FE Power Forums
FE Power Forums => Non-FE Discussion Forum => Topic started by: fryedaddy on December 30, 2017, 01:50:11 PM
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i f you took a,say 500 hp engine and put it in a car,how much hp would you lose on the toploader compared to the c6 at the rear wheels?
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Assuming stock internals, the C-6 would eat about 35HP more than a toploader. That's why the switch to a C-4 is so popular; they take way less HP to run...
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To a certain extent, it depends on the internals on the C6. Originally, many 'ordinary' bearings in a C6---now possible to rollerize them. Last I knew, Motorsport had some of these parts available. Back shortly after 2000 I did an article for Mustang Illustrated that showed a C6 done-up with an overdrive and the rollerized parts available at the time.
KS
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I had a discussion about this subject when installing a KenneBell supercharger on my 5.0. Jim Bell figured a C6 or AODE would take about 45-50 peak rwhp compared to a Tko Tremec. These were based on basically stock transmission with higher line pressure shift kit. Amazingly they had tested a couple well put together C4 trans that actually matched the rwhp of a Tremec. I would guess most of these tests were in the 350-500 flywheel hp range.
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I'M doing this from memory, but I believe the number that they used for a modified C6 with roller bearings and all would free up about 20 rwhp. The fact that a C4 has less rotating mass and can be made to live beyond 1000 bhp makes it popular.
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I don`t know about the actual HP differance, but when I switched my Fairmont over to the Jerico 4 speed, from a pretty goood C6 , which had all the low drag needle bearing internals available from Ford Motorsport at the time, 8" convertor, and Art Carr (Ford Motorsport) trans brake, which allowed for 5200 RPM launches (4500 with footbraking), the car, with NO other changes picked up 1/2 second and 6 MPH in the 1/4 mile. 10.55ET @126 MPH, vs 10.03 @ 132 MPH with the stick. Even the very first pass with the Jerico, with way too much clutch, a low RPM launch, hitting the rev limiter 3 times, and having the car all over its lane, was a 10.26, 3 tenths quicker than the C6s best numbers. Acording to my trusty Moroso Power Speed calculator, that 1/2 second 6 MPH gain was worth 60-65 HP, which sounds awfully high, but the numbers on the ET slip don`t lie.
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Jay or others, are you seeing any AODs or any other OD automatic holding together behind an FE in Drag Week or other racing?
I really like the idea of a strong automatic in both my Mustang and my F100, but want OD and have heard more hate with the AOD than the C-4
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I haven't heard anything good about the AOD either; I know a couple people who have had lots of problems with them, despite claims that they can take 1000 HP when properly modified. I'd never risk one behind a strong FE, when an option like the Gear Vendors overdrive is available. The C-4 plus Gear Vendors held up well for me on several Drag Weeks, behind 700 to 900 HP engines.
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Since the C6 is a supersized C4, wondering where the additional power loss is coming from?
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Please explain 'super-sized' as applying to C4-C6. I don't see the comparison except in VERY general terms.
There was a very-viewed 'Turbo' website, frequented particularly by those interested in the '5.0 Ford' Mustangs that took over and wiped-out the Buick turbo craze some years ago. It had a plethora of tech information and many 'sub-' boards. The thinking on the website seemed to be that the C4 could, with proper attention, hold +/- 1000 HP but at that point it was about done. Many of the '5.0' Mustangs had out-powered the C4, according to the comments.
When Jon Corrunker was racing the Thunderbolt, and then the '68 CJ Mustang, he and a guy named Bannister co-owned 'Corban Performance', primarily a Ford transmission shop. I worked at T&C Livonia with Jon and was involved in the goings-on at Corban. At that time Doug Nash was just getting started and was working from his home garage in Garden City. He'd moved past his small-block stocker and had built 'The Bronco Buster', an all aluminum-bodied approximation of an early Bronco---built as a funny car, with a fuel small block. Corban built the C4 transmissions for that car. We rebuilt four of them on a weekly basis, so he'd be able to get through a weekend of racing. He commonly had a C4 last no more than one or two runs.
We've learned since then, but Jim Paquet of JPT, (Ray's brother) was selling C4 transmissions all over the world---had a world map in his office with colored pins for all his customers---and was also of the opinion that 1K was 'all she wrote'.
