I just wanted to preface with thanking this forum for basically providing me with a wealth of Cadillac HT engine information that nobody else on the internet could provide. The most popular Cadillac forum on the internet couldn't even really provide any solid information for anything. The Fiero guys truly are the mad scientists of the automotive hobby, and I can't thank them enough.
So here's what I have and here's the rough plan I have.
I own a 1988 Cadillac Eldorado with the original TBI 4.5 V8 and 4T60 transmission. Both unopened to by knowledge. I've mostly stuck to custom suspension and exhaust upgrades with this.
I was heavily considering a full LS4 swap, but as you can imagine, "bottom dollar" quickly gets thrown out of the window when you add up the transmission building costs, fuel system, cooling system, exhaust system, and ECU. I have bills to pay, and student loans sucking the life out of me.
A 4.9 swap is about as close to drop-in as I can get with almost zero modifications.
However, I want to do a 4.9 swap WITH the Allante Intake (Why make life easy?), and I could use this forums help for a rough guestimate of what "gotchas" I might need to address. I have read the fuel system runs at a higher pressure for the MPFI Allante variant, so I'm assuming the bare minimum I would need to perhaps swap an Allante fuel pump into my Eldorado's tank.
Mounts would all be the same, and theoretically, even the exhaust should just bolt in without an issue.
Now I do see a thread about swapping the intake, but it seems like you all were talking about tuning it, but I don't see much on the ECU used or any intake mounting concerns.
That's kind of where my questions start. If I want a 4.9 with the Allante style MFI intake, I need to block off the EGR and I see at least have it tuned to run with the EGR off and increased air flow. Do you guys just use a modified 4.9 ECU or an Allante 4.1 ECU? I've really only messed with my carbed smallblock on my C10, so I'm honestly not even sure how to push any sort of "tunes" to a pre OBD system anyway. Er, I'm assuming my these would be pre OBD1. Do I need to burn a PROM chip for it?
Additionally, since I'll have the engine out and have to take things apart anyway, are there any recommended cams for the 4.9 I can order? Additionally are there any preventative maintenance things I should do? I'm assuming a water pump, head gaskets, or at the very least valve cover gaskets?
I'm shooting for like a 2k job if I do everything myself. Obviously an optimistic estimate at best.
I'm hoping that this topic can be a good reference point for anyone else in the future attempting a 4.9 swap into a Cadillac of the same era. If the Caddy forums can't help, at least this one can.
When I first saw this thread, and then the picture, I thought that you were apparently going to pull a Cadillac 4.9 out of the car in the picture... and just use it for parts, and I was horrified. Then I read that you're upgrading a 4.5 to a 4.9, and was relieved. I don't know anything about the 4.9, but there are a lot of people here who do, so I hope you get all the information you need. That car looks amazing... and I can't wait to see what it's like when it's got a 4.9 in it.
[This message has been edited by 82-T/A [At Work] (edited 08-01-2024).]
This forum is made for Fiero owners that collect, maintain and upgrade their cars. While some here have done 4.9L Cadillac swaps in their Pontiac Fieros there is nothing here to help Cadillac car owners. I would suggest you go to a Cadillac forum for info.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
This forum is made for Fiero owners that collect, maintain and upgrade their cars. While some here have done 4.9L Cadillac swaps in their Pontiac Fieros there is nothing here to help Cadillac car owners. I would suggest you go to a Cadillac forum for info.
Miss the part where I wrote they aren't much help and the Fiero community actually does more with the Cadillac HT engine family than actual Cadillac owners?
I'll wait for someone who actually has a Caddy swapped Fiero to get some advice on changing over the engine. If I didn't say anything about swapping this into my Eldorado, you wouldn't know the difference anyway. Thanks for the valued input.
This forum has been the BEST source for Caddy HT V8 build knowledge on the internet, and it is thanks to the creative and hardworking folks in the Fiero community.
[This message has been edited by brandon8696 (edited 08-01-2024).]
This forum is made for Fiero owners that collect, maintain and upgrade their cars. While some here have done 4.9L Cadillac swaps in their Pontiac Fieros there is nothing here to help Cadillac car owners. I would suggest you go to a Cadillac forum for info.
While I agree this should be in the non-fiero section of the forum, Dennis. Turning this guy away, when a good amount of fellas here may have an answer to this question seems kinda backwards. Saying there is nothing here to help a Cadillac owner is both silly and an outright lie. I know plenty of W-Body owners who come here for 3.4DOHC info. Lets get him to the right spot on the forum and see what comes up.
While I agree this should be in the non-fiero section of the forum, Dennis. Turning this guy away, when a good amount of fellas here may have an answer to this question seems kinda backwards. Saying there is nothing here to help a Cadillac owner is both silly and an outright lie. I know plenty of W-Body owners who come here for 3.4DOHC info. Lets get him to the right spot on the forum and see what comes up.
