kevin87turbot

iTrader: (2)

Where did you get that torque rating from for the TCI planetary? It is incorrect. The design limit is much higher than that. It has been tested to over 1200 ft lbs without failure.

kevin87turbot

iTrader: (2)

Quoted from TrueBlueGTO,
"A TCI 6x 4L80 still falls in line with the stock 4L80 because the main ratios do not change. The extra 'split' gears may keep the engine within a narrower powerband, so the engine pulls better than a built 4L80, but each gear (and overall average) torque multiplication is still the lowest of the bunch".

Actually, the TCI 6X ratios are significantly changed from stock.
They are: 2.97, 2.23, 1.57, 1.18, 1.0, .75

kevin87turbot

iTrader: (2)

[QUOTE=poorhousenext;14449294]Got a question.


Kevin, this ones for you.

Why would you want to take a 4L80E, Give it 5 non overdrive gears that almost gear it the same as a 6 speed T56 manual trans, except for a 1:1 5th gear and only 1 OD gear thats 0.75 instead of 0.67, or at least a 0.70?

I'm sure from post people have made on this site and others, People realize that they are going to be screaming down the road at 150 RPM higher than if 6th gear was 0.70 if they swap to a 4l80E or 4L80E based 6 speed.

Thats way to many RPM to accept for a stronger transmission. Never mind they probably need the extra mechanical advantage of it to help the engine overcome the 4 X 8 Sheet of Plywood in a Hurricane aerodynamic of the older cars they want to install it in.

Are you looking for gas mileage? We don't need no stinking gas mileage.

Seriously though, the 6X gear ratios are more performance oriented that fuel economy oriented. I've probably already told you, but I removed the transbrake 4L80E from our test vehicle and installed the 6X in it. On back to back trips to the track with atmospheric conditions within 100', it went from a best of 12.44 with the 4L80E to a best of 12.29 with the 6X.

Litte more gear comparsion to get people thinking. A 1.15 or 1.18 4th gear ratio may be of help when trying to decide on what rear end ratio you can get away with vs if you have a 1:1 4th, both at strip and on the street.

If you don't have a 1:1 final drive trans gear, then you might want to watch what your top speed will be at max RPM with some gear ratios are stay away form longer runs of more than 1/4 mile are you may find you are going to be in O.D. sooner than you thought and the car passing you is still in a 1:1 gear.

TrueBlueGTO

So it is even whips the stock 4L80...but it's still not enough to overcome the deficit in the first 2 gears compared to the 6L80/90.

It's funny how so many people claim the 4.02 ratio first gear makes a 6L80/90 useless, but yet they'd jump at the chance to get 526 tq power with a 4L70. (526 x 3.06 = 1609 in 1st gear) or 648 tq with the 4L80.

poorhousenext

Like I said, "I'm not a smart man] , Taught to bring my on sword to a fight if I thought fight might be even, if not bring a good gun. Looked at your way of looking at things as always trying to learn.. Decided to just unsheathe my sword, but bring the gun just in case, just try to keep it in it's holster for now.

Need to warn you with a little advice. "Never argue with a Fool, they'll drag you down to their level and beat you with their experience...

This Fool, is going to see if he can drag you down to his level using info previously posted by others.

I don't think your statement above about the TCI 6X six speed gearing being no better than that of a 4L80E gearing is all that accurate... So I decided to look at it like you have, only I thought I might better use Red Neck pencil & paper as this fool's not educated enough to try to do it with Spreads & Sheets or combination of both. We use them on beds...

You might want to use that Spread & Sheet to verify I didn't use my pencil to tilt the numbers to my favor.

Looks like the TCI 6X may just be able to come close to being able to hold it's on against the 6L in gear dept. It being able to do that may just hinge on how well the 6L's and its way gear shift hand off can improve RPM drop between shifts over way ya'll judge all other automatics by. I think it might just lessen the drop some, but remember I'm a Fool so don't let me drag you down to my level.

I change TQ to that of a LS3 376/480HP crate engine and rear end gearing to that use in Pontiac G8's with 6l80E transmission. Cyphered the numbers and came up with below results...

Copied the RPM Retention and Drop data on both transmission to see how that might even the fight a little bit too.

I kind of like the TCI 6X chances in a 1/4 race of equeals and like it more when you stretch the race out to a mile.

