from the 1970s F1 car regarding stiffness
also significantly, these had 4 main bearings (not 7 like a V12)
and the flat 12 Ferrari road cars BB etc
your project is similar
a 135 deg V16 could reasonably be designed for 5 main bearings (not 9), but this needs to be determined in week 1
you don't need to have exactly 135 deg
bound up with this area of decision is the issue of importing cylinder heads etc eg from an existing V8 or motorcycle

a 120 deg V12 could also do what you want (and could have 4 main bearings ?)

regarding smoothness/balance ie cancellation via the crankshaft of forces and moments due to rotation/reciprocation
the V12 and V16 are in this respect conceptually perfect regardless of the V angle (so why make a V16 ?)
in all our engines there are (even in the V12 and V16) net/uncancelled forces due to valve accelerations etc

traditionally the V angle is chosen to give equally-spaced and small firing intervals (firing is unrelated to balance)
this is of little value in modern high rpm engines because their inertial forces with rotation/reciprocation are much greater than their firing forces, and occur at twice the frequency (in a 4 stroke)
so the inertial forces dominate crankshaft design
(which is why some high rpm straight 4s eg MotoGP are now made with cross-plane crankshafts)

non-traditional (large eg Ferrari 180 deg) V angles can reduce related bending moments on the crankshaft
and thereby allow fewer main bearings, with further benefits to weight, bulk and friction via crankshaft design

BTW I agree with the previous post
but compatible with Solidworks there will be packages ? eg to model the dynamics of your 5 main bearing vs 9 crankshaft design

[Dragoon119]

is the crankcase intended to be seperate from what you have called the cylinder bank/cooling jackets ???

No, These are going to be all one unit. If I was building an air cooled engine I might contemplate this but not for this appilication.

also, some relatively modern motorcycle engines can 'easily' form the basis of a seperate crankcase V16 around 5-6 litres
somewhat like the Powertec V8, but you can avoid making anything above the crankcase mouth

Yeah, I do remember the Powertech V8 Lovely little engine.

I think you should look at the Ferrari flat 12 from the 1970s F1 car regarding stiffness
also significantly, these had 4 main bearings (not 7 like a V12)

I'm definatly going to look into that but I think I can form at least three suggestions into why Ferrari did what they did. Since the cylinder bank is in a 180 degree orientation the cylinders naturally cancel each other out. This in turn negates some of the reasons for including more main bearings. And I can only guess that the counter balances were also different than regular 60 degree V12 engines as well.

a 135 deg V16 could reasonably be designed for 5 main bearings (not 9), but this needs to be determined in week 1
you don't need to have exactly 135 deg

I do not want to skimp on main bearings, I know I'm fighting a serious battle with friction here. But I'd prefer lower rpms to a warped crank any day of the week.

bound up with this area of decision is the issue of importing cylinder heads etc eg from an existing V8 or motorcycle

I already looked into doing this and figured that it's best to mill out the heads just like the engine block. If I wanted to do something like motorcycle inline 4s on a common block than I would need to weld in something similar to the BRM in the middle of the engine that operates a seperate set of gears in the heads for DOHC to work. Then at the very end of the day, I would only be able to install one side as the other would be facing the wrong direction.

a 120 deg V12 could also do what you want (and could have 4 main bearings ?)

regarding smoothness/balance ie cancellation via the crankshaft of forces and moments due to rotation/reciprocation
the V12 and V16 are in this respect conceptually perfect regardless of the V angle (so why make a V16 ?)

