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Old 08-31-2010, 01:17 PM   #1
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4L60 vs 6L80

I had a run in with a TT G8 that got me wondering about the benefit of the six speed transmission. (GTO-1 , G8-1)

For arguments sake, how much e.t. improvement could you expect from a swap to a 6 speed auto (if any)? Let's say in a GTO capable of 11.5x?
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Old 08-31-2010, 01:19 PM   #2
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your tcm would have to be compatible... its not.
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Old 08-31-2010, 01:23 PM   #3
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Quote:
Originally Posted by Farsighted770...View Post
your tcm would have to be compatible... its not.

This is just a theoretical question, I have no interst in putting a 6 spd auto in my car. I'm just wondering what sort of performance improvement it would offer.
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Old 08-31-2010, 01:24 PM   #4
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How hard would it be, Is it even possible to swap tcm from doner g8? or would you have to swap whole wiring harness?
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Old 08-31-2010, 01:30 PM   #5
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Quote:
Originally Posted by bridges...View Post
How hard would it be, Is it even possible to swap tcm from doner g8? or would you have to swap whole wiring harness?

harness, computer, reluctor/cam position sensor(and cam phase blockoff), knock sensors(maybe?) and that may not be all... its more trouble than its worth.

and to the OP it would depend on the gear ratios, you could use a drag computer/simulator with the six speed just plug in the values from the 4spd vs 6spd and look at the difference... its all in a vacuum though so results may vary, yada yada yada

as an aside a company called gear vendors offers overdrive/underdrive units for the 4l60, essentially turning the car into a 7 or 8 speed car or something like that.
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Old 08-31-2010, 01:30 PM   #6
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If I were to attempt a 6 spd upgrade I would just spend the coin on TCI's package, complete w/controller.
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Old 08-31-2010, 01:36 PM   #7
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At 11.5 you're probably going through the traps in 3rd gear. I don't know the 6 speed gearing, but if it did have to make that additional shift into 4th gear that certainly wouldn't help the ET.
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Old 08-31-2010, 02:18 PM   #8
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TCI makes a 6 speed auto out of a 4L6xE shell I think.

My on the improvement would be:

A lot.

Your talking about being able to run the VIOLENT drag racing ratios of the 6L80E or better if custom like the TCI unit. Have you seen the gear spread in the 6L80E? Dont be mistaken and think its got a deep over drive like an M6, its barely better than an A4 actually. It just has a ton more gear up front to convert torque and make more use of low speeds without demanding of engine RPM. This is the big reason many auto makers are going to 6, 7 and even 8 speed autos in EVERYTHING these days. Gears are a torque multiplier. Its a beautiful thing.

4L6xE:
1st: 3.06, 2nd: 1.63, 3rd: 1.00, 4th: 0.70
6L80E:
1st: 4.02, 2nd: 2.36, 3rd: 1.53, 4th: 1.15, 5th: 0.85, 6th: 0.66

As you can see the final overdrive is barely deeper. The big difference is the bad ass gears up front. Hell it doesnt even go 1:1. Soon there will be people that figure out a sure fire way to haul ass is to take the 3.45 geared L99 Camaro, get rid of its AFM BS, add a nice stall and the other nice mods we all do and go smurf some crap up. M6s want a 40 roll? lol sure. NP with that tranny.

In closing:

6L80E or equivalent = Better than M6 gear ratios + a Torque Converter.

Wheres your god now clutch fans?
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Old 09-01-2010, 12:14 AM   #9
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First, only the '05/06 would be able to easily upgrade to a 6L80/90 with a plug and play. GM Engineers are quoted as saying that acceleration times of up to 7% were seen.


So:

13.5 >>> 12.555
13.4 >>> 12.462
13.3 >>> 12.369
13.2 >>> 12.276
13.1 >>> 12.183
13.0 >>> 12.09
12.9 >>> 11.997
12.8 >>> 11.904
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Old 09-01-2010, 04:04 AM   #10
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The 05/06 will have just as hard a time as any upgrading to a 6L80. On the 6L80, the TCM is INSIDE the trans and the tables and values that can be adjusted on that trans are mind blowing. Were talking individual shift pressures, shift times, TM...etc for EACH GEAR as well as advanced adaptive learning properties.

