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YOUR RESEARCHM96 Build Questions
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Suggestion
I would inspect the IMS shaft really carefully where the Hyvo chain sprocket is interference fitted as these have a tendency to spin on the shaft (you may be welding this anyway) also I think I would also replace the cam chains on this engine, they would of been put under stress and the chain rollers are press fit (not one piece cylinders) meaning they could go at any time which would be the last thing you want after doing all this work then to have to do it all over again.
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Suggestion · Original poster
However I'll be running the early VC1 heads as I'm not changing over the electronics and I want a throttle cable!
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Suggestion · Original poster
Only time, testing and probably a few set backs will tell what the results will be.
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Suggestion
I would inspect the IMS shaft really carefully where the Hyvo chain sprocket is interference fitted as these have a tendency to spin on the shaft (you may be welding this anyway) also I think I would also replace the cam chains on this engine, they would of been put under stress and the chain rollers are press fit (not one piece cylinders) meaning they could go at any time which would be the last thing you want after doing all this work then to have to do it all over again.
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Planning an M96 rebuild for a winter project.
Questions:
- Any caveats around a light honing of the lokasil cylinders to get a good ring seal?
- Will M97 3.8S int. manifolds fit the M96 3.4 or M96 3.6L heads?
- Are the timing chains on all 3.4 & 3.6L cams the same? (not main IMS chain)
- What is the service limit for decking the block or heads to true them up?
Also, has anyone disabled the secondary air injection ports that were cast into the US spec heads?
Anyone know the included angle of the Int/Exh valves ? Is it close to 28� ?
Thanks
3.4's are 5 chain engines and 3.6's are three chain engines, so no the chains are not compatible. You need to do some research on these engines before you undertake the rebuild.
Have you watched the YouTube on the Boxster engine rebuild. Have you gone through the Pelican Parts write ups on a tear down, have you gone through LoGrays rebuild posts?
I have some Porsche documents and information that has lots of information o. The engines, how they function, the differences between the VarioCam and VarioCamPlus engines, etc.
Ther are lots of special tools involved, some of which can be fabricated, and some worked around. If you are contemplating a total rebuild you should probably invest in a set of the tools.
Not to discourage you but it is worth it to learn as much about the engines and a rebuild before you decide to undertake the project.
Hi Doug. yes I've been researching my options for months and have hit the items you referenced. All excellent resources. This will be about my 10th build but my first M96. Looks like a PITA actually
but I like a challenge.
I realized the 3.4 & 3.6 cams use a different chain routes but was curious about some 3.4 to 3.6L conversions (not Nickies) I'd seen. I was thinking they both may use a similar chain "type" .. should have said cam gear style.
I need to get my engines both out and inspect everything. Asking questions on a forum is just going to get me in trouble.
- Bill
Porsche makes and sells plates to block off the ports left open after removing the secondary air injection system. At least they do for the 2.5L Boxster engines and I assume the same parts will work on the 3.4 and 3.6L M96 engines.
Might be... we'll have to see what the final project winds up being. I may actually build 2 different engines to compare them and learn. Still in the exploratory stages.
As I do with all my projects I'll be documenting extensively and creating some sort of technical reference on the web for others.
Project Goals:
Increased longevity: No new ideas here. I'll be going to FSI & LNE to cover those issues.
Increased performance: Target is to at least meet X51 performance, although my expectation is that it can be greatly exceeded given enough time and $.
It appears that the M96 racing/modding community is both tight lipped and small. I spent years working with performance and racing vendors when I was building and racing non-Porsche engines. It will be interesting to see what some of my pals can come up with in the way of custom components.
Only time, testing and probably a few set backs will tell what the results will be.
- Bill
Monetarily speaking, the more you invest in strengthening and adding power to the M96 platform, the closer you get to GT3 territory. And the inherent flaws of the M96 will always make it vastly inferior to the GT1 engines - IMS, wet sump, etc.
