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I have a 93 SDV with the 4.9 and I am convinced that the 4.9 is one of the best engines Cadillac made. Here's my question: What is the 4.5 like? I know the Allante has the 4.5 (at least until it got the first gen Northstar), and the earlier SDV has the 4.5. So, is the 4.5 as reliable as the 4.9. I saw a 90 Couple Deville with the 4.5 and am just wondering what it is like.

Thanks,
 

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2010 DTS
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87,573 Posts
I am not sure how reliable the 4.5 is, but I think it is basically a bored 4.1. Given the choice, I'd prefer the 4.9.
 

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2018 Mazda 6 (Venus) 1964 Impala (Betty) 1991 Miata (Dolly)
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14,333 Posts
4.5 had throttle body injection in 1988 and 89. Got port fuel injection and a bump in power in 1990. The 4.5 in the Allanté had a specific intake and other enhancements that gave it more power compared to the 4.5 in other Cadillacs.

I can vouch for the reliability of the 4.9. My '91 DeVille has 257,000 miles on it, and the engine remains rock solid. Still gets up and goes, too.
 

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1990 350 Brougham (The cruiser), 1988 Mark VII LSC (The DD)
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5,545 Posts
I had the 4.5 in my '88. It was fairly reliable, but the car was not taken care of by previous owners and had seen better days. It chewed through 2 water pumps in just as many years (the first one was already shot when I bought the car), but other than that it was a very good engine.
 

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1998 Seville STS / 2013 Chevrolet Impala
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1,889 Posts
4.9 all the way!

I mean, they're pretty equal in terms of reliability ( though I suppose the 4.5 would go through water pumps faster because it has to rev higher), but who ever had a problem with more power, more torque, and more cubes? :D

Even though I do think that a turbocharged 4.5L Allante with a Muncie 282 5-speed stick would be the coolest car on the planet.
 

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I had a 4.5 in the 88 Coupe Deville I used to own. Really was a great engine, with the exception of the main bearing thump at around 70k miles. I fixed that, sold it a few years later to a friends son. Was still running well over 100k miles until he got rid of it. Heard a head gasket went, but it was fixed and still driven as far as I know. My 4.9 '95 had 160k miles when I got rid of it last fall. No engine issues, except that it had the main bearing thump for the last 30k miles or so. I do like my 98 northstar I have now. Got it for a decent price because I suspected head gaskets and I was right. I fixed that, and it's been great for about 8k miles so far. Lets hope it lasts a long time yet.
 

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2011 Crown Vic LX, 2009 Chevy Malibu 2LT
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WEll, I can honestly say I've owned a few of each. 2 4.9's in '92 and '95 devilles, a TBI 4.5 in a '89 Eldo, and a PFI 4.5 in a '90 Eldo. The are all remarkably similar, especially the PFI 4.5 and 4.9. I'd have to say that my '90 4.5 PFI Eldo feels the fastest, though it's a smaller car than either of the 4.9 powered Devilles. In terms of reliability, the TBI 4.5 wins hands down. No injector or FPR troubles, no bearing thump, and just plain rock solid. While the others were reliable for me, there were a few fuel system repairs on the others that stop them from winning reliability over the TBI. Just search here for fuel injector and fuel pressure regulator replacement...

By the way, the 4.5 PFI and the 4.9 are near identical engines in every way. The only real difference was the 1-year connecting rods used in the 4.5 PFI engine and the crankshaft giving the longer stroke in the 4.9.The 4.5 PFI shared the block, pistons, heads, intake manifold, fuel system and ignition system (all new for 1990) with the 4.9. The only differences were the crank and connecting rods, which gave the 4.9 greater displacement. Externally the only major difference was the A.I.R system on the 4.5 that was deleted for the 4.9.
 
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