KS
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Well, the C4 came first of course, then in general terms the internals of the C6 were based off of the C4 except the C6 got a low/reverse clutch pack instead of a band. And the C6 gears, etc were larger. Just can't figure were all these power losses are coming from compared to other automatics. Windage losses?
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My guess would be mainly from the incresed mass of the much larger internal components. Everything was larger, as the C6 was intended for much more powerful and heavier vehicles than the C4 was designed for. All that extra weight takes power to get rotating and keep spinning. Same reason manual transmissions take much less power.
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C6 parts are huge and heavy compared to C4 is why they rob so much power , Ken no roller bearing ever invented is going to make a C6 equal to a C4
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I read somewhere, that the estimate for losses in the pump and converter, plus windage were on the order of 30- 45% in an automatic.
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To a certain extent, it depends on the internals on the C6. Originally, many 'ordinary' bearings in a C6---now possible to rollerize them. Last I knew, Motorsport had some of these parts available. Back shortly after 2000 I did an article for Mustang Illustrated that showed a C6 done-up with an overdrive and the rollerized parts available at the time.
KS
I have a c6/GV setup. It's freaking awesome for a street car. Reasonably cheap to build and bulletproof.
I used to have a build of that here on this forum, I moved it to my own page after photobucket killed the links.
That said, if I was racing, the c6 wouldn't be something I considered. As Rory mentions above, the real deal isn't in HP loss, it's in acceleration of parts. The c6 drums and rotating parts are considerably heavier than a c4's.
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And yet the TH400 has many enthusiasts. I don't remember ever setting one next to a C6 and comparing, but physically they're about the same size. Any comments? (I'm curious and looking to learn.)
KS
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I haven't seen the inside of a T400 in a long time and I remember little to nothing.
I can't speak intelligently on that.
However, I've done lotsa c6's....
The direct drum and rev/high drum are super heavy.
Plus think about those weights, 2nd gear to 3rd the band has to release and accelerate that heavy Rev/High drum up to speed from a stop. I know FrankMerkyl has made a billet aluminum drum that sheds a good bit of weight off that, but still.
I always think the "this transmission takes up X amount of HP" is stupid and really misses the point. I mean, yeah, put both vehicles on a wheel dyno and it looses X amount of power, but it takes the track to see the real effects because a lot of it is shift recovery, etc
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C6 and T400 , both big but the T400 doesn’t use a band for any foward gear , the Race/modern T400’s use a totally different gear train , Stock verses Stock they are pretty equal in performance and durability with the edge going to the T400 in the performance catagory
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Drew , TCI used to have the aluminum drum ( may still ) I have never used one but heard they get wore out quickly, if that’s true might it be a Track only upgrade , if someone not worried about a couple tenths at the Track a C6 is fine
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I am not sure if anybody still uses them, but for years, there was a lot of 428 CJ Stock Eliminator racers who used big $$$ C6s that basically had all MoPar TorqueFlite 904 lightweight internals fit inside the C6 case.
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Drew , TCI used to have the aluminum drum ( may still ) I have never used one but heard they get wore out quickly, if that’s true might it be a Track only upgrade , if someone not worried about a couple tenths at the Track a C6 is fine
The C6 Aluminum drum subject came up a couple years ago, I had tried the TCI version and replied that I saw the high wear issue and no performance change. That might be the discussion you remember. Here's a link to that thread:
http://fepower.net/simplemachinesforum/index.php?topic=2614.msg25472#msg25472
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I am not sure if anybody still uses them, but for years, there was a lot of 428 CJ Stock Eliminator racers who used big $$$ C6s that basically had all MoPar TorqueFlite 904 lightweight internals fit inside the C6 case.
That would be a “Pro Trans” C6. They are still the trick set up for the Ford Stock Eliminator racers. Not cheap, but supposed to be quicker than a prepped C4. Link to their website:
http://www.protransracing.com
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The C6 Aluminum drum subject came up a couple years ago, I had tried the TCI version and replied that I saw the high wear issue and no performance change. That might be the discussion you remember. Here's a link to that thread:
http://www.460ford.com/forum/41-auction-block/210058-there-billet-aluminum-c6-direct-drum.html
Yup.... been two years since he turned those loose.
I guess I could call him, but honestly I don't know that I would use one anyway. Odd that there was no performance gain with your car.... I'd think 9lbs to 3 lbs should have mattered. *shrugs* Never know till you take it out for a few runs.
