Apex996

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

dcdrechsel

Great project !What have you done with the cylinders ?Hone,sleeve or ........

Apex996

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.

Imo000

Nicely detailed pictures. Must have taken an insane amount of power to snap that chain. Have you figured out hos and what happened yet?

Apex996

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.

keytohwy

Great pics, thank you.

infrasilver

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.

Apex996

>> you may be welding this anyway

Yes, tig welding the sprockets on the IMS. And the new engine will have all new parts.

Apex996

Anyone have the PN# or link to the info for the Secondary Air Injection block off plates?