TCI 6X (4L80E based)
475 TQ X 2.93 1st = 1391.75 X 3.27 = 4551.02

475 TQ X 2.23 2nd = 1059.25 X 3.27 = 3463.75

475 TQ X 1.57 3rd = 745.75 X 3.27 = 2438.60

475 TQ X 1.18 4th = 560.50 X 3.27 = 1832.84: Avg TQ = 939.31 & Avg @ wheel = 3071.55

475 TQ X 1.00 5th = 475.00 x 3.27 = 1553.25

6L80/90
475 TQ X 4.02 1st = 1909.50 X 3.27 = 6244.07

475 TQ X 2.36 2nd = 1121.00 X 3.27 = 3665.67

475 TQ X 1.53 3rd = 726.75 X 3.27 = 2376.47

475 TQ X 1.15 4th = 546.25 X 3.27 = 1786.27 , Avg TQ 1075.88 Avg @ wheel 3518.12

4.75 TQ X 0.85 5th = 403.75 x 3.27 = 1320.63

TCI 6X (4L80E based)
2.93
2.23 -- 76.10% (high) RPM Retention -- 23.90% RPM DROP
1.57 -- 70.40% (high) RPM Retention -- 29.60% RPM DROP
1.18 -- 75.16% (high) RPM Retention -- 24.84% RPM DROP
1.00 -- 84.745% (high) RPM Retention -- 15.255% RPM DROP
0.75 -- 75.00% (high) RPM Retention -- 25.00% RPM DROP

6L80/90
4.03
2.36 -- 58.56% (high) RPM Retention 41.44% RPM DROP
1.53 -- 64.83% (high) RPM Retention 35.17% RPM DROP
1.15 -- 75.16% (high) RPM Retention 24.84% RPM DROP
0.852 -- 74.09% (high) RPM Retention 25.91% RPM DROP


I'm not into juiced or or High HP engines that make their power high up in the RPM range either. I like my cars to be fun reliable drivers. I try to make a combination work for me. You can't play your way if your goal is a Pro Touring Car. They have to be more than a straight line one dimension car or just a daily grocery getter.

I agree with you that a 6L can live behine 400 TQ all day long, junkyard are not.

Question: Can it make 50 passed a Drag strip and live, along with that daily driving? For the answer to that you might want to pay a vist to my friend over on Corvette Fourm.....

PS: Hope you don't take offense at my try at adding a little humor to this novel of a post... A Fools job is to entertain, not educate...

TrueBlueGTO

PoorHouseNext you can't trick me...my roots are in the south, so i know a 'possum when I see one...you're hardly a fool! lol

I'm a true competitor...so I always welcome a challenge...winning, of course, is to be expected, but losing is not the time to turn into a sore loser, but an opportunity to make one a better competitor bc one (should) learn from the experience. I welcome anyone reasonable to find ****** in my armor/theories...I assure you that it will only happen once because next battle that weak link will be welded up like a sumbitch!! lol

Seriously though, I'm an advocate of the 6L80/90 bc I did the number crunching...and no matter how I looked at it...there was nothing out there that compared with all around value. I just use some good ol' common sense. Don't get me wrong. The aftermarket is great at offering great products...but they are usually IMPROVEMENTS to OEM. Further, they're only improving what the OEM already was aware of, but simply didn't want to spend the production money on to fix. Considering that the OEM has a multi million dollar budget, engineering nerds with scientific know-how to challenge NASA, and access to international technologies, it doesn't take a genius to see that they know something we don't when they make a part, more or less, the standard part across the board. So why fight it? Why make excuses for what you don't understand? As I did and as you do...ask questions. Seek answers. Embrace the technology.

Sure a '62 Impala SS with heavy BBC, gas dumping carbs, a Powerglide and 4.30 gears is a great nostalgic muscle car...but would I want to retrograde the driveability of my '07 TBSS into one? Nah

Being in a recession with raising gas prices, the high cost of performance parts and related labor to install them all, a LOT of people are tightening up the belts. So if I can have a daily driver that is great to drive every day, still gets decent mileage, and rather than embarrass me it gives the guy with $7k worth of dedicated mods a hissy fit...I'm on it. And if it's with parts that any GM dealer can get and service...even better!