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I haven't seen the inside of a T400 in a long time and I remember little to nothing.
I can't speak intelligently on that.
However, I've done lotsa c6's....
The direct drum and rev/high drum are super heavy.
Plus think about those weights, 2nd gear to 3rd the band has to release and accelerate that heavy Rev/High drum up to speed from a stop. I know FrankMerkyl has made a billet aluminum drum that sheds a good bit of weight off that, but still.
I always think the "this transmission takes up X amount of HP" is stupid and really misses the point. I mean, yeah, put both vehicles on a wheel dyno and it looses X amount of power, but it takes the track to see the real effects because a lot of it is shift recovery, etc
Here's an interesting take on a real-world trans hp loss from a Ford and a Buick:
http://www.hotrod.com/articles/ccrp-0311-drivetrain-power-loss/
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And yet the TH400 has many enthusiasts. I don't remember ever setting one next to a C6 and comparing, but physically they're about the same size. Any comments? (I'm curious and looking to learn.)
KS
I had to steal this old Car Craft statement from the 'Net 54 460 Forum as the original but now dated CC article seems to have disappeared:
Just in case you're curious, power loss for various auto transmissions:
Please remember these are approximate values, and were provided by Car Craft Magazine.
Powerglide_____18 hp
TH-350________36 hp
TH-400________44 hp
Ford_C-6______55-60 hp
Ford_C-4______28 hp
Ford_FMX______25 hp
Chrysler_A904__25 hp
Chrysler_727___45 hp
Not having ever run a C-6 in competition, we did run an C-4 in a dragster. The internals are markedly lighter in all respects to a C-6. More to the point, a 2-speed Power Glide's internals are even lighter than a C-4's.
And yes, this CC article has been criticized to death by some but I do believe it quite valid. There are some real-world back-to-back tests on the 'Net where racers swapped in a 'Glide for another 3-speed noted above (take your choice) and in almost all cases, even w/o changes to accommodate a 'Glide's charcateristics (engine, tune, shift points, rear gearing, etc.) the reductions in e.t. were quite positive. In fact, most racers use as we know a 'Glide whenever feasible and that ain't no accident!
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I know the original topic is "wheel hp" but that article again misses the point..... It is only testing frictional loss
a 2lb flywheel vs a 50lb flywheel with the engine at full power doesn't show the lack of acceleration ability when being tested for hp. It isn't a linear scale.
Anyway, good luck.
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I always think the "this transmission takes up X amount of HP" is stupid and really misses the point. I mean, yeah, put both vehicles on a wheel dyno and it looses X amount of power, but it takes the track to see the real effects because a lot of it is shift recovery, etc
I'm with Drew on this. I always cringe when I see something like that old Car Craft article because forever after one part of it it gets repeated as "fact" without any thought into what were the testing procedures, any qualifiers the article might have mentioned, or other factors, like Drew mentioned, that might affect the "real world" outcome that was intended, like will my race car run quicker?
You can't put a set number on something like "...how much power will I lose with a C6", there are quite a few variables. For example, the amount of clutches a C6 has will affect it's internal drag, and to a small amount it's rotating weight. A stock C6 could have anywhere from as few as 11 clutches or as many as 15-16, what did the transmission that was tested have? Also as Drew mentioned, when it's in the car, what affect will shift timing have? Ford made hundreds of different C6 valve bodies, all with a different calibration for a specific application, some would no doubt give a better ET than others on any given combination, but may not show up just measuring power loss through the trans. Likewise different combinations of servo pistons & band apply lever ratios. Looking at that Car Craft chart you'd think switching to a Powerglide would automatically make your car go quicker, yet I know plenty of racers who have switched and gone significantly slower, generally due to reducing the first gear ratio and changing the rpm spread between shifts. They didn't necessarily change trying to find a quicker ET, there are other reasons to change, and also may not have optimized the combo, but the point is just you can't fixate on one thing like the power loss through the transmission.
There's no doubt you would probably pick up some significant ET going from a C6 to a C4, Jay Brown has documented his experience here and what he gained. Of course a person also needs to remember that part of the ET will also be from the overall weight reduction of the car, and not just the power loss through the trans. Likewise you could possibly gain some more going to a manual transmission, but maybe not if the clutch combination or gear ratios are not correct for your combination. And with a manual transmission the drivers ability will also affect the ET.
