Advanced Engineering Tech - Where does RPM come from?

I'm doing some light research on high RPM engines. I have a few questions about the subject, thus far?

1. What is the single, most influence in spinning an engine to, let's say, 9500 rpm?

A lightweight rotating assembly?
A short stroke?
Head flow in terms of cfm?
Camshaft specs?
Induction setup?
Anything else?

I'm just curious to know what is needed to create, sustain and harness good power, at 9000 plus RPM.

lightweight and short stroke. 327 ci in my avatar spins to 9.... nothing all that special to it, I don't think...

Well, if you have parts that aren't going to come apart and valvesprings that actually have enough pressure to sustain that RPM range, any engine dimension can do it in theory. But don't expect to get there for cheap.

Edit: Btw, Higgs Boson, nice name! haha

Valvetrain, valvetrain, valvetrain.

balanced rotating assembly + supporting mods

What specifics about valve train components are you speaking of? Weight? Components? Please do elaborate. Thank you...

balanced rotating assembly + supporting mods

Supporting mods, such as? Please do elaborate.

What specifics about valve train components are you speaking of? Weight? Components? Please do elaborate. Thank you...

Everything has to work well together, so if you are wanting to spin a motor that high, you'd best be investing some serious time using one of these:

http://www.spintron.com/vtrain.htm

In general, the lighter the valvetrain components, the better provided durability isn't compromised. The rest of it will depend on what you're building.

Maybe ask these guys some questions:

http://youtu.be/nsa6kq-qqIE

I'm doing some light research on high RPM engines. I have a few questions about the subject, thus far?

1. What is the single, most influence in spinning an engine to, let's say, 9500 rpm?

A lightweight rotating assembly?
A short stroke?
Head flow in terms of cfm?
Camshaft specs?
Induction setup?
Anything else?

I'm just curious to know what is needed to create, sustain and harness good power, at 9000 plus RPM.

If you take a look at the physics of a reciprocating component like a piston, your limiting factor in ultimate rpm will be the strength of the components. As you increase rpm, you increase the acceleration of the pistons and other components by the square of the increase in angular velocity (rpm). Therefore the heavier a part is the more force it will need to withstand. This is why aluminum or titanium are often used, materials that have a higher strength-to-weight ratio than steel.

Decreasing stroke is one way to get a lower piston acceleration at higher rpms.


So the lighter you are able to keep the moving components, the faster they will ultimately be able to move in an engine. This obviously doesnt take into account the valvetrain you'd need as others have mentioned or the airflows you'll need to support that (there is a reason high revving engines are a little smaller).

you dont have any where near the information to answer the questions. you need all the spec of engine and what you what to do with it .

10k rpms for 2 second is way different then 10k for 30 second than 10k for 5 mins,

same thing 100 hp vs 500 vs 1000

a 10k 4 cyl will have different needs then a v8 a ford v8 will have different needs then a LEX v8

you can build a motor that will live at 10k rpms but cause of miss match parts will eat it self if run at 8k for 30 seconds

THE BIGGEST THING WITH HIGH RPM ENGINES IS MONEY MONEY AND MORE MONEY

What an engine needs to be efficient at high RPM is sufficient airflow through the entire intake tract, the entire exhaust system and the proper camshaft timing.

What an engine needs to survive at those rpm levels is sufficient strength to weight ratios on all moving parts.

The engine will also need a supporting cast of sufficient fuel system, gearing, cooling and reduced accessory system speeds.

Once you determine your target power levels and the RPM required to achieve them are, you can get specific on the components needed.

@speedtigger...thanks...the stat ements that you posted put things into more perspective for me. I specifically started this thread to discuss some theories and facts and experiences from people that have very hi-winding lsx engines, that make hi-power at those rpm levels.

@ Big Rich 954 RR...I didn't think that anyone needed specs for an engine to discuss theories of what it takes to achieve a specific RPM range. I do not have engine specs, because I do not have an engine that will spin 9500 rpm, nor am I trying to build one...yet...lol. What I do have, is a interest in learning from others with experience and knowledge , that are willing to share ideas, thoughts, etc. Thank you for your input, though...

i dont care how light and strong your bottom end is if its not balanced it wont live at high RPM, which is where my answer "balance" comes from.

a well balanced heavy combo will outspin a lighter out of balance setup everytime.

supporting mods would be everything else needed to make the power in that range.