I'm sure the guys over on Corvette forums are having issues with their 6L80 transmissions after beating them on the strip. While I'm over there asking questions, my very first question would be if they are running a stock GM tune or not? Is their plight any different than the C5 guys with their 4l65's or C4's with their 700R4's? No...the power goes up...the transmission's ability to handle it is maintained. BUT recall, I said that the 4L80 was not decided for such dedicated drag racing abuse...it just holds up a hell of a lot better than a 4L70. If guys want a car that's going to see regular drag use, then they need to get a Ford Cobra Jet, Mopar V10 Drag Pak Challenger, or wait for whatever GM has up their sleeve for the Camaro. For the guy who wants something to take the 50+ passes at the track...up the ante to a 6L90 . Haven't heard any of the Cadillac or 2500 truck guys complaining of failure on those.

My job is just about getting ACCURATE information and options out there. Like Joe Friday...just the facts!

Plus, this is the most entertaining and mutually informative thread I've been part of in a while!! Keep the brain storming coming!

slow67

iTrader: (2)

Where did you get your info? When you increase the ratio in a 4l80/th400/th350, the max tq input goes down (sometimes significantly).

kevin87turbot

iTrader: (2)

I work at TCI.

kevin87turbot

iTrader: (2)

I understand what you're saying TrueBlueGTO, but you have left a few factors out of your analysis. Poorhouse pointed out one of those factors, the rpm drop on the gear changes. If we were powered by a 400 ft lb electric motor (source of a more constant input torque), then the rpm drop wouldn't have as much effect on the performance of the vehicle, but in real life, we have an engine torque curve to consider as well.

To get where your headed, you'd be better suited using some vehicle simulation software.

The 6L80E transmission is a very good one for a 426 hp LS3 (or something similar) in a late model Camaro. However, if you do the analysis, it's not necessarily the quickest one (for this application) of the transmissions that you considered.

I hope I don't come off as a know-it-all, because that is not my intention.

poorhousenext

The entertaining thing about this thread, may be 2 fools debating topics they really may not have a clue about.

Friend said this thread has become about like watching congressmen debate each other on C-SPAN...

By the way, if your roots are from the South, were your forefathers horse traders or Irish travelers from South Carolina? You got to be one great sales persons with that Spread & Sheet thing...

In that shuck & jive answer are you saing I won round one, or are you just jiving me?

You have it easy. You only have one stepchild transmissions to defend. I have two. No matter how it goes, one of my two stepchilds has to lose because to have a debate, we both can't favor the same stepchild.

I hope you mean that statement.

I'm thinking Joe Friday has turned over in his grave. I believe your have skewed the facts, at least in case of the TCCI 6X.

My brain has been storming since I got back from checking on the TCI 6X project car 115 miles one way away. I hope you will still be both challenged and entertained by whats coming next....

Are better yet, round 2 goes to poorhousenext too...



I believe you should at least take the TCI 6X off of Spread & Sheet.

Helen Keller, Ray Charles, Stevie Wonder and Ronnie Milsap can see through it now.

This really makes me feel bad about bringing a Sword to this fight too. At first I though it was fair fight, but the more I looked at that Spread & Sheet I saw what Ray, Stevie, Ronnie did, an what Helen kept shouting at me about too.

Your adding the TCI 6X to mix and then adding 56 Foot pounds of Torque to make it's averages match that of the 6L80E's made it really jumped out at me.

Made this Jethro feel like Einstein.

Next was your statement about Torque winning the race, not Horse Power. I use to believe that too, until those Horsepower Fools dragged me down to their level and beat me with their experience.

Your coverall theory seems to have major holes in it.

One being it assumes a single moment in time/RPM as a constant for all moments in RPM time in a run.

Your using peak TQ that you may only see at one moment in time as if that peak Torque number is a constant across engine's entire RPM range. Yet on either side of that peak it is either rising or falling.

Torque is constantly changing across RPM range. It only reaches it's peak once and may are may not hold that peak for more than one Revolution of Engine.

While two engines may make the same peak Torque, one may make it early in the RPM range while the other one may make it later in the RPM range. That makes a difference.

Engines can have a Narrow RPM TQ band, Wide RPM TQ power band, or even a Broad TQ band.

