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4.5 litre versus 4.9 litre


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I'm new to this forum (today is my first day) but not new to forums in general. I've been a member of GM Diesel forum for years and it has been very helpful. I have read through a number of posts in this forum alredy which made it easy to decide if I should join. I look forward to reading through more of the groups posts.

Ok, enough jabbering, I'll get to my question. I currently am own a '91 DeVille with 140,000 miles on it. Great car that I have driven for years to keep miles off my trucks. Just recently I have the opportunity to buy a '90 Coupe DeVille with about the same miles on it. The '90 hasn't been driven in 4-5 years and the guy wants it off his property. When it was parked years ago he claims the car ran fine and nothing was really wrong with it. I plan to buy the car and to drive it until something breaks then I'll turn it into a parts car or something. I'm curious how different the motor and transmission between the two cars. Is it possible, for example, to pull the tranny from the '90 and bolt it to the '91 with the 4.9 liter motor? Are there other differences that I should be aware of between the two cars?

Thanks for reading my post.

I hope everyone has a Merry Christmas!!

Greg

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Many of the engine parts should interchange. The 4.9 was a stroked 4.5 engine. I believe both cars had the same 4T-60E transmission but it is hard to say if they will be a direct interchange.

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

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A friend of mine robbed a 4T60-E from his 4.5 parts car and installed it onto his 4.9.

Not sure if there was a lot of mucking around, but I recall it only taking him a days time.

So it must not have been too different and difficult.

Not sure on the engines however... I thought they were both port injected with the same intake manifold but its highly possible I am highly wrong lol.

A bit off thread topic but one sound I really miss is a 4.5 at WOT on the highway. Such a low, droney, and beautiful sound.

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A friend of mine robbed a 4T60-E from his 4.5 parts car and installed it onto his 4.9.

Not sure if there was a lot of mucking around, but I recall it only taking him a days time.

So it must not have been too different and difficult.

Not sure on the engines however... I thought they were both port injected with the same intake manifold but its highly possible I am highly wrong lol.

A bit off thread topic but one sound I really miss is a 4.5 at WOT on the highway. Such a low, droney, and beautiful sound.

Thanks for the feedback!! I already have the other car as a parts car and maybe just having it will be insurance enough that I'll never have transmission problems with my '91.

I don't dare use WOT on my '90 with the 4.5 litre yet. It seems to have a slight knock, especially at startup. Once I have a little more confidence I'll blow the cobs out of her. I'm already in hot water for buying another old Caddy...the only thing that could make the situation worse is if I blew the motor within weeks of buying it!!

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Many of the engine parts should interchange. The 4.9 was a stroked 4.5 engine. I believe both cars had the same 4T-60E transmission but it is hard to say if they will be a direct interchange.

Thanks for the feedback KHE. I have done some more research and it does sound like a lot of parts/peices are interchangeable. I haven't found anything that says that the trannys are direct replacements but it sounds like it works.

I bought the other car which now means my original '91 will last forever!! :)

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