Never heard that in50 yrs
Did you read that in consumer reports?
Low speed torque and driveability ?
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Did you read that in consumer reports?
He is 12yrs old, loves Fords, & pretends to want an A-body Mopar....
Hmmmm, and how does it calculate the difference between a 727 w/a soggy juicewheel and a Dana60, vs a rollerized 999 w/a tight juicewheel and an 8.25"...??? Asking for a friend...
Dan the man
Well-Known Member
You probably never looked up how to calculate horsepower. You can put your car on a chassis dyno and that gives you rear wheel horsepower only ( at least that's what they only show when they test your car's power, I've never heard of them giving flywheel horsepower on a chassis dyno.
Dan the man
Well-Known Member
They only showed figures for power loss between a automatic and a manual transmission, they didn't break it down further than that. If you look up how to calculate wheel horsepower you'll see what I mean. Every time I post something that I've read and researched about you guys always think it's wrong or I don't know what I'm talking about, when in fact I'm only trying to share information that I've read, was told about
You can only guess what the flywheel hp numbers are from chassis numbers. It's gonna vary with the various drivetrains some are gonna eat more hp than others.
Newbomb Turk
Well-Known Member
That’s because I’ve tested that in real life. There isn’t a formula that can calculate the difference between tires or how the tires are positioned on the rollers or how much load is on them when the car is strapped down.
What do you do about tire pressure with your formula?
The power loss of say my drag car with 14-32 tires and a stick is different from a car with street tires and a turbo 400.
Can you see that whatever formula you found while researching is flawed unless it covers all the minutiae?
If you have a formula I’d love to see it.
Dan the man
Well-Known Member
Not bad, your wrong on all 3. Better luck next time
Fair enough but doesn't mean what you read is right, don't necessarily mean what were saying is right either, no proof is being presented either way, you really have nothing to base an argument on so you shared what you heard fair enough, now you can judge the new info accordingly and make whatever you want of it adjust or not.
But really don't make sense to argue the point.
Dan the man
Well-Known Member
I can only post what's been published, if it's incorrect it's not my fault. I posted a formula earlier what's been listed in how to calculate rear wheel horsepower, I can't be responsible if they don't show all of the different variables.
Dan the man
Well-Known Member
It's hard, got to take a lot with a grain of salt, even the experts don't always agree so it hard for the little guy. If I was you I'd get David Vizard's "how to build horsepower" and "performance with economy" get those two books go over and over them till it sinks in and that will give you a basic foundation to build on. I'm not saying David Vizard is the final word or even the best, but you could do a lot worse and he gives a very complete understanding of the entire drivetrain, plus I'd watch all of Richard Holdeners videos a bunch of times no other place your gonna get a bunch of dyno information. That should give you a decent understanding to work from.
junkyardhero
Well-Known Member
some of the most comfortable and capable cars that i've driven are no great shakes on paper, the 73 buick century regal with a 455 was no exception.
but one of the absolute best was a trashed out 73 doo doo brown 4dr dart that i'd bought for the **** hot 340/4spd that turned out to be mostly **** and not so hot. in an act of anger i purchased a very rusty 67 new yorker with a 383 2bbl that found a home in that turd mobile.
it was amazing to drive. aside from the oil pan swap, i didn't nothing to the motor except electronic ignition and whatever the cheapest headers were from PAW to make it fit. big dumb torque right off idle, and a 2.92 suregrip made for parking lot smokeshows, passing at speed even loaded down with three dudes and enough beer and gear for a long weekend camping trip was effortless.
while driveability is subjective, i think anybody can agree that two footing something at a stoplight that sounds like it's about to stall out until it hits 2K sucks all the way around. maybe i'm just old and washed, but i don't need the drama that the thrill of massive horsepower also brings. give me all the midrange torque and something that handles good and stops great and i'm happy.
Funny thing is that I was just looking through those two books for some info on cold air's effect on power. Turns out its in Urich & Fisher. But while skimming through I noticed I noticed he didn't really understand how the low speed/idle circuit worked. That's the thing. He was a great writer and had enough freedom to do some interesting independent tests that he then shared in his books and articles. I think that's part of the charm of his books, at least his earlier ones like those two, we're learning with him. But that's also a cautionary point with Vizard, which I've detailed previously if someone wants to search it out.
I definitely wouldn't take everything he says as gospel but he does give a fairly good overview with decent depth that someone should come out with a fairly decent understanding of a performance drivetrain.
