AURORA

You know in your heart that this is the engine for your Trooper!!!!

Here is the link to the GM-4L30E which is found in 91 and later Rodeos, and 92 and later Troopers. It indicates that the maximum engine torque of the 4L30E   is 258 ft-lb. (350 Nm)

Notice the differences between the picture of the Aurora engine on the left and the Northstar engine on the right.

The Aurora is a smaller displacement version of the Northstar as such they both have the same exterior dimensions. Both the Aurora or the Northstar would require the same effort. So ya gotta ask yourself "if there is no differences in the swap, why not go with the more powerful Northstars?" Here is my opinion why the Aurora is a better choice.

This link shows the L37 variation of the Cadillac NorthStar. The L37 makes 295 lb-ft @ 4400 rpm, and about 230 ft-lbs. of torque at 800 rpm and doesn't exceed the torque rating of the 4L30E until around 3300 rpm. Unless you intend to attempt land speed record attempts in your Trooper you will probably use maximum torque while 4-wheeling at low speeds and fairly low rpm. In that case installing the Northstars would work but could shorten the life of the 4L30E. You might want to consider doing a transmission swap as well. These folks might be able to help

http://www.chrfab.com/Transmissions.htm


The Aurora L47 power curve chart indicates that 200 ft-lbs of torque is available at 800 rpm and maximum torque is 260 ft-lbs, just 2 ft-lbs more than the maximum rating of the 4L30E. That places the Aurora in a range that does not exceed the capability of the 4L30E transmission.

During a discussion with an Isuzu Master Mechanic, I found out that one of the things that the transmission communicates with the engine computer (perhaps the only thing) is when it is about to shift to the next higher gear. Immediately prior to the up shift, the transmission commands the engine to momentarily retard the ignition timing. The retarded ignition timing reduces the power the engine produces during up shifts, reducing the strain on the transmission. It is the opinion of the Master Mechanic that the 4L30E transmission is operating at it's upper limit behind the stock 3.2L or 3.5L V-6s, and that either the Aurora, or Northstar engines could easily exceed what the 4L30E could take. He recommended that if you were to install one of these V-8s on the 4L30E transmission that you NEVER let the transmission do a FULL THROTTLE up shift

Since the MUA5 is placed behind the same engines that the 4L30E is then I assume the MUA5 has similar torque limitations and so would also be able to handle the output of the Aurora as long as you don't do full throttle up shifts

Before considering such a swap, consider cost effectiveness. It may be
cheaper and easier to just supercharge/turbocharge your existing engine.

GOOD LUCK


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Copyright 2005

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