fbirch

Deleted

fbirch

I found the pic below of an LSX engine with dimensions noted. Unfortunately I couldn’t find anything similar for the M96. A friend of mine has an M96 in his Cayman, so I’ll try to measure it this weekend.

In terms of rear overhang/handling, the dimension that matters most is the distance between the face of the transaxle flange and the center of mass of the engine. Although each engine will have ancillary bits hanging off rear end of the engine as mounted in the car (i.e., the left side of the block in the picture below), the location of the center of mass should be mostly influenced by the big bulky bits – the crankshaft, block, heads, pistons, con rods, etc. All of those items should be stretched out over a longer distance on an engine with 4 cylinders spaced 110mm apart than one with 3 cylinders spaced 118mm apart.

So the only way that I could see the LSX having the same flange-to-center-of-mass dimension as an M96 is if Porsche did something weird such as putting a very thick flange on the transaxle side of the M96 engine case (i.e., right side of engine as pictured below). Of course the LSX picture below doesn’t include the adapter plate you’d have to sandwich between the LSX and the stock Porsche transaxle, which effectively pushes the whole engine to the rear of the car.

Izzone

Great Scott will have one more pos vette engine to crash cars with

You can put lipstick on a pig but it's still a pig

Sac religious, this topic should be over

mdrums

You need to talk to him

Izzone

I will

Frankenstein cars are horrible to sell

If one is insistent about modding, mod a car to fit in a specific race class

Most gutted cars end up there

fbirch

My neighbor has an ‘08 997 C4S with an M97, and I just put a tape measure on his engine case. It’s not completely clear looking at the engine from the underside with hoses and plumbing in the way, but the length of the case body itself appears to be around 18-18.5 inches. This dimension is analgous to the 21 inch dimension for the LSX case. There are some thin aluminum castings attached to the end of the M97 case that extend its overall length, but those lightweight ancillary bits are beyond the end of the main case body, and shouldn’t have much impact on the center of mass of the overall engine assembly.

BTW, that 18-18.5 inch measurement matches up fairly well with the approximate answer you get if you measure the M96 case length on the picture below, measure the bore spacing on the same picture, and then scale the case measurement with the known bore spacing.

So it appears the M96 has nearly the same case dimensions as the M97,and it's somewhere around 18-18.5 inches. That would put it 2.5-3 inches shorter than an LSX (main engine body, not absolute overall engine length), and you still have to add another 0.5-1 inch to the LSX to account for the adapter plate you’ll need to add to the LSX to reuse the stock transaxle. So the center of mass of an M96 should be 1.5 to 2 inches farther forward for the Porsche engine than for a transplanted LSX. If my recollection of 991 press releases is correct, that’s significantly bigger than the forward placement of the engine in the 991, which Porsche claims to yield a measurable improvement in handling.

That doesn’t mean it would be unworkable to transplant a Vette motor into a 996. I’m sure you could play around with camber, spring rates, etc., and get something that handled okay. Lots of people have them and seem to like them, so they can’t be all bad. But some degree of extra rear weight bias is just one more undesirable attribute in addition to the ones that have already been pointed out (resale value, gearing, transaxle durability, cooling in big power applications, rev-ability character, condemnation from Izzone, etc.).

fbirch

As much as I’m inclined to agree, the guy who just blew up his Porsche engine probably doesn’t think they’re too “sacred” at the moment. Besides, the topic is a fun mental exercise for any true car nerd.

kk2

lsx is a much better decision than wasting time with m96s.

Search for username white out or whiteout.

10 GT3

LSX block is ~22" long.

I went underneath both my GT3 and my 911 S/C and here are the measurements for the length of the crankcase"

911 S/C 3.0L: ~20.5" long
Mezger 3.8L: ~22.0" long

It looks like the better versions of these flat 6's are longer and hence carry their weight further aft than the lesser M96/M97 versions. BTW, I have never heard anyone complain about the length of a Mezger engine over a M96/M97.



When looking at LSX vs M96/M97, it is really hard to make any judgement for the M96/M97 being a better engine. With all the RMS/IMS issues, those engines doesn't even come close to making the list of the best engines ever made (although I am sure the Megzer would be on it). While I know it is possible to fix all the issues with an LS7 (cylinder liners, exhaust valves, rod bolts and oiling system), I don't have the confidence that the issues with the M96/M97 engines can ever permanently be solved (even with the LN Engineering update). Never the less, I would still not put a LSX in the back of a 996; it just needs something that better matches the characteristics of the car.

I did find out the Audi 4.2L R8/RS4 engine could be an interesting option. It is 430 lbs and just 20" from crank pulley to bell housing.

This thread is really in the wrong forum. It has nothing to do with GT2s/GT3s or even any Mezger engine based car. I think it would be very appropriate to move this thread to the 996 forum (hint admin).

993Brendan

My brother has a Lexus IS300 with an LS3 swap in it. Sick car, sleeper factor is entertaining but I'd rather just buy a C5 Z06 for the money.

fbirch

Well, Porsche apparently thinks that lighter, shorter engines are worth pursuing for their rear engine cars, even the GT3. Not only did they drop the Mezger in favor of a lighter, more compact 9A1 variant, but they also undertook R&D efforts to reengineer both the transaxle and chassis to allow forward placement of the whole drivetrain. Apparently, even one inch was enough to make a difference.