He didn't have the depth - that's the problem. If I had known enough to pick up on his misunderstanding...
Some of it was the limitation of his knowledge at the time, and some of it was the limitations of the publications he wrote for. I am a lot more cautious now and sift carefully. There's a difference between something working in one situation, or couple, and beleiving versus knowing that it can be generalized to a class of situations.
Don't get me wrong. I like those books and I agree they are worth reading.
Some of it was the limitation of his knowledge at the time, and some of it was the limitations of the publications he wrote for. I am a lot more cautious now and sift carefully. There's a difference between something working in one situation, or couple, and beleiving versus knowing that it can be generalized to a class of situations.
Vizard is a great writer. His info is pretty good.
But be careful. If you are not careful, sometimes trying to follow him will take you down a rabbit hole.
Mine was a long and somewhat expensive journey.
Eventually I learned what was real, what was applicable to the situations/carbs I was working with, and therefore my mistakes were a part of learning.
But it all started with trying to do some of the things suggested in Vizard's How to Build Horsepower V2
Don't get me wrong. I like those books and I agree they are worth reading.
Newbomb Turk
Well-Known Member
If you really want to learn, you should find a shop local to you with a wheel dyno and go watch them run it. Hand around, grab a broom and sweep up. Make yourself fit in. Most people will teach those who want to learn if they aren’t jack asses.
I don’t know why you couldn’t do the same for an engine dyno.
It’s great to read and learn, but eventually you have to get out there and start testing what you think you know before posting off the wall stuff.
TrailBeast
AKA Mopars4us on Youtube
Back to drivability.
One of my best drivability cars was a lincoln mark 4.
Everything worked, it rode fantastic, was extremely comfortable and was a power house if needed.
It wasn’t fun, but it was reliable and comfortable.
One of the most fun cars was a 70 Roadrunner with a built 440 and a four speed.
That car was about as basic as it gets.
It only had front buckets, a shifter, steering wheel, headlights, rear lights, a speedo and temp/oil pressure gauges.
No choke, no heater, no interior lighting, no stereo, no sun visors.
OMG that car was fun to drive.
What a guy would call drivability just sucked.
Temperamental until it was warmed up.
It was loud, obnoxious and it spun tires way to easy.
Almost literally shouldn’t have been on the streets, but fun as hell.
I’ll trade quite a bit of drivability for the fun factor, but I still miss that Lincoln sometimes.
One of my best drivability cars was a lincoln mark 4.
Everything worked, it rode fantastic, was extremely comfortable and was a power house if needed.
It wasn’t fun, but it was reliable and comfortable.
One of the most fun cars was a 70 Roadrunner with a built 440 and a four speed.
That car was about as basic as it gets.
It only had front buckets, a shifter, steering wheel, headlights, rear lights, a speedo and temp/oil pressure gauges.
No choke, no heater, no interior lighting, no stereo, no sun visors.
OMG that car was fun to drive.
What a guy would call drivability just sucked.
Temperamental until it was warmed up.
It was loud, obnoxious and it spun tires way to easy.
Almost literally shouldn’t have been on the streets, but fun as hell.
I’ll trade quite a bit of drivability for the fun factor, but I still miss that Lincoln sometimes.
What a few of Us are pointing out is that You are posting approximations, and calling them formulae, they are not. They are only rough ballparking, even tho' they're derived empirically, it's a mean avg. stab. Better than nothing, but hardly a formula.......& Your head is still intact, well physically,.......
Funny, to me driveability is not a factor of torque at all. I have run as an A-Body "daily driver" a 4 speed 170 cu in slant six & 4 speed, stock 273 Commando & 4 speed, 273 Commando with 1.88 J heads & 4 speed, 71 340 & 4 speed, and a factory 383 & automatic. Almost all had 3.23 gears and factory manifolds and the best factory exhaust. All were quite driveable. The small blocks were very similar, the 170 was nice and had a nice rpm range, and the 383 easily ran very fast. I loved them all. Probably the least driveable was the 273 with the 1.88 J heads, which was my favorite combination. It revved so quick, it was a pain to drive in town. So for me torque has little to do with driveability. I don't see the point of spinning tires for very long or pulling the front tires off the ground on the street. I am sure driveability does vary a great deal from person to person.