Thank goodness someone with some nuance. Yes, if Cliff can get this over to the other section of the forum, that would be extremely helpful. I'd do it myself, but I don't see any interface options to do so. Everything I've learned about Caddy HT modifying, manual swapping, tuning, and even turbo/supercharging has come from this forum over the years. Fiero guys are some of the most creative car builders I've ever met, and I can link dozens of Cadillac topics if they truly think there is "nothing" here haha.
Thank goodness someone with some nuance. Yes, if Cliff can get this over to the other section of the forum, that would be extremely helpful. I'd do it myself, but I don't see any interface options to do so. Everything I've learned about Caddy HT modifying, manual swapping, tuning, and even turbo/supercharging has come from this forum over the years. Fiero guys are some of the most creative car builders I've ever met, and I can link dozens of Cadillac topics if they truly think there is "nothing" here haha.
My buddy is basically the foremost expert on 4.9 Caddys... he's done all kinds of Allante 4.9 swaps, primarily into citations. He even built one that works off hydrogen. If you absolutely don't get the answers your looking for here, I'll share his contact information with you. But I don't want to bug him if the questions can be answered here... but I know there's tons of 4.9 people here, so I hope you get some help!
Let me make sure I am getting this right. You currently have a caddy with the 4.5 in it correct? You are looking swapping the 4.5 out for the 4.9?
Yessir.
However, the big questions for me pertain to swapping over the Allante intake, making sure I can tune the ECM for it, and if I need to upgrade my fuel pump.
Here's what I DO know what gathering information, in case anyone from Google or whatever come across this post.
89-92 Allante intakes have the correct cooling channels and gasket match perfectly with the later 4.9 engine. Pre 89 Allante intakes have provisions for EGR though, if you really don't want to deal with tuning, you can modify the cooling channels.
I can tune an ECM for EGR off, and play with the tuning a bit to accommodate the better air flow of the Allante intake.
In response to that other user asking about the gains? I honestly can't say any dyno numbers. Most of the dyno numbers I see posted on here are of heavily modified engines in Fieros.
What I can say is that the Allante intake flows more air and fuel than the TPI setup, and thus can give you a small gain over the 200hp rating of the 4.9. I also like the cleaner setup of the MPFI system, and according to several Caddy owners, it just runs cooler without the EGR system heat soaking everything.
If I can get some definitive information on self tuning, and pushing tunes to the ancient ECM, I'd then like to perhaps order a cam for the engine. That's realistically a stretch goal.
The good news is I am in no rush. My stock 4.5 is tired, but it can still handle weekend cruises without much fuss.
1. The ECM can be tuned. You can go thru the trouble to get everything yourself to do or us this guy Sinister. I used him to tune my 4.9 to run with the Allante intake. (throttle body, upper intake, and lower intake). The EGR will just be tuned out or turned off, however the tuner does it.
2. The 4.5 and the 4.9 fuel pumps are the same, no worries there.
3. With the Allante stuff, I would try and grab the rocker arm supports from the Allante car. These are stronger than the 4.9. Less prone to problems.
4. Make sure you grab the hard fuel lines with some extra hard line still attached to the fuel rail, those are impossible to find. Also the fuel pressure regulator attached to the fuel line, it is no longer made as well. Unobtanium.
Unfortunately there aren't a lot of upgrade parts available. No one here has ever reported finding a cam upgrade. Also, it can be tough to find simple things like replacement head bolts, etc. This may limit some of your plans. But, as a 4.5 owner you are probably already used to this.
Supercharging or turbo charging is possible. If you go this route then you'll definitely want to invest some time in learning how to do your own tuning.
Unfortunately there aren't a lot of upgrade parts available. No one here has ever reported finding a cam upgrade. Also, it can be tough to find simple things like replacement head bolts, etc. This may limit some of your plans. But, as a 4.5 owner you are probably already used to this.
Supercharging or turbo charging is possible. If you go this route then you'll definitely want to invest some time in learning how to do your own tuning.
The only thing you are incorrect on is the cam. Delta makes off the shelf camshafts for the 4.5/4.9 motors. They will also build a custom camshaft if you ask for it. I know this first hand.
1. The ECM can be tuned. You can go thru the trouble to get everything yourself to do or us this guy Sinister. I used him to tune my 4.9 to run with the Allante intake. (throttle body, upper intake, and lower intake). The EGR will just be tuned out or turned off, however the tuner does it.
2. The 4.5 and the 4.9 fuel pumps are the same, no worries there.
3. With the Allante stuff, I would try and grab the rocker arm supports from the Allante car. These are stronger than the 4.9. Less prone to problems.
