Scott Marzahl

Standard Ratio Gearset - 3.37, 1.99, 1.34, 1.0, .67 (1.38 step change in 1st, 33% RPM drop in overdrive)
RS400 (400 torque): 1-1/16 x 10 spline input shaft, SAE 8620 nickel-moly steel alloy
RS500 (500 torque): 1-1/8 x 26 spline input shaft, SAE 9310 chrome-nickel-moly high strength steel alloy, CNC ground gears

Close Ratio Gearset (new)- 2.80, 1.99, 1.34, 1.0, .67 (.81 step change in 1st, 33% drop in overdrive)
RS600 (600 torque): 1-1/8 x 26 spline input shaft, SAE 9310 chrome-nickel-moly high strength steel alloy, CNC ground gears

Maybe its just me but does anyone question why the step between first and secone gear in the wide ratio is so big, its like a granny gear and then there is a huge drop to second. For a 327 I'm thinking the RS600 is the better choice but I certainly do not need the torque rating it offers or the added price to get a close ratio box.

Les

I called them yesterday to inquire about this. They have no plans to make the 400 or 500 version with the close ratio first gear- the 600 is the only choice if that's what you want. I'm interested in a unit for the car in my avatar because it has 4.10 rear gears and the close ratio Muncie 4 speed that it came with. The 600 is my only option or 1st gear would be worthless. He said the 600 is the same trans as the 500 except with the close ratio 1st gear. I asked about the different torque ratings between the two, wondering if the extra torque multiplication of the lower 1st gear ratio in the 500 made it more vulnerable to failure, but never got a clear answer. Other than that he was real nice and very helpful. I'm in no rush so I'll see what kind of reviews they get as more people start using them.

Billysvette

How much hp can each trans handle? Does anybody know?

gkull

HP is "number" that is why they give a TQ rating and the TKO 600 is a 24 hour test not just a motor that flashes to 600 every once in awhile

This is a good read

There's been a certain amount of discussion, in this and other files, about the concepts of horsepower and torque, how they relate to each other, and how they apply in terms of automobile performance. I have observed that, although nearly everyone participating has a passion for automobiles, there is a huge variance in knowledge. It's clear that a bunch of folks have strong opinions (about this topic, and other things), but that has generally led to more heat than light, if you get my drift :-). I've posted a subset of this note in another string, but felt it deserved to be dealt with as a separate topic. This is meant to be a primer on the subject, which may lead to serious discussion that fleshes out this and other subtopics that will inevitably need to be addressed.
OK. Here's the deal, in moderately plain english.


Force, Work and Time
If you have a one pound weight bolted to the floor, and try to lift it with one pound of force (or 10, or 50 pounds), you will have applied force and exerted energy, but no work will have been done. If you unbolt the weight, and apply a force sufficient to lift the weight one foot, then one foot pound of work will have been done. If that event takes a minute to accomplish, then you will be doing work at the rate of one foot pound per minute. If it takes one second to accomplish the task, then work will be done at the rate of 60 foot pounds per minute, and so on.
In order to apply these measurements to automobiles and their performance (whether you're speaking of torque, horsepower, newton meters, watts, or any other terms), you need to address the three variables of force, work and time.

Awhile back, a gentleman by the name of Watt (the same gent who did all that neat stuff with steam engines) made some observations, and concluded that the average horse of the time could lift a 550 pound weight one foot in one second, thereby performing work at the rate of 550 foot pounds per second, or 33,000 foot pounds per minute, for an eight hour shift, more or less. He then published those observations, and stated that 33,000 foot pounds per minute of work was equivalent to the power of one horse, or, one horsepower.

Everybody else said OK. :-)

For purposes of this discussion, we need to measure units of force from rotating objects such as crankshafts, so we'll use terms which define a *twisting* force, such as foot pounds of torque. A foot pound of torque is the twisting force necessary to support a one pound weight on a weightless horizontal bar, one foot from the fulcrum.

Now, it's important to understand that nobody on the planet ever actually measures horsepower from a running engine. What we actually measure (on a dynomometer) is torque, expressed in foot pounds (in the U.S.), and then we *calculate* actual horsepower by converting the twisting force of torque into the work units of horsepower.

Visualize that one pound weight we mentioned, one foot from the fulcrum on its weightless bar. If we rotate that weight for one full revolution against a one pound resistance, we have moved it a total of 6.2832 feet (Pi * a two foot circle), and, incidently, we have done 6.2832 foot pounds of work.

