Yes really... torque is measured in units as they relate to distance and force... Newton /meters, tonne force/ meter, and for the dinosaurs foot lb and inch lb Ect...... increase the weight.... and boooom the unit is higher... surprise surprise...
So how much will a 10 lb increase in flywheel weight increase hp? (I know I'm gonna regret this, but I just cant help myself...)
So theres no direct relationship between torque and horsepower, they are independent of each other? Fascinating, I am learning so much here, please continue...
You don't want to answer that? Ok well, lets throw a little math out here, and see how it breaks down Heres how torque is calculated, I don't see any input here for flywheel weight Engine Indicated Torque (Ti): where: Ti = engine indicated torque [Nm] imep = indicated mean effective pressure [N/m2] Ac= cylinder area [m2] L = stroke length [m] z = 1 (for 2 stroke engines), 2 (for 4 stroke engines) n = number of cylinders θ = crank shaft angle [1/s] And here is how you calculate hp Engine Indicated Power (Pi): , where: imep = is the indicated mean effective pressure [N/m2] Ac = cylinder area [m2] L = stroke length [m] n = number of cylinders N = engine speed [rpm] z = 1 (for 2 stroke engines), 2 (for 4 stroke engines) Vc = cylinder swept volume [m3] Ve = engine swept volume [m3] Ti = engine indicated torque [Nm] ω = engine angular speed [1/s] Anyone notice anything? 1) theres no input in the torque formula for flywheel weight, or reciprocating weight for that matter. 2) Horsepower is simply torque measured over time. If you increase torque (twisting force) at any given rpm, you will increase hp at that rpm, EVERY TIME DOESNT HAPPEN ANY OTHER WAY. And once the physical parameters or the engine are established (bore, stroke rod length ect) THE ONLY way to increase torque at any given RPM is to increase mean effective pressure(push harder on the piston) in the cylinder. Hanging a heavy flywheel on the end does nothing towards generating more torque. Heavy connecting rods (reciprocating****embly) do nothing either. They have NO ROLE in increasing the twisting force available at the end of a crankshaft. Man, I have read some far out stuff on the HAMB, and I usually let it pass, but WOW. An engine with a heavy flywheel will be harder to stall when you let the clutch out, but its not because the engine has more torque, its because the flywheel is heavier, and it resists changes to its speed more UP OR DOWN, due to its momentum. In fact, if you run a sweep test, which is pretty much the standard, increased reciprocating weight will show a decrease in torque, because more power is consumed in accelerating that added mass, leaving less at the end of the crank. Increasing the weight of your flywheel (or, god forbid your connecting rods or pistons, in other words reciprocating weight) wont generate a single ft lb more torque. But then, it is usually a losing proposition to argue with a guy that tells you he has invented a perpetual motion machine as well...
I ran this 383 hard for about 10 years before I sold it. It could pull tree stumps, took my builders advice on the cam. Good thing he didn't do what I thought was the right cam.
If you want low speed torque look at what engines in the '20s & '30 had. Long stroke,low compression and short duration cams.
Yup! I put 120,000 miles on my blown 383 in the OT bus (avatar) GOBS OF TORQUE!!! Got 7.5-8.2 MPG. weighing 22,000 lbs. Holley 650 spread bore with secondaries wired shut. 250*-260* XE Comp Cam 1.6 roller rockers 1.7 intake and 1.6 exhaust in small port truck heads. B&M 144 at 2-3# boost. 1.5" X 40" headers 3000 rpm @ 60 mph Then it broke the snout off the crank! Put a 427 tall deck in with similar set up (except blower) and got 6.5-7.0 mpg. (Not as torquey)
I love this. Has a blown 383 in a BUS, breaks the snout off the crank, so naturally, he replaces it with a BB.
