996 M96 Engine Project
Discussion
For past few months been searching for an M96.1 engine as a project. One appeared on a popular auction site, slightly overpriced, but made an offer and it was mine. Madness, as it has intermix issues, but it turns 360 so IMS failure is unlikely. So my first aim is to strip down and assess the damage. So this post will follow complete breakdown the engine.
So the engine is from a 996 3.4 Tip with approx. 133K miles with manual throttle. It is a long term project and I am likely to get some specialists involved on the rebuild. How that will evolve is undecided yet? Priority is to build in reliability using some 997 components and further research on 10-20% power increase. All depends on costs and keeping it simple.
So the engine is from a 996 3.4 Tip with approx. 133K miles with manual throttle. It is a long term project and I am likely to get some specialists involved on the rebuild. How that will evolve is undecided yet? Priority is to build in reliability using some 997 components and further research on 10-20% power increase. All depends on costs and keeping it simple.
It will almost certainly have a cracked head. New heads are available complete (with valves, retainers, springs etc.) from Porsche at sensible money.
Converting it to 3.7L will provide a sensible boost in performance and depending on your chosen method can improve cylinder strength. Converting the engine to closed deck on a 100mm bore is the ideal but expensive to do properly.
Don't use the 997 IMS etc. there are much better options including cylindrical roller bearings available these days. Also that engine will likely have a dual row bearing anyway, failure of which is extremely rare.
Run it on a 99 C4 ECU which will allow you to run the 996 GT3 DBW throttle body and has a proper CAN implementation to drive whatever dash pack or data system you fancy. The 99 ECU is also pre OBD2 so only requires a single lambda per bank and will run the version of Variocam on that engine out the box.
Converting it to 3.7L will provide a sensible boost in performance and depending on your chosen method can improve cylinder strength. Converting the engine to closed deck on a 100mm bore is the ideal but expensive to do properly.
Don't use the 997 IMS etc. there are much better options including cylindrical roller bearings available these days. Also that engine will likely have a dual row bearing anyway, failure of which is extremely rare.
Run it on a 99 C4 ECU which will allow you to run the 996 GT3 DBW throttle body and has a proper CAN implementation to drive whatever dash pack or data system you fancy. The 99 ECU is also pre OBD2 so only requires a single lambda per bank and will run the version of Variocam on that engine out the box.
@poppopbangbang @Dammit thanks for input
Having done intermix before on my current 996 I suspect the crack will be bank I, cylinder I. Until I get to internals who knows? The 3.7 sounds like a viable option and will contact Hartec on more details about their upgrade.
The additional pipework from the oil scavenger pump in the photo - is this the mod to provide oil feed direct to IMS?
Having done intermix before on my current 996 I suspect the crack will be bank I, cylinder I. Until I get to internals who knows? The 3.7 sounds like a viable option and will contact Hartec on more details about their upgrade.
The additional pipework from the oil scavenger pump in the photo - is this the mod to provide oil feed direct to IMS?
No, it’s a second stage scavenge pump that sits on top of the standard one which takes oil from the front of the head (via the hard-line), where oil can build up under heavy braking. The heads each have a sump with a scavenge pump, on the right hand bank the sump is at the rear, so fine under acceleration but not fine under braking as the oil is held away from both sump and scavenge.
This is done by us, but it's a version of the X51 dual-stage scavenge pump.
The X51 unit (a re-issue, presumably from the a different supplier to the first iteration) is currently available from Porsche - however, it runs backwards, pumping oil into the heads rather than out.
This, I would suggest, is sub-optimal.
The X51 unit (a re-issue, presumably from the a different supplier to the first iteration) is currently available from Porsche - however, it runs backwards, pumping oil into the heads rather than out.
This, I would suggest, is sub-optimal.
Dammit said:
is currently available from Porsche - however, it runs backwards, pumping oil into the heads rather than out.
This, I would suggest, is sub-optimal.
Yes I heard this, what the balls, pardon my French?!?!This, I would suggest, is sub-optimal.
Dear OP, a head swap is a weekend job with enough beer, it's November already wtf.. [jest] Looking forward to updates.
It's not a minor problem, certainly surprising that it's made it's way into production.
We're building two 3.7's and a 3.9 at the moment, in the middle of nailing down rod and piston dimensions to hit the compression/squish/valve clearance that we need.
Whilst we build those we're fitting a dual-stage scavenge to two engines along with our new tappet chest to my engine for testing:
(That's a prototype btw, see if you can spot why it's not usable).
We're building two 3.7's and a 3.9 at the moment, in the middle of nailing down rod and piston dimensions to hit the compression/squish/valve clearance that we need.
Whilst we build those we're fitting a dual-stage scavenge to two engines along with our new tappet chest to my engine for testing:
(That's a prototype btw, see if you can spot why it's not usable).
@dammit thanks for your updates. I will watch your project with interest. What is the ultimate goal with this development; race or street? "What's wrong?" Can't see from your photos, but are the cam lobes in contact with the cam chest (I always called it a cradle :-) )
My project is far away. The top of the engine has been stripped back. This includes inlet manifolds, fuel line & injectors, starter motor, alternator, vacuum lines + AOS, knock sensors, oil fill and dipstick, oil level sensor, oil cooler and wiring loom. The water pump was removed and sheered one bolt. The oil pump to be removed and already one bolt sheered through corrosion. Despite all efforts to soak bolt heads in WD40, you just know that a bolt is about to break just by the feel. Not much can be done about it before it's too late.
The pulse sensor on the bellhousing proved to be difficult to remove despite best efforts. Held in place by a single bolt it simply did not want to come out. In the end had to knock it out with a piece of wood from inside bellhousing dowsed in wd40/silicon spray. Whether this is common, but would not like to attempt this job with engine in the car.