I just measured my 3.6L Mezger and got measurements close to yours – 21-21.5 inches, depending on where you declare the end of the case to be. I don’t know how far forward the transaxle flange of a GT3 is positioned relative to the transaxle of an M96/M97 car. But it wouldn’t surprise me to learn that GT3’s have more rear weight bias overall than M96/M97 cars. You’re correct to point out that we’ll all bought GT3’s in spite of that. But the GT3 offers other, compensating virtues (e.g., a track record of robustness, demonstrated in endurance races around the world, 8000+ RPM’s, the ability to track it fairly close to the way it comes from the factory, etc.) that you won’t get with a 911+LSX combo. That’s not a knock against the LSX; it just wasn’t engineered to go in the back end of a 911.

I agree with you that the M96 is hard to get excited about, given all its issues. I wonder if anyone has come up with a way to retrofit a 9A1 into an M96 car. The wiring harnesses are likely incompatible, but would it be any more incompatible than an LSX wiring harness? The 9A1 seems to be a pretty solid motor, much improved over the M96 and M97, and its overall layout is much closer than any V8 to what Porsche designed the M96/M97 cars to accommodate. By now, there should be good donor availability from wrecked cars. If I had an M96 car with a blown motor, and was looking for something other than an M96 to transplant into it, a 9A1 would be my first choice. 400HP, lightweight, compact, high-revving, low CG, happy to live in the back end of a 911, and reasonably robust – those are all pretty good attributes.

fbirch

Agreed

utkinpol

it is odd why no one really takes this challenge.
I looked at the wiring diagram, signal bus of 997.2 engine ECU and 997.1 is very similar, but most builders simply ignore this part of work as it is easier to pull out entire 997.1 wiring harness and put in 997.2 harness into their project cars, but for an average Joe such a project is simply cost prohibitive as it is an insane number of hours to pay for if job gets done at the shop.

as I know nobody really ever tried to 'mate' siemens 997.2 ECU with 997.1 signal bus. yet you are correct, to 'mate' LS3 motor is even more difficult and as I understand to get that done you pretty much discard entire 'stock' Porsche wiring. probably OK for a race car if you do not need immobilizer, PCM, you drop linkage to front ECU, you only have motec ecu with 'on/off' switch and custom racing dash.

speaking of M96 - it is not a bad motor, one can rebuild it with LN Eng. nickies cylinders, new pistons, proper rods that do not brake off, it is a doable job but as anything Porsche related labor cost of such services is insane, parts prices are also quite insane while nothing really is that different there from any vette or BMW rebuilds, still, it costs nearly twice more.

also, just to 'get' 9a1 motor in a crate if you have M96 is not cheap as factory created special hoops to jump over to complicate the process is you do not have a matching 'core' to return back, they will not accept M96 even if it is not blown as a 'core' for a replacement 9a1. so you would have to buy it outright for full retail, close to $40k.
and then you go and look at this:
http://www.ebay.com/itm/CHEVY-427-LS...-/181168150272

and it suddenly starts making sense, financially.

fbirch

Wow, $40K for a 9A1?! That’s ridiculous, even by Porsche’s standards! You can buy a whole car with a 9A1 in it for not a lot more than that. I wonder what dismantlers charge for low-mileage donors from wrecked cars. Of course they’ll know what Porsche charges for a new engine and will likely set their prices accordingly.

Maybe the right strategy for a person such as the subject of the original post – someone who has an M96 car with a bunch of nice track upgrades and a blown motor – is to buy an early 9A1 car, transfer all his track upgrades onto that car, and part out whatever is left from the original car. He won’t recover much value from his existing car, but at least he’ll have “free” upgrades for his next Porsche.

Before I went down the route of trying to transplant a Vette motor into a 996 intended for track usage, I’d want to see some other guinea pig build one and mercilessly thrash it on track for two hard years without blowing it up, breaking anything, or constantly having to tinker with it, preferably with many of the DE’s occurring in 100 degree heat on some southern track during the height of summer season. Even then, I don’t think I’d be happy with such a combo. I’d rather just buy a Vette. C5 Z06’s are dirt cheap.

10 GT3

Except Porsche hasn't started racing them yet. Remember that they had such a lack of confidence in the design that the current 991 GT3 race cars still have and are still winning races with Mezger engines. The 9A1 engine series has been out in street cars since 2008 (2009 model year) and this is now 2013. This is the 5th year since the introduction of the 9A1 and Porsche is still not racing them. Hmmm... Coincidentally, Porsche never raced the M96/M97 engines. Also, none of these race cars use any variant of the street 7-sp PDK Double-Clutch Automatic Gearbox.

They instead get a true sequential 6-sp gearbox manual (no automatic mode at all). Porsche purchased a year ago, 2 years worth of Mezger blocks (for risk mitigation) so they still have another year they can race with Mezgers if they still feel the 9A1 is still not up to snuff. Until the day Porsche builds a factory race car with 9A1/street PDK combination and successfully wins a real competitive endurance race, there is absolutely zero evidence to support that this combination is any better than what it replaces.

$40K of a 9A1 mass market motor is truly ridiculous! A Metzger 3.6L or 3.8L is only $35K for the engine. I wonder also if that 9A1 would even matte up to a M96 gearbox?