3.4 or 3.6 Conversions? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Thumper · 03-02-2007, 07:55 AM

I'm thinking ahead just a bit, as my 2.7 still runs nicely. But when the day comes when it's time to retire the tired old friend, I'm thinking that it's time to really consider an upgrade to a 3.4 or 3.6. RUF will do a 3.6 conversion, but they want to sell me the entire RUF upgrade which is nearly $30K (I don't really like their wheels or body kit).

Other things to consider, what else would need to be upgraded? Brakes? Suspension? Also, who are the reputable shops that will do the conversion?

Those that have done this, please chime in.

Thanks,

Jeff

porsche986spyder · 03-02-2007, 08:01 AM

I'm not sure about this, but I believe you can only do the 3.4 or 3.6 engine swap if you change your transmission also. You will need the Boxster "S" type trans. in order to get the 6 speed gear box. So if you have the 2.7L base model like me, you have to upgrade the trans and clutch too. Otherwise you have all that new power with no way to use it. You will also need a new CPU for the new engine. Can't use the 2.7L CPU codes on a 3.4 or 3.6. Unless they re-program it for you. Better brakes would also help, but bigger may not matter.

Thumper · 03-02-2007, 08:05 AM

I've got a tiptronic so that shouldn't be much of an issue. I know, I know, but in a major metropolitan area with heavy traffic, a tip can be a welcome way to cruise. Plus, once you get the hang of the steering wheel shifters, it can almost be as much fun as a standard transmission.

Having a tiptronic does not necessarily mean that I squat to pee.

porsche986spyder · 03-02-2007, 08:10 AM

Quote:

Originally Posted by Thumper

I've got a tiptronic so that shouldn't be much of an issue. I know, I know, but in a major metropolitan area with heavy traffic, a tip can be a welcome way to cruise. Plus, once you get the hang of the steering wheel shifters, it can almost be as much fun as a standard transmission.

Having a tiptronic does not necessarily mean that I squat to pee.

But even with the tiptronic, you still only have 5 gears with the 2.7L. The 6th gear would still be required weather you have an auto or manual.

Thumper · 03-02-2007, 08:41 AM

There are 996's with 3.4's and a 5 speed tiptronic. So I don't think that a 6th gear is required.

porsche986spyder · 03-02-2007, 08:45 AM

Quote:

Originally Posted by Thumper

There are 996's with 3.4's and a 5 speed tiptronic. So I don't think that a 6th gear is required.

If that is true, then you got me. Sounds like it's posible with your car to do then. I would definately upgrade the clutch, CPU and brakes then. Good luck if you decide to do this mod.

03-02-2007, 09:10 AM

Tiptronic doesnt have a clutch though... Brakes are fine, suspension Id recommend upgrading, not because of the conversion, but because if its time for a conversion, its time for new springs and shocks. If you take the cpu from the car you got the engine from you shouldnt need reprogramming, youd be in line for a 3.6 conversion. Us 97-99 boxs can do the 3.4 no sweat without a bunch of jerry rigging.

Bavarian Motorist · 03-02-2007, 09:39 AM

I think you need to upgrade transmissions to handle all the new power. That's what I've heard anyhow.

idheaton · 03-02-2007, 11:27 AM

I have had a 3.4L conversion done in my 99MY and while 3.6 and 3.8 conversions can be done, imo, unless its a track car, the additional hp as well as the additional cost involved probably isnt worth it.

Some clarifying points:

Part of the reason a 3.4L (e.g. '99 996) conversion is easier (and less expensive) other than the price of the engine is because the 97-99MY is non-eGas so no rigging is involved to make it work. 3.6/3.8 engine are eGas and have to be rigged which adds to cost.
The old transmission can be used on 3.4 - 3.8 conversions, if it's a manual then a stronger sport clutch is used to handle the additional power and i was told a tip should handle it fine as well.
Some parts were used as donor parts off of my 2.5, such as fuel rails (boxster and 996 are opposite of each other), old flywheel (996 flywheel was about 5-10mm thicker and would scrub the bellhousing if used), a few other small pieces i do not recall.
My old ECU was used although it had to be sent out to be reprogrammed for the proper mapping of the 3.4, otherwise you end-up with a 3.4 that has approximately the same power as the old engine yet backfires like crazy under hard acceleration from incorrect oxygen/fuel mix. I am not sure whether the old ECU can be used regarding a 3.6/3.8 swap.
New headers/cats are definitely required for the engine although you can get away with using your old muffler (that is what i am doing presently)
Stock brakes are fine for daily street use. I'd consider upgrading if it were a dedicated track car.
Downshifting in some instances becomes an option as opposed to a have-to...

hope this helps some.

Thumper · 03-02-2007, 11:41 AM

Quote:

Originally Posted by idheaton

I have had a 3.4L conversion done in my 99MY and while 3.6 and 3.8 conversions can be done, imo, unless its a track car, the additional hp as well as the additional cost involved probably isnt worth it.