OK. Remember Watt? He said that 33,000 foot pounds of work per minute was equivalent to one horsepower. If we divide the 6.2832 foot pounds of work we've done per revolution of that weight into 33,000 foot pounds, we come up with the fact that one foot pound of torque at 5252 rpm is equal to 33,000 foot pounds per minute of work, and is the equivalent of one horsepower. If we only move that weight at the rate of 2626 rpm, it's the equivalent of 1/2 horsepower (16,500 foot pounds per minute), and so on. Therefore, the following formula applies for calculating horsepower from a torque measurement:

Torque * RPM

Horsepower = ------------

5252


This is not a debatable item. It's the way it's done. Period.
The Case For Torque
Now, what does all this mean in carland?
First of all, from a driver's perspective, torque, to use the vernacular, RULES :-). Any given car, in any given gear, will accelerate at a rate that *exactly* matches its torque curve (allowing for increased air and rolling resistance as speeds climb). Another way of saying this is that a car will accelerate hardest at its torque peak in any given gear, and will not accelerate as hard below that peak, or above it. Torque is the only thing that a driver feels, and horsepower is just sort of an esoteric measurement in that context. 300 foot pounds of torque will accelerate you just as hard at 2000 rpm as it would if you were making that torque at 4000 rpm in the same gear, yet, per the formula, the horsepower would be *double* at 4000 rpm. Therefore, horsepower isn't particularly meaningful from a driver's perspective, and the two numbers only get friendly at 5252 rpm, where horsepower and torque always come out the same.

In contrast to a torque curve (and the matching pushback into your seat), horsepower rises rapidly with rpm, especially when torque values are also climbing. Horsepower will continue to climb, however, until well past the torque peak, and will continue to rise as engine speed climbs, until the torque curve really begins to plummet, faster than engine rpm is rising. However, as I said, horsepower has nothing to do with what a driver *feels*.

You don't believe all this?

Fine. Take your non turbo car (turbo lag muddles the results) to its torque peak in first gear, and punch it. Notice the belt in the back? Now take it to the power peak, and punch it. Notice that the belt in the back is a bit weaker? Fine. Can we go on, now? :-)


The Case For Horsepower
OK. If torque is so all-fired important, why do we care about horsepower?
Because (to quote a friend), "It is better to make torque at high rpm than at low rpm, because you can take advantage of *gearing*.

For an extreme example of this, I'll leave carland for a moment, and describe a waterwheel I got to watch awhile ago. This was a pretty massive wheel (built a couple of hundred years ago), rotating lazily on a shaft which was connected to the works inside a flour mill. Working some things out from what the people in the mill said, I was able to determine that the wheel typically generated about 2600(!) foot pounds of torque. I had clocked its speed, and determined that it was rotating at about 12 rpm. If we hooked that wheel to, say, the drivewheels of a car, that car would go from zero to twelve rpm in a flash, and the waterwheel would hardly notice :-).

On the other hand, twelve rpm of the drivewheels is around one mph for the average car, and, in order to go faster, we'd need to gear it up. To get to 60 mph would require gearing the wheel up enough so that it would be effectively making a little over 43 foot pounds of torque at the output, which is not only a relatively small amount, it's less than what the average car would need in order to actually get to 60. Applying the conversion formula gives us the facts on this. Twelve times twenty six hundred, over five thousand two hundred fifty two gives us:

6 HP.

Oops. Now we see the rest of the story. While it's clearly true that the water wheel can exert a *bunch* of force, its *power* (ability to do work over time) is severely limited.


At The Dragstrip
OK. Back to carland, and some examples of how horsepower makes a major difference in how fast a car can accelerate, in spite of what torque on your backside tells you :-).
A very good example would be to compare the current LT1 Corvette with the last of the L98 Vettes, built in 1991. Figures as follows:

Engine Peak HP @ RPM Peak Torque @ RPM

------ ------------- -----------------

L98 250 @ 4000 340 @ 3200

LT1 300 @ 5000 340 @ 3600


The cars are geared identically, and car weights are within a few pounds, so it's a good comparison.
First, each car will push you back in the seat (the fun factor) with the same authority - at least at or near peak torque in each gear. One will tend to *feel* about as fast as the other to the driver, but the LT1 will actually be significantly faster than the L98, even though it won't pull any harder. If we mess about with the formula, we can begin to discover exactly *why* the LT1 is faster. Here's another slice at that formula:

