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What makes the Northstar 290 HP instead of std 275 hp?

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My 2006 DTS Luxury III has a deep oil leek K rail or oil pan. It needs to be torn down all the way to get this done. I hate to have them do this and not improve the horsepower. What is the difference between the std 275 HP Northstar and the Performance 290 HP Northstar. Is it the Cam, bigger Fuel ports ? I stopped putting speed parts on my cars in 1969. I will probably have my Cadillac dealer do it. My engine only has 70000. I never had any problems with my other Northstars. I will have all new gaskets etc installed as they build it back up. I intend to keep the car. I realize with front wheel drive much more than 325 hp could be problematic with torque steer. I had a 455 Toronado of course it probably had 200 hp in 1976.

Any ideas?



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Not sue what a K rail is... But the oil manifold plate that is between the oil pan and the block can start to leak.

The higher HP Northstar has more agressive intake cams coupled with a different final drive ratio in the transmission. That said, it is not a matter of installing the 290/300 HP intake cams. The PCM in your car is not calibrated to make use of the extra fuel and unless you changed the final drive ratio in the transmission, you really wouldn't realize the benifits of the more agressive intake cams.

People buy horsepower but they drive torque. The 275 HP Northstar actually makes more torque than the 300HP version. I have both versions and I can tell you there is very little difference between the two.

The Northstar was originally intended to have only 270 HP but GM marketing felt there was a demand for 295 HP so the way they got the 295 HP was to use hotter intake cams and a different final dive ratio in the transmission. These engines became 275 and 300 HP when the composite intake was introduced with the 1995 model year. Subseqent changes in how the engines HP was rated lowered the values slightly. Really, all the low hanging fruit was picked in the design - the factory really didn't leave much, if anything on the table. Some have re-routed the exhaust crossiver pipe in order to eliminate the reduction where it passes under the frame crossmember and there is at least one who installed a supercharger - I think it was Mark99STS on this board.

'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Thanks Kevin. I was afraid what you described would be the situation. I have wondered about the crossover pipe. I saw a picture of one removed and the junction came in at a contrary angle and there was extra pipe sticking through. Exhaust has always been the easiest way to punch things up a bit and improve mileage. This is my 3rd Northstar and I really never needed more whammy. It has a great power band after take-off.

I bought my wife a 2014 SRX Premium so I am not interested in buying another car this decade. My DTS bucket seat is the most comfortable chair I have and I still feel good about the car.


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  • 4 months later...

I know this is and old thread ( just realized I heave been replying to many older threads in my enthusiasm as a new member) but just in case anyone is serious about doing this in the future. As long as you know what engine your cams came from, and assuming they are correct for your heads, ( bucket lifters vs roller followers ) Madtuner.com will program your PCM with the factory fuel/ air map leaving everything else alone. They will even do a performance tune for said engine.The caveat is: the dealer will likely not knowingly do the cam install ( most won't let your provide your own parts ) , most mechanics will likely not do the cam install (unless you provide your own and " forget " to mention it. Make sure you bring the correct timing gears as well, yours may not be right for the cams ) and NEVER, EVER have the PCM reflashed by the dealer for any updates. It may also be illegal, depending on your state laws.

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