You know, guys talk about "torque motors" and horsepower like they are two separate things, or mutually exclusive or something. You cant make more hp without making more torque, and visa-versa. When I look at a dyno sheet comparing two intakes or something, I honestly don't even care that much if the number I am looking at is torque or hp, all I am looking at is the numbers, and more importantly, the rpm they occur at. I am only really interested in area under the curve between shift point and shift recovery point, it doesn't matter to me whether the numbers I am looking at are ft lbs or hp. Some guys worry about power down at the converter flash point, more power at converter flash is only gonna help accelerate the car if the tires are big enough and the chassis is sophisticated enough to dead-hook, and in most street-driven cars, that's not the case. Otherwise, it just makes the car hellaciously hard to launch consistently. The idea that 10 ft lbs difference in torque at WOT at 2800 rpm on the dyno makes any kind of predictable difference in how the vehicle operates at 2800 rpm part throttle cruise is bogus, when you are cruising down the highway at 2800 rpm, the dynamics of whats happening inside the motor vs whats happening as it passes 2800 rpm at WOT during a sweep test on a dyno are totally different, and whether or not that 10 ft lbs at WOT at 2800 rpm has any relationship to what the engine is doing at 2800 rpm part throttle cruise is pretty much coincidental. What guys REALLY mean when they talk about "torque motors" is they mean motors that make peak torque at a relatively low rpm. In terms of gross torque numbers, if you build two 383's, and one makes peak torque at 4000 rpm, and the other makes peak torque at 5500 rpm, one thing i can tell you, the peak torque number the higher rpm combo makes is gonna flat out BURY the peak torque number generated by the engine that makes peak torque at 4000. So really, which one is the "torque motor"? Really, they should say "low rpm motors" but that just doesn't have the same ring to it. But if people described it correctly, a lot less of this*****amamie bs would get into peoples heads in the first place.
So anyways ...... is the pissin' contest over fellas' ? On topic beatings for everyone !! Yeeeha ! Hey @B.A.KING .... what's your budget man ? That's the primo question here. As well .... do you want the warm feeling of building it yourself, or just making a fuzzy phone call with credit card in hand ? I have two off topic vehicles with 383 stroker motors. One Vortec headed, heavy flywheel, roller cammed 5k$ engine .... and one TBI 383 from BluePrint Engines that cost 3400 bucks for an automatic. Love them both !! The latter engine is in a 2WD lowered Suburban that pulls trailers occasionally. Runs great !! Gas mileage rules. The first engine was a learning experience, built by me for a driveable (barely) 11.93 E.T. 117 mph Jeep CJ7. Not the smartest thing in the world to bend your front fenders with, not to mention squeezing soft top frames askew like lemons ... but ....anyways ..... 383's rule ! They will move your sh#t very well. That's it. Merry Christmas brother !!
hey, I may not always knock the stuffing outta someone, but when I do. I stay on topic. I read a LOT of stuff on here that, well you know...and I usually just watch it fly. But when some guy starts telling guys that they can make more torque by running a heavier flywheel, or even more outrageous, a heavier reciprocating****embly, I just gotta say something. I like (some of) you guys too much to let that kinda bs stand. Merry Christmas to you too Kid, hell 'tis the season, Merry Christmas to Hi-Helix too!
An old engine builder, now passed, once told me: "To make useful torque with any engine, you want a short duration cam, with a ton of lift. High-ratio rockers, if you can." I've been using that theory. Seems to be working, so far. Of course I know about lobe separation angles these days, too. It is not always possible, or cost-effective to alter the crankshaft throw, and/or rod length.
Some words of wisdom right there, if you give a***** about making good torque, anyway. Be a cold day in hell before you see me put a 110 lsa cam in any unblown 383...And that's what that guy in Mexico with the computer program is gonna want to sell you...
The true definition of torque is when you wake up with morning wood and you press down on your "Big Johnson" and your heels lift off the floor. Merry Christmas and a Hokey New Year.
