Where does RPM come from?
04-21-2012, 10:31 AM
#21
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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.
04-21-2012, 04:42 PM
#23
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 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.
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.
04-21-2012, 05:39 PM
#24
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 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.
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.
04-21-2012, 08:48 PM
#26
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...
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...
04-22-2012, 02:50 AM
#27
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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.
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
04-22-2012, 11:21 AM
#28
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.
04-22-2012, 03:35 PM
#29
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.
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.
04-23-2012, 06:48 PM
#30
FormerVendor
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!
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!
04-23-2012, 08:11 PM
#31
@ 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"...
04-23-2012, 08:29 PM
#32
e you 
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 $$$$ to achieve this by participants of this thread. I never knew you had to spend money for a theoretical idea or a theoretical engine build.
You mentioned rpm being dictated by camshaft. Would you care to elaborate? Are we talking specific lobe design? A specific duration range? Does a engine like or need a tighter/wider lobe separation to achieve high rpm? And how does lift play in this engine orchestra?
Again...all useful info is greatly appreciated...thanks for your contribution.
I am not sure what you are getting at, but you want to build a high rpm motor. Us big block guys use cubic inch to over come having to spin a smaller motor to the moon to achieve the same goal.
Camshaft is what dictates rpm period
And if you pick a camshaft that makes power from 8000-10500 then the rest of the components have to be up to snuff. And uh yeah they have to be quality components. Nascar engines see these rpm's for hours at a time. If for some dumb reason you are building a motor just to say you can spin it to 9500 rpm then i think you are missing the point.
Camshaft is what dictates rpm period
And if you pick a camshaft that makes power from 8000-10500 then the rest of the components have to be up to snuff. And uh yeah they have to be quality components. Nascar engines see these rpm's for hours at a time. If for some dumb reason you are building a motor just to say you can spin it to 9500 rpm then i think you are missing the point.
I never said, not once that I wanted to or was building an engine like this. What I did say several times, was I wanted to discuss theories and parts and components needed for sustained RPM...that was pretty much it...I have a thirst for knowledge about this type of combination...I was told that I needed big $$$$ 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.
