6T75 6 speed conversion
As I said, making it all fit properly and flush is done, computer driven speed bumps are the only slow down at this point. If anyone has any solutions, send them over and we'll get this thing figured out!
Seems like a well needed adjustment for the community.
The short story is this: I believe I can get an ECU to operate the LS4 with the 6T70 transmission. There are already existing combinations of the E67 and the 6T70 (wth internal T43 controller), and HP Tuners has a huge amount of access to E67 parameters. I have in fact become convinced that I can drive almost any NA or supercharged late model non-DI and non-Turbo engine using that computer because of the high degree of configurability available.
So I can get an ECU+transmission combination from, for example, an Equinox with the LY7 and then reprogram the E67 with the parameter values straight out of the tune for the LS4 engine. In theory the controller should then be able to run the LS4 no problem.
My problem is that I cannot green-light the LS4 in my project unless I know I can get the starter on it with the 6T70. If you've figured that part out, please by all means let me know how. That is really and truly the only barrier to the LS4 project.
BTW, if you are worried about the torque capacity of the 6T70 I think the 6T75 internals will swap right in. While that may sound horrendous it's probably easier than finding an E67 combination with the 6T75 (I don't think there are any; all 6T75 uses that I know of are SIDI engines).
Also, I have to note that the ultimate goal of my project is an all-wheel-drive performance Epsilon car. I've been dreaming of this for probably a year or more and recently discovered that most of the parts will plug and play. In fact I could take a G6 or Malibu with the LY7 and 6T70 and create the all wheel drive car using the LY7. I'm just used to more power seeing as I currently drive a very modified LSJ powered Cobalt SS exceeding 300 HP (probably closer to 340-350 HP).
Anyway, the point is I am super super close to having all the techincal challengs answered, and then all I would need is to save the money to get the car and parts and make it happen. I hope people are still watching this thread; this is the closest I have seen to a solution that would meet my HP requirements! Thanks!

Here is the LS4 starter location... notice the back side of the starter will be well into the area occupied on the 6T75 valve body/front cover housing.


The other starter option would be to place a starter under the oil pan either using the prototype LS4 pan (or a modified LS4 or LS2 GTO pan - but both of these will require modification). Here is the LS4 prototype pan:


GTO oil pan:

LS4 oil pan:
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http://www.fiero.nl/forum/Forum2/HTML/119430.html
http://www.fiero.nl/forum/Forum2/HTML/119430.html
EDIT: Or does it not matter since the starter could be moved to this new location? The only issue with moving the starter could be the cover over pipe (cheap and easy to replace).
Last edited by GXP25; Oct 27, 2011 at 08:41 PM. Reason: Added some more info.
Here are Dan86GT's pictures:


There shouldn't be any room issue against the block (new starter location circled in red - approximate):

EDIT: Larger image: http://i43.tinypic.com/206zix1.png
And another image:

fieroguru, could you ask Dan86GT if his proposed module would be able to communicate with the E40 ECM?
The short story is this: I believe I can get an ECU to operate the LS4 with the 6T70 transmission. There are already existing combinations of the E67 and the 6T70 (wth internal T43 controller), and HP Tuners has a huge amount of access to E67 parameters. I have in fact become convinced that I can drive almost any NA or supercharged late model non-DI and non-Turbo engine using that computer because of the high degree of configurability available.
So I can get an ECU+transmission combination from, for example, an Equinox with the LY7 and then reprogram the E67 with the parameter values straight out of the tune for the LS4 engine. In theory the controller should then be able to run the LS4 no problem.
My problem is that I cannot green-light the LS4 in my project unless I know I can get the starter on it with the 6T70. If you've figured that part out, please by all means let me know how. That is really and truly the only barrier to the LS4 project.
BTW, if you are worried about the torque capacity of the 6T70 I think the 6T75 internals will swap right in. While that may sound horrendous it's probably easier than finding an E67 combination with the 6T75 (I don't think there are any; all 6T75 uses that I know of are SIDI engines).
Also, I have to note that the ultimate goal of my project is an all-wheel-drive performance Epsilon car. I've been dreaming of this for probably a year or more and recently discovered that most of the parts will plug and play. In fact I could take a G6 or Malibu with the LY7 and 6T70 and create the all wheel drive car using the LY7. I'm just used to more power seeing as I currently drive a very modified LSJ powered Cobalt SS exceeding 300 HP (probably closer to 340-350 HP).
Anyway, the point is I am super super close to having all the techincal challengs answered, and then all I would need is to save the money to get the car and parts and make it happen. I hope people are still watching this thread; this is the closest I have seen to a solution that would meet my HP requirements! Thanks!
Last edited by GXP25; Nov 2, 2011 at 03:23 PM. Reason: Added some more info.
EDIT: Or does it not matter since the starter could be moved to this new location? The only issue with moving the starter could be the cover over pipe (cheap and easy to replace).
Here is the Metric version:

Here is the one with the starter notch:
Here is the Metric version:

Here is the one with the starter notch:

An adapter plate would be used to mate the 6T75's high feature bolt pattern to the LS4's metric.
I haven't looked at the LS4's block up close in person (you'd have a better chance and letting me know), but I'm wondering if there's a little more room near that area where the 6T75's "pocket" is facing the LS4 block for that slight overhang of the starter.
Thanks for asking the question about the ECMs.
An adapter plate would be used to mate the 6T75's high feature bolt pattern to the LS4's metric.
I haven't looked at the LS4's block up close in person (you'd have a better chance and letting me know), but I'm wondering if there's a little more room near that area where the 6T75's "pocket" is facing the LS4 block for that slight overhang of the starter.
Thanks for asking the question about the ECMs.
Besides, the 6T70 is probably more widely available.
I wonder if Dave at TEP has any magic he can sprinkle on these?
The TCM is designed to be standalone. We want people to be able to use it behind any engine/ecm combination, even carbureted engines, electric motors, etc. Each engine configuration is going to have its own way of dealing with the torque management issue. We are planning on putting several different ECU's on this build to make sure we have everything covered.
Dan
Besides, the 6T70 is probably more widely available.
I wonder if Dave at TEP has any magic he can sprinkle on these?
I think we all know that GM tends to rate their transmissions however they feel like. I tend to look at gear ratios and the vehicle the transmission is originally put behind.
The 6T70 is used in compact to mid-sized vehicles whilst the 6T75 is used in crossover SUVs with the intent of towing.
It also comes down to torque management with these new clutch-to-clutch transmissions (6L80/90, 6T70/75).

The wheel should be a direct swap and you should be able to keep your airbag. There might be color issues with the Super.