4. Make sure you grab the hard fuel lines with some extra hard line still attached to the fuel rail, those are impossible to find. Also the fuel pressure regulator attached to the fuel line, it is no longer made as well. Unobtanium.
I greatly appreciate the help with this, and I think this has given me the confidence to start piecing this build together.
My only question I think I still have is in regards to the fuel system. Let's say worst case scenario I get screwed into making my own hard lines. Can I just get a fuel pressure regulator that is for the OEM operating range of the Allante? That would be like 45-50 PSI, right?
From the info I gathered, my own comfortable skill set, and my budget, I think I will ditch the idea of a cam swap, and just stick to the Allante intake on the 4.9 with an EGR delete and tune. Even if I squeeze out 215-225hp from it with my cat delete exhaust, I'd be a happy camper.
The 4.5 with only 155hp and 240ft-lbs of torque moves the little Eldorado pretty well, so I think 200+hp and 275+ ft-lbs should be zippy. Er well zippy by my extremely low standards haha.
I think next check I'll pick up the Allante parts, because I'd like to polish them before installation.
I appreciate the help, and I hope this doesn't become one of those threads that never gets a post with the finished results haha.
Unless you have the skills to make your own fuel lines you absolutely need the rails and everything that is attached to them. The injectors are not straight in the intake either, they are angled which would add difficulty making lines.
My advice it to find all the parts. But, in theory, yes you could make all your own stuff and have an aftermarket regulator. Once you see what I am talking about you will have a better idea.
I will take some pics of my stuff and show you later today.
The fuel regulator is what the purple vacuum line is attached to. The fuel inlet has the AN fitting on it. The outlet is on the regulator. The inlet is the tricky one, and I would recommend making sure you have it and the regulator.
[This message has been edited by Spadesluck (edited 08-05-2024).]
The fuel regulator is what the purple vacuum line is attached to. The fuel inlet has the AN fitting on it. The outlet is on the regulator. The inlet is the tricky one, and I would recommend making sure you have it and the regulator.
I now understand exactly what you meant in your last comment. Sir, you are a gentleman and a scholar.
Alright, so I have a rough understanding of the fuel system needs, I have a rough understanding of the ECU tuning I'll need, and I have a rough guestimate of the mounting of it all. I suppose my last query is the EGR delete, which I'll see if I can find anywhere on this forum or the Caddy forum.
Spadesluck, do you have any firsthand experience with the EGR delete on these? Also, any weird wiring harness issues I need to worry about. I've read from several sources on here and the Caddy forums that the 4.9 PFI harness should just plug and play with the Allante connections.
I figured I may as well ask while I have you here. Hopefully this info can help other folks too.
[This message has been edited by brandon8696 (edited 08-06-2024).]
I have first hand experience with the regular 4.9 intake to Allante swap. A few wires will need to be lengthened, atleast in for the Fiero format. But it is just about a direct swap. I beleive one connector needed to be changed. If you do a search on this forum there a a few threads about it.
If you get all the Allante stuff...lower intake, upper intake, throttle body, fuel rails etc....there are no provisions for any EGR. It just needs to be tuned out. Simple enough.
Oldjoedad, who is in this thread is a guru on the 4.9 wiring. He could potentially help you out with that as well. Just message him and ask when you get to thst point. I can also help, but he is more knowledgeable on that than me. I do have all the wiring schematics, but they are for what goes to where for a fiero application.
I had a scrapyard out of Arizona on Ebay pull be the entire top end from a 4.5 Allante. 376 bucks after shipping and taxes. Honestly not the worst price considering no yards by me are overflowing with Allante engines, and I didn't want to freight drop an entire engine just for parts.
They have the upper and lower intake, fuel rails, fuel pressure regulator, hard lines, and throttle assembly. The only thing they didn't include was the hose and air box, but my OEM one may just plug right on? When I mentioned my project, I guess they have an employee or an associate that owned a Caddy swapped Fiero and has done the same thing, so they had a good idea of exactly what I needed for the project. Honestly if this place does a good job shipping everything out, I may get the 4.9 from them as well.
If anyone has any suggestions on the best 4.9 I can get for this swap, let me know. I'm assuming I need to stick to a 91-93ish example for a pre OBD ECU and harness? Honestly sort of talking out of my ass until I do a little more research on it.
The project is IN motion though, and I'll be polishing the intake assembly myself, and then painting the 4.9 in a GM Corporate Blue most likely.
They were able to work with me and include all of the necessary fuel line and regulator components.
The next step over the next year will be to gather the 4.9, get the PCM flashed for my needs, and hopefully get the top end polished. I've noticed the intake isn't raw aluminum, but rather coated in something. I may have a professional service strip it, polish it, and clear coat it.