The TCM that talks to the E40 in the 05/06 is way out of its league in trying to deal with the new 6L80 parameters.

It sucks that it has to be that way but it is what it is.
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Old 09-01-2010, 08:09 AM   #11
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so the g8 has a diff tcm but does it have the same/similar ecu? It does have the same motor so maybe it is just a matter of matching pinouts on our ecu to the new tcm???
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Old 09-01-2010, 10:20 AM   #12
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It uses a different ECM. I'm sure there could be someone to invent and program a plug and play controller to act as a bridge between the two but I highly doubt it will ever happen. The E40 is only prominent in the GTO, very few (if any id have to look it up) other models used it and those that may have upgraded to the more advanced units in 2006.

What I'm getting at is the demand for a plug and play option for the GTO is very very low. The R&D cost and the return on the units would be fools math. As easier route would be a non-electric old style vaccum controlled setup like people do with the 4L80E I think.

All in all look at it this way: people have gone 8s with the 4L80E and 9s (or maybe faster) with the 4L6xE series. Being that the 6L80E doesn't have a noticably better overdrive, its not the end of the world to not have it. It just let's the new breed go faster with less aggresive setups.
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Old 09-01-2010, 04:14 PM   #13
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Possible - yes

Likely it will ever happen in a 04-06 in the next 5 years - No

Id love a 6l80 in my car, 1st gear would be brutal and id have next to no deadspots.
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Old 09-01-2010, 05:07 PM   #14
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"go faster with less aggresive setups"

Thats the golden ticket now isnt it? For me I dont care about the first gear. My first gear and half of second is worthless now and im basically stock. Im thinking more for "highway use". 3rd is ok on the highway but the shift to OD the car falls flat. If the 6L80 makes a car 7% quicker....then what can someone with a 4L65 do to gain back that "loss". make 7% more hp? get a crazy high stall?
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Old 09-01-2010, 05:13 PM   #15
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CVT? lol
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Old 09-01-2010, 06:06 PM   #16
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Quote:
Originally Posted by CoolAid...View Post
It just let's the new breed go faster with less aggresive setups.

That was my experience, 60-130 against a 6.0L TT G8 (530 rwhp/57X rwtq) I pulled him a car once, he pulled a car and a half on me once. We never got a chance for a tie-breaker.

It just got me wondering how much better the 6L80 was, from a 60-65 roll I think it has huge advantage.

TCI's six speed auto is close to $6k for the whole package, but if it is good for .8 to 1.0 in the 1/4 it might be worth it.
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Old 09-01-2010, 06:54 PM   #17
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Geez, $6K?? $3K is enough for me....
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Old 09-01-2010, 07:40 PM   #18
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Quote:
Originally Posted by CoolAid...View Post

6L80E or equivalent = Better than M6 gear ratios + a Torque Converter.

Wheres your god now clutch fans?

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Old 09-01-2010, 07:57 PM   #19
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Quote:
Originally Posted by 00ttvr6...View Post
"go faster with less aggresive setups"

Thats the golden ticket now isnt it? For me I dont care about the first gear. My first gear and half of second is worthless now and im basically stock. Im thinking more for "highway use". 3rd is ok on the highway but the shift to OD the car falls flat. If the 6L80 makes a car 7% quicker....then what can someone with a 4L65 do to gain back that "loss". make 7% more hp? get a crazy high stall?

All depends on what your goals are. For me I care a lot about my first gear. I run DRs full time and make a habit out of good launches. My first gear and half of second is the bane of most more extensively built cars existence.

If your a full time roll racer than yeah, 6-speeds are nice. If your looking for respect or dominance than embrace the dig and first gear. People truly fear dig runs. I've never seen anyone have trepidations about running a roll. Anyone can run a roll. 16 year old high school girls trying to merge onto freeways are giving it the same effort.

Not picking on you here, just saying. Everyone has heard the "I dont know man, I cant hook up......It just spins........I spent thousands and thousands on power and dont want to buy $300 tires and a few suspension parts if necessary". People really do fear the dig. My high stalled A4 feeds on their fear. Its sustenance. Drag racing from a dead stop hasnt changed since the 1920s. The only thing thats changed is peoples ability to handle it.