From the photo you can see bad oil stains over bank I (similar on bank II reverse side). This is common as AOS becomes clogged up with reside oil and likely a clue to eventual failure. The RMS looks good, not sure if its been replaced. The IMS housing looks original by the amount of corrosion. However, it looks like someone has attempted to check it as one bolt is new - perhaps given up due to corrosion. I will have fun removing this component, no doubt.
Approximately 9ltrs of oil in the M96, but I've managed to empty ~10lts of caffe latte! The sump plug took a breaker bar to remove & the oil filter canister I cannot budge. Who knows what oil service was done on this...
My project is far away. The top of the engine has been stripped back. This includes inlet manifolds, fuel line & injectors, starter motor, alternator, vacuum lines + AOS, knock sensors, oil fill and dipstick, oil level sensor, oil cooler and wiring loom. The water pump was removed and sheered one bolt. The oil pump to be removed and already one bolt sheered through corrosion. Despite all efforts to soak bolt heads in WD40, you just know that a bolt is about to break just by the feel. Not much can be done about it before it's too late.
The pulse sensor on the bellhousing proved to be difficult to remove despite best efforts. Held in place by a single bolt it simply did not want to come out. In the end had to knock it out with a piece of wood from inside bellhousing dowsed in wd40/silicon spray. Whether this is common, but would not like to attempt this job with engine in the car.
From the photo you can see bad oil stains over bank I (similar on bank II reverse side). This is common as AOS becomes clogged up with reside oil and likely a clue to eventual failure. The RMS looks good, not sure if its been replaced. The IMS housing looks original by the amount of corrosion. However, it looks like someone has attempted to check it as one bolt is new - perhaps given up due to corrosion. I will have fun removing this component, no doubt.
Approximately 9ltrs of oil in the M96, but I've managed to empty ~10lts of caffe latte! The sump plug took a breaker bar to remove & the oil filter canister I cannot budge. Who knows what oil service was done on this...
Result of a proper crap engineering at its best i would say. That oil buckets really remind me my old 986 2.7 before the rebuild. My indie also replaced oil cooler and all radiators due to intermix, inevitable damage was there in such short time.
I was going to ask whats your aim? The job itself so painful and labour intensive...
Ive recently grabbed a Wv air-cooled 1300 engine on ebay, simply to learn the fundamentals and rebuild myself for the next project! (A knackered 964
)
I was going to ask whats your aim? The job itself so painful and labour intensive...
Ive recently grabbed a Wv air-cooled 1300 engine on ebay, simply to learn the fundamentals and rebuild myself for the next project! (A knackered 964
)ooid said:
Result of a proper crap engineering at its best i would say. That oil buckets really remind me my old 986 2.7 before the rebuild. My indie also replaced oil cooler and all radiators due to intermix, inevitable damage was there in such short time.
I was going to ask whats your aim? The job itself so painful and labour intensive...
Ive recently grabbed a Wv air-cooled 1300 engine on ebay, simply to learn the fundamentals and rebuild myself for the next project! (A knackered 964)
It's side-line project with no rush to rebuild an m96 ground up. Priority is to rebuild with reliability in mind. Original intention is for power output to match original factory specs. However, with more research I may increase capacity. What I do with the final rebuilt engine is undecided? I may replace my C4 engine, buy a donor car or sell the engine on.I was going to ask whats your aim? The job itself so painful and labour intensive...
Ive recently grabbed a Wv air-cooled 1300 engine on ebay, simply to learn the fundamentals and rebuild myself for the next project! (A knackered 964
)In my late teens I rebuilt a Triumph Dolomite Sprint engine. First mass production 16 valve head driven by single cam (inlet) and rocker (exhaust), quite an innovative design. It was renowned for warped heads and gasket failures. All was fixed with power increase and twin weber 45s.
Perhaps a slight tangent but also related to the end goals of this thread; is to separate the oil/coolant exchanger for an external air/oil type, with a thermostat, possibly positioned ducted under where the engine bay fan is and with that engine bay fan on an oil temperature sensor relay. Probably very far down the road for this build but certainly addresses and reduces the head load on the cooling system on the m96/7.
@Bullet-Proof_Biscuit
Interesting concept - not sure if this has been attempted. Sure you could tap off where the oem oil cooler sits & plug the coolant. The oem oil cooler also helps to assist oil to temperature when cold or at least until an equilibrium is reached looking at the design. Might be one for @dammit to comment on.
@Touring442
Not one to comment having never seen engines side by side. Some parts are shared in the short block 3.2, but PET shows different part numbers. Beyond that there is not much shared top end with heads, cams, variocam, intakes, fuelling and harness. I suspect it would not be cost effective to sort out.
Interesting concept - not sure if this has been attempted. Sure you could tap off where the oem oil cooler sits & plug the coolant. The oem oil cooler also helps to assist oil to temperature when cold or at least until an equilibrium is reached looking at the design. Might be one for @dammit to comment on.
@Touring442
Not one to comment having never seen engines side by side. Some parts are shared in the short block 3.2, but PET shows different part numbers. Beyond that there is not much shared top end with heads, cams, variocam, intakes, fuelling and harness. I suspect it would not be cost effective to sort out.
My 3.7 litre engine is made from 3.4 heads and a new 3.2 Boxster engine case/crank/crank carrier.
Not that we're using them, but the 3.4 911 cams are the same as the 3.2 Boxster, volume in the heads is very slightly smaller in the 3.2 and of course the bores are smaller - but we machined those out and replaced them.
Not that we're using them, but the 3.4 911 cams are the same as the 3.2 Boxster, volume in the heads is very slightly smaller in the 3.2 and of course the bores are smaller - but we machined those out and replaced them.
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