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It just seem the premise is if you lose too much low speed torque from cams, cr, single plane, big heads, the consensus seems it's gonna hurt driveability from losing torque. Which don't make sense to me for one like you said /6, small cid V8 already have a lack of torque, they don't need a 3500 rpm stall to get moving.
Plus we drive around at part throttle which is just a fraction of the power available at any given rpm, so if we generally don't need all the power available to us how is a little less gonna effect it when your not using it anyways.
When it come to cams I think were talking overlap. When it's comes to single planes, carbs, heads were talking probably velocity.
What happens when an engine makes more power when you increase the air temperature?
Isn't that the problem? As you progress on your journey and you look for answers and the previous sources cannot provide you need to look elsewhere. There is a very well know Chinese saying:
"When the student is ready the master will appear."
ir3333
Well-Known Member
When driveability is discussed concerning longer duration cams it is the the low rpm power that is questioned.
I've often mentioned that when i ran the mopar performance .474 or comps XE268 low rpm torque was not strong.
if i hit it when driving slow, acceleration was lazy until higher rpms were reached. Everything else was fine.
I've often mentioned that when i ran the mopar performance .474 or comps XE268 low rpm torque was not strong.
if i hit it when driving slow, acceleration was lazy until higher rpms were reached. Everything else was fine.
Here a 340 torque stock on the left fully modded with an xe268h cam on the right, it's not showing under 3000 rpm but it's unlikely the xe268h is making less stock to at least 2500 possible 2000 rpm.
So your driving around at say 2000 rpm you hit the throttle, at 3000 rpm all these mods make more power that even stock peak torque so that's no problem, under 3000 rpm how long do you really spend there 1-2 seconds ? Say the xe268h takes a somewhat drastic drop off in torque, at 2500 rpms there tied and by 2000 rpm it's 20 lbs-ft shy of stock 340 is that really the cause of this lazy part. Say where talking 280 lbs-ft that would mean any small engine like a 4 cylinder would be lazy at any hp eg.. 400 hp or a big cammed 440 that's got soft bottom that's still making more torque than these 340's wouldn't they have no choice but to be lazy the whole time. It's just not making sense to me.
Phase 1:Stock 340 baseline, Chrysler electronic ignitionPhase 2:Replace small production AVS with Edelbrock 800 CFM carbPhase 3:Replace factory HP manifolds with Hooker 151/48-inch headersPhase 4:Replace factory iron 340 HP intake with Edelbrock Performer RPM Air GapPhase 5:Replace SSI springs and retainers with Engle #604LS retainers and #993 springsPhase 6:Replace stock 340 HP cam with Comp Xtreme Energy 268
| Torque | ||||||
| RPM | Phase 1 | Phase 2 | Phase 3 | Phase 4 | Phase 5 | Phase 6 |
| 3000 | 324.2 | 342.3 | 349.5 | 361.4 | 361.0 | 375.8 |
| 3200 | 320.7 | 338.3 | 351.1 | 362.3 | 362.3 | 376.4 |
| 3400 | 322.7 | 347.0 | 359.9 | 371.6 | 371.5 | 388.4 |
| 3600 | 328.0 | 348.2 | 368.7 | 380.4 | 379.1 | 402.2 |
| 3800 | 326.8 | 350.7 | 368.4 | 382.9 | 382.7 | 412.0 |
| 4000 | 327.6 | 351.3 | 367.6 | 383.1 | 383.1 | 409.3 |
| 4200 | 324.3 | 348.8 | 366.3 | 382.7 | 382.9 | 409.0 |
| 4400 | 316.4 | 342.7 | 363.2 | 383.5 | 383.6 | 411.4 |
| 4600 | 306.9 | 339.3 | 357.7 | 382.7 | 382.1 | 406.3 |
| 4800 | 300.6 | 335.7 | 351.4 | 375.4 | 374.8 | 401.3 |
| 5000 | 292.6 | 328.5 | 345.7 | 370.4 | 368.1 | 396.0 |
| 5200 | 284.1 | 320.1 | 334.1 | 357.2 | 357.1 | 388.1 |
| 5400 | 266.2 | 306.3 | 320.3 | 341.2 | 345.6 | 375.5 |
| 5600 | 252.6 | 295.0 | 309.7 | 329.1 | 331.7 | 365.2 |
| 5800 | 279.6 | 295.4 | 314.8 | 318.2 | 350.6 | |
| 6000 | 288.1 | 309.3 | 335.8 | |||
| 6200 | 266.7 | 316.6 |
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