ITS ALL IN THE COMBO, but when talking about high rpm you have to start with balance.

Good point, kind sir...

@speedtigger...thanks...the stat ements that you posted put things into more perspective for me. I specifically started this thread to discuss some theories and facts and experiences from people that have very hi-winding lsx engines, that make hi-power at those rpm levels.

@ Big Rich 954 RR...I didn't think that anyone needed specs for an engine to discuss theories of what it takes to achieve a specific RPM range. I do not have engine specs, because I do not have an engine that will spin 9500 rpm, nor am I trying to build one...yet...lol. What I do have, is a interest in learning from others with experience and knowledge , that are willing to share ideas, thoughts, etc. Thank you for your input, though...


Ok i guess we are just not going to be able to understand each other. Cause i dont see how you can discuss theories of a engine if you dont have any spec /goals or building a engine to fit a planned event.

Ive played with a few high rpm engines i was one of the first people that start to play with 180 degree cranks and 3 inch strokes for the small block when everbody wanted 4inch.

RPM is not just a number to shoot for like i want to rev to 10k rpms the load and time spent at said rpm means more then a number.

There has to be a said reason to rev a engine that high and for a LS engine there not many good reasons to.

EX take a stock ls2 engine destroke it to 2.75 put stronger valve springs in it high duration cam with easy rollers and med lift spin it to 12k rpms.
WILL IT REV TO 10-12k yes will it be good for much NO but will make a lot of noise for a short time.

i dont care how light and strong your bottom end is if its not balanced it wont live at high RPM, which is where my answer "balance" comes from.

a well balanced heavy combo will outspin a lighter out of balance setup everytime.

supporting mods would be everything else needed to make the power in that range.

ITS ALL IN THE COMBO, but when talking about high rpm you have to start with balance.

Most of my back ground is cars and aerospace engineering. I know a huge amount of info and love to talk thoerys. but you guys arent giving any thing to be able to talk about.

What are you talking about ( a balanced heavy combo will outspin a lighter out of balance one )?? What is this outspin you talk of ?

Most of my back ground is cars and aerospace engineering. I know a huge amount of info and love to talk thoerys. but you guys arent giving any thing to be able to talk about.

What are you talking about ( a balanced heavy combo will outspin a lighter out of balance one )?? What is this outspin you talk of ?

well, we know ANYTHING can spin until catastrophic failure, what i am saying is that threshold is much higher on a balanced bottom end than an unbalanced one, correct?

so the balanced combination will spin higher (more RPM) before catastrophic failure.

the reason i dont bring up much else is because he isnt very specific in what he was wanting, if you bring up power production and efficiency at XXXXx rpm then this conversation would be totally different, but i'm taking all that out and being as basic as possible, if that makes sense.

basically saying what you are, time spent at xxx rpm is a very valid subject when asking a question like this. is he asking about power or reliability at xxxx rpm? who knows...

LEE12609 OK i see what your saying. I guess i though you were talking about over balancing to deal with the higher RPMS or caling in the oil weight at higher RPMS.

well, we know ANYTHING can spin until catastrophic failure, what i am saying is that threshold is much higher on a balanced bottom end than an unbalanced one, correct?

so the balanced combination will spin higher (more RPM) before catastrophic failure.

the reason i dont bring up much else is because he isnt very specific in what he was wanting, if you bring up power production and efficiency at XXXXx rpm then this conversation would be totally different, but i'm taking all that out and being as basic as possible, if that makes sense.

basically saying what you are, time spent at xxx rpm is a very valid subject when asking a question like this. is he asking about power or reliability at xxxx rpm? who knows...

Balancing the crank is so fundamental, I don't think it really even needs to be mentioned. It's along the lines of correct bearing clearances or even a good torque wrench.

I think the OP is looking more for design aspects for high RPM, since he mentioned airflow and lightweight components.

That being the case, I think that a stable valvetrain is #1. The components in the valvetrain need to as stiff and light as possible, and the camshaft needs to be designed with those components in mind so that it will not cause the valvetrain to be unstable at the target RPM range.

