Dylan49

I'm in Dallas but i really would like a tow hitch for my Reatta. I'm swapping in a 4.9 from a Cadillac (not that I'm going to be towing alot with it) but I plan on cutting my Cadillac in half and making the rear end a trailer and I figure I would take that to car shows.. and probably use it if i move somewhere.. anyways, would you be willing to ship?

Not fully related to the swap... Here is the El Camino I'm buying thats going to be my new daily driver and allow me to take my Eldorado out of commission so I can pull the 4.9 out of it. It comes with it's original 350 and the quadrajet. Since it's my new daily I'm only going to be doing regular maintenance on it until it decides it doesn't want to run anymore. If you've been following along you know I've been building what i hope to be a hot lil 283 as my first full engine build. I figure when (or if) the 350 dies i can drop the 283 in and then i can really beef the 350 up, likely get vortec heads + Intake for it, get some headers and a better cam and it should wake up enough for what I want to use it for. Theres also a lil sketch the trailer I'm planning to make out of the trunk/rear seat section of the Eldorado. I bet it would be cool to be driving down the road watching a Reatta tow half of an Eldorado lol. Would be fun to show up to sema or a car show like that.

Im almost certain if done properly a single exhaust can be just as efficient as true duals. I figure Ill start off using most of the original Eldorado exhaust at first

I'm also on the east side of Dallas btw!

Looking at them side by side I think to have the optimal exhaust I need to look into using a different fuel cell. If I could route it straight and then under the rear suspension I think it could work out decent

Oh my bad I read that wrong at first, thanks for the info on that transmission btw cause I'll definitely start trying to look out for one

Are you referring to needing different axles to stand up to the extra HP and torque?

I do think it would be fun to try and build the 4.9 to compete with the Northstar and LS. Obviously I need to gain 100 HP to make that more of a reality and that's much easier said than done. That being said the 4.9 is 300 CID so pushing 300 HP out of it should be attainable. If they pushed out 283 HP back in the early mechanical fuel injected 283 why can't I get 300 hp out of a tpi 300?? I would definitely dub the engine: "The Northstar Killer" the more I think about it the more obsessed I'm becoming lol. I feel like it's my duty to produce a 300 hp boosted 4.9 and destroy one Northstar and one LS in a legit drag race with the Reatta lol

Yeah it's one of the easiest way for the most stock HP but I'm not into doing the easiest most boring swap I like doing out of the box things. What's cool with the 4.9 swap is mechanically it's as easy as it'll get, what's going to be a challenge is engine management and getting everything to communicate with the Buick BCM and cluster/touchscreen

The reason I want to start with the exhaust mufflers once the swap is complete is because I really want to drive the car around asap and that's something that I can still do that with. When I do the Allante intake I'll have to wait for my ECM to be released before I can drive it again

Not much more HP but the Torque is great and the V8 sound is also nice, plus I'm gonna love steering the Reatta with that Powe steering boost haha

My 92 Eldo is PFI not TBI, from my understanding the 4.5s started out as TBI and then halfway through their life they got a head upgrade and PFI. The Allante 4.5 is the only one that had the TPFI right?

Not a whole lot of info here I didn't know already haha

Right, the only thing I can guarantee that will actually happen is the swap itself. And the 3 mufflers in the rear. And that's short-term happening within the next 6 months. Any headwork will be done way after, and the Allante intake swap requires me to collect all the necessary parts first. Like I said my main priority is to have it drivable asap. The only thing stopping me from starting is the need to a new daily driver. Although I suppose i could start on taking the Buick subframe out... I have a small apartment one car garage that I somehow need to use to cut my Cadillac up and keep the ass end in the very back for when I'm ready to make it a trailer. Keep the 4.9 off to the side, and then get the Buick back in to drop ITS subframe. Going to be a bit of musical chairs. All of this is happening though because I'm trying to plan a move to Arizona within the next 2 years to settle down for good. I just turned 25, ive taken my Reatta and it's 3.8 everywhere from hwy 1 in California to lake superior in Minnesota. It's seen the grand canyon and mt Rushmore. It's my favorite thing in existence i think lol. What needs to happen for me to make the move is: I need to downsize from 3 cars to 2. The plan is to have the Buick 4.9 tow my homemade Cadillac trailer with a bunch of my stuff. And then use the El Camino that im purchasing soon to get the rest of my stuff, maybe tow a small uhaul trailer behind it. I'm from the Bay area in California but ive been living in Dallas the past few years. All I know is that I want to build my Buick and move to Arizona lol hopefully y'all are down with that and can maybe point me in the right direction for a few things!

