What engines use the 7.8 DME ? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

NewArt · 12-05-2018, 02:31 PM

As most of you know, I’m trying to source a new motor for my car. It’s a 2004 Boxster S so it uses the motronics 7.8. I know that I can plug in a 3.6 from certain years of the Carrera by adding a few wires and a 996 tune. I’m trying to make a list of possible engines that use this DME and what electronic modifications would be necessary to make everything play nice together. An anyone help me out here?
Cheers, James

PaulE · 12-05-2018, 04:43 PM

I suppose you've seen this Pelican article which has info on the 2003-2004 cars? Before I decided to have my shop rebuild my 2003 S engine, they had a totaled 987 Cayman S with a crate 997 3.8 engine that was being parted out. They said it would work in my car with the ECU, but I passed as the total cost was way more than I wanted to spend. But they said it would work, which is consistent with the article. Good luck, I feel your pain!

particlewave · 12-06-2018, 06:33 PM

..........

Smallblock454 · 12-07-2018, 01:07 AM

986:
M96 2.7 228 HP
M96 3.2 260 HP
M96 3.2 266 HP

987:
M96 3.2 280 HP

996:
M96 3.6 (320 HP) from 2002 on with electronic accelerator pedal.
M96 3.6 (X51) from 2002 on; X51. Might not fit easily in 986 engine compartment because of height
M96/97 3.8 (381 HP) from 2003-2004. Might not fit easily in 986 engine compartment because of height
The 996 M96 Turbo engines from around 2002 on also work with a DME 7.8 but there will be some problems to get them into a 986.

The DME needs to be flashed to the engine and car.

NewArt · 12-08-2018, 04:46 AM

Cool! Thank you for this list. I believe that my add-ons such as headers and deep sump from my 3.2 3-chain should fit okay on a 3.6 as they are essentially the same motor?

NewArt · 12-08-2018, 06:06 AM

Quote:

Originally Posted by PaulE

I suppose you've seen this Pelican article which has info on the 2003-2004 cars? Before I decided to have my shop rebuild my 2003 S engine, they had a totaled 987 Cayman S with a crate 997 3.8 engine that was being parted out. They said it would work in my car with the ECU, but I passed as the total cost was way more than I wanted to spend. But they said it would work, which is consistent with the article. Good luck, I feel your pain!

Actually, although I have the 101 book, I hadn’t consulted this article on the web site as I figured that it only dealt with Waynes 2000 Boxster. On reading it now, I see that it contains a wealth of pertinent information!
Thanks!

PaulE · 12-09-2018, 03:37 PM

I hope you get a good engine. I've been following your threads as my own 2003 S engine failed in July after I drove up to Mt. Tremblant from NJ and before I got on the track! I struggled with what to do with my own car for a while. I finally decided to have my shop rebuild the engine, and the case was sent out to LN for 3.6 Nickies. LN has completed the machining but its now in line at the platers for the new liners to be plated so that LN can do the final polishing and precision finishing. Once the case comes back from LN it shouldn't take too long, but the wait has been hell!

Gilles · 12-09-2018, 03:55 PM

Quote:

Originally Posted by PaulE

I finally decided to have my shop rebuild the engine, and the case was sent out to LN for 3.6 Nickies.

Paul, I believe that you will be Very Happy with your decision of going with the LN 3.6 Nickies, the wait would be well worth it

NewArt · 12-09-2018, 04:43 PM

Quote:

Originally Posted by PaulE

I hope you get a good engine. I've been following your threads as my own 2003 S engine failed in July after I drove up to Mt. Tremblant from NJ and before I got on the track! I struggled with what to do with my own car for a while. I finally decided to have my shop rebuild the engine, and the case was sent out to LN for 3.6 Nickies. LN has completed the machining but its now in line at the platers for the new liners to be plated so that LN can do the final polishing and precision finishing. Once the case comes back from LN it shouldn't take too long, but the wait has been hell!

You were lucky enough to have a core to rebuild! It’s gonna be fun!

PaulE · 12-10-2018, 06:22 AM

Quote:

Originally Posted by NewArt

You were lucky enough to have a core to rebuild! It’s gonna be fun!

Would you consider a rebuild of your engine if you had the parts? There are core parts and rebuildable engines out there for sale. What pieces do you need? You may have posted that but I forget or missed it. When I started down this path, I communicated with Charles Navarro as I had just missed their clearance sale on M96 engines. He told me they could sell me a good used crank that had been magnafluxed and polished for about $2,000 if they rebuilt my engine and it needed one. It turns out we caught my problem soon enough that the only parts (outside of all the parts typically replaced in a rebuild) I absolutely needed were a new Intermediate Shaft, IMSB and timing chain paddle on the rear of the engine.

