Engine Upgrade 3.4 to 3.6

When I did my search I couldn't find an exact thread. I did, however, glean from many posts that a 3.6 is NOT a direct swap with a 3.4 in a 99C2. Is that an accurate statement?

Based upon comments I have read here, yes that is correct, it is not a direct swap.

From what I heard it will fit but if you have a '99 then there are some differences especially when it comes to connecting the throttle since '99's had a cable and later years did not. There are some other things that are not the same but not sure what to be honest. So hopefully someone will chime in on this thread that has done this swap. I too am interested as that would be my preferred thing to do is increase engine size when the time comes. However now that I think about it, I wonder what the weight increase (if any) is with the 3.6 over the 3.4 ? Wouldn't this play a role regarding suspension and handling of the car ?

Note - the swap is difficult, but not impossible. C.

I think there is guy is going through this change on the 6speed board (it's down for maintenance for now so I'll have to check later). He's also documenting what he's doing. There are a lot of 99 guys who'd be interested in this change...me included. If the change to a 3.6 motor turns out to be doable why not just move up to the latest 3.8 with the power kit option?

Didn't JimB do it in his old 996?

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Yes, and it also said if he had to do it again he'd just buy an '02

Paul (paul 996) is doing the conversion right now to his car.

Sounds like a lot of trouble for a very minor performance increase.

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I wouldn't be doing it for the minor performance increase, it would be for a better block than the 3.4 and for more up to date accessories and upgrades done to the 3.6. The 3.4L is now 2 versions old and so parts etc. are not going to be as common for these as is with the 3.6. But I agree...if someone is doing this just for power increase it is a lot of trouble and not worth it IMHO.

Yo Demon... Actually, auto makers are required to cary parts for their cars for a minimum of 15 years (or somthing like that). I have heard various versions. Between 15-20 years is what I think is the time frame. Porsche has historically been VERY good about keeping the parts bin full for enthusiasts. C.

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Oh I understand Chad, just that they are not required to make anymore, just have enough to sustain demands (very calculated by manufacturers who have been doing this for a while). Just that our 3.4's were not made for long, not like a Mustang 5.0 which lasted for years and still today parts are made for them. But it is nice to know that I can at least get parts for my 3.4 for years to come, but will the cost go up as the parts become harder to find...I want to say a big yes to that

Kinda of makes an inexpensive 99 a problematic choice when compared with an 02 or later!! I remember when my old E28 BMW 535is had a 3.5 liter motor and a guy was complaining his 533is only had a 3.3. The difference in size wasn't that much of an issue. It was the improvements he was missing out on!! While I know that cable throttles have been around for years, I have been very happy with "fly by wire" in the newer models!!

yea i'm not able to discern any differences between cable and wire. in fact, the best response has been with the e46 m3 which is wire.

I think there is a little confusion here in regards to the throttle cable statement I made. I wasn't making a point about any differences in the throttle connection in regards to how it works for anyone, I was making a point that in '99 it was a physical cable and after that it was a wire, this obviously has to be taken into consideration when doing the swap unless the 3.6L throttle assembly can accomodate a cable and the computer system is OK with that.

My car turned out great but I would not do it again.

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Thanks Jim for your input here. I really have no plans and no reason to do this swap, but if I had to and a 3.6L was easier to come by and cheaper, then maybe I would. Then I would consult with someone that has done the swap (i.e. you )

I was kinda thinking along the lines of the 99 for a track car to mod with an engine upgrade later, but as has been said before..... The cheapest way to do it is to buy someone elses car who has already done the upgrades!!!

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I thought it was done? Pete

Hi, someone told me to come here since I was mentioned. Yes my 99 is getting a 3.6 put into it. Yes, my 3.4 did blow first and I decided for the same money instead of putting a 3.4 in put a 3.6 in. A 3.8 did come up but would have been a little more figuring out, but not much. Anyhow, my car is not done yet for a bunch of silly reason. Shop was in the middle of relocating facilities right in the middle and then at the last minute, completely unrelated to the swap they have been getting some weirdness with my ecu accepting the new 3.6 programs. That is resolved and it is in final shakedown mode now. It really is not a very complicated process, but not a direct swap. -Paul

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Paul, How did you handle the variable cam lift? There isn't even a connection in the 99's harness for it and I'm sure the 99 computer won't control it. Did they put in a new harness and 3.6 computer? Did you convert to e-gas or stick with the cable throttle body? Just curious. Jim

hmmm...I am under the impression that if you swap engines, you need to swap harnesses, and ECU's. Am I mistaken? C.

Paul, Who and what did they do exactly to your ecu? The reason I ask is cause I'm still having problems with my 3.8 even though I sprung the money and went with FVD's 3.6 to 3.8 upgrade tuning.The verdict is still out on my opinion of FVD. Edi

I am not the tech wiz here just the paying customer. My old cable based throttle was fitted to the new engine. My 99 ECU was reflashed with the 3.6 fuel maps and the variocam is handled with a dedicated control system and harness. That is as much as I know.

If you completely swap harness and ecus then you need to completely update the car to the new systems...ie. throttle pedal, instrument cluster and likely a whole lot that I am omitting. The new ECUs don't talk to the old instruments; different bus architecture. Doing this is another way to go and also viable. Just not the way mine was done.

I just finished a swap on a 99 3.4 to a 3.8 x51. It is not easy to do, only a couple of folks in the country have real experience doing it. You need to rewire your car and add a 2002 DME, egas pedal encoder, change to a returnless fuel system, and then find a vendor (only two I could find) who knows how to program 2002 DME to run a 3.8 x51. Note - you will end up paying up today, but the hope is this is the last time you have to do such a swap. I would not waste time doing a 3.6 x51 swap, not enough bang for the buck and the only real difference over the 997 3.8 x 51 is that you don't have to change to a returnless fuel system or buy a custom program (saves you a couple of grand...but you get an old generation motor and alot less horsepower and torque) VMAN

I did the wiring changes for swapping a 3.6 into an e-gas 3.4. The approach there was to use the 3.6 DME and simply rework the wiring harness. This involved moving approximately 25 connections at the DME, adding two conductors from the DME to the harness connectors in the engine compartment (for the variable valve lift controls), and using the dual-element temperature sender from the 3.4 (with a wire to the engine side of one of the harness connectors) to supply the instrument cluster with engine temperature information. And of course the MAF sensor needed to be replaced with the sensor for the 3.6. Those changes can easily be made in a few hours if you have access to both early and late DME schematics, know how to read them, and use the Bosch connector tools and wiring repair kits to move/add the required conductors. I've only briefly looked at the schematics to compare the mechanical throttle and e-gas implementations, but I can't imagine that adding an e-gas throttle assembly and associated wiring would add much in terms of complexity for the swap. It seems very reasonable to me that the entire swap could be easily completed in a weekend.

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Paul, When you get the car back, please do a write up of your impressions of the swap and the driveability of the conversion. I'm eager to see the character of the car as a friend and myself are thinking of this conversion when the time comes. Pete