As far as the 7% thing? Well besides the Corvette lucky for me most 6L8-E cars are pig heavy compared to my 3,580 Goat and thats where I make up the difference.
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Old 09-01-2010, 08:32 PM   #20
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Quote:
Originally Posted by Black04A4...View Post
I had a run in with a TT G8 that got me wondering about the benefit of the six speed transmission. (GTO-1 , G8-1)

For arguments sake, how much e.t. improvement could you expect from a swap to a 6 speed auto (if any)? Let's say in a GTO capable of 11.5x?

When it comes down to it a converter makes up for a lot with the "dead zones" on the 4l60 with it's crappy gear ratios. On a lot of the 6l80 cars depending on the combo I usually recommend a fairly light converter in addition to a gear swap in the rear and then those 4 gears are very useful in the quarter mile and from a roll. Most 6l80 setups with big converters don't do any better than a middle of the road converter with it's gearing the way it is. Of course this depends on where the power is and what the motors powerband is. In your example with a TT G8 he isn't worried about torque since turbos are torque monsters. For a GTO capable of 11.5 and the benefit it would get it all depends on the combo and if he has a converter already.
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Old 09-01-2010, 08:34 PM   #21
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Quote:
Originally Posted by CoolAid...View Post
People truly fear dig runs.

The only people I know of that fear dig runs are inexperienced drivers with setups that aren't going to do well at dig runs and they know it. An auto is point and shoot so of course auto guys love dig runs. Hell my buddies heads/cam/N2O f-body from 8 years ago went 10.60s and it literally was hit the gas and hold the wheel straight.
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Old 09-02-2010, 07:38 AM   #22
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With 8, 9, and 10 second cars? Yeah I could see that. But back in "the majority of people world" in the 11.5 and higher area not everyone has a 8 second drag chassis or full suspension and hooking up on pavement is not as prominent as some think.

You've been way too fast for too long Nic lol

EDIT:

Speaking of Nic, wernt you for awhile running 11.9@125+ in your 600whp Goat cause it couldn't hook? No disrespect, just sayin. We should line em up Dig-120 or 130 some time I'll give you a roll afterward for the hell of it even though we know what will happen.

Last edited by CoolAid; 09-02-2010 at 07:53 AM.
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Old 09-02-2010, 08:47 AM   #23
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Quote:
Originally Posted by CoolAid...View Post
Speaking of Nic, wernt you for awhile running 11.9@125+ in your 600whp Goat cause it couldn't hook? No disrespect, just sayin. We should line em up Dig-120 or 130 some time I'll give you a roll afterward for the hell of it even though we know what will happen.

Yup, and that's what it still runs since I still won't put a tire on it to make serious passes as I have no interest in it. I think the second and last pass it went 11.7 @ 130 with a whopping 2.15 60'. LMFAO! If I am going to go drag racing the Camaro is much more entertaining. The Camaro back in the day with a 224 cam, mild ported stock 241s, and a 100 shot went 10.80 on a Hoosier QTP and it had a nearly stock suspension. I ran that from a dig every chance I got and it was a manual transmission so I've really got no qualms about running from a dig regardless. Hell if you think you can handle my 2.1 60's in the GTO we can setup a date to make it happen. We don't need to do no stinking rolls, I like digs.
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Old 09-02-2010, 11:15 AM   #24
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Nice previous times.

Sounds good to me. Should be a decent race up to about 120 or so. By then your twins will have already made the calculations like Chewy.

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Old 09-02-2010, 11:26 AM   #25
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Quote:
Originally Posted by CoolAid...View Post
Sounds good to me. Should be a decent race up to about 120 or so. By then your twins will have already made the calculations like Chewy.