Then after I started on the rebuild path I saw that Porsche dealer parts departments were clearing out their rebuilt M96 engines. Still pricey but a known quantity.

jsceash · 12-10-2018, 01:05 PM

Top off your build with a set of these.

https://www.fvd.net/us-en/FVD10397522/connection-rod-set-carrillo-986-987-boxster-987-cayman-996-6-pc.html

PaulE · 12-10-2018, 03:09 PM

Quote:

Originally Posted by jsceash

Top off your build with a set of these.

https://www.fvd.net/us-en/FVD10397522/connection-rod-set-carrillo-986-987-boxster-987-cayman-996-6-pc.html

They are on my list of things to discuss with my shop before they start the build. I see LN also sells Carrillo rods made to LN's specifications. Hard to know where to draw the line. Money's just something you throw off the back of a train....

Quadcammer · 12-11-2018, 04:55 AM

Id skip the rods and just install a set of arp bolts in your stock rods. The rods dont break, the bolts fail or the bearing spins causing the broken rod

PaulE · 12-11-2018, 10:36 AM

Quote:

Originally Posted by Quadcammer

Id skip the rods and just install a set of arp bolts in your stock rods. The rods dont break, the bolts fail or the bearing spins causing the broken rod

I like that. If I stay with the stock rods, will definitely use ARP rod bolts. What causes bearings to spin? Isn't it due to loss of lubrication? Does Carillo CP rod offer a more precise bearing fit than the Porsche powdered metal cracked cap rod that would provide a more precise fit and maybe help prevent spun bearings? Am I getting into how many angels can dance on the head of a pin territory here?

Gilles · 12-11-2018, 04:40 PM

Quote:

Originally Posted by PaulE

I like that. If I stay with the stock rods, will definitely use ARP rod bolts. What causes bearings to spin?

The low quality rod bolts used by Porsche do tend to stretch under constant high rpm's, but if you use good quality bolts (ARP) you would be ok, specially since you are not trying to build a 'low cost racing engine'' and you can save a good amount of cash (perhaps for a nice head prep..?)

Quadcammer · 12-12-2018, 08:17 AM

Quote:

Originally Posted by PaulE

I like that. If I stay with the stock rods, will definitely use ARP rod bolts. What causes bearings to spin? Isn't it due to loss of lubrication? Does Carillo CP rod offer a more precise bearing fit than the Porsche powdered metal cracked cap rod that would provide a more precise fit and maybe help prevent spun bearings? Am I getting into how many angels can dance on the head of a pin territory here?

I don't think the issue is the rod bearing clearance, but rather due to heat, potential loss of oil pressure due to starvation/foaming, oil viscosity dropping, etc.

You can certainly try to adjust bearing clearance, but I'd say thats less of an issue.

911monty · 12-12-2018, 08:50 AM

I'm probably wrong here but my last experience with stock powdered metal cracked cap rods was the rod bolts cannot be replaced because they are integral to the cap alignment. Has that changed?

Gilles · 12-12-2018, 12:28 PM

Quote:

Originally Posted by 911monty

I'm probably wrong here but my last experience with stock powdered metal cracked cap rods was the rod bolts cannot be replaced because they are integral to the cap alignment. Has that changed?

I believe that the rod bolts can be upgraded but the rod caps cannot be swapped as you mentioned.

jsceash · 12-14-2018, 05:08 PM

Quote:

Originally Posted by Gilles

I believe that the rod bolts can be upgraded but the rod caps cannot be swapped as you mentioned.

ARP Bolts are an upgrade but the caps can not be changed or interchanged. The carrillo rods are stronger, but better yet they are lighter than the stock rods. The Original rods vary in weight by several grams. My set of Carrillo rod were within .5 grams of each other.

Gilles · 12-15-2018, 08:51 AM

Quote:

Originally Posted by jsceash

ARP Bolts are an upgrade but the caps can not be changed or interchanged. The carrillo rods are stronger, but better yet they are lighter than the stock rods. The Original rods vary in weight by several grams. My set of Carrillo rod were within .5 grams of each other.

As a low cost (huge..) improvement, you can only install the ARP studs and rebalance the OEM rods...
Of course, being there considering the Carrillo rods would be a 'huge step up' 😁

Honestly, originally I budget on my engine rebuilt (using LN Nickies) a set of Carrillo's along with a head work from Hoffman Automotive

However, it is difficult to draw the line, that is the reason I said that you could 'only replace' the conrod bolts with ARP's to keep te cost down..
.