Some clarifying points:

Part of the reason a 3.4L (e.g. '99 996) conversion is easier (and less expensive) other than the price of the engine is because the 97-99MY is non-eGas so no rigging is involved to make it work. 3.6/3.8 engine are eGas and have to be rigged which adds to cost.
The old transmission can be used on 3.4 - 3.8 conversions, if it's a manual then a stronger sport clutch is used to handle the additional power and i was told a tip should handle it fine as well.
Some parts were used as donor parts off of my 2.5, such as fuel rails (boxster and 996 are opposite of each other), old flywheel (996 flywheel was about 5-10mm thicker and would scrub the bellhousing if used), a few other small pieces i do not recall.
My old ECU was used although it had to be sent out to be reprogrammed for the proper mapping of the 3.4, otherwise you end-up with a 3.4 that has approximately the same power as the old engine yet backfires like crazy under hard acceleration from incorrect oxygen/fuel mix. I am not sure whether the old ECU can be used regarding a 3.6/3.8 swap.
New headers/cats are definitely required for the engine although you can get away with using your old muffler (that is what i am doing presently)
Stock brakes are fine for daily street use. I'd consider upgrading if it were a dedicated track car.
Downshifting in some instances becomes an option as opposed to a have-to...

hope this helps some.

Thanks! This is the type of info I was looking for. Who did your conversion?

idheaton · 03-02-2007, 12:39 PM

Roock Autosport in Atlanta Ga.

http://www.roockusa.com/products/boxster.htm

heres some pics of the 3.4 in my boxster

http://picasaweb.google.com/ian.heaton/99634LEngine

racer_d · 03-02-2007, 02:17 PM

The other non asked question was $$$

A 3.4 or 3.6 conversion is likely $12k-15K, maybe more? That's a lot of money to dump into a car whose resale value might only be $12-15K by the time you do the conversion. It might be "cheaper" to sell the 2.7 and to buy a "then used" 987S for example. Just a thought.

Having spent $8k in "upgrades" to my $6k 914 years ago, I too must say it was not the most economical upgrade, but it was fun

03-02-2007, 02:42 PM

It depends on who you are really. If I was older and had a steady job, house, family, ect... and I already had my boxster for a year and/or paid it off and had it as a weekend car, Id 3.8 it. If you love a car, you do, nothing you can do to help it, and I know that a 3.8 boxster, with pss9, and a new gahh top would be the sweetest car ever. Now add a 996 front conversion, ruf rgt bumper, sideskirts, GT3 seats, gemballa rear bumper with the exhaust out the middle of the bumper, short shifter, and some nice wheels and you have litterally the awesomest car out there. The best part is, you can keep it for as long as you want since you have space for it and a second car as a dd. Thatd run you like 35-40 grand, but if your not worried about resale then who cares. Plus the 20 grand for an older boxster and youve got a super 60 grand car (cayman money).

David_J · 03-02-2007, 02:51 PM

I've considered doing a larger engine in my 2001 S. I have already sunk a lot of money into it on other mods. The Boxster doesn't have to be my daily driver, but I make it one because I enjoy driving it. I've also considered upgrading to a 996 TT, but still fall back to the fact that I like my Boxster. Yes there are a lot of them out there, but the are a lot of 996's as well. When I go on drives with the group of Porsche guys, I am one of 2 or 3 Boxsters. Everyone else has some sort of 911. I like being the different one. I would really like the car even more with a 3.8 in it. The current plan is to keep the Boxster for awhile, but with me that could change. I seem to average a new car every 1.3 years since I turned 16. I've had the Boxster for almost a year now and I still am doing modifications. It's nice to have a car that still looks good no matter what year you drive.

-David

kouks · 03-02-2007, 03:05 PM

Quote:

Originally Posted by idheaton

Roock Autosport in Atlanta Ga.

http://www.roockusa.com/products/boxster.htm

heres some pics of the 3.4 in my boxster

http://picasaweb.google.com/ian.heaton/99634LEngine

Well done mate! This looks like a brilliant cost effective conversion. I know what I'll be doing when me 2.7 packs it in....

*evil kouks wants the 2.7 to explode*

pecivil · 03-02-2007, 03:53 PM

I kept the 5 speed for my conversion, it works just fine. it remains to be seen how long the cluthc lasts. I put a new one in with the swap, but it was not a "sports" clutch, just the stock one.

My ecu was reprogrammed by revo, kept the stock ecu.

I got headers/cats muffler.

The car is SO much more fun. It simply rockets. Cost about 15 grand all told. I decide it was worth it every time I hit the gas!!

tholyoak · 03-03-2007, 05:40 AM

There is a lot of misinformation in this thread. If you are considering the swap, check out my posts over on Renntech. The reason it is more difficult to put the 3.6/3.8 in the earlier cars has nothing to do with egas. Also in my opinion the gearing of the 5 speed is quite well matched for the torque of the larger engines.

Todd

Thumper · 03-03-2007, 08:58 AM

Got a link?

tholyoak · 03-03-2007, 11:25 AM

http://www.renntech.org/forums/index.php?showtopic=11411&hl=

http://www.renntech.org/forums/index.php?showtopic=4798&hl=

Should get you started, or just do a search under my username

Todd

Thumper · 03-03-2007, 12:14 PM

Thanks Todd. I also had another member send me your .pdf file write-up. This doesn't look to be as much trouble as I had originally thought. Since my 2.7 isn't giving me any trouble thus far, it will allow me some time to round up the pieces/parts I'll need for the swap and scout out a deal on the motor. Plus I do have RUF Autocentre close by to fall back on.