LOL at the pic. What's weird is the GTO launches better on the street than at the track because it was such a bad combo of wheel hop and tire spin that I would just lowjofoot it out of the gate since I didn't want to break anything. On the street on an unprepped surface it just spins without the wheel hop so I can ride it out a bit more without breaking parts. It should be a good race near the finish line but 1st and 2nd gear is always interesting in this thing.
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Old 09-02-2010, 11:55 AM   #26
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Using car test2000 I gave a A4 GTO enough power to run 11.72 @ 119. With the A6 it runs 11.59 @ 117.82. Its only a computer but it gives you some idea. The A6 optimize launch RPM is 500rpms lower however.
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Old 09-02-2010, 12:39 PM   #27
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LOL @ ur sig. So without highjacking this thread, what is the best combo to make a a4 car run hard on the highway? big stall? And if so, will a big stall keep the car from falling on its face when it hits OD? Im thinking 4k stall and 3.91's......
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Old 09-02-2010, 02:01 PM   #28
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Using car test2000 I gave a A4 GTO enough power to run 11.72 @ 119. With the A6 it runs 11.59 @ 117.82. Its only a computer but it gives you some idea. The A6 optimize launch RPM is 500rpms lower however.

That seems to give the A6 less advantage than I thought it would.
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Old 09-02-2010, 02:06 PM   #29
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Well,this question goes back a long way.
Remember the '83 Monte Carlo SS with the 180Hp L69 and 3 speed auto?
Then came the '84 with the 200R4 and a 3.06 1st compared to the THM350s 2.48(?)
The 3 speed MCSS was quicker due to 1 less shift in the 1/4.

I think where the 6spd autos can have an advantage is in lower cruising rpms.
But they do have crazy low 1st gear ratios.
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Old 09-02-2010, 05:53 PM   #30
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Quote:
Originally Posted by CoolAid...View Post
It uses a different ECM. I'm sure there could be someone to invent and program a plug and play controller to act as a bridge between the two but I highly doubt it will ever happen. The E40 is only prominent in the GTO, very few (if any id have to look it up) other models used it and those that may have upgraded to the more advanced units in 2006.

What I'm getting at is the demand for a plug and play option for the GTO is very very low. The R&D cost and the return on the units would be fools math. As easier route would be a non-electric old style vaccum controlled setup like people do with the 4L80E I think.

All in all look at it this way: people have gone 8s with the 4L80E and 9s (or maybe faster) with the 4L6xE series. Being that the 6L80E doesn't have a noticably better overdrive, its not the end of the world to not have it. It just let's the new breed go faster with less aggresive setups.

That's the very key. As has been stated already, not everyone is willing to make the same level of compromise to just to have bragging rights for 1/4 mile time. If a low ET at the track is the ultimate objective, there are hundreds of different vehicles that offer a better start than a nearly 2 ton, independent suspension, EFI car....and for way cheaper.

Torque converters are only useful and needed for one thing and one thing only...controlling the engine rpm in relation to a drivetrain that isn't or barely is moving. It's only there so that we as daily drivers can come to a full stop without the engine stalling and accelerate smoothly and quickly. Once the drivetrain is in motion up to whatever the STR is, the torque converter then locks up and essentially becomes a rotating mass burden on the engine, not much different than an A/C compressor. Hence all super high performance vehicles use manuals and or no torque converter.

Therefore the trend is to rid the transmission of the torque converter and any functions/components that rely upon it. Freeing up those loads that the tc demands means an engine needs less HP to obtain better performance. With the 6L80 the single clutch system is a progressive step in that direction. The new 8 speed dual clutch in the new Charger is even more advanced progression.

I digress. Therefore, if you are a 'digs' racer, torque converter selection is critical as it requires you to perfectly match your suspension/tire's traction limit with your engine's torque curve. That get's expensive and makes the vehicle less and less tolerant of day to day driving abuse/use and or road course/corner carving. Further, what unfortunately can and does completely undermine a tc selection is A) when you mod your engine and change your torque curve and/or B) when if your transmission's gear ratio's drop off RPMs from your ideal torque curve (http://www.gearvendors.com/hrgm4s.html). The latter requires a tailored choice on final (rear end) gear ratio and/or stuffing new/better gear ratios in the tranny. This is why most tend to just upgrade to a 4L80 as it has better stepped gears, keeping the engine RPM's in a narrow band.

So if that's why the 4L80 is the primary choice for going faster, it's clear why having an extra 2 gears keeps the engine in a narrow power band/torque curve and result in even faster acceleration. Additionally, 4th gear in a 6L80 is not 1:1 its 1.15 ( I believe), so you still have a better torque multiplication in fourth gear than a 4L has in 3rd. AND I get to have low highway RPM friendly 3.42 or 3.73 rear end gears.
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