Jump to content

4.5 swap for 4.9


Recommended Posts

Hi this is my first post.

I am in the process of swapping a 4.5 out of a 90 deville and putting in a 4.9 from a 91 deville in it's place. is there any special modifications that I should be aware of? I have both cars on the lot. the 91 has a blown tranny and the 90 had a blown engine. the 90 being in better shape I am restoring it with the engine from the 91. this is the wife's car and she wants to drive it like yesterday :D a little help here guys

Link to comment
Share on other sites


Hi this is my first post.

I am in the process of swapping a 4.5 out of a 90 deville and putting in a 4.9 from a 91 deville in it's place. is there any special modifications that I should be aware of? I have both cars on the lot. the 91 has a blown tranny and the 90 had a blown engine. the 90 being in better shape I am restoring it with the engine from the 91. this is the wife's car and she wants to drive it like yesterday :D a little help here guys

It is going to be VERY difficult to get the 4.9 to be compatible with the electronics and wiring in the 1990 car... Not to say it can't be done but it would be much easier, faster, and probably cheaper to repair the 4.5 engine or find a salvage yard engine.

You state the 4.5 engine is "blown" but has there been any diagnostic work performed to see what the actual problem is? The 4.5/4.9 engines are very reliable.

Edited by KHE

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

Link to comment
Share on other sites

nope you got it backwards I am putting a 4.9 where a 4.5 used to be the 4.5 is dead so the 90 deville is getting an upgrade. It's gonna happen I just need some idea on modifications. She really wants her car back :D

Link to comment
Share on other sites

nope you got it backwards I am putting a 4.9 where a 4.5 used to be the 4.5 is dead so the 90 deville is getting an upgrade. It's gonna happen I just need some idea on modifications. She really wants her car back :D

See my modified post. I discovered I had it backward.

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

Link to comment
Share on other sites

This should be a fairly straightforward swap and you will probably gain a few ponies in the process. The 4.9 is physically identical to the 4.5 so it will fit right in. I have to check my sources but I believe the intake manifold on the 1990 4.5 is the same as the 4.9 but it might have different injectors. However, the fuel calibration on your 1990 is probably different than on the 1991 so you should figure on swapping over all the black boxes and possibly the wiring if there is any difference. Anyways, good thing you have the donor car right there so you can swap over any necessary parts.

Also, you might want to swap the grills and headlights as well. The slightly restyled 1991 looks better in my opinion.

IPB Image
Link to comment
Share on other sites

I guess a hole in the block constitutes "Blown" :D Anyway the 4.5 is out of the car and the 4.9 is on an engine stand and I am transferring all the lines that I can (AC...Power Steering,,,ECT) before putting the 4.9 in the body. Like I said I have the 91 body here if there is anything else that I need to transfer also. (like maby the "brain") I just need someone who has attempted this kind of transfer to give me some pointers. I'm in way over my league here. I've swapped motos in older cars but nothing this new. :D

Link to comment
Share on other sites

I guess a hole in the block constitutes "Blown" :D Anyway the 4.5 is out of the car and the 4.9 is on an engine stand and I am transferring all the lines that I can (AC...Power Steering,,,ECT) before putting the 4.9 in the body. Like I said I have the 91 body here if there is anything else that I need to transfer also. (like maby the "brain") I just need someone who has attempted this kind of transfer to give me some pointers. I'm in way over my league here. I've swapped motos in older cars but nothing this new. :D

You will need to transfer the brain (ECM & BCM). Also, spend some time inspecting the wiring / plug connections between the 2 cars. Pay attention to the connectors that plug into the transmission as well. If there are any differences, you will want to transfer the wires as well.

How many miles are on the transmission from the 1990?

IPB Image
Link to comment
Share on other sites

185,000 miles but it seems ok (i guess) thanks I will keep in mind to transfer the brain boxes also. Ok I guess I am ready to put it into the body as soon as my buddy gets here with the cherry picker (it's mounted on the back of his truck :P ) wish me luck and I will keep posting until it is on the road again for anyone else attempting this kind of swap.

Link to comment
Share on other sites

185,000 miles on the original tranny is very high. Most don't make it this far. These trannies are not known to be the most robust. Since you already have the engine out of the car, I would seriously think about having the transmission rebuilt / freshened. At this point I would have new clutches put in, new seals, rebuilt Viscous Clutch Converter (VCC) and a new sprag gear. I would also consider installing a Transgo shift correction package to handle the extra power from the 4.9 engine. If you are mechanically inclined, you can certainly rebuilt the transmission yourself and save tons of $$’s. I rebuilt my own transmission and can answer questions if you are interested.

IPB Image
Link to comment
Share on other sites

Just got off the phone with the original owner of the 90 caddy. He says he had the tranny redone at 100,000 miles. It looks as tho he may be telling it true. I hope so. thanks for the heads up tho

Link to comment
Share on other sites

Ok I'll keep that in mind. I'm working on a very limited budget and I think I'll try it as it is. worst comes to worst I'll just have to pull it out again...*SIGH* but at least I'll have some idea what I am doing :D Thanks again!!!

Link to comment
Share on other sites

I applaud your efforts for keeping an older but high quality car on the road. In this bad economy, there will be more people rethinking about buying new and end up keeping their old car running. You should end up with a nice running car once the swap is complete. I wish you the best of luck and do keep us posted.

IPB Image
Link to comment
Share on other sites

Ok the motor went in fine! the wiring harnesses are for the most part the same. there are some changes in how the fuel lines are attached but even that was no problem today. I did however have to change the throttle bodies due to tranny linkage diffrences. all and all, so far you are right Ed it is a fairly straightforward swap. I will be spending a bit of time doing all the electrical hookups and such, including the "brain". Thanks again for your help!!! I will keep you posted on the progress :D Like I said, this is the wife's baby and when momma is happy everyone is happy!!! again Thanks!!!

Link to comment
Share on other sites

  • 10 years later...
3 hours ago, Bossdadx3 said:

I have an 88 sedan DeVille project it has the 4.5 what upgrades can I do the plan I have is to have a supercharger put in it ...is this a possible modification 

Research using the 4.9 intake on it.  It adds horsepower.  If I recall this was popular with the Allante crowd.  I dont think you are going to find anyone that makes a supercharger for that engine.

See this thread for more discussion of 4.5 vs 4.9

4.5 vs. 4.9.... Allante....questions...... https://www.cadillacforums.com/forums/showthread.php?t=1993

 

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

Link to comment
Share on other sites

The Allante intake/fuel injection for the 4.5 gave it 200 hp, and the Allante kept that engine when the 4.9 came out.  That's known to give a performance boost with minimal or no problems while an engine switch is... an engine switch.

Engine cooling and lubrication such as the oil-cooled piston skirts may not be sufficient for 150 hp more than what the engine was designed for.  It really takes a clean sheet of paper to do a supercharged engine that has sufficient reliability to actually drive normally on the streets and highway.

The STS-V, for model years 2005-2009 model years, used a 4.4 liter supercharged Northstar that is rated at 465 hp.  A full swap of engine/transmission/ECM may or may not be feasible.

EDIT:  I don't have a parts manual that has both the regular 4.5 l and the Allante special 4.5 l, but I would consult one to make sure that they have the same cam timing and lift, and the same valve sizes.  If not, you can decide whether to update the cam and heads to match the Allante intake/fuel injection.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...