From a cost/benefit standpoint, the project could quickly become unattractive. Just something to think about - my opinion.
Sounds like you'd benefit from my "M96 101" Engine Rebuild School. The next one is in December, all hands on. We cover all the questions that you asked in depth.
http://www.flat6innovations.com/clas...rebuild-school
Tony should be there, but Worldpac wants this to be the last class that we tag-team. He adds so much from a diagnostic approach using the PIWIS and etc and we make a great team. He should be there, but I don't suppose that its written in stone.
I've made some progress on the M96 engine build project. Still in the measuring / planning phase for much of it. However the case work is well under way. Should have the bottom end going back together early next month.
- Align bored carrier
- New coated bearings, sized.
- Carrillo rods, JE Pistons, Custom pins
- Tig welded IMS gears
- Dynamic balance of entire rotating assembly incl. clutch and LWFW
The heads (where the magic happens) are a challenge. There is almost zero tuning info out there. However I've made some port molds of various heads and done some analysis of the runners, volumes, pressure wave calcs, etc. to try and get to a good base config for the parameters within which I'll be running. the 3.6L heads have nice chambers and runner shapes. Would not be terribly far off those of the early GT3s once ported. However I'll be running the early VC1 heads as I'm not changing over the electronics and I want a throttle cable! So I have some work to do to see about getting these small port heads to flow. Cams are being evaluated by my grinder to see what we can do with them. The valve sizes will also be looked at. I'd like to run 40/34... we'll see.
Will be reporting back as I start to bolt things together. Final tuning will be done on a dyno by a shop with extensive M96 experience and the ability to custom tune the ECU.
Below are some pics ...
1 - 3.2/3.4 heads with 3.8L 997 X-51 headers
2 - Intake runner appears the same for 3.4 & 3.6L. Plenty of CSA to support bigger intake ports.
3 - 3.2L chamber showing both 37/32 & 40/34 valve pairs.
4 - Exh port molds. 3.2L left & 3.6L right
5 - 12:1 JE Piston with stock 3.6L valves all shined up
6 - 12:1 JE Piston showing valve angles & ring grooves
Stay tuned... all will be revealed
Here is a gallery of photos from the initial 3.6L teardown. Engine was in great shape but for a broken IMS chain. The original IMS bearing in fact was still like new!
Picasa Gallery
When I return from vacation & the Rolex 24 I'l will post an an analysis of the 3.6L vs 3.2/3.4 heads I've done. That will be followed by a report on the further development of the engine into a club sport toy.
It was a stock engine so couldn't have been any more than 273 lb/ft that snapped it. That is, if the engine torque had anything to do with it. Could have been a failed chain, or that scavenge pump may have seized first. Will probably never know exactly.
I'm leaning towards the failed pump as whatever it was stopped the IMS first... the valves never touched. If the pump seizes, it stops 4 of the cam chains and the IMS stops. The crank would then be trying to spin a "locked" IMS ... this could snap the chain instantly. Its' amazing failures like this can leave the engine in such good shape.
May also have happened on start-up. At any significant RPMs would have inertia and I think we'd be looking at pile of junk parts. I've seen a new (1500 mi.) 997 3.8L Carrera S snap a chain just after engaging 1st gear to pull away from a stop sign.
Yeah great pics there, reminds me of my rebuild due to cam chain snapping. I'm really surprised the Hyvo chain snapped before the cam chains especially due to the scavenger pump looking like it seized. Those Hyvo chains are tough compared to the dual row cam chain.
I would inspect the IMS shaft really carefully where the Hyvo chain sprocket is interference fitted as these have a tendency to spin on the shaft (you may be welding this anyway) also I think I would also replace the cam chains on this engine, they would of been put under stress and the chain rollers are press fit (not one piece cylinders) meaning they could go at any time which would be the last thing you want after doing all this work then to have to do it all over again.
I've got a couple of pictures what happened to mine around the IMS and Cam chain.
I hope this helps a little.
