The Stovebolt Site Forums The Shop Area Engine Shop Whats the better automatic ?

Fellow stovebolters your help please.
Justb finished my 270 for my 1948 GMC panel. And just wondering what automatic would be best. I have an open drive line with 373 in the rear end. I guess the 270 is makeing 220+ hp.Looking for an overdrive unit. Don't know much about them so please be gentle.
Thanks Dave

You don't have much in the way of options, either the 200R4 or the 700R4. Either would do, but the 700 is a stronger tranny. Click here for details

The 2004Rs have the BOP bellhousing pattern. The strong units were used in the 85-87 Grand National and T-type cars that had the turbo V6, so a properly prepared unit can handle quite a bit of power & rpm. Just depends on what bellhousing will fit your engine.

Hey Chip,

You are in the automotive electronics industry right? Do you know of any good references to the controls / diagnostics information and any embedded controller designs for the 4L60E / 4L80E trannys?

I have a controller designed now for ignition and fuel injection control and would like to get some info on the digital interface to these trannys so I can program different shift patterns depending on whether I want cadillac behavior or fire breathing drag strip behavior.

Ken

Thanks for the imfo, is anyboby out there running a 700R4 behind an inline 6 ? Any more tid-bit would be help.
Thanks again. Dave

Is 200+hp. average for a 270?

Are you running Jack Daniels in the gas tank of that GMC Panel ? What did you do to that 270 to make you think it is cranking 220 Horsepower ?

I'm just curious, how are we going to bolt this automatic transmission to the 270? I know there are Hydra-matics that came in GMC as a option, but would a modern auto OD tranny attach the same as the Hydra-Matic?

I know there is an adaptor plate available, but I haven't heard much good about it.

If there is a good way to mate a modern OD tranny to a GMC inline six, I would really like to hear about it.

http://www.hotrodders.com/t6236.html
-
I suppose the adapter to mate a late automatic to an old stovebolt would be more durable if it was to be made out of T-1 steel. The tranny would have to be built up to make the shifts more firm as too much power would be lost in the soft shifting of stock a tranny
-
http://www.garlits.com/html/waters_and_sughrue.html

Ken,

Darn, you're paying attention......

I don't have any special references on hand, I can only speculate how they work. If I remember correctly, these trannies use electronic solenoids to shift, monitor govenor pressure and control TQ lockup, as well as a geartooth sensor for speedo output. I don't know if the tranny sends discrete analog/digital data to the PCM from each sensor/solenoid, or if it uses a CAN bus. I'd imagine it'd be a somewhat daunting task to control the tranny if you don't know what signal conventions are used.

http://www.4l60-e.com/

http://www.sallee-chevrolet.com/Transmission_Control_Modules/4L60E_4L80E.html

http://www.compushift.com/

http://www.pdqparts.com/content/pdf/CUA0102-1.pdf

If you get a chance, email me as I'd like to know how you did it, what micro you used, etc.

hope this helps

chip

I designed a DeviceNet interface for the controller that I am using for industrial applications. It was based on a canbus chipset and the hardware layer is the same as canbus, just need to figure out the canbus protocol . . . if it were easy, girls could do it

I am using a motion controller board that has a Motorola DSP56303 processor and it has a PC104 bus on it as well so that an Intel based single board computer can host the system. I have all the code roughed out and tested on the engine control side and have loaded FreeDOS on the intel processor and am running a small graphical user interface from it. The OS and application files all fit on a 32Mb compact flash.

I know it doesn't sound very practical, but I have dozens of these systems that we have developed for the semiconductor industry to control robotic workcells for Seagate hard drive assembly lines. I know the architecture and it has great digital and analog I/O capabilities as well as deterministic scan times (I can set up a routine to manage spark / injector timeing and set/reset of digital I/O with a bandwidth of up to 20kHz scan rate.) The distributor is now a 1024 line incremental encoder with a marker pulse for absolute reference after the first rev. Three coils will fire 6 cylinders with 2 plugs firing at a time (one on the compression stroke and the other on the exhaust stroke).

I'll look at the references you put up and map out a strategy. On the one hand, I would probably rather use a 5 spd overdrive, on the other hand, I really want something my wife can drive. Either way, the electronic hacking I am doing is a lot of fun, just hope I don't screw it up and create the worlds "second" most expensive boat anchor.

Ken: Far out! For the ECU, is it set up as a MAF or speed density type system? You may be able to look up some ANSI, UL or IEEE standards for canbus networks protocols.

The plan is MAF because I don't have a clue about what to expect with a speed density system and if all goes well this will be a miller cycle engine with a whipple supercharger in a year or two and the drawbacks of having an MAF in the induction system go away when you are stuffing it with a positive displacement supercharger.

The reality of it is, it can be programmed either way, I just don't like to use an implicit solution that requires monitoring temps, pressures, etc. where if your sensor drifts with temperature or you change something about the induction system and you are immediately tasked with recalibrating and re-characterizing the sensor. MAF is simple and I understand it. I'll find a sensor that can handle 110% of what I expect to ever need and all tuning can be accomplished in real time from a terminal with the engine running.

Fellow bolters. I guessing that this trany swap is going to be more than a just a slam dunk ?
Thanks for all the imfo I'll keep you all posted on my progress. As far as the 270 making 220 hp.It's 0.60 over lots of head work,headers, four hole holly,hei for spark, nice pistons nice rods.
Again thanks for all the help Dave.

Dave, Ken and Chip are a little more informed than most of us down to earth bolters.
The stock GM Hydramatic that will bolt right up to your 270 is fully capable of handling the HP and torque you can get out of that engine. The old Hydramatic was used in pickups, big trucks, bigger military trucks and tanks.

As stated above, the hydramatic was used in the duece and a half military truck (korean vintage). The automatics were so bad that most of the ones around here (still running) have Clark manuals put in them. There is a company making a full manual valvebody for them but in the end it is too much money for very little gain. The ONLY reason to use the automatic in the military trucks is the fact that the low range is in the tailshaft of the tranny, not the transfer case. Buffalo Ent. advertises a STEEL adaptor plate and custom flexplates to do a conversion to the later automatic. This should also allow you to use later model transmissions with appropriate bellhousing. I'd like to see some adventurous soul try a new venture five speed.

Jason, I believe you are referring to the dual range Hydra-Matic in the military trucks. The civilian trannys are not the same..