One engine can even make less TQ than the other one, but if it's TQ power band is Wider or Broader, or it hold it drop off from peak higher and longer after 5225 RPM where both TQ and HP equal each other, which by the way is what makes Higher Horsepower numbers, you'ved ignored.

Example of Broad Power band.

Same 2 cylinder, 4 stroke engine with only change made to it is the exhaust system. All 3 of the changes made within 1 Ft lbs of Peak TQ at about the same moment in Time/RPM. Two made about the same peak HP too, while the one with the Broad Power Band had and increase in peak HP and higher TQ on both sides of it's peak.

Do you really think the other 2 changes can beat the change that gave the engine a Broad power Band, where TQ from 2500 to 6500 RPM is within 15 ft lbs of it's peak from 2500 RPM to 6200 RPM? Peak is the same, but only at one moment in time/rpm.



Also, if your Theory that TQ wins races is correct, then a LS3 376/480 with 475 Ft Lbs of TQ will beat my LS7 that only makes 470 Ft Lbs of TQ. LS3 480 HP, LS7 has 505 HP.

Do you really believe that 5 extra peak torque of the LS3 will Beat the extra 25 HP of the LS7?

Or that on the dyno sheet above, that because the peak TQ is same all 3 will be a dead heat. No 2 changes produced the same TQ band accross the same RPM range.

Is the 6L80/90's gearing better because of it's higher average, or is skewed badly by just one gear? It appears to be skewed by mostly 1 gear. If you compare the 400 TQ numbers the 6L 1st and 2nd beat the TCI 6X 1st & 2nd gears only. The 6X 3rd & 4th gears beat the 6L 3 and & 4th.

While 1st gear provides the better mechanical advantage to get weigth moving, it revs through the gear quickly. 2nd gear is a little better.

But 2 gears (3rd and 4th) engine will be in for the most time on top end where engine is fighting both higher air resistance, along with tire resistance favor the mechanical advantage of the 6X's 3 & 4 gearing.

2 +'s for each. Can the 6X make up the 6L's off the line dig. Probably, by just lauching at higer RPM?

Next is similar to the dyno graph except Peak TQ does not occure at same RPM.

Lets say your engine makes it's peak 400 TQ at 3800 RPM while my engine makes it peak Torque higher, at 4500 RPM. We both launch at 3800 RPM. isn't the 6l's gearing advantage negated because you are at peak TQ at launch and now TQ is going to ge going down hill to 6500 RPM. The 6X's TQ is still rising untill it gets to 4500 RPM before it to starts downhill but much farther up in RPM range, where most likely peak HP will be higher to keep the car moving at faster pace.

Next we start shifting. Question now becomes will you see your peak TQ again are not. Again you will be mostly on the down side of your TQ curve, whille again because my peak TQ is higher in band both it and my gearing, especially 3rd and 4th gears with their better mechanical advantage.

Now take a good look at what happened when you gave the 6X 56 more Ft Lbs of TQ so you could show, "Look what it took to make the 6X competetive average wise to my beloved 6L transmission.

Never mind that the 6X is killing 6L in 2nd, 3rd & 4th gear.

Seems your saying the 6L's average says it will stay with or beat the 6X even with the engine in front of the 6X making 56 more foot pounds of TQ.

Didn't you say TQ wins races, not HP. Doesn't that 56 Ft pounds of TQ Trump your Spread & Sheet 6L80 badly skewed average in this case. Look at the what 3 out of 4 gears are telling you.

Bottom line. I would at the least remove the 6X comparsion.

Better sill, I would thrown that Flash drive with the Spread & Sheet on it in the trash

TrueBlueGTO

I'll bite.

I didn't overlook it. I actually addressed it in an earlier post. Engine torque curves vary. So as there are millions of possible torque and hp curves out there, I can't very well have a representation of every scenario.

The purpose of my post had the assumption the individual making the decision actually knew what his engine's dyno chart was. Some engines have a flat torque curve. Some do not. The difference, if any, that a 20-30% RPM drop off can make in terms of putting a specific motor out of it torque band can only be determined by the engine builder/user. Such percentages of RPM change can be easily addressed a number of ways...torque converter, revving the motor higher before shifting, or changing the final drive ratio. It's up to the end user.