As has already been stated, valvetrain is the #1 most important thing for turning RPM on a pushrod engine. Keeping the bottom end together is childs play compared to designing and successfully running a 10k RPM capable valvetrain system. Now, actually making good power at that RPM is another story and I doubt you'll get many to talk about that on LS1tech of all places.

Keeping the bottom end together is childs play compared to designing and successfully running a 10k RPM capable valvetrain system.

For a child with a big wallet.

Balancing the crank is so fundamental, I don't think it really even needs to be mentioned. It's along the lines of correct bearing clearances or even a good torque wrench.

I think the OP is looking more for design aspects for high RPM, since he mentioned airflow and lightweight components.

That being the case, I think that a stable valvetrain is #1. The components in the valvetrain need to as stiff and light as possible, and the camshaft needs to be designed with those components in mind so that it will not cause the valvetrain to be unstable at the target RPM range.

i agree honestly.

the reason this cant be answered is because there is no right or wrong answer, there is no "single" most important part/piece/step to spinning a motor to 9500rpm, it takes a combination of the correct parts and assembly technique.

light
strong
balanced
rod/stroke ratio
etc

all plays a role in JUST the bottom end, much less supporting that RPM on the top.

Balancing the crank is so fundamental, I don't think it really even needs to be mentioned. It's along the lines of correct bearing clearances or even a good torque wrench.

I think the OP is looking more for design aspects for high RPM, since he mentioned airflow and lightweight components.

That being the case, I think that a stable valvetrain is #1. The components in the valvetrain need to as stiff and light as possible, and the camshaft needs to be designed with those components in mind so that it will not cause the valvetrain to be unstable at the target RPM range.

To me, balancing the crank/rotating assembly is a given standard for any horsepower level above 350. This is the approach/ideaology that I have always taken. There has been lots of good responses, thus far in this thread. The things specifically that I am wishing to discuss, gain clarity and gain knowledge about is the types of components needed to make and sustain a specific RPM level (9000 for example).

Maybe I wasn't as clear as I thought I was with my question. So, I will add the following questions to the mix so that we can all discuss specifics...

There are several types of crankshafts on the market, for example. Which style would help achieve my goal in theory? A knife-edged crank, a super light crank, one made from 5140 or one from 4340 steel?
What types of cylinder head flow characteristics should one be looking at for 9000 rpm in a drag race combination? What type of intake port configuration should be considered? Will a cathedral port support my goal? Should I be looking at a rectangular port?
What type of induction setup? Monoblade, 4150 style Carb or 4150 style throttle body? Two 4150's? Intake design...custom sheet metal? Short runners, long runners?
Is a ultra-high (14:1 or higher) compression ratio necessary? Are there any piston coatings that should be considered for the RPM range specified What type of connecting rods are used for such an engine? Aluminum? What weight and strength?
Any secrets and or machining tips for a hi-powered, hi-rpm , LSX type of engine that you with experience care to tell, besides the most obvious...balancing...
Should I be looking at a specific fuel octane? A specific oil? Specific engine bearings? What type of oiling system works best?
I won't even ask about cams yet...lol...

I hope that I was able to clear some things up...sometimes I think faster than I type. Thanks for everyone's input thus far.

so you want a theoretically build engine, not "where does RPM come from".....

big difference.

Well, my theoretical build has to do with high RPM...I have been building engines for a long time...mostly street combinations, that make peak power below 7000 rpm...I pretty much know how to build engines...lol
What I want is info about what dictates RPM and what components are needed for high RPM, as it relates to an LSX type of engine...

To me, balancing the crank/rotating assembly is a given standard for any horsepower level above 350. This is the approach/ideaology that I have always taken. There has been lots of good responses, thus far in this thread. The things specifically that I am wishing to discuss, gain clarity and gain knowledge about is the types of components needed to make and sustain a specific RPM level (9000 for example).

Maybe I wasn't as clear as I thought I was with my question. So, I will add the following questions to the mix so that we can all discuss specifics...

