: 4.0 to 4.6 swap ?



cadillacstars
06-14-04, 08:01 PM
Any of you fellas have any experience in swapping a 4.0 aurora motor with a 4.6 northstar? Iv'e got a '95 Aurora with a very loud upper engine knock (no not lifters) and i want to put a northstar in it. I know both have very similar configurations, it'll fit. But i'm wondering about the electronics. can you reflash the computer in a '95 aurora to accept the northstar, or would you have to swap PCM's also? anyone with any experience in this matter your help would be very appreciated:hmm: :hmm: :hmm:

Aurora By Olds
06-14-04, 08:13 PM
do it.
The only real thing you will have to look at is the final drive ratio of the trans. If you end up with a 275hp engine you will be fine, but if you have the 3.41 gears and toss in a 300hp, it will be doggy as hell. Either way, you could just swap the original intake cams from your 4.0 (if theyre still good) into the 300hp 4.6L and it would become a 275hp. If the aurora has the autobahn package, you would have the 3.73 (something like that) gears and the 300hp would work perfect.
Nothing should need to be modded, as they (the 4.0/4.6) are the same engine, basically.
I would have swapped one into mine, but just as it was out and being slopped back together, I couldnt find a 4.6 anywhere at all....just my luck.
I would love to have an Autobahn Aurora with a 300hp 4.6 in it...that would be sweet. I would definitly consider a 4.6 if youre going to swap the engine though. Its basically the same engine, just cheaper (used) and has more power :-)

Vesicant
06-14-04, 09:01 PM
I bet Bbob's gonna post here and say theres going to be some PCM/Engine management conflicts if you use the stock aurora items.

So youll need to swap the electronics out while your at it.

cadillacstars
06-14-04, 09:18 PM
is the '95 aurora pcm a flashable pcm or is it a replaceable prom? i have resources to have a new prom burnt. the aurora is an obd I in 1995, however it has an obdII connector. all of its electronics in 95 for all thoughts and purposes are obdI , as it does not run a MAF, and it is accessable with a Tech 1 scantool

Aurora By Olds
06-14-04, 10:30 PM
The engine management is completely identical.
The only difference is the MAF on the later OBDII engines as stated above, which can be solved by using the 4.0 intake/TB (same as the 4.6).
The ONLY difference I can think of at this time between a 4.0 and a 4.6 is the bore.
And the cams in the 300hp version obviously.
Someone jump in if I am forgetting anything, please.
The PCM should compensate for fuel/air management and the whole works.
It's much like swapping a Chevy 305 with a 350.
I know you can get replaceable proms, however, I dont know exactly what they entail.
Ive asked a few companies, but with no response. (apparantly they dont care to push their merchandise)
Personally, I think the only benefits of a Prom chip would be to eliminate the speed limiter as well as the power retard that goes along with the Traction Control.
Just my $0.02

Aurora By Olds
06-14-04, 10:37 PM
Oh, and if anyone doesn't believe it can easily be done, donate me a good crate 4.6 and I'll prove it :lildevil:

cadillacstars
06-14-04, 10:47 PM
aurorabyolds is the 4.6 a bored 4.0, or stroked: or both? i've heard it was a strokrd 4.0 but i could be mistaken

mike98c
06-15-04, 12:32 AM
aurorabyolds is the 4.6 a bored 4.0, or stroked: or both? i've heard it was a strokrd 4.0 but i could be mistaken
Bored.

Aurora By Olds
06-15-04, 10:40 PM
Yup, stroke is the same, bore is the only difference.

Aurora40
06-23-04, 12:09 PM
Definitely post up how it turns out if you do it. :)

cadillacstars
06-23-04, 10:04 PM
It was a friends aurora, he found a 4.0 CHEAP. so he decided not to do it. needlless to say I was very disappointed.:crying: :crying: :crying:

58 Biscayne
11-08-11, 03:16 AM
Kind of the oppisite but can you put a '99 Aurora 4.0L into a '99 STS? I've got the head gasket issue and possibly a cracked block (coolant running out between the head and block in front). I have access to an Aurora 4L already out. Can I use it's long block and swap over my intake and brackets/mounts?

89falcon
11-09-11, 01:15 PM
Kind of the oppisite but can you put a '99 Aurora 4.0L into a '99 STS? I've got the head gasket issue and possibly a cracked block (coolant running out between the head and block in front). I have access to an Aurora 4L already out. Can I use it's long block and swap over my intake and brackets/mounts?

You should be able to....but the car....and the driveline.....was designed for the 300hp engine......not sure you'll be please with a fairly big drop.....especially at the lower RPMs. After all that work, you'd probably be much better off trying to find a 4.6 donor engine....and an SLS engine will work...you just need to swap the intake cams.