M96 3.4 & 3.6 engine weight and LS Swap talk

[BufordTJustice]

I have seen several videos and posts across the forums recently about these LS engine swaps for 996 911's. I keep hearing that the LSX (LS2/LS3) is LIGHTER than the M96. You know who keeps saying this. It's all over youtube and other forums. But my research has determined this is false.

 

The M96 (3.4 and 3.6), with all accessories, and including the entire exhaust system (yes, cats too), is roughly 440 pounds, +/- 5 pounds. Subtract the weight of the exhaust system (and all LS swaps argue they use the factory Porsche exhaust system), and we arrive at a number much closer to 410-420 for the M96 engine minus exhaust. This is assuming roughly 20-30 pounds for the OEM exhaust, which I have not been able an accurate separate weight (feel free to add this if you know it).

 

However, the LS3 (all aluminum, 6.2, GM crate motor) weighs 465 pounds with ZERO accessories (not even the pulleys, brackets, or belt tensioner), and NO HEADERS (much less an entire exhaust system). Including accessories (PS pump, Alternator, Water Pump, but still no AC compressor), and headers, the engine assembly weighs about 500 pounds, not including the mounts.

 

As a data point, the ultra lightweight LS7 motor weighs 454 pounds completely naked.

 

So, a 996 with the M96 3.4/3.6 is going to be at least 80 pounds lighter than a 996 with an LS motor installed (possibly closer to 100 pounds lighter). Assuming one would pay the $22K+ for an LS7, and assuming that would fit and be compatible, the weight difference would drop to "only" 50-60 pounds.

 

As soon as we start talking about CG height, polar moment, etc.... things get even worse for the LS Swap. Not to mention it putting extra strain on the transmission mount.

 

I hope this sheds some light on the subject and puts to rest some of the absurd claims I see being made about LS Swaps. I got tired of hearing the ridiculous claims.

 

Long live the M96!!!!!!

Edited May 24, 2017 by BufordTJustice

[Wallace Sparks]

Horsepower + maintenance +cheaper can't go wrong


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[Loren]

Creekman can substantiate what you say (since he did  it)...

 

 

[creekman]

First of all the 996 weight depends on it's accessories so its total weight is a moving target.  However I don't know what all this leads up to if you want the extra horse power and a simple engine that produces a lot of grunt.  I installed a LS3 480 HP, some GM specs says it's 495 HP, I won't argue that point...

 

I put the car on aircraft scales and I'm 160 lb. lighter, however that is with the removal of the front diff.  Also all the accessories are attached on the bottom of the engine, not on top, lower CG.  The installation uses an electric water pump so no mechanical water pump.  I can tell you it's no quick substitute for replacing the IMS bearing, clutch, etc.  Making the Porsche and GM computers talk to one another was the biggest challenge.  It's not for the shade tree mechanic...  Now there's a lot of these conversions that throw used parts at the project, never deal with the blinking lights on the dash and only want to go 0-60 with their hair on fire, but to do it factory takes a lot of time and money.

 

I don't think debating about a few pounds either way is really the question, it's time, money, performance, engine longevity, something different that is breath taking to drive.  I took my car into the local Porsche dealership to put it on their OBD machine.  When the guy drove the car into the mechanics stall the entire shop stopped working, took pictures, got under the car and were all in awe of the installation.  Fortunately I didn't have to pay for the down time...

 

I removed the front differential in favor of putting a taller ring and pinion in the car.  At redline in 6th gear it pencils out at 206 MPH, not with me in it...  At 80 MPH it's turning 2750 RPM, it's a lot quieter that the Porsche engine that is turning more RPM's.  Bottom line, it's simple horse power and when you lift the deck lid you can see a real engine, not an air cleaner.  Sorry in advance if I offended anyone... 

[BufordTJustice]

First of all the 996 weight depends on it's accessories so its total weight is a moving target.  However I don't know what all this leads up to if you want the extra horse power and a simple engine that produces a lot of grunt.  I installed a LS3 480 HP, some GM specs says it's 495 HP, I won't argue that point...

 

I put the car on aircraft scales and I'm 160 lb. lighter, however that is with the removal of the front diff.  Also all the accessories are attached on the bottom of the engine, not on top, lower CG.  The installation uses an electric water pump so no mechanical water pump.  I can tell you it's no quick substitute for replacing the IMS bearing, clutch, etc.  Making the Porsche and GM computers talk to one another was the biggest challenge.  It's not for the shade tree mechanic...  Now there's a lot of these conversions that throw used parts at the project, never deal with the blinking lights on the dash and only want to go 0-60 with their hair on fire, but to do it factory takes a lot of time and money.

