engine swap project planning advice.

[brad bedell]

I'm in a bit of an 'unusual' situation as that I have a low mileage 03 996tt engine, a pair of Tial turbos, intercoolers, accessories/harness, etc laying around. I'm looking for something unique to do with it. Since I don't have the car yet, I have the luxury of finding the car that is best suited to the swap.

That said, I've searched and am either using the wrong search terms or can't find the facts for the noise. I've read Todd's 3.4 engine swap pdf (now out-dated) and have read most of Wayne's book via google-online. I'm currently waiting for a copy to arrive for the final reading. (Edit* it arrived two days after I ordered it!)

Ideally, I'd like to use a 2005 987 car, but a 03-04 might be a better choice. This is where I need some help. I've done engine swaps similar to this (V6 in an MR2, GS400 engine in an IS300, Celica GTS engine into an MR2 spyder) However with some of the Porsche terminology and interchange I admit I'm a bit lost. I know the key to making this a street legal car and a *nice* driver will be the proper understanding of the electronics.

My questions are:

1. What is the best year model for this swap.
2. Will the Boxster 6 speed bolt to the 996tt block? (I know the flywheel is different) I've read conflicting data about the transmission bolting to the block in my searches.
3. Can the 2005 7.8.4 DME control the turbo engine with reflashing? (I know rewiring/modifying/adding to the boxster harness will be necessary)
a. If it can't, will the '05 chassis accept an earlier 7.8 996TT DME?
b. If not, would the 03/04 Chassis do it or accept the 996TT DME to the Chassis?
4. Who can I hire (local to Dallas TX or mail-order) to help with the programming? I wouldn't be opposed to purchasing or renting a PST2.
5. I'm assuming I can get IPAS codes for the car I purchase, but am unsure if I provide a dismantler's receipt for a DME if I can get the IPAS for the used parts.
6. Who can I hire for information/Parts? Having learned about late model engine swaps myself. I know this information and experience wasn't come by cheaply.
7. Air flow meter. Will it work with the TT unit or will I need to come up with some sort of AFM modifier?
8. Can a 2005 boxster 7.8.1 DME be back dated to a 996tt code? *or* would I need to convert the turbo engine to the 997 electronics. *or* can I put a 7.8 DME in the chassis, flash it with turbo code and make the rest of the car happy without substantial computer(s) replacements. (rephrased from above)


Flow/problems of this project would be: (assuming the transmission bolts up) I do assume that I will lose most, if not all of the trunk.
1. Physically, bolt everything up, identify the sensors that will need to be changed/modified. Remove wires/pins from the 996tt harness and integrate them into the Boxster harness. Variocam/boost solenoids, etc.
2. Reverse intake manifolds. (I have 997GT2 manifolds that I can cut/modify a bit if necessary)
3. Oil cooler may get in the way of the reversed intake.
4. Oil tank is likely to be modified or relocated or all of the above.
5. Convert the chassis to a return style fuel pressure regulator or convert the engine to returnless fuel. (?)
6. Once bolted up and major items are 'in'. Start plumbing everything.
7. Cuss a bunch for how tight all the plumbing will need to be.


Clearly, this is a high overview of this project and only addresses the engine portion of this conversion. But at this point, answers to the above questions will aid in my desire to go forward with this project. The only way I'm interested in seeing it through is if it's possible to make a nice car out of the project. From Todd, Wayne's and Brad's posts they all feel that the proper year car will aid in this equation.

For those of you curious, some of my projects are here: BEDELLRACING.COM Look under projects. They are a bit outdated, but show the work I've done.

Thanks in advance for any guidance!

-Brad

[Wayne 962]

Hi Brad:

1- See the book / article for about 5000+ words on what best engine combinations will work. Link: Pelican Technical Article: Boxster Engine Conversion Project - 986 Boxster (1997-04) - 987 Boxster (2005-08)

2- The Boxster six-speed is basically the same as the 996 transmission. I'm just guessing, but I don't think it will bolt too smoothly to the block (not without some special clutch parts maybe? not sure).

The Turbo engine is a dry sump engine, and will not fit in the Boxster without some major chassis modifications. You're talking about re-engineering the whole car. I think someone recently did a GT3 dry sump engine into a Boxster, and it cost more than a real GT3.

-Wayne

[brad bedell]

Thanks Wayne. I understand that this will be a pretty large engineering nightmare. It's been a while since I took on something like this swap. The Lexus GS400 engine in an IS300 swap would likely be my most accurate comparison. I've done several late model engine swaps that are similar to this in concept and work. Just none on a Porsche.