Horsepower * 5252

Torque = -----------------

RPM


If we plug some numbers in, we can see that the L98 is making 328 foot pounds of torque at its power peak (250 hp @ 4000), and we can infer that it cannot be making any more than 263 pound feet of torque at 5000 rpm, or it would be making more than 250 hp at that engine speed, and would be so rated. In actuality, the L98 is probably making no more than around 210 pound feet or so at 5000 rpm, and anybody who owns one would shift it at around 46-4700 rpm, because more torque is available at the drive wheels in the next gear at that point.
On the other hand, the LT1 is fairly happy making 315 pound feet at 5000 rpm, and is happy right up to its mid 5s redline.

So, in a drag race, the cars would launch more or less together. The L98 might have a slight advantage due to its peak torque occuring a little earlier in the rev range, but that is debatable, since the LT1 has a wider, flatter curve (again pretty much by definition, looking at the figures). From somewhere in the mid range and up, however, the LT1 would begin to pull away. Where the L98 has to shift to second (and throw away torque multiplication for speed), the LT1 still has around another 1000 rpm to go in first, and thus begins to widen its lead, more and more as the speeds climb. As long as the revs are high, the LT1, by definition, has an advantage.

Another example would be the LT1 against the ZR-1. Same deal, only in reverse. The ZR-1 actually pulls a little harder than the LT1, although its torque advantage is softened somewhat by its extra weight. The real advantage, however, is that the ZR-1 has another 1500 rpm in hand at the point where the LT1 has to shift.

There are numerous examples of this phenomenon. The Integra GS-R, for instance, is faster than the garden variety Integra, not because it pulls particularly harder (it doesn't), but because it pulls *longer*. It doesn't feel particularly faster, but it is.

A final example of this requires your imagination. Figure that we can tweak an LT1 engine so that it still makes peak torque of 340 foot pounds at 3600 rpm, but, instead of the curve dropping off to 315 pound feet at 5000, we extend the torque curve so much that it doesn't fall off to 315 pound feet until 15000 rpm. OK, so we'd need to have virtually all the moving parts made out of unobtanium :-), and some sort of turbocharging on demand that would make enough high-rpm boost to keep the curve from falling, but hey, bear with me.

If you raced a stock LT1 with this car, they would launch together, but, somewhere around the 60 foot point, the stocker would begin to fade, and would have to grab second gear shortly thereafter. Not long after that, you'd see in your mirror that the stocker has grabbed third, and not too long after that, it would get fourth, but you'd wouldn't be able to see that due to the distance between you as you crossed the line, *still in first gear*, and pulling like crazy.

I've got a computer simulation that models an LT1 Vette in a quarter mile pass, and it predicts a 13.38 second ET, at 104.5 mph. That's pretty close (actually a tiny bit conservative) to what a stock LT1 can do at 100% air density at a high traction drag strip, being powershifted. However, our modified car, while belting the driver in the back no harder than the stocker (at peak torque) does an 11.96, at 135.1 mph, all in first gear, of course. It doesn't pull any harder, but it sure as hell pulls longer :-). It's also making *900* hp, at 15,000 rpm.

Of course, folks who are knowledgeable about drag racing are now openly snickering, because they've read the preceeding paragraph, and it occurs to them that any self respecting car that can get to 135 mph in a quarter mile will just naturally be doing this in less than ten seconds. Of course that's true, but I remind these same folks that any self-respecting engine that propels a Vette into the nines is also making a whole bunch more than 340 foot pounds of torque.

That does bring up another point, though. Essentially, a more "real" Corvette running 135 mph in a quarter mile (maybe a mega big block) might be making 700-800 foot pounds of torque, and thus it would pull a whole bunch harder than my paper tiger would. It would need slicks and other modifications in order to turn that torque into forward motion, but it would also get from here to way over there a bunch quicker.

