AndrewMT996

First, let me apologize as I'm sure buried in this forum are some answers to my question. My sporadic reading of the 996 forum has yielded some bits of information and my handful of search attempts have pointed to a few others, but I haven't seen this addressed directly.

Question: What options are there for an engine replacement or renovation for a 996? This excludes a stock rebuild, salvage replacement or rebuild. Regardless of whether the M96 has an unfairly bad reputation, I've already had one go bad on me and I'm not willing to roll the dice again. For the purposes of this discussion, also assume that selling as a roller is not is not an option and that the car is going to be kept long term for maximum enjoyment!

Obviously, Flat 6 Innovations is the first that comes to most people's minds. For the purposes of this discussion, I'm going to be considering them the gold standard. I've read enough of Jake's post to know that his brusque style rubs some the wrong way, but from the people I've talked to, no one disputes the quality of his work.

Now, what other alternatives are there and what are the pros/cons of each? I know the GM engines are one option. I've heard maybe putting a later model 911 engine in. What else is worth looking into?

Ahsai

Not a lot of choices given your requirements.

If you are afraid to roll the dice for another M96 engine, you have only two choices left:
1) JR engine ($18-20k) which removes all inherent issues with the M96 engines
2) LS swap ($15k I think) but that's not what Porsche intended

Note even 997 engines have some issues of their own plus I don't think it's an easy swap anyway.

Also note there are rebuilders out there using LN nickies to reconstruct M96's but the cost will not be much less expensive than JR's.

Cuda911

For the record, forget the LS swap. I already contacted Renegade about this. A cool idea, but you will be into it for at least 25K, between the cost of the motor, the adapter kit, wiring harness, labor etc.. etc., etc.. I see that you are in Texas, so not an issue. But, CA residents should think long and hard about this due to smog issues. It's not an impossibility, but certainly requires some effort and luck.

Jake Raby

When considering a swap you have to think about the future even more so than when going with a reconstructed M96. Future buyers are concerned with conversions, and that effects marketability of a car IF you ever decide to sell it.

I think its important to keep a Porsche marketable to Porsche enthusiasts, they are the ones who spend money on the cars.

There are options, some better than others, and others that just don't make any sense.

ferfont1

Well with a little research and do-it-yourself stuff you can be into an ls swap cheap! I spent under $4k for my swap.
Ls1 motor intake to pan: $1500
Adapter plate kit: $1200
Spec porsche clutch: $700
Wiring harness: $100
Motor mounts: $100 in materials (buddy hooked up the welding)
Dyno tune: $600

400hp/400tq to the wheels at a fraction of the cost of a tt or gt3.

Nothing was bought from renegade hybrids.

But for California you would need to buy the GM crate e-rod ls3 motor that comes with a c.a.r.b. exemption to put into any model car and be legal. That costs about $8k from jegs, but that also includes ecu and tune.

Ahsai

The OP's engine only has 60k miles, can it get away with no resleeving and new pistons? That should save quit a bit if possible.

Jake Raby

More than likely, no. Generally speaking we see .001" of bore deformation (ovality) for every 10K miles of service. There's no way I would reassemble an engine with .006" ovality. We also generally see .0005" of taper in bores per 10K miles of service, and again, I'll not accept that.

There are exceptions, where an engine doesn't see these values, but they are few and far between. If these cylinders have this much deformation at let's say 60K miles what will they be at when the clock strokes 100K miles? Will the engine burn oil, lose ring seal and create a ding on my reputation? The chances are too high for me to accept. Been there, done that, and see others take themselves out all the time because their standards are not solid enough, or they make exceptions.

I will only reuse factory cylinders if ovality is less than .002" and taper is less than .0015" on all cylinders of the engine. If not, the engine must be reconstructed, and sleeved.

To determine bore deformation requires engine disassembly, and the use of the proper precision measuring devices. Once these values are gathered, one can make a decision about what should be done moving forward.

Here's one of my cylinder charts from an engine that we measured today. It had 45K miles and had a cracked head. This one is not a candidate for repair, and must be reconstructed, with new cylinders. If someone were to repair this and put it back on the road without quantifying these values, the engine would be a disappointment waiting to happen.

Ahsai

Thanks, Jake. That's very informative. Basically you measure the ovality and taper and base on the current milaege you can predict the wear rate of this engine and any potential issues down the road. Maybe even some current measurements are already way out of spec like cyl #2.

dgjks6

If it were me, here is what I would do. From the other thread I assume a Flat 6 is out of the question at this point. I would buy a used engine off ebay for 6K, ship the car and engine to CA to either UFO motorsports or 9xx mtorosports (they used to be partners). They do a rebuild/refresh with install for $7500 including install and checking and pay for labor 1 way. Total out of pocket would be about $13-14K and you would be back up running in a few weeks with and engine with a warranty for 1 year.

They upgrade a few parts but it is not the same as a reconstruction.

I had UFO rebuild my motor last year and could not be happier.

dgjks6

Oops, just saw your pic. Add a few thousand to my recommendation. My car has a 3.4 and you can get a used 3.4 for $5-7K. 3.6's seem to be more.

c4racer

That GM crate motor LS3 is only CARB approved for 1995 and earlier cars in CA btw. So makes for some interesting potentially legal retrofits but 996 isn't one of them. It can still be done but requires a BAR referee cert which is a serious pain

Joe Ricard

Why not a motor from a GT3?
or take care of the one you have and not get worked up about it potentially failing. Keep your eyes and ears open for a motor you want, if it takes a year fine. Do a proper Porsche engine swap / upgrade.

andy92782

If I lived in TX like the OP and didn't have to deal with the smog inspection gestapo like CA has, I'd do LSx swap all the way.

roadsession

THIS is a great solution IMHO

Jake Raby

Cylinders 2 and 5 are always the worst and are generally out by twice as much as all the others. This is de to the open deck design allowing the hottest coolant to these regions, and the cylinders have the least support.

There are lots of times where the other 4 cylinders are very close, or at spec, and the two center cylinders are project killers, being way too far out.

There's tons of engines that are being "rebuilt" out there for cheap prices that have nothing with the cylinders addressed. The builders are throwing them together cheaply and aren't even measuring the bores (if they even own a bore gauge or know how to use it) and those engines are just a temporary band aid that provides zero resolution to the root of the problem. Ignorance is bliss, and since cylinder deformation isn't visually notable. they think that everything al gonna be ok.