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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHReplaced 3.4 engine with a 3.6 engine
Leading reported evidence
Replace 3
Performed · outcome unconfirmed
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Performed · outcome unconfirmed · Original poster
Cost wise as I had expected this ran about 1k less than a 3.4 reman and install.
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Suggestion · Original poster
My car is still running on a cable throttle and retains my original 5.2 based DME but with 3.6 specific programming and a dedicated black box to run the variocam +.
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I know it has been a while.. some may recall that my engine broke back in early Aug. I took about a month to figure out what to do (having several back to back business trips putting me away from home for several weeks made it easy to put off a decision).
Right after Labor day I decided follow my buddy Michael's footsteps and put a bigger engine in the car than it originally had. So no 3.4 replacement... It was going to be a 3.6 or 3.8 depending on what I found and the prices. Long story made short: I thought that I had bought a 3.6 X51 for a great price and it ended up being just a regular 3.6. Since the shop doing the work is in Atlanta (Roock Sport) no one figured it out until the engine was already in the car. Okay, water under the bridge. It is just a lost 25 hp or so.
Picked up the car on Friday in Atlanta.
1st impressions; fires up perfectly hot or cold, drives completely normal, if you put put around town you wouldn't know that anything was done here. Everything works as you would expect, all the dash lights do there things, cruise works, etc.
Now the differences are that there is considerably more torque everywhere and the cam switchover at 3k and 4kish are followed by a very noticeable power surge. The car has a lot more power above 4k than before. I have actually had a few sideways moments during switch over in 1st and 2nd under full throttle. (It is really cold out though)
So Friday after tearing around Atlanta with the Roock guys I hit the highway and drove straight through to Reston, VA. Speed limits were very forgiving and traffic allowed 80+ most of the way. Somehow also managed to get 27mpg on both tanks considering that I kept running up the gears when there was a vast expanse of open road ahead.
I am curious to see how healthy it is, so will be doing a dyno pull some time over the winter.
Over all really really happy with the outcome. Glad to be back and have my car back.
Last note: Here is a picture of my old 3.4 with a connecting rod sticking out of it. Guess it didn't want to be in there anymore.
Awesome Paul...Congrats.
There have been a number of people going through similar ordeals and could use some input. How much was the swap and what was the timeframe involved?
Thanks,
C.
Chad sure thing.
Follow up on the project: The guys at Roock are really competent and thankfully have the extended resources (their location back in Germany) to get help when things go wrong.
My ECU probably qualifies for a business class upgrade they must have overnighted it over a 1/2 dozen times.
My car has technically been ready for over a month but I allowed them the extra time to work through a few electronic issues so that they could make it 110% bullet proof.
I guess the key is for anyone thinking about doing something like this, check out the qualifications of the shop, whether they have experience doing this type of conversion before and most importantly; do not expect your car back in 1-2 weeks. It is possible but don't expect it. If you need than then a direct swap is in your future not an upgrade.
My engine was in and running (but roughly) after the 1st week but took several more to get everything with the DME /ECU just perfect and tuned right. My car is still running on a cable throttle and retains my original 5.2 based DME but with 3.6 specific programming and a dedicated black box to run the variocam +. Clearly e-gas cars have a slight advantage here and additional options as well.
Cost wise as I had expected this ran about 1k less than a 3.4 reman and install. Although I think that my core charge would have been lost considering there is a hole in the block and I don't think Porsche accepts those.
Congrats on the return Paul!
I cant believe your broke a rod, it must of lost oil pressure on the rod bearing and spun. 996 rods are so short I have a hard time believing it broke from just RPM, had to of lost oil pressure.
Tippy,
There were no mis-shift drama's here. Just standard DE track usage. A few of us suspect oil pressure as well. Track we were on runs CCW and there are several high speed, sustained high G left handers. It think the total for this specific track and corner combo is 3 M96 based engines.. 2 996s and 1 boxster.
Winter projects... 1) Baffled Oil pan from the X51 or the BK unit. Going to do the homework on it.
2) 3rd Center Radiator
Paul - good job! Congrats!