On the other hand, as long as we're making quarter mile passes with fantasy engines, if we put a 10.35:1 final-drive gear (3.45 is stock) in our fantasy LT1, with slicks and other chassis mods, we'd be in the nines just as easily as the big block would, and thus save face :-). The mechanical advantage of such a nonsensical rear gear would allow our combination to pull just as hard as the big block, plus we'd get to do all that gear banging and such that real racers do, and finish in fourth gear, as God intends. :-)

The only modification to the preceeding paragraph would be the polar moments of inertia (flywheel effect) argument brought about by such a stiff rear gear, and that argument is outside of the scope of this already massive document. Another time, maybe, if you can stand it :-).


At The Bonneville Salt Flats
Looking at top speed, horsepower wins again, in the sense that making more torque at high rpm means you can use a stiffer gear for any given car speed, and thus have more effective torque *at the drive wheels*.
Finally, operating at the power peak means you are doing the absolute best you can at any given car speed, measuring torque at the drive wheels. I know I said that acceleration follows the torque curve in any given gear, but if you factor in gearing vs car speed, the power peak is *it*. An example, yet again, of the LT1 Vette will illustrate this. If you take it up to its torque peak (3600 rpm) in a gear, it will generate some level of torque (340 foot pounds times whatever overall gearing) at the drive wheels, which is the best it will do in that gear (meaning, that's where it is pulling hardest in that gear).

However, if you re-gear the car so it is operating at the power peak (5000 rpm) *at the same car speed*, it will deliver more torque to the drive wheels, because you'll need to gear it up by nearly 39% (5000/3600), while engine torque has only dropped by a little over 7% (315/340). You'll net a 29% gain in drive wheel torque at the power peak vs the torque peak, at a given car speed.

Any other rpm (other than the power peak) at a given car speed will net you a lower torque value at the drive wheels. This would be true of any car on the planet, so, theoretical "best" top speed will always occur when a given vehicle is operating at its power peak.

"Modernizing" The 18th Century
OK. For the final-final point (Really. I Promise.), what if we ditched that water wheel, and bolted an LT1 in its place? Now, no LT1 is going to be making over 2600 foot pounds of torque (except possibly for a single, glorious instant, running on nitromethane), but, assuming we needed 12 rpm for an input to the mill, we could run the LT1 at 5000 rpm (where it's making 315 foot pounds of torque), and gear it down to a 12 rpm output. Result? We'd have over *131,000* foot pounds of torque to play with. We could probably twist the whole flour mill around the input shaft, if we needed to :-).

The Only Thing You Really Need to Know!

Repeat after me. "It is better to make torque at high rpm than at low rpm, because you can take advantage of *gearing*." :-)
Thanks for your time.

George

Billysvette

Ive got a headache now I just wanted to know if these transmissions could handle high hp or torgue. are they as strong as the tkos?would it hold up to a 572 GM crate engine?

Les

George likes giving people headaches. The numbers assigned to each transmission correspond to their torque rating- 400, 500, and 600.

MotorHead

I put ~ 600tq through miine evey timei I take it out more then one too, they will hwndle anythhng you put through it short of a S/C big block

Billysvette

Thank you,kinda what i thought.

zwede

That would be a good Q for Keisler. When Tremec rates a transmission it's 24 hours sustained load. Does Keisler rate the same way? If so, I wouldn't hesitate to put a transmission rated for 500 ft-lbs behind a 600 ft-lbs motor. Actually, that's exactly what I did years ago: The original Tremec TKO (rated 500 ft-lbs) has lived behind my 550+ ft-lbs 454 for years with no problems at all. I recently bumped the cam & compression up a bit and I'm making closer to 600 ft-lbs now. I don't expect any problems.

ToniH

I too would like to hear from Keisler how the new RS boxes compare to TKO's in strength.

weinh

Sounds like the torque on the layshaft and the final gear set, created by 1st gear ratio, is the bottleneck in terms of tolerable mechanical stress.

2nd to 5th gears are able to handle the 600 ft-lbs anyway and by reducing the 1st from 3.37 to 2.80 leads to exactly 20% less load which is needed to increase torque capacity from 500 to 600 ft-lbs.

Carsten

MotorHead

Someone here has the TKO 600 on a chassis dyno at around 1000 HP or so with no problems.

Between two identicall transmissions it seems the first gear dictates the HP/Torque rating. The lower the first gear the lower the tranny is rated at.

If you look at the front page of the Keisler website they have 2 trannys
there that I believe are identical except for the first gear. The one with the 2.8 1st is rated at 600ft/lbs and the one with the 3.37 1st is rated lower at 500 ft/lbs

Kevin68

gkull, Thanks for posting that. It improved my understanding of HP vs Torque, in a practical (automotive) sense, well beyond what my physics classes ever did.