I'm guessing my experience not gaining any ET with the aluminum drum is probably due to that one change just not being enough to measure a difference on my particular combination - taking advantage of lightening all the internal components, and maybe running it in a higher horsepower or lighter car could have different results. But I wanted to check what doing that one change would do, the rapid wear issue I found kept me from continuing with that change.
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Its easy to overstate the importance of the weight of the reciprocating components. I think the reason that the C-6 is such a power hog is because of its internal friction, and the weight of the internal components is not as important. You can calculate the amount of power required to accelerate an object of specific mass at a known acceleration rate, so let's do that for a couple of flywheel examples.
First we need to know the flywheel weight and diameter. Let's use some realistic examples, say a 16 pound aluminum flywheel vs. a 40 pound steel flywheel. Both flywheels are 13" in diameter. In the English system of units we will be calculating each flywheel's moment of inertia in a unit called Slug-Feet. So, to start with we have to convert the flywheel's weight into its mass in Slugs, which means dividing the weight of the flywheel by the acceleration due to gravity (32.2 feet/sec^2). So for the aluminum flywheel we have 16/32.2, or 0.497 Slugs. For the steel flywheel we have 40/32.2, or 1.242 Slugs. Then, we need the radius of the center of mass of the flywheel. This is basically a radius where the mass on the outside of the radius equals the mass on the inside of the radius. Its kind of like center of gravity of an object, if that makes it more clear. For a perfect disc, the radius of the center of mass is 0.707 multiplied by the actual radius. For our flywheel, 0.707 * 6.5" is 4.595". However, the center of the flywheel is typically recessed a little so it weighs less, and there's a hole in the middle of course, so to try to be more accurate we're going to cheat the center of mass radius up to 5.0". Finally we will divide that number by 12 to get the units in feet, which is 0.417 feet.
Now we can calculate the moment of inertia, which is simply the mass in slugs multiplied by the radius of the center of mass squared. So, for the aluminum flywheel, this is 0.497 * 0.417 * 0.417, or 0.0864. For the steel flywheel, we have 1.242 * 0.417 * 0.417, or 0.216. Comparing these numbers, we can see that it will take 2.5 times the power to accelerate the steel flywheel compared to the aluminum flywheel. Of course, this is just the ratio of the weights of the two flywheels. But now that we have the moment of inertia for each flywheel, we can figure out exactly how much torque is required to accelerate the flywheels at a given rate.
Let's start with a high acceleration rate, say 1000 RPM (rotations per minute) per second. In order to use the moment of inertia calculation we have to convert this to radians per second^2 (radians per second per second). There are 6.28 radians in each revolution, so this is 6280 radians per minute per second. Divide by 60 and we have 104.67 radians per second^2. Multiply this by the moment of inertia and you get the torque in lb-ft required to accelerate the flywheel at this rate. So, for the aluminum flywheel this is 9.05 lb-ft, and for the steel flywheel this is 22.6 lb-ft. So, you will gain about 13.55 lb-ft of torque at the flywheel if you change from a steel flywheel to an aluminum flywheel and accelerate at 1000 RPM/sec.
Now let's do a lower acceleration rate, say 300 RPM per second, which is typical for a dyno pull. For 300 RPM per second the acceleration works out to 31.42 radians/sec^2. For the aluminum flywheel, torque to accelerate at this rate is 2.71 lb-ft, and for the steel flywheel the value is 6.79 lb-ft. So, on the dyno, if you swapped from a steel flywheel to an aluminum flywheel and ran your dyno pulls at 300 RPM/second, you would see about 4 lb-ft more torque.
Now having said all this, let's think about where the big inertia losses are inside a transmission. Remember that the bigger the diameter of the component, the larger the radius of the center of mass will be, and the more torque it will take to accelerate for a given mass. Obviously, a big torque converter is a relatively large diameter, heavy object, especially when filled with fluid, so going to a smaller diameter converter will take a big chunk out of the torque required. But how about the internals? Earlier in this thread there was some discussion of a 3 pound aluminum drum vs. a 9 pound steel drum. I don't know offhand what the diameter of a C-6 drum is, but I'm going to guess about 7", from measuring the outside of a C-6 that I have here. Doing the previous calculations and using 80% of the radius of the drum for the radius of the center of mass (again just an estimate, because most of the mass of the drum is at the outside), I come up with 1.59 lb-ft required to accelerate the heavy drum at 1000 RPM/second, and 0.53 lb-ft required for the light drum. So, swapping to the lightweight drum will get you about 1 lb-ft of torque when accelerating at 1000 RPM/second.