To add some more fun to the forum, my exhaust setup for this is going to mimic the newer style civics like this: only I'm going to be using 2 spintech 6000s on the outside and a Porter shorty on the inside. I'm also gonna put a Borla Polyphonic Harmonizer behind all 3 of them. I haven't done much research into aftermarket cats yet if anyone has any recommendations. I'd like to get a set of custom headers done for this as well. I have noticed that the civic has tank conveniently has a slot for the exhaust to fit under where our Buick does not, would I be able to take a hammer to my tank and "make" a slot or would it be better for me to try and find an aftermarket tank? Likely the order of operations for this will go like: 1. Complete the swap with the base engine as is. 2. Civic style muffler setup 3.Allante intake/Valvtrain swap 4. Custom Headers/Low Boost turbo (yes I do want to put a 4g63 turbo on my 4.9) 5. After it likely blows a gasket I would have the heads ported and look into going a size up on the valves if possible. Obviously if it was to blow at anytime before step 5 I would do all the machine work then but I want to do this project and drive it as much as possible so I want to be able to drive it stock and then upgrade 1 by 1 and really feel how much each upgrade eventually does. All while enjoying the use of my beloved first car.

So I checked out rockauto to see if the 4.5 and 4.9 heads have different valve sizes and they are the exact same. Now I just need to verify if theres anything different with the intake runner design. I also verified that the stock cams for both engines are very similar if nol so that takes that out of the equation. Really didn't think a tune + intake could generate 20 HP but I guess with stock engines that are designed to be underpowered that's all it would take for GM engineers to make it happen.

Hey y'all, its been a while. Wanted to let everyone know this is still happening. Sorry for not replying at all I didn't have any email notifications and nobody replied to my post until a few days after so I figured nobody cared or thought I was actually going to go through with it. Anyways, a couple clarifications: 1. I will not be going rwd with the 4.9, I had plans to go rwd with a 283 that I'm building on the side but with my current living and money situation that isn't realistic for me. 2. Currently my Cadillac is my daily driver, I actually use it for my lawn care business but I'm going to be purchasing a very clean daily driver condition El Camino in the next few weeks to become my new daily. Once that happens I'm going to cut my Eldorado in half and make a trailer out of the ass end. And then cut the body off the subframe/powertrain. 3. I'm definitely going to look into using the 3.8 sensors on the 4.9 to help with my gauges. 4. I'm looking for people with knowledge on the Allante 4.5 and the 4.9, i know I'm going to use the Allante intake but I would like to try and find some info on if the Allante 4.5 has other bolt on upgrades that could be transferred to the 4.9. Are the heads better flowing? Do they have bigger valves? Would it be just as cost effective to have the stock 4.9 heads port matched to the Allante intake? Did the Allante have a different cam profile than the 4.9? Is it possible it's just as simple as the intake + a retune? Like I said before I don't really want to tear too much into the engine because I really would like to have fun and drive it around asap but I would like to try and unlock some potential with factory GM parts. Again, sorry for taking so long to reply! I'm definitely going to do this swap and I hope i can get some knowledge from everyone on things I might not know about. Thanks again everyone!

Does anyone know if there are any differences in the heads between the Allantes 4.5 and the 4.9 in the Eldorado and DeVille? Does one possibly flow better or have bigger valves? It's just interesting that the intake manifold really picks up 20 HP, maybe it's the cam profile as well?

I know there is a matter of matching data streams i just don't really know how to go about that, do I need any more equipment than a laptop? Is it possible for me to get the ALDLstuff file and match the bytes on my laptop and then send the actual BCM unit off to sinister to have it flashed to the bytes that I manually reorder in a basic program like Excel or ms word or something? If someone put a Northstar in an 89 you would think a 4.9 would work easier. I know the screen wasn't functioning properly in the Northstar but it was still on and displayed SOMETHING.

What's up guys! New to the forum but I've been reading posts from here since I bought my Reatta in 2017. I've always had big plans for it going from wanting to turbo the original 3.8, twin charging a series 1 or 2 3.8, doing the 4.9 swap all the way to swapping in the SBC 283 I'm building and convert to rwd but I've realized that's out of my means at this point in my life... Maybe in the distant future. But I want something. I own both an 89 Reatta and a 92 Eldorado. I have alot of fun driving the Eldo and love that the 4.9 is fairly simple. I also know they share the exact same subframe so mechanically this is a bolt on swap that I should be able to do in my tiny apartment garage on jackstands. That being said, I know I'm going to run into issues with touchscreen and cluster functionality. I've been told that if I use a 1989 Cadillac BCM in place of my 89 Reatta BCM that I may still have control over my radio, climate control, and possibly working gauges. (Which is all I care about) the other touch screen extras are cool but I can live without them as long as I have access to the regular stuff. I know the onboard diagnostics will also not work anymore which is fine with me. I know this swap has been done at least once but it's hard to find any info or even any pictures on the Reatta it was done to. I'm wondering if anyone could help shed some light on this for me? To conclude this I plan on doing some very mild mods to the 4.9. it already is fun enough to drive for me in the Cadillac, i figure a few hundred less pounds in the Buick would make it even more fun in addition to: Allante Intake swap, ported heads with the intake matched, and a custom exhaust system. I have no desire to go further into the engine than that. And it already has enough power to smoke the tires a bit which is awesome. Again, I know mechanically this swap should be "cake" where I have a bunch of question marks is making it communicate with the Reatta instrumentation, windows, gas cap/trunk and whatever else might communicate through the ecm/BCM. The combo I plan to try to use is a 1990 Eldo 4.5 ecm reflashed for the 4.9 by Sinister, with an 89 eldo BCM. I've included a crappy Photoshop of what my Reatta would look like with the engine in there. I definitely like it