There are several types of crankshafts on the market, for example. Which style would help achieve my goal in theory? A knife-edged crank, a super light crank, one made from 5140 or one from 4340 steel?
What types of cylinder head flow characteristics should one be looking at for 9000 rpm in a drag race combination? What type of intake port configuration should be considered? Will a cathedral port support my goal? Should I be looking at a rectangular port?
What type of induction setup? Monoblade, 4150 style Carb or 4150 style throttle body? Two 4150's? Intake design...custom sheet metal? Short runners, long runners?
Is a ultra-high (14:1 or higher) compression ratio necessary? Are there any piston coatings that should be considered for the RPM range specified What type of connecting rods are used for such an engine? Aluminum? What weight and strength?
Any secrets and or machining tips for a hi-powered, hi-rpm , LSX type of engine that you with experience care to tell, besides the most obvious...balancing...
Should I be looking at a specific fuel octane? A specific oil? Specific engine bearings? What type of oiling system works best?
I won't even ask about cams yet...lol...

I hope that I was able to clear some things up...sometimes I think faster than I type. Thanks for everyone's input thus far.



What kind of money are you looking to play with ?

Cause a 2500 dollar LSX block would help alot with high rpm or a 4-5000 dollar Warhawk and RHS alum. NO WORK DONE TO BLOCK

a billet center weight crank is a good start about 3500k NO COATING OR BAL OF CRANK

about 2000 dollars for dyers 300m rods GOOD TO GO PRICE

allpro or mast heads 5000-9000 canted for the high rpm flow with 1-2k for rockers jesel or TD GOOD TO GO PRICE

DRY SUMP 4-6 grand

Your at about 20-25K with only the bare main parts and no fitting work

A REAL 10K RPM BUILD MAY COST 35 GRAND FOR A DRAG ENGINE 50 PLUS GRAND FOR A ROAD RACER OR MARINE TYPE

Thanks for your input, Big Rich...now I feel like we are moving along...so why is a billet crank the way to go? Are there any other heads choices? Is a canted valve head a must for this type of build? What type of airflow, cfm, etc, should I be looking at? In no way am I doubting you, I'm simply trying to learn more. Again , thanks for your input.

I am not sure what you are getting at, but you want to build a high rpm motor. Us big block guys use cubic inch to over come having to spin a smaller motor to the moon to achieve the same goal.

Camshaft is what dictates rpm period

And if you pick a camshaft that makes power from 8000-10500 then the rest of the components have to be up to snuff. And uh yeah they have to be quality components. Nascar engines see these rpm's for hours at a time. If for some dumb reason you are building a motor just to say you can spin it to 9500 rpm then i think you are missing the point.

Mainly you need a lot of cylinder head cross section per cubic inch displacement so that engine will make hp at higher rpm you want. At some point you can not get any more intake cross section on a given bore. The only way to go then is destroking so that cross section now has to feed less inches so those same inches now can go to a newer higher rpm before the intake port is too small.

Of course with rpm going up so do most of the loads on the engine go up even faster like was said at the square of the rpm. So twice as fast equals 4 times more force or 3 times as fast equals 9 times the force and pretty soon parts don't live long anymore!

@ racer7088...thanks for your input...that's ould explain why most builders use short strokes for these types of engines...It was SAM engine build and combination that started my interest and research. Trying to wrap my head around 1000 horsepower from a NA engine...Insane...especially from a "small block"...

e you I am not sure what you are getting at, but you want to build a high rpm motor. Us big block guys use cubic inch to over come having to spin a smaller motor to the moon to achieve the same goal.

Camshaft is what dictates rpm period

And if you pick a camshaft that makes power from 8000-10500 then the rest of the components have to be up to snuff. And uh yeah they have to be quality components. Nascar engines see these rpm's for hours at a time. If for some dumb reason you are building a motor just to say you can spin it to 9500 rpm then i think you are missing the point.

:bang: I never said, not once that I wanted to or was building an engine like this. What I did say several times, was I wanted to discuss theories and parts and components needed for sustained RPM...that was pretty much it...I have a thirst for knowledge about this type of combination...I was told that I needed big $$$$ to achieve this by participants of this thread. I never knew you had to spend money for a theoretical idea or a theoretical engine build.

You mentioned rpm being dictated by camshaft. Would you care to elaborate? Are we talking specific lobe design? A specific duration range? Does a engine like or need a tighter/wider lobe separation to achieve high rpm? And how does lift play in this engine orchestra?

Again...all useful info is greatly appreciated...thanks for your contribution.