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Supercharged 97 Buick Park Avenue Ultra 3.8 into a 98 GP GT

B

BackwoodsEngineering

New member
I can pick up a complete 97 Buick Park Avenue Ultra (supercharged 3.8) car for less than the cost of a salvage yard NA 3.8 for my 98 Grand Prix GT. Will the 97 motor swap over completly? Since I will have the complete car for harness, pcm, etc. Someone told me to find a 98^ car, but the 97 is priced right. Opinions, thoughts, and ideas would be greatly appreciated.
 


The trans in the Ultra is bad. Drives good on flat land up to 35 - 45 mph, but slips going up any type of hill. Would I be able to use the 4T65E trans already in my 98 GT forthe sake of testing? And then swap in a 4T65E-HD once I find one in good working order?
 
You can but I would just keep the better gear ratio of the non hd. You just need a diff PCM to run the L67 with the NA trans.
 
I'll have parts galore. 01 GP SE 3.1 parts car, 97 Park Avenue Ultra, and the 98 GP GT. Which PCM of these cars should I use then with my non HD trans? Trans in the 98 GP GT is good. SE's too. This will be my first project in w body ownership.
 


I'd use the 98's trans. It doesn't matter much that it's not hd. You'll have to get a tune on the pcm though.
 
Any recomendations as far as a good place to mail my PCM to for a tune? Or would I be ok having a fellow member from the area do it? Performance mods would be Speed Daddy header/exhaust kit, intake, cat delete but running a resonator, and if it would be beneficial maybe egr delete.
 
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Your best results would come from an in car tune by a member who knows what they're doing. Mail tunes or "box" tunes don't have the ability to monitor the car for the tune they just have to make a generic tune.


edit: damnit smutty lol
 
Ok. Thank you for info. The SD's I picked up when there eBay seller started selling them again. Came in the mail on Wednesday. :) Now, to sell my used pair of XS Power headers I picked up. lol. Any other little tricks or tweaks I should do while the engine is out? Thinking gasket replacement, plugs, wires, etc. For the exhaust, I am running the SD kit, then I should run no cat........toss in a resonator/glasspack on the way to reduce drone, and my stock mufflers with oval tips should finish up the rear end alright? Otherwise I have Dynomax mufflers in the box still. I just want to be as prepared as possible, cause this will be a lot of wrenching.
 


If you run the GT trans and torque converter, you have to also run the GT flex.

I'd run your 98 Trans with the 97 motor if you go that route. Just plug up the vacuum fittings on the 97 supercharger. Your 98 wiring harness will hook right up. You'll only have to get two plug adapters from Intense or ZZP. One is for the MAP sensor, the other is for the BBV sol. if you use it. I have boost bypass running just off vacuum. Also, if you run SD headers you'll have to make you an extension harness for the front O2 sensor. SD's relocate your front O2 about 12-14" further downstream and the original harness will not reach. Since you'll have a spare harnesses, I'd make your own with the correct pigtails. I did with mine, I had a spare harness here with some butt connectors and electrical tape 5 minutes taadaa... Or you can buy that one to, don't know how much it is..

I'd remove the EGR also, unless you take this car on high mileage roadtrips... You'll see a slight decrease in MPG is you do. If it's a daily driver car around town with minimal road trips, you won't know the difference in MPG. I removed mine so I would not have hot exhaust gas circulated through the supercharger, I am trying to keep the compressed air as cool as possible.. Also have the rear O2 deleted if you run catless, also gives you a spot for a wideband install later down the road. :D
 
How would I do a proper EGR delete? the XS Power headers I have just has a bolt welded into the EGR tube. Is there a better way that can be reversed? Not planning to do too many high mileage roadtrips with the car, besides visiting a friend about 3 hours away here and there, and going to car shows/meets in Wisconsin. My daily driver is actually a 95 Blazer that gets a whopping 16 mpg. :th_laugh-lol3: Might as well do the wideband right out the gate. Would Summit Racing be my best bet? Thanks for the heads up about the adapter/wiring info.
 
ZZP (and Intense I believe) sale EGR block off plates. Other use a coin and coper RTV to block off both ports, but that would require you to get the "blocks" off your EGR piping. Since you have two motors, you should have a spare EGR setup so you can possibly do this. I have access to a lathe so I made aluminum plugs to put in the holes along with copper RTV. I broke both EGR pipes and took the "blocks" off them and bolted them in place to hold the plugs in (you can see in the pics, and I am running Speed Daddy headers). Then have it tuned out.. :D Yes so MPG is a moot point... LOL

Your friends are (IMO):

Best Friend: INTENSE-Racing.com
Decent Friend: ZZPerformance | 3800 Performance Parts | Largest Aftermarket Supplier!

 
The SD headers are brand new still in the box. No modifications done yet. About 2 weeks prior to ordering those, I bought a set of XS Power headers from a local guy that had the welded shut EGR tube. I was thinking that if I can tap some threads into the tube, I could just put an allen head plug into them. That way all I would need for removal is to unscrew it. I would hate to cut up my SD stainless steel headers. They look like a piece of art, imo. Lol.
 


You shouldn't have to cut anything regarding the headers. If you notice in my pic, I cut the EGR tube to remove the piece that attached to the Lower Intake and the Manifold/Header. I have a spare EGR setup. If I want to run my EGR, all I do is unbolt the pieces and remove the plugs like original and screw the EGR back on, bolts right up.
 
You are in the right spot!!! Now to get pics and start a build thread or just continue this one.. :D Congrats!!
 
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