Scott Marzahl

According to an older post I found in the C2 section Keisler stated that the RS400 can be ordered with a close ratio 2nd gear set making it a RS400C and for future HP upgrades all one has to do in change the main input shaft. What about the internal bearings and gear cuts, do they all remain the same? From the limited information about these RS transmissions it seems to read or imply that these are starting out as used transmissions and the advertsing states something to the effect that all worn parts are replaced or upgraded I for one being a mechanical engineer want to read/see exactly what has been upgraded in these T45s. The T45 has been known to have had problems in the Mustangs over the years which do not put out anywhere close to 500 or 600 ft lbs of torque. What has Keisler done above and beyond what BW did during the design and testing of these units for production?

Also with regards to the use of Carbon fiber, we all know at least one top rear-end rebuilder who will not use carbon fiber clutch disks for the simple reason they do not hold up in high torque/ HP applications, fine for a mild HP application otherwise they comes apart. So it will be very interesting to see how these transmissions hold up in some of these applications.

Before I plunk down this much cash I want to know exactly what I'm buying.

gkull

I changed out my 4.11 rear gears with my tko 600 because first gear was kind of worthless. In a full on drag race type launch with sticky slicks. You really needed a shift light because in about 1.5 seconds or 60 feet you already have to yank it down into second gear because you would be going into the rev limiter at 7000 rpm.

4.10 is fun in OD. I had a friend that want to experiece high speed in my vette. so just for fun I ran it up to just over 6000 rpm in 5th (@180mph)

This will help your figure out what tranny a rear gears you need


http://www.secondstrike.com/Technical/GearCalc.asp


Second Strike Gearing Calculator

4.10 rear end gears

335 Rear Tire Width 35 Rear Tire Aspect Ratio 17 Rear Rim Diameter

Speed (MPH) in Gears at RPM

Gear 1st 2nd 3rd 4th 5th
Trans Ratio 2.87 1.89 1.28 1.00 0.64
Overall Ratio 11.77 7.75 5.25 4.10 2.62
Split 1.52 1.48 1.28 1.56
Rev/Mile 9,309 6,130 4,152 3,243 2,076
1500 10 15 22 28 43
2000 13 20 29 37 58
2500 16 24 36 46 72
3000 19 29 43 55 87
3500 23 34 51 65 101
4000 26 39 58 74 116
4500 29 44 65 83 130
5000 32 49 72 92 145
5500 35 54 79 102 159
6000 39 59 87 111 173
6500 42 64 94 120 188
7000 45 69 101 129 202

Ray Y

OK it's been a couple of months since this post came to life about the RS tranny's.....IS ANYBODY RUNNING ONE YET THAT CAN COMMENT ON HOW WELL IT PERFORMS IN A C3?

I called Kiesler today to order a new speedo gear for my TKO600 since I've just installed a new 3.73 rear gear set, while looking up their phone number on the website I saw the RS advertisement. Of course I had to inquire about it since my biggest beef with the TKO is hitting 3rd gear consistently if pushing it hard. Lead time is quoted at 90+ days right now I was told that one of the gear vendors had gone TU and they were scrambling to find a second source, hence the long lead time. They did acknowledge the 24 hrs at 600 ft lbs for torque rating and said "probably OK" for instantanous 650 ft lbs. The only option they have for >700 is a 6 speed. This would be cool for a road race/strip combo application with the close ratio of the new RS600 and if 1:1 was 4th gear then 0.82 and 0.67 final OD.

I think I'll wait a year and see what's happening then.

MN80Vette

I am in line to receive a RS500 in June. I hope to find another C3 with a TKO for a side-to-side comparison at Car Craft Summer Nationals in St. Paul. Of course, we'd post our impression here. You may not need to wait a year to see what's happening with TKO vs. RS conversions.

shmoky

GREAT I will be waiting and looking for that comparison MN80

shmoky

shrekviper

I'm waiting for my RS600 still. I ordered just before X-MAS '10...which puts me as one of the first.

I think the RS500s may have started to ship.

JD ZR1

I have a 67 L79 350 hp with 3:70 rear gear. Any ideas on using the new RS trans 400 vs 500..non racing just cruising.