The key thing to note here is that the diameter of the component has an outsized effect on the torque required to accelerate it, because the radius of the center of mass of the component is squared in the equation. The internal components of the transmission, with the exception of the torque converter, are all relatively small in diameter. They just won't make a big difference. The same thing goes for harmonic balancers, crank journals, driveshafts, etc. The smaller the diameter of the driveline component, the less torque it will take to accelerate it. I look at gun-drilled axles, for example, and can't believe that there is any tangible benefit to gun drilling them, because the diameter of the removed material is so small.
In any case, the small diameter of the interior components of a transmission make me believe that lightening them up will not have a significant effect on power consumed by the trans, and that's why I think internal friction is the big issue with the C-6.
One more relevant piece of information is contained in the chart below. Here, I took the same engine on the dyno and accelerated it at three different rates, 100, 300, and 600 RPM/sec. Obviously, the slower you accelerate, the more power is available from the engine:
(http://fepower.net/Photos/Posts/AccRates.JPG)
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TCI used to have the aluminum drum , I was considering doing mine back in the late 90's , fought the 2-3 shift for years with different servo's and levers , found Merkl way after the fact on 460. com about the bath tub route too big causing the 2-3 check ball to not function in a timely manner , the next time I go through it the TCI Trans brake VB is going trash can but my car is a manual trans now..... as far as the C6 power rob I would guess planetary gears helical angle is causing more friction than the straighter cut gears just like manual transmission along with big heavy parts
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I read somewhere, that the estimate for losses in the pump and converter, plus windage were on the order of 30- 45% in an automatic.
Not to be argumentative, because I've seen articles that quote similar figures, but just for discussion, where I have issues with these statements is in the real world results. I've been drag racing for a long time, and I've followed the NHRA records for that time. For a class like Stock Eliminator, the closest thing to the type of cars most of us have, the records on any given class are generally within a tenth of a second between the stick shift cars and the automatics, and the automatic isn't always the slowest. This has been the case for 30+ years, even with all the changes in drag race manual transmissions. If it was a "rule" that an automatic always had a power loss of a third to almost half there would be a significant difference in there elapsed times, and yet for decades that hasn't been the case.
Now to be fair, this isn't exactly an apples to apples comparison. I just looked at the NHRA records hoping I might find a pair of 428 CJ Mustangs to make the example and unfortunately there weren't any of our FE racers holding the records at this time, there are a couple '69 big block Camaro's in A/SA and A/S respectfully, and they are within a tenth of a second of each other, and plenty of other examples if you go through the list comparing. But I realize this isn't a comparison of the exact same car and engine with just a transmission change, but my point is just that if a blanket huge power loss always applied we would see large differences in the ET, and they're just not there, and the general trend is always the same.
But this is all a bit off topic of the original question of what the measurable rear wheel power loss would be. Not everyone is drag racing their car, and in the case of drag racing I think a lot of people forget the advantage an automatic has with a torque convertor multiplying the torque at stall, it was just meant to say be careful of numbers that get thrown about of "X" amount of horsepower or a percentage of loss as being definitive. For any given car & combo you may or may not feel it in the seat of the pants or driving experience.
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Kevin---
As you might imagine, I have followed this particular subject with more than a bit of interest. You wrapped it all up very succinctly!
Thank you.
KS
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a lot of good info.thank you
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I'm with Drew on this. I always cringe when I see something like that old Car Craft article because forever after one part of it it gets repeated as "fact" without any thought into what were the testing procedures, any qualifiers the article might have mentioned, or other factors, like Drew mentioned, that might affect the "real world" outcome that was intended, like will my race car run quicker?
I actually agree but LOVE to post that now old article!
Why, one may ask?
Simply because I'm trying to draw out much more modern, compresensive and track-tested articles on the very same subject, rear wheel hp notwithstanding. So far no takers nor articles.......
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the original question was comparing a c6 to a top loader,not other automatics.but still a lot of great info and opinions