Regardless of what engine you are building, and what specific components you use, you can absolutely ruin it by selecting the incorrect camshaft. Same with shoveling the wrong carburetor on top. If you are shooting for a street performer, and you put your peak torque at 5500rpm, you are not going to be a happy camper. Knowing how you are actually going to operate the vehicle is key. You need to be realistic. Sure, you can make big numbers on a dyno, and still end up with an engine is un-drivable. I have a 200 in the machine shop that will go into my Falcon. I had Clay Smith grind me up a bump-stick with 108º LSA. The intention being to keep the torque peak as low as possible. The final gearing is effectively identical to 2.56:1, with a 1:1 top gear. This is for a honest daily-driver, and road trip car, that needs to not be ornery, or get 8mpg. I could give a rat's patoote how much torque it makes at 5500rpm. It will make some, and it will be enough for the rare times it is actually there.
I also have thought about the blue print series of motors really hard.i mean lets face it in a tow vehicle, 5000 rpm is probably tops , so i guess i should have said Low RPM motor.Love to/have built them myself,but now with the job i'm working it makes it kinda hard. Not impossible but 12 hrs a day does cut into my building time. And on weekends i'm trying to head to a show some where to de-stressNot to sound a like a jerk but budget is not that big of issue right now. And now its past midnight,MERRY CHRISTMAS TO ALL.
Low speed torque means higher combustion pressers be sure to build as much quench into the motor as you can. It's no fun the build a motor that you have to back the timing off to keep it out of detonation. A zero deck 350 with a .040 head gasket and flat top pistons and vortec heads is over 10 to 1 with a RV cam that's to much.
Another cold sharp shock. Two 383's both built by the same shop. One makes peak torque at 3400, the other makes peak torque at 5000. Compare the torque numbers for both at 3400... Reality is one******y mistress...Carb formula fans, also note the peak power manifold vac. number on the mild motor. Anyone want to hazard a guess as to why that's important and what that number tells you?
For those that are interested, the AVERAGE torque across the test range is listed at the bottom of each page. Average torque across the band for the so-called "torque motor"? 433. Average across the band for that stupid useless motor with 5000 rpm torque peak that only a crude and unsophisticated knuckle dragger would build? 480... Which one is the "torque motor"?
George, I agree with yours, and Helix's views here. An engine can be optimized for useful power in the rpm range where it serves. I suspect there is an ideal flywheel weight. You are correct that it doesn't factor into HP, this is a physics-engineering calculation. No boxing gloves reqd. There would be a 'good' weight choice for an application, apart from extreme motor builds like a 'fueler'. A flywheel might resemble a capacitor, absorbing and releasing energy, reducing vibration, matching balance of system's moment-of-inertia, improving shaft HP delivered, all come to mind.
absorbing (storing is probably more accurate??) energy? Yes. Creating energy, which is what it has to do if it is going to "increase torque"? Nope, not ever. No boxing gloves, just physics. Really trying to get it through to guys here, and I know I am wasting my breath, but there is nothing magic about "torque" and it is inextricably linked with horsepower, also simple math and physics. they are two sides of the same coin. Earlier I said that when I look at a dyno sheet, I don't even care if it shows me torque or HP. I thought this would generate some comment, but it hasn't. First off, it will be clear by what the numbers are doing which one you are looking at, you don't need anyone to tell you. If the numbers are climbing as rpm goes up past peak torque you are looking at HP, if they are falling, you are looking at torque. And it takes a few quick jabs on a pocket calculator to turn one into the other. Theres this total********* mythology that "torque" is somehow "superior" to horsepower, or has some magical "property" that horsepower doesn't have. Total*********, and anybody that understands how either one is calculated, and how they relate to each other should understand that. And as post #56 makes abundantly clear, building an engine that makes peak torque at a lower rpm doesn't make an exponential increase in torque, or make your engine into some kind of magical "torque motor" contrary to popular magazine mythology, in actual fact, it has the opposite effect. It just means it makes peak torque at a lower rpm.
The Jalopy Journal
