any guesstimate on torque with gears & stall ?
08-19-2012, 08:46 PM
#22
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Ok, after doing more re-search and speaking with others on this topic, not on this forum, this is what the conclusion was. Torque multiplication and effienciency are directly affected with a higher stall, and also gears. More torque is created, otherwise the same OEM LT1 car with factory stall and gears would have the same ET's as the car with higher stall and gears. HP may not change, but might, but torque does surely. My original question was to " guesstimate " what the added torque might be, which is difficult to figure. I'm at the conclusion, as are others, the torque without a doubt is more, but the number is unknown. I was told the best way to determine is to race another LT1 car, modded, cam, etc., with its HP & torque numbers a known element, then see how far off and compare ET's.............Anyway, I'm done with this topic, thanx for your advice.
08-19-2012, 09:55 PM
#24
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Theory is just that. If you are so sure do a search! It's likely that you lost hp, the issue is that horsepower is a function of torque (tq*rpm/5252) and although auto trans with convertors multiply torque they lose more hp because of the multiple clutch packs. You may have upped the tq multiplier from 2.1 to 2.5 but you will never see it on a dyno graph because they account for tq multiplication.
Hp, tq, and acceleration and very different things. Take a look at wikipedia for me before you correlate the 2
Hp, tq, and acceleration and very different things. Take a look at wikipedia for me before you correlate the 2
08-20-2012, 11:06 AM
#29
It multiplies torque at that input shaft of the trans not at the wheels bro. It doesnt add actual torque number to the motor or wheels. You did absolutely nothing to add power or torque. The motor is making the same exact amount of power before. Like said before, you honestly probably lost hp/tq at the wheels by adding the converter but it makes the car e.t faster due to the power being applied where it needs to right of way. Your not waiting for it to come into the powerband. Its already there when you floor it.
I think your still a little lost on the whole how a converter works.
I think your still a little lost on the whole how a converter works.
08-20-2012, 03:07 PM
#30
OK, I can’t stand the fingernails on the chalkboard any longer. Here’s how it works:
Changing the gear ratio most certainly does change the torque (at a given engine RPM) at the rear wheels in direct proportion to the change in ratio. That’s what they do. That’s why the car will accelerate faster (again, at a given RPM). This is not what the dyno measures.
The dyno measures Horsepower (which cannot be multiplied by gearing) and then calculates Engine Torque (- Drivetrain losses, of course). This is why you will see no difference other than likely a slight loss in both due to larger inertial losses (due to accelerating all the rotational mass of the drivetrain more quickly)—the dyno measures HP which does not change and then calculates how much torque the engine must be producing to make that amount of HP at that RPM.
However, if you plot the two graphs vs. time, you will see the car with the new gears did, in fact, accelerate the drum more quickly (in about the exact proportion to the change in ratio). You will also see the run ended at a lower drum speed (MPH) meaning in an actual race you may accelerate faster in each gear with the new gears but you must shift at lower speeds…which is why there’s a limit to what changing gearing can do (double the gearing the car will be twice as fast!...nope) once you get moving it’s really HP that wins races.
A loose converter throws a little wrench into the mix because it changes its torque multiplication throughout the run. Most dyno software needs (or at least used to, I haven’t kept up with the latest) to pick a single “gear ratio” for the entire run in order to calculate the torque. This is why you sometimes see unrealistic torque spikes on the low end of some graphs where the converter isn’t locked. For evaluating engine performance, those should be ignored.
Changing the gear ratio most certainly does change the torque (at a given engine RPM) at the rear wheels in direct proportion to the change in ratio. That’s what they do. That’s why the car will accelerate faster (again, at a given RPM). This is not what the dyno measures.
The dyno measures Horsepower (which cannot be multiplied by gearing) and then calculates Engine Torque (- Drivetrain losses, of course). This is why you will see no difference other than likely a slight loss in both due to larger inertial losses (due to accelerating all the rotational mass of the drivetrain more quickly)—the dyno measures HP which does not change and then calculates how much torque the engine must be producing to make that amount of HP at that RPM.