The only thing I would have done differently with your post is give it a title that is more descriptive of the topic. Something like "
Replaced 3.4 engine with a 3.6 engine
" or "
Swapped my 3.4 engine with a 3.6
" or "
Converted from 3.4 to 3.6 engine
"
As Chad said, this have been a topic of much interest to many guys here and I think one of the titles I listed above (or something similar) would make it easier to find on a "search" 6 months from now. I don't think that you can change the title yourself, even though you are the thread owner. Maybe you can contact one of the Moderators and ask them to change the title for you.
Again, congrats and I hope this one lasts long after you have sold the car!
Tim.. There ya go title changed. Good suggestion
Sell the car? No way. Gonna drive it until the engine pops again and just put in another 3.6 or go to a 3.8.
Contrary to popular belief putting in a new engine in the 996 every 2 years (assuming you need on that often) is still cheaper than a top end rebuild that I had to do on my 993 after 2 years of hard driving. And it was guaranteed to need it again after the same hours of similar use.
Not for nothing but I think it works the other way around
A 3.6 engine working with a 99's cable throttle.
Bottom line this approach was to retain as much of the car's original electronics and minimize the surgery. Re-use the 99's DME but program it with 3.6 fuel maps. Take the 99's throttle cable and air distribution tube and connect that to the 3.6. Throttle body was enlarged a bit to match the 3.6's. Add a separate black box developed by the tuner that handle's all of the variocam plus "stuff". Also something with the fuel supply was done.
Mechanically and electronically the car thinks that there is a 3.4 in there but has new programming to optimize the a/f ratios and a black box to drive the Variocam +.
The alternative is to try to convert the 99 to egas, swap the harness, ECU and dash with new stuff from a 3.6 based donor car.
That won't work because the 3.6 needs DME 7.8 for VariCam Plus. DME 7.8 is egas only so you need to change to egas parts (i.e accelerator pedal/switch, wiring, etc.). You can add the black box but using a 7.8 DME is a much cleaner solution (IMHO).
Engines weigh the same thing as far as I know. The 3.6 has a longer stroke vs the 3.4. Bore was the same (without checking). They really are the same engine on the outside.
Well I guess that I must have a really creative imagination since I clearly am imagining driving my car with a 2003 3.6 and a 1999 DME 5.2 and a cable throttle.
As for the DME 7.8 and egas, accelerator, etc.. I think I said that already too? No?
FWIW, if you swap in a DME 7.8 then you don't need the black box because the DME runs VC plus.
I have the log book to prove it can be done. The scruts at last year's Daytona club race couldn't figure out how my car could be going so fast with a 3.6L engine but 5.2 software.
Paul, I hope they didn't hit you too hard for the "black box". It's just a $100 rpm switch.
Glad to hear everything is to your expectations Paul. So are there any downsides to the swap other than a lighter wallet? Do all of your accessories work ie. trip computer, etc..?
Pete
Glad to hear it. I hope it brings to miles and miles of smiles.
PS- can I get a ride in it sometime? I would love to see how much more power it has than my stock 99.
Pete
hey Jim....am putting in a 3.6 with variocam and lift....what about this "black box" being a rpm switch.....I will need that switch over unit......anyone know where to get one AND a reprogram of a 3.4 DME?
congrats on the success of the swap, but how exactly does one not know that it's an X51 engine or not? Couple of DEAD giveaways are the aluminum intake manifold instead of plastic, the x51 oil pan which is deeper and some oil lines which are larger. I also believe the exhaust ports are larger too.
Oh, and of course, the part number of the engine, no?
I'm sure i'm missing some things here.
For program try
Softronic
.
I've seen their programs being used in similar conversions. Scroll that page down for details.
IIRC I've also read that "black box" being a SMT-6.
THAT THREAD REPLY IS MOST INTERESTING....can u guys give me more on that switch-smt item.....what is it and how do I obtain one??-graci-M
I am forging ahead and installing later engine with later cam advance and lift-seems that is the greatest challenge-will contact Softronic-