Although I prefer to keep with stock passenger motor torque curves as that's in keeping with the bang-for-the buck concept, let's take a look at a very specific engine in question... a crate LS3. Obviously, you did your homework to pick an (expensive) engine that happens to have a torque curve and HP peak that work beautifully with the TCI 6X gear ratios. (It just ought to for a combined cost of $13,000+labor!)

As you planned, PoorHouse :

1) When you hit your HP peak at 6000 RPM and shift, the TCI 6X puts your RPM's right more or less at the beginning of your peak torque plateau each time.

2) Whereas the 6L80/90 is putting the engine at a lower RPM each shift, which corresponds to 15 and 40 lb/ft less torque from the engine for the first two shifts.

HOWEVER, while that may be all well and good ONCE you've got a 3000+lb vehicle rolling and the engine up into the high RPM band. What about the power and time from idle (or brake torqued) RPM in first gear until the engine hits its torque/hp stride?

And that -40 lb/ft deficit in the 1-2 shift and -15 lb/ft in the 2-3 shift from the engine's output? Doesn't matter because you've got superior torque multiplication in the 6L80/90. That gives the TCI 6X a net torque product of nearly 900 LESS lb/ft of torque EACH revolution of the tires through the first 3 gears, and still 700 lb/ft less through the whole race!! Sure it makes more torque in the last shift, but the race is over by then.

Now, sure you could put lower (higher numerical) gears in the 4L80 to help it get the mass moving off the line. It will even help it zip through it's narrow RPM band between shifts, but now you're motor is screaming on the high way and, once again, the motor has done all the work...and well you're spending more money and labor energy to match what a single transmission swap accomplishes with less fuss and number crunching on ratios.

Again...if you already have the funds for exotic stuff...go for whatever combo you want from the ground up. But if you're on a budget and limited to what's already in a stock vehicle and/or cheap parts, 6L80/90!

TrueBlueGTO

I love the C-SPAN reference!!

Torque does win races. HP is simply a mathematical manipulation of torque figures....hence they always meet at 5250. Torque is a measure of power or force in a rotational direction (as opposed to linear). Horsepower is the measure of how QUICKLY that torque rotation occurs. Hence at higher RPM's torque falls off because centrifugal forces (objects in motion tend to stay in motion and all that jazz) cause the rotating mass to essentially accelerate/spin faster than the initial force can keep up.

It's the phenomenon of breaking your back to get a car rolling from a standstill, but once it's moving downhill you can't keep up with it. The ability of modern engines to take a lot of that torque and keep itself together at high RPM is what allows them to generate mind boggling power, when compared to older motors whose components would have exploded under the stress. It's why super exotic engines are super lightweight, make little torque, but spin to ridiculous speeds and make crazy HP.

With that said, you keep overlooking the one thing that is key to this comparison...SAME MOTOR...SAME REAR END RATIO. With the same motor (i.e. dyno chart) all you're doing is shifting the ENTIRE CURVE upward by the multiple of the transmission's gear ratio....regardless of where it is on the RPM scale. So it doesn't matter what the PEAK power is or minimum power is ..the whole curve is multipled 4.xx times in a 6L80/90's first gear and only 2.xx times in a TCI 6X's first gear. More torque to the wheel....more horsepower to the wheel.

So the only reason to remove the TCI 6X from the chart is to save it from embarrassment.

poorhousenext

I'll rather meet you at the transmission shop and give you a ride home in my 6X car if you want to try and prove the performance part of the 6L to me....

Thought I was going to get invited to square dance, I seem to be getting waltzed around....LOL I can't quite buy into your answer.: I'll stick with practical experience over therory....

All my example have used a 3.27 rear gear, 28.0" dia tire and same TQ and HP motor. I used a 3.27 rear end because GM used that ratio in the G8 pontiac with 6L80E due to its weight and aerodynamics and because it matched the top speed and performance of the manual 6 speed that came with a 3.70 rear end.

I would never consider a 4.10 with a 6L80E unless it was for rock crawling.

6L80e with 4.10 rear end and 28.00" dia tire will limit you to 115 MPH in it's final non overdrive gear and if you have a 26.0" tire, 106 MPH. To me a 4.10 rear gear is not a realistic rear gear for 6L transmisson in a car. Truck maybe. Not even sure you wouldn't have to shift into 5th to make it thru 1/4 mile with 400 Ft lbs of TQ.

