Bought an M96.21, but it has E-gas and 7.2 loom? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

So, this is a five chain engine, for sure. I thought all five-chain engines had cable-gas and DME 5.2. Can the 7.2 DME also run the five-chain engines or is something going on here?

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Not correct; many five chains had e-gas, and all 2000-2004 used the 7.2 DME.

The E-gas setup was adopted in 2000 when the 2.7 and 3.2 were introduced, along with the single-row IMS bearing that was phased in during that first year. The 2.7L and 3.2L engines remained 5-chain through 2002, and 3-chain production started for the 2003 model year. Any 5-chain engine should be compatible with DME 5.2 as long as you re-use your car's intake plenum to retain the cable throttle, as far as I'm aware. Also use your car's existing wiring loom, as the loom that comes with this engine will have a plug for the E-gas and its pedal capacitor and won't have the plug for the IAC valve. The 2.5L engine has a pretty big throttle body for its displacement and won't meaningfully choke down any later engine, but you can upgrade to a '99 Carrera throttle body later if you wish. This may require a tune for the larger displacement.

Thanks for clearing this up. I used to know all this at one point, but it's been too long. It never occurred to me that this engine could have a single row IMS, but now that you mention it... with my luck it's probably single row

Just as well I bought a 3.4 TB along with the engine

Are you keeping the 2.5's 5-speed transmission? If so, the 3.2 with the shorter gear ratios will take off like a bat out of hell, should be an awesome driving experience. The 2.5 has the shortest 1st and 2nd gear ratios including final drive of any production 6-cylinder Porsche, and matches the 944 for the shortest water-cooled Porsche gearing. The 914 beats it for shortest gearing of any Porsche, though.

Here's a related thread: https://986forum.com/forums/performance-technical-chat/75535-2-7-swap-2-5-blown-motor.html Truegearhead had it running with no problems and tracked it. As stated in that thread, I had a 2000 986 S that was running a 1997 2.5L engine with the intake from a 2.7L (eGas). Truegearhead had a 1997 986 track car that he swapped a 2.7L engine into with the 2.5L (cable TB) intake. Truegearhead eventually swapped an Audi V8 into his and added twin turbos.

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I am keeping the transmission. I hope it will be suitable for my track. I had trouble reaching 5th on the straight with my 2.5l so, hopefully this combo will let me reach it sooner.

Quotes source post: 670790

Sorry to say, but that's not correct. In general the facelift cars (228 HP, 260 HP, 266 HP) with glas rear window and glove compartment do have a DME 7.8. The engines do have vane-cell adjusters (Flügelzellenversteller). The DME 7.2 was used in 220 HP 2,7 litre and 252 HP 3,2 litre models with engines that had no vane-cell adjusters (Flügelzellenversteller). The DME 5.2.2 was only used with 2.5 litre engines in the 986. It was used with 3.4 litre engines in the 996. The wiring looms of the different ecus are different. And from 5.2.2 to 7.2 they are completely different - completely different connectors in the wiring loom. From a technical standpoint a 7.2 can run a 2.5. But not without massive adaptions.

You are correct, I should have said 2000-2002.

Quotes source post: 670828

But, I should be able to run the 3.2l I bought with my 5.2 DME and loom?

This isn't plug & play. One main problem is the ecu mapping, as the dme 5.2.2 has a completely different system architecture than the 7.2. So there is no stock mapping for a 3.2 with a DME 5.2.2. Afaik loom lengths and connectors might differ. But i've never done a conversion like that myself. So you have to discover that yourself. If you had bought a 3.4 from a 996 with a 5.2.2 it would be easier and more plug & play.

As far as I know the only differences btw. The 2.5 and the 3.2 5-chain engines are the resonnanse flap on the plenum and the difference in flow and displacement. I am probably going to flash the DME with the 3.4 tune to compensate. I will use an Arduino to control the flap at a set RPM.

That difference won't matter much, as you'll want to use the 2.5's plenum because it has all the brackets for the throttle cable and the right positioning to use your existing intake tube. It won't restrict the flow of a 3.2, as people use that plenum with 3.4's and don't see issues with flow. You'll give up a little low-end torque due to the fixed resonance, but it'll be an easier installation.

That's interesting. It gives me more options. I have been under the impression that the 3.2 will benefit from improved breathing, so I've bought a 987 airbox, MAF and intake tube along with a 3.4 cable throttle body. I will also do some light porting/matching the ports to the intake runners to minimize turbulence. It's also nice to know the flap is not strictly necessary. I think it will be easy to make it open with an Arduino, but I may just run the engine for a while without it until I can find the time to code it and make it work.