When I was designing the vehicle I though very hard on the engine to use for this appilication. Here was my observations:

V8- Compact, light weight, can make the nessassy power. However it will not run smooth enough without redesigning the engine mounting points and installing dampers to reduce engine vibration in the cabin.
V10- Compact, difficult to source, will not provide the engine sound necessary for the appilication.(I'd be limited to the Viper engine. Or be forced to basically repeat this process with a straight 5 from a Volvo or motorcycle.)
V12- Long, smooth, relatively high rpms, with the right heads and intake combination it can be made to sound very beautiful. However, the engine would not make the required sound or be as smooth as I want for this application. Also unless I go with a 60 degree V which would be rather high. I would need to design a offset crank for the engine.
Hince I went with the V16, since it would provide the power of the V12, V10, and V8 all with relative smoothness, and the distinctive sound I want out of the exhaust pipe.

traditionally the V angle is chosen to give equally-spaced and small firing intervals (firing is unrelated to balance)

Firing cannot be unrelated to balance since the whole meaning of balance is the cancellation of the combustion vibration with an equal force which is why flatplane engines have exhaust crossovers to negate the effect and produce a "balanced" feel.

I have an an issue with the usage of the word design in this thread. Those solidworks tutorials are not doing design, they are drawing a picture of an engine

I understand, I'm addressing the issues with that engine in my design but I'm also aware that a separate pair of eyes is better than one at spotting mistakes. Which is why I started this thread to iron out the mistakes with people equally or more knowledgable than myself before I pull this thing from my hard drive into reality

[xxChrisxx]

I have an an issue with the usage of the word design in this thread. Those solidworks tutorials are not doing design, they are drawing a picture of an engine

I understand, I'm addressing the issues with that engine in my design but I'm also aware that a separate pair of eyes is better than one at spotting mistakes. Which is why I started this thread to iron out the mistakes with people equally or more knowledgable than myself before I pull this thing from my hard drive into reality

A design isn't something that comes together by chance. As components aren't something that are there to look pretty, they have a very specific job to do and form comes from function.

It's easier to use an example.

So lets take step 1 of the SW tutoiral before designing a conrod. You can't just say, this is what it looks like, i'll figure out how it works later. As how can you know the geometry is good?

The job of the conrod is, to transmit gas pressure and inertia forces, allow oscillating motion with the minimum friction.

So to even attempt to design a conrod you need the following information:
Displacement (bore and stroke). Max. cylinder pressure, Max engine speed, Reciprocating mass (ie piston weight), Crankpin data (diameter and width) and desired rod to throw ratio. Maximum permissible stresses/design factors.

Even if you aren't designing your own component, you'll need this information to even spec an off the shelf part.

At the scheme stage (where we are), we probably won't know all this information. So we can make assumptions, so long as they are sensible, with a view to redo the calculations at a later time when more information is known.

[Tommy Cookers]

traditionally the V angle is chosen to give equally-spaced and small firing intervals (firing is unrelated to balance)

Sorry, I have messed up my quoting .....
DRAGOON SAID Firing cannot be unrelated to balance since the whole meaning of balance is the cancellation of the combustion vibration with an equal force which is why flatplane engines have exhaust crossovers to negate the effect and produce a "balanced" feel.
I SAY I don't agree, an engine shows the same vibration whether rotated by its own power or by external power
the point of flat-crank V8s is to avoid the need for exhaust crossover

with a V16 the crankshaft is a problem, solving this will dictate the rest of the engine and vehicle design
eg the BRM and the Cizeta have a central power takeoff
(often necessary with fewer cylinders eg the W196 M-B, 60s F1 Hondas, the 80s Porsche F1 engine and many motorcycles)
the Veyron does not have a V16 and this vehicle design is not driven by the engine design

the frequency and magnitude of the variation of firing loads and (more importantly) inertial loads
will give the crankshaft excessive torsional oscillation/stresses and cause premature failure
unless its natural frequency is high enough
with the long crank of a V16 this usually necessitates central power takeoff to make the crank behave as 2 short cranks
with end takeoff the V16 crank will need to be (unreasonably ?) short and thick to have a high enough natural frequency
with a moderate bore:stroke ratio 5 main bearings would shorten the crank (a high b:s ratio would prevent this)

you need to use suitable software for this critical part of the design (or import some expertise)
the Veyron and Cizeta look better now ?
(you could do a 135 deg similar to Cizeta, based on modifying existing cranks, heads etc)

EDIT 16th today we learn that Gordon Murray asked Honda for a V12 or V14 for the Maclaren F1 supercar