On the other hand a 3.27 rear in a G8 GM used, will give you a more realistic 144.00 MPH, while manual 1:1 4th gear with 3.70 rear gear is 146.00

By comparsion, my 6L80 car has a 3.07 rear gear, and 6X car has a 3.54. Both have a top non overdrive speed of 153 MPH. That is if the 6l80 car had a 28.0" Dia tire rather than a 25.56" dia one.

I grew up with bell shaped narrow band TQ muscle cars that would pull you back in the seat.

I fell in love with car that felt like it was slow because it didn;t pull me back in seat, just went from 0-120 2 seconds quicker with it's broad power band....LOL

Your vision is tunneled down to one aspect, "That all you are going to need to do is add a 6L80 and live happly ever after."

Look at all the members here either upgrading their engines are buying late model LSX engines to swap in, then start to think about a transmission when they blow the one they have. Most had rather do that, than hope a 6l80E will fit and work in their car, plus try to impress their friends with it's performance.

By the way, I really didn't pick a 6X to go with the LS3.

Up until September of last year chassis had a built 4L65/70E in it that cost me nearly $3000.00 dollars because it had to be sent back to be converted to 4L70 equivalent due to fact it wasn't compatable with LS3's ECM due to lack of ISS sensor. $2500 more got me a TCI 6x with TCM, wire harness and paddle assembly. I was still needing to buy a wire harness for the 4L65/70 along with a TCM to control it.

Reason I sold the 4L65/70 and replaced it with TCI 6X was because the car it's in went from being my fun daily driver to close to a one of a kind wide body Muscle car....LOL

The 6L80E has taken it's place for at least a year as my fun to go ride to grocery store in....LOL

The 6X may still be entered in a few Pro Touring car competition events this year, that I would not attemp with the 6L80E.


6X chassis & 6L80E chassis are the same, just enigne and transmission differences.





Here is what happened to the 6X car that made me upgrade it to a 6X transmission. Bottom line to much money in it to stay with CHEAP in it. It can run up to 12.56 wide tire on rear. Only has a 11.5 wide tires now.

I'm not ashamed of spending the money on them are call them what they are, Novelty cars.... I took care of family first and me last.









6L80E car is stock bodied.







PS: While researching, I stumbled across somthing on a website I think I want to ask you about how it might work...

TrueBlueGTO

Gorgeous cars! I followed that thread for a quite a while. And I'd love to take a ride in either Vette! My dream road course car project is a C5 Z06 with a 6L90....then a LS2 GTO with 6L90 and GV O/D Unit!! 12 speeds!!! Of course as it turns out only 10 are useful, but alas......that may have to wait until at least next year to even think about.

ANYHOOOO...only issue, PoorHouse, is...you're arguing points that I'm NOT making or saying. You're pigeon holing my statements to fit your tunnel vision. I never said a TCI 6X would not make a car fast. I never said the 6L80/90 is the ONLY transmission any and everyone will ever need. I never said the 6L80/90 is a perfect transmission. I simply said that apples to apples, oranges to oranges....all other vehicular factors being equal...a 6L80/90 will out accelerate all the other transmissions. PERIOD.

So of course if you mix and match motors with different torque curves it requires a complete different evaluation. With different motors, maybe the 6L's will be quicker...maybe they won't!

You keep bringing MPH calculations into the argument. The objective of a performance car, to the casual user, is to cover a finite distance (e.g. quarter mile) as quickly (minimum time) as possible. No one gives a hoot if your trap speed is 100 mph if it took you over 16 seconds to cover the 1/4 and you lost the race. lol Sure it shows you have great top end, but, assuming your launch and shifts were perfect ...so? MPH is a velocity ... simple speed...it's a simple direct ratio...distance:time measurement....miles per hour. A newer 200 HP Hyundai V6 can do 140 MPH as can a 210 HP 350 V8 TPI 80's Firebird. What's the difference? How much time it takes for them to get to 140 MPH. If you have 2 miles of open highway, they will both get to 140, but one is going to do it in a hell of lot shorter distance than the other, burning a lot less fuel, and working a hell of a lot easier. Acceleration, not speed!

