All Things Chev

Whats the science behind the change Ralph? Is more fan blades - greater drive or smoother drive? Why did you change - what are the drivers? As you stated in a previous entry Marks4x4 were playing around with a computer code manipulation - what are your thoughts on this re success and why didn't you go this way? Is this auto tranny controlled with an electronic system or mech only? I don't know anything about auto trans design or theory - eager to learn.

I'm using the 6L90 auto trans which was never fitted behind the 6.5, as the convertor is matched to the LS LSA.
Physical difference between the two required that the mounting PCD be matched to the 6.5 flex plate. The LSA has a higher stall than is ideal for the 6.5, and reducing stall speed is harder than increasing it.
The trans is controlled by a stand alone controller that is fully programmable.
Marks 4WD and Quadstar in the USA all did not divulge any info about what to do to get it to work.
The clue here is that the 6.6 Duramax does have the 6L90 fitted in one application, and my convertor specs now match it.
Will be a drive it and see how it goes.

Quote:

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Originally Posted by poindexter

I'm using the 6L90 auto trans which was never fitted behind the 6.5, as the convertor is matched to the LS LSA.
Physical difference between the two required that the mounting PCD be matched to the 6.5 flex plate. The LSA has a higher stall than is ideal for the 6.5, and reducing stall speed is harder than increasing it.
The trans is controlled by a stand alone controller that is fully programmable.
Marks 4WD and Quadstar in the USA all did not divulge any info about what to do to get it to work.
The clue here is that the 6.6 Duramax does have the 6L90 fitted in one application, and my convertor specs now match it.
Will be a drive it and see how it goes.

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Thanks Ralph. One further question, I have read the comment regards 'stall' but what exactly does this relate to? Is it the rpm needed before the auto trans will actually 'drive' thru to the rear wheel or is it a pressure point - as you can tell I don't know much about this but have heard the term used hundreds of times without giving it much thought.

Torque converter stall speed is the maximum amount of engine RPM that can be achieved in an automatic transmission-equipped vehicle while the transmission is in a forward operating range without generating any driveshaft motion

Quote:

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Originally Posted by poindexter

Torque converter stall speed is the maximum amount of engine RPM that can be achieved in an automatic transmission-equipped vehicle while the transmission is in a forward operating range without generating any driveshaft motion

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So what determines where the stall point is? Is this linked to a torque setpoint or something else? I see performance vehicles advertised with 3000rpm stall points - petrol engines - whats the stall point you are going to be sitting at or is that adjustable or trimmable with the computer?

Stall is a function of convertor turbine size, ie. the smaller the higher the stall.
You can do it in software only by engaging the lock up early

Quote:

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Originally Posted by poindexter

Stall is a function of convertor turbine size, ie. the smaller the higher the stall.
You can do it in software only by engaging the lock up early

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Thanks, I have a bit of time on my side at site at the moment so have been reading up on this - interesting stuff for a novice auto trans guy!

This arrived in the mail...

sorry about not rotating the image.

Attachment 78020

You're tempting me Ralph! Now would probably be the time to do this mod especially with the front coming off the motor - decisions decisions

OK< is this the DS2 or DS4 gearset? Do you know what the function is of the 'reluctor' - its an additional gear it seems. I think I will buy this since I have plenty of time to do the conversion now and the wait wont be noticed.