Cadillac Owners Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
6 Posts
Discussion Starter #1
My deville has the 4.5 Northstar. The only hp rating I found so far on it is 180. It feels stronger. My friend says some cars get rated differently than others to show lower hp for insurance and other reasons. Anyone have any ideas on the hp diff between the 4.5 and the 4.9? I see they rate the 2003 4.6 at 300.

Just curious.
 

·
Registered
Joined
·
11,009 Posts
ok, you are all confused...

the Northstar is 4.6l and has 275hp or 300 hp and 295 ftlbs of tourqe or 300 (depending on model)

the 4.5 and 4.9 and pretty much the same engine, but the 4.9 is a strocked version of the 4.5....it also has PFI (over TBI that the 4.5 has) the 4.5 is a bored out version of the HT4100

the 4.5 (your engine) has 180hp and 240 ft lbs of tourqe

the 4.9 (like I have) has 200hp and 275ft lbs of tourqe

no, you can not easily swap the 4.5 to a 4.9 either

Hope this helps
 

·
Registered
Joined
·
1,093 Posts
little bit more info.....

the 4.5 had two variations (three if you count the alante's....for simplification, we're not) the difference is the type of fuel injection 88-89 (175HP) had TBI like the ht4100, the 90 (180hp) had PFI like the 4.9

other than fuel delivery there is not much diference b/w the 88/89 and the 90, part of the hp difference comes from the lack of a "smog pump" on the 90+ engines, a device that I understand the theory behind but not the practical use of, it uses engine power to piontlessly suck air out of the air intake like some sick twisted reverse supercharger then it dumps the clean air into the exhaust to supposedly make the catylitic converter reduce emissions better! (yeah right)

sorry about the rant

as I understand it the difference b/w the 90's 4.5 and the 91+'s 4.9 is the displacement, a larger plenum chamber in the intake manifold and higher flow fuel injection
 

·
Registered
Joined
·
548 Posts
CadiJeff said:
little bit more info.....

the 4.5 had two variations (three if you count the alante's....for simplification, we're not) the difference is the type of fuel injection 88-89 (175HP) had TBI like the ht4100, the 90 (180hp) had PFI like the 4.9

other than fuel delivery there is not much diference b/w the 88/89 and the 90, part of the hp difference comes from the lack of a "smog pump" on the 90+ engines, a device that I understand the theory behind but not the practical use of, it uses engine power to piontlessly suck air out of the air intake like some sick twisted reverse supercharger then it dumps the clean air into the exhaust to supposedly make the catylitic converter reduce emissions better! (yeah right)

sorry about the rant

as I understand it the difference b/w the 90's 4.5 and the 91+'s 4.9 is the displacement, a larger plenum chamber in the intake manifold and higher flow fuel injection
and you know what is stupid about that is that it only turns on the air pump when it's cold and when at WOT,wish i could disable it so i could maybe(highly doubtful) free up some HP. but i think that the cpu won't work correctly with it disabled and screw up the rest of the car.
 

·
Registered
Joined
·
1,093 Posts
here is an idea instead of disableing it reverse it (sorta) rerout the intake tube to the air cleaner box and the out put to the hole in the air intake
eh doubt it would make a difference.....but it sounds good on paper
 

·
Registered
Joined
·
53 Posts
I read somewhere that the 4.9 liter ran at 278 horsepower. Is this way off base? Y'all seem to think it is much lower...
 
1 - 10 of 10 Posts
About this Discussion
9 Replies
7 Participants
CadiJeff
Top