Acceleration is an exponential measurement of speed. It's a measurement of CHANGE in the speed. The ability to change the speed quickly. Like HP is the measurement of how QUICKLY the RPM can get from 4000 to 5000. HP readings are nice, but they're useless without the corresponding torque readings.

Case in point: Two engine peak 400 hp at 5000 rpms on an engine stand with no load. Put them in two identical vehicles, on a chassis dyno and Engine A puts down more power. Why? Because if you look at the torque numbers in relationship with the HP numbers at a given RPM, Engine "A" has superior (flatter) torque to push through the drivetrain and dyno load drag. Now put both vehicles on the road and Engine "A" with its superior torque should prove its worth even more because now the higher torque is pushing against the drag of aerodynamics but with the added help of the same horsepower of Engine "B". This is allowing the engine to get through its flatter torque curve more quickly....leading to quicker acceleration.

I remember years ago when I held a dyno session. The 200 HP V8s and 200 HP V6's did their thing in usual fashion putting down some both poor numbers and good numbers. Then we put this 170 rated I4 on the rollers. OH MY STARS IN HEAVEN! I swear it took that slug 2 full minutes to pull to its redline!!! No torque ANYWHERE...lol...and HP that only occurred at the top.

If your two Vettes both had the motor and same rear gear ratio, the 6L80 would spank that 6X each and every time.

Now what I said, many times, is exactly the same thing. IF YOU'RE ON A BUDGET....you own an (near) OEM spec vehicle.... you want to perform a SINGLE COMPONENT mod to your vehicle...the BEST BANG FOR YOUR BUCK (increased DD driveablity pleasure, durable, increased acceleration, no need to alter other drivetrain components, performance does NOT undermine other mods) is a 6L80/90. Best of all...any tuner can tune/program and any mechanic can fix it because it uses generic GM software and parts!

Is it perfection in a cast aluminum case? No. Is it it indestructible? No. Are there other alternative that will make the car accelerate faster? Yup. Are there cheaper ways to make the car go faster? Of course. Are there easier ways to go faster. You know it! But if you want one component that increases ALL levels of performance and put the least amount of additional stress on other components, in-it of-itself, for under $6000 installed...6L80/90.

joecar

Can you make a spreadsheet of the dynojet graph in post#70 (can you post a .csv of it)...?

Then plot curves (one for each gear) of engine torque multiplied by gear ratio...

[ ignore axle ratio and drivetrain losses for now ]

repeat this for each transmission (plot each on a new chart).

joecar

Even thou the pullable/useable torque band goes from 2500-6500 rpm (or whatever the range is), during an upshift you want to keep engine rpm close to the peak torque... the idea is to have the engine pull from near peak torque (hardest pull) thru to peak power (fastest moving) and beyond;

i.e. the idea of a close ratio box is to keep engine torque above the 90% or 95% line;

a high stall converter that matches the cam (torque curve) helps to keep engine rpm up in the 90% after each shift ("shift extension");

(requires upgrading the valvetrain to allow shifting at higher rpm)

ET/TS have been found to improve when shifting as high as possible.

slow67

iTrader: (2)

Was that 1200 ft/lbs just driving on the street or did it get beat on with slicks at the track?

kevin87turbot

iTrader: (2)

Poorhouse,

Those are some beautiful cars! I'd love to take a ride in either of them!

Quoted from Trueblue
"I simply said that apples to apples, oranges to oranges....all other vehicular factors being equal...a 6L80/90 will out accelerate all the other transmissions. PERIOD."

If you're talking quarter mile acceleration, this is incorrect. If you're talking about 60' acceleration, then I wholeheartedly agree! As long as traction is available, the 6L80E will definitely have the advantage over the other transmissions discussed. In the following simulations, I modeled a 4th gen F-body with a stock LS3 power curve, 3.73 gears and a 3000 stall converter. I started with a base weight of 3700 lbs with a 4L60E trans. You can see it in the first graph. For the second graph, I changed the base weight to 3730 lbs and modeled the 6L80E. The third graph is 3730 lbs and has the 6X.

Look closely at the engine RPM range throughout the quarter mile and I think you'll see where your logic is flawed.

kevin87turbot

iTrader: (2)

Actually, that guy does both. The FEA analysis suggests a higher limit yet with the billet carriers that are currently used, but I've never tested it at a higher level.

slow67

iTrader: (2)

What about your 2.75 gearsets?