3.4 DOHC to 3.8 Swap in 96 Monte Z34

[Nick07]

I'm lookin at taking out my royal pain of a motor (3.4 DOHC) and putting in a 3.8 Series II Supercharged motor in. My car is a 96 Monte Z34 and the donar car would probably be a grand prix or maybe one of the park avenue's with that motor. Any pointers or advice on the best and cheapest (and easiest) way to go about the swap please let me know. Also this would be a first encounter in my book so there's probably some key things I'd miss during the swap

[thisnametooktolong]

dont cut wires

Make sure you swap the Fuel pump too. Your old one will not handle the flow. If you use your old tranny, place a cooler on it. and take it easy 99% of the time. after all you dont have the HD version of the 4t60e or the 4t65 in your car. Running the wrong electronics is a pain with a programmer and a lot of work (or a good tuner). The same holds true for the transmission you have to swap emp sensor and wire harness if you dont

[Nick07]

Let me add a little more info for those who are gracious enough to give me their advice... I'm putting in the supercharged 3.8 Series II with the tranny that is specifically designed for that motor, a new ECM, complete new wiring harness so I don't have to mess with cutting and splicing for wrong plugs and such, and I'm gonna get the transaxles (half-shafts), knuckles, etc. off of a Grand Prix. More or less I'm looking for advice as to if I have cut the frame, if I can use the same motor and tranny mounts, where I can get an ECM for as cheap as possible (a GOOD one), things like that. Any advice or tips will be greatly appreciated though. PLEASE COMMENT!

[matthewboyleZ34]

I wouldn't recommend to do the swap. I, too, have a 3.4L and everyone likes to downplay it into a hunk of junk. I have had all the problems that everyone complains about and fixed all of them too. Look at the specs for a 3.8L (stock no Supercharger) and the specs for a 3.4L DOHC (stock). The 3.4 has 215hp and the 3.8 has a mere 200 hp. If you add a supercharger to the 3.8L (depending on which vehicle you pull it from) you will get at most 240hp. I have looked into this deeply and the only ones I've seen do the L67 swap are the ones that only had a 3.1L engine. I would recommend to rebuild your 3.4L DOHC and beef it up with a supercharger. You could get around 270 - 280 hp out of it with the right cams, intake (supercharger), and exhaust system. This is what I plan to do. Please let me know why this would be a bad idea if it is. DOHC is a much stronger engine!

[Nick07]

I'm not gonna say what I think you should do cuz ultimately that's up to you. I have considered rebuilding my 3.4 cuz it would save the hassle of trying to find compatible parts for a 3.8 supercharged swap. I feel more comfortable with putting in a 3.8 versus keeping the 3.4 because I'm more familiar with the 3.8, it's way easier to find parts for (especially the supercharger, I don't really like turbos), and it in turn I think would benefit me more. Mind you I'm not just looking for a swap, I eventually plan to completely rebuild the 3.8. I have a friend that rebuilds motors for a living and he's suped up a couple 3.8's for some people. He said he'd help me out with some things and point me in the direction I want to go. One kid paid him $4,000 cash to rebuild his 3.8 supercharged, the kid got his car back 3 weeks later with 372 Fwhp and 404 tq. Take note that those numbers aren't from the flywheel, it's from the wheels. I too really like the DOHC motors though, they got their problems but what motor doesn't. Anyway, I'm not even sure if I'm still doing this cuz I wanna get rid of this car and buy a truck and get me another Mustang.

[mrl390]

Originally Posted by matthewboyleZ34

I wouldn't recommend to do the swap. I, too, have a 3.4L and everyone likes to downplay it into a hunk of junk. I have had all the problems that everyone complains about and fixed all of them too. Look at the specs for a 3.8L (stock no Supercharger) and the specs for a 3.4L DOHC (stock). The 3.4 has 215hp and the 3.8 has a mere 200 hp. If you add a supercharger to the 3.8L (depending on which vehicle you pull it from) you will get at most 240hp. I have looked into this deeply and the only ones I've seen do the L67 swap are the ones that only had a 3.1L engine. I would recommend to rebuild your 3.4L DOHC and beef it up with a supercharger. You could get around 270 - 280 hp out of it with the right cams, intake (supercharger), and exhaust system. This is what I plan to do. Please let me know why this would be a bad idea if it is. DOHC is a much stronger engine!

Good luck with that one. Where exactly do you plan on putting this supercharger? On top of the motor so you will have to custom make a LIM to get it to work and then the supercharger will stick out the top of the hood? Or do you plan on putting in a centrifical supercharger in the space that isnt there under to hood for one. Oh and again, you will have to do this completely custom as well. The only theoretical way to get a supercharger to fit under the hood would be to somehow find a kit that uses the extended drive that runs over the top of your engine to the front of the motor and the supercharger sits at the back. Even if you do find a supercharger that works, all the brackets will have to be custom, all the tubing will be custom. You will have to relocate the battery and washer bottle, somehow find a place to mount an intercooler on the front of the car. Not to mention it will be a nightmare of trial and error with tuning. Then you will still need cams which arent made, ported heads ported intake, larger throttle body, bigger injectors. All of which you will need to do all on your own cause no one makes any of these parts nor will do the work on the engine for you. The LQ1 is not a practical engine to supercharge. That said, it isnt as strong of a motor as the L67 anyway. The stock L67 blocks have been tested to hold up to some insane power. Not to mention that there is a ton of aftermarket parts out there and companies that do work on these motors. You can make some incredible power out of an L67 for relatively cheap. No one has really tested the strength of the stock block of an LQ1 to see what it can handle.