However, if you plot the two graphs vs. time, you will see the car with the new gears did, in fact, accelerate the drum more quickly (in about the exact proportion to the change in ratio). You will also see the run ended at a lower drum speed (MPH) meaning in an actual race you may accelerate faster in each gear with the new gears but you must shift at lower speeds…which is why there’s a limit to what changing gearing can do (double the gearing the car will be twice as fast!...nope) once you get moving it’s really HP that wins races.
A loose converter throws a little wrench into the mix because it changes its torque multiplication throughout the run. Most dyno software needs (or at least used to, I haven’t kept up with the latest) to pick a single “gear ratio” for the entire run in order to calculate the torque. This is why you sometimes see unrealistic torque spikes on the low end of some graphs where the converter isn’t locked. For evaluating engine performance, those should be ignored.
08-20-2012, 04:14 PM
#31
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Just put the mutherfuker on a Dyno , it's what? 50~75 bucks?! And you'll know.
Don't forget to add all your stickers together and multiply by .0069 for your hidden horse power.
Don't forget to add all your stickers together and multiply by .0069 for your hidden horse power.
08-20-2012, 05:04 PM
#32
A Torque Converter is a Torque Multiplier as is any gear ratio above 1.0:1 whether in a transmission or rear axle! There are parasitic losses with any torque multipliers but that's a different subject!
You would probably have to talk to an engineer to get an accurate answer to your question!
08-20-2012, 05:28 PM
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Ok, after doing more re-search and speaking with others on this topic, not on this forum, this is what the conclusion was. Torque multiplication and effienciency are directly affected with a higher stall, and also gears. More torque is created, otherwise the same OEM LT1 car with factory stall and gears would have the same ET's as the car with higher stall and gears. HP may not change, but might, but torque does surely. My original question was to " guesstimate " what the added torque might be, which is difficult to figure. I'm at the conclusion, as are others, the torque without a doubt is more, but the number is unknown. I was told the best way to determine is to race another LT1 car, modded, cam, etc., with its HP & torque numbers a known element, then see how far off and compare ET's.............Anyway, I'm done with this topic, thanx for your advice.
A lt1 car making 250 hp at 5000 rpms and 300 tq at 3200 with 3200 stall and 4.10 gears runs 13 flat. Not because the engine is making more power or tq. It runs faster because it can launch at max developed tq and climbs to 5000 rpm quicker because the driveshaft is spinning quicker.
The 1500 stall car is only making say 200 tq out of the hole and 190 hp.
The 3200 stall car is making 300 tq out of the hole and 230 hp.
Both start from a dead stop which means nothing is being multipled as far as gears are concerned.
Car 2 wins because it is making 100 pounds of tq and 40 hp more out of the hole and gets to max hp quicker.
Tq and hp are not multipled the speed or better yet the amount of time it takes to get to max tq and horsepower is multipled.
Last edited by 93 LT1 Vette; 08-20-2012 at 05:49 PM.
08-20-2012, 05:49 PM
#34
The problem with your scenario is the car is moving when its moving down the 1/4 mile not standing still. Different ratios and torque converters multiply the torque produced by the engine as it moves down the track. Statically you are correct in motion you are not.
08-20-2012, 06:12 PM
#35
I am a mechanical engineer and the way he phrased his question he was asking for rear wheel dyno number guesses, which is why I gave him the answer I gave. If he wanted the amount of force being delivered 1 foot away from the center of the tire it is a completely different question.
Last edited by bufmatmuslepants; 08-20-2012 at 06:24 PM.
08-20-2012, 07:02 PM
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I am a mechanical engineer and the way he phrased his question he was asking for rear wheel dyno number guesses, which is why I gave him the answer I gave. If he wanted the amount of force being delivered 1 foot away from the center of the tire it is a completely different question.
08-20-2012, 07:32 PM
#38
You're thinking of power--until something moves no work has been done so no power has been applied/consumed.
08-20-2012, 07:45 PM
#39
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LoL this is still goin on Just DYNO the sombitch already LoL Yes a transmission & gears multiply But the ****** motor hasnt had one mod SO ITS STILL STOCK except for gears that are close to stock & a Little stall converter Still gonna run 14s or 13.9 LoL
08-20-2012, 08:06 PM
#40
The original question was asking his question correctly and others took it off on a tangent! If all factors being equal and you had repeatable runs down the strip there are probably some HP calculators that can give you ball park figures on you numbers of theoretical HP/Torque increase due to torque multiplication.