Is there an online journal of the GT3 swap? I'd like to see how they did the tank. I'll do some searching. I'm not sure how they spent more than a GT3 unless they paid a shop for ALL of the labor and paid near OEM retail for the parts. Keep in mind, I'll be doing all the work myself and am not afraid to source used parts. (I have a TIG, Mill, lathe, band saw/etc in the garage) I already have the engine on the shelf. If I'm careful with the initial car purchase, the only big ticket item (sans my 4-500 hours of time) will be the car itself.


I purchased and read the swap section in your book. It didn't mention anything about potentially flashing in the Twin Turbo firmware to the DME. I can't find if it's physically the same piece of hardware or not. I'm not really interested in any of the other NA engine swaps. I'd just assume buy another 996tt if the electronics can't work.

My biggest concern is:

1. Can the 2005 987 chassis take the 7.8 DME? I assume that one would have to flash in the 997 TT code to this DME to make it happy.

a. If 997tt engine electronics would be necessary, I'll be looking for the earlier 03/04 cars. Which leads to the next question.

2. Will the Boxster/996 7.8 DME accept the 7.8 Twin turbo DME code? Is this box the same physical hardware? If it will, I'd be looking for an 03/04 Boxster chassis with the 7.8 DME.

Thanks again for your input!
-Brad

[brad bedell]

Also, anyone happen to have the length of the Boxster engine? From crank pulley to transmission mounting face? I should verify this somewhat fits in the chassis due to the different timing chain setups.

[BYprodriver]

Originally Posted by brad bedell

Also, anyone happen to have the length of the Boxster engine? From crank pulley to transmission mounting face? I should verify this somewhat fits in the chassis due to the different timing chain setups.

20 inches

[brad bedell]

Originally Posted by BYprodriver

20 inches

Thanks! Turbo motor is ~20" without getting too geeky. *edit* mis-measured prior.

[brad bedell]

I guess now I understand the frustration for all of those who asked 'expert advice' on the v6 mr2 swap... This is quite humbling. I'll just keep editing/rambling amongst myself until someone knows an answer or feels the need to correct me.

I'm still digging. I see mention in older threads that the transmission will bolt to the block and also see mention that it won't. Does anyone know for sure? *edit* I know for sure. It won't. (based on photos I'm seeing) Not without an adapter plate. So 996tt transmission, flip it around will be the only solution. Does anyone know of a reverse ring gear or if the Boxster 6 speed ring gear will fit? *or* if I could hybrid a 996tt transmission front housing to the boxster transmission case? (I did this with the V6 Mr2)

I am still unsure on the DME. One person on Renntech shared this from the Durametric site:
996
ME7.8 for 2002-2004 (Engine)
ME7.8 for 2001-2005 Turbo, GT2 (Engine)
986
ME7.8 for 2003-2004 (Engine)

987
ME7.8.1 for 2005-2008 (Engine)
997
ME7.8.1 for 2005-2008 non-turbo (Engine)
ME7.8.1 for 2005-2009 Turbo and GT2 (Engine)

Based on this chart, I'd assume that I 'can't' use the 7.8 on the 987 and would have to update to the 997 engine electronics. Which is fine, it might be best for a 03/04 car. However, if the 986 7.8 DME won't work with the 996tt engine flash, I could open my search for the cheaper 01/02 chassis and just buy a new/used DME with the difference of money. (of course, search out the IPAS codes for the used bits first)

However, if the 7.8 DME would work on the 987 chassis with minimal disturbance, I'd rather have the 987.

Anyone have any insight on the electronics? I'm intentionally avoiding the mechanical talk at the moment as I really won't know how it will all fit in the chassis until the engine is bolted up and electronics are finished enough for troubleshooting.

[brad bedell]

p.s. if you feel that I don't understand what it takes to do an engine swap of this nature. Take a couple of minutes and check out my projects page on my site listed in the first post.

[brad bedell]

To clarify above: When I say transmission front housing, I mean this piece, #1, AKA the front transmission case:


It's very likely that it won't fit, but worthy of finding someone who rebuilds transmissions that might know. I'll go digging for LSD part numbers to see if the Boxster 6 speed and TT 6 speed share the same one.


This is the motor mounting area. Looks like 4 studs replace the green bolts for the 6 speed.
I can't see in PET, but I seem to recall studs instead of bolts in this location.