[Jrs3800]

I agree with the above post...

In the earlier years the Regal( Other W Body ) used the 3800 V6 early on while the rest of the W's were using the 2.8,3.1 and 3.4 DOHC.. A 3.8 will fit in the engine compartment just as well as the 3.4 DOHC..

And the Stock M90 Blower will be nestled neatly between the heads... The 3800 Series II and III are all a dime a dozen... Parts are more than plenty and Mods are all there to make a 3800 go from mild to wild or in between..

Lets look at it this way... The stock L36 NA is supposedly reliable to 300 HP... The L67 is supposedly good to the tune of 600 HP, That not saying it'll last at 600 HP... But there are quite a few making that kind of power on a stock bottom end...

and when you get to the series III Bottom end you get Powered Metal Forged rods as opposed to cast..

There are plenty of cams for the series II and III, Rockers... Intakes... PCM's and Tunes... Personally I would pull the 3.4 DOHC and sell it to someone that wants it and build up a 3800 SC...

[Nick07]

I 100% agree with Jrs3800 and mrl390, both stating the reasoning behind wanting to switch motors. The 3.4 is a good, strong motor don't get me wrong. There just isn't sh*t for aftermarket parts and they are pain to work on, not to mention it's a pain in the rear just to find used replacement parts. Right now I'm actually lookin at sellin the car and gettin somethin different matthewboyleZ34, if yer interested in another Monte or a spectacular parts car than she's all yours buddy! $1200/obo, check out http://www.cardomain.com/ride/3379967 for pictures

[matthewboyleZ34]

Quote mrl390: "Good luck with that one. Where exactly do you plan on putting this supercharger? On top of the motor so you will have to custom make a LIM to get it to work and then the supercharger will stick out the top of the hood? Or do you plan on putting in a centrifical supercharger in the space that isnt there under to hood for one. Oh and again, you will have to do this completely custom as well. The only theoretical way to get a supercharger to fit under the hood would be to somehow find a kit that uses the extended drive that runs over the top of your engine to the front of the motor and the supercharger sits at the back. Even if you do find a supercharger that works, all the brackets will have to be custom, all the tubing will be custom. You will have to relocate the battery and washer bottle, somehow find a place to mount an intercooler on the front of the car. Not to mention it will be a nightmare of trial and error with tuning. Then you will still need cams which arent made, ported heads ported intake, larger throttle body, bigger injectors."

1) Yes you can modify an M90 Supercharger to fit on the LIM. That's not what I had in mind.
2) I was considering an easier route by doing a centrifical supercharger with a drive shaft that runs it at the back of the engine. They do make one: http://www.pfyc.com/pc/GA3017/GAUNDE...arger+Kit.html
3) Yes, along with most modified engines, you will have to relocate OEM configurations.
4) I have since decided on a Turbo application where, once again, I would have to make custom parts and weld and relocate some things to make room for the turbo.
5) It's probably easier to do the L67 conversion since the idea has been raped and repeated countless times :eyes rolled:
6) We (3.4 DOHC owners) can change the timing on our cams to suit whatever we need (turbo/sc) as far as that goes. If you're refering to lobe and duration then regrinds are possible. Larger than 42# injectors are a must if you're running forced induction. Port and Polish heads/cylinders/intake/exhaust is optional. PC tuning is a must
7) I'm sure you already know this kind of stuff is also required for the L67 swap.

Quote mrl390: "The LQ1 is not a practical engine to supercharge. That said, it isnt as strong of a motor as the L67 anyway. The stock L67 blocks have been tested to hold up to some insane power."

1) Let's compare LQ1 to L36. I think you're confusing the idea that the L67 is a bone-stock L36 long block with a supercharger on it. It's not.
2) I'm interested in seeing the INSANE POWER these blocks can hold up to. It would be nice to check the stats of the two motors. Maybe we can find a magazine company that specializes in V6 performance to do an article "LQ1 vs. L36". Just dreaming...

**Disclaimer**
Most importantly, I don't claim to have all the answers and certainly am not an expert on anything pertaining to these motors. What I have stated I have researched on and some of that info is through forums like this (which is based mostly on opinion).

I do agree that the aftermarket for L67/L36 is HUGE and there is nothing for the LQ1. And by nothing, I really mean, like nothing... I have found some lighter lifters and that's about it.

I personally would like to and I plan to rebuild my 3.4 DOHC. First and foremost I want to keep my 97 Monte Carlo numbers matching. Secondly I want to be one of the few that can utilize untapped power from the motor and kick the Mustangs and Camaros to the curb with my sleeper. All that said, sorry for sending this thread way off topic!! Giggety

[matthewboyleZ34]

Quote Nick07: "I'm actually lookin at sellin the car and gettin somethin different matthewboyleZ34, if yer interested in another Monte or a spectacular parts car than she's all yours buddy! $1200/obo, check out http://www.cardomain.com/ride/3379967 for pictures"

Too late for this! I just bought a commuter 97 Monte Carlo LS 3.1L. I got a deal I couldn't pass up on and its the same year and color as my Z34. Got it for $650.00 with new tires and aluminum five star wheels. The clearcoat is coming off the hood, small scrape across pass side door, and broken motor mount. Everything else is in excellent shape. This is my first step in the rebuild of my Z34. I now have a backup car while I rebuild it.

Yours seems like a great deal as well though I can't find myself driving that far to get it! I'm passionate about the 5th gen Monte Carlo Z34s but by no means am I crazy! Thanks for the offer though.