 

I don't think debating about a few pounds either way is really the question, it's time, money, performance, engine longevity, something different that is breath taking to drive.  I took my car into the local Porsche dealership to put it on their OBD machine.  When the guy drove the car into the mechanics stall the entire shop stopped working, took pictures, got under the car and were all in awe of the installation.  Fortunately I didn't have to pay for the down time...

 

I removed the front differential in favor of putting a taller ring and pinion in the car.  At redline in 6th gear it pencils out at 206 MPH, not with me in it...  At 80 MPH it's turning 2750 RPM, it's a lot quieter that the Porsche engine that is turning more RPM's.  Bottom line, it's simple horse power and when you lift the deck lid you can see a real engine, not an air cleaner.  Sorry in advance if I offended anyone... 

Thanks for sharing. No offense in my part.

 

But the all-aluminum accessories of the 911 A) aren't that heavy and B) don't equal more mass than part of the block and all of the heads of an LS.

 

I don't know what else got discarded off of your car, obviously A LOT, but the wider body and suspension bits apparently weigh a bit more than a narrow body coupe. Having driven many LS powered machines (including several C6 Vette coupes around 3200 pounds), I just can't imagine losing the character of power delivery of my M96. I'm a huge fan of the LS, just not for me in a 911. I'm glad you're happy with your conversion.

 

However, my numbers (sourced from GM and this forum) stand. The LS2/3, with it's nodular iron crank, is simply heavier than the M96.

 

 

 

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[creekman]

Either way whether the LS motor is lighter or heavier, the difference compared to the HP increase is the big difference.  Just think how hard your M96 has to work to get 150 HP more...  Hey, it's all in the eyes of the beholder.  

[judgejon]

"Back in the day," I had a '62 Chevy with a hot 283, and then a '68 Camaro with a great 327.

I remember seeing a thread from a member of the forum in Santa Rosa, CA, about installing a short-block chevy in an older 911.

Looked interesting, and .... with a short block Chevy I just might be able to change my own spark plugs again.

I remember when the insurance guy came out to inspect my old 911SC to be sure it actually had a Porsche engine in it.  Always wondered why..

Now I know.  This is a great read.  Question:  why not just get a Z06 Corvette in the first place?  Cheaper, faster, etc.  Maybe cause it's still a Chevy?

Cheers to all...

[BufordTJustice]

29 minutes ago, creekman said:

Either way whether the LS motor is lighter or heavier, the difference compared to the HP increase is the big difference.  Just think how hard your M96 has to work to get 150 HP more...  Hey, it's all in the eyes of the beholder.  

 

The HP difference is huge, that is true. So is the apples-to-apples weight difference. Also, there is a zero percent chance that the CG of the LS is even within 5 inches of the M96's CG. The centerline of the mass of the M96 is slightly above the crank. The centerline of the mass of an LS is far above the crank. And since the crank must align with the transmission, the CG is forced further away from the ground.

 

Also A large part of the rear chassis has been removed, along with the rear crash substructure. That's a fairly decent weight savings right there. It is difficult to find what else has been discarded.

 

It seems that the Renegade build (and all others, from what i can see), requires substantial removal of metal from the rear of the chassis, and the rear crash structure. Couple that with removing the front diff, front halfshafts, front CV joints, and the front driveshaft (and all mounting hardware), and it seems logical that one could find a net weight loss of 160 pounds when transitioning from a C4 to a C2.

 

Glad you're happy with yours. To each his own. Reducing chassis rigidity while adding power just isn't my personal cup of tea.

 

Std 996 rear structure:

 

 

 

LS mod'd rear structure:

 

 

 

 

 

 

 

[judgejon]

wow, that is one good looking major league job well done.  Fascinating to see how it all fits.  Clearly takes years of engine work and great skill.  cool.

[creekman]

Thanks Judgejon...  come take a drive...

 

Buford, after your reply I needed to go to the garage and make sure the back end of the car hadn't fallen off.  You're a purist and that's ok, you've exaggerated some of the install alterations.  I installed 4130 tubing mostly just to finish off the sheet metal.  I believe Porsche has pushed the flat 6 about as far as it can go.  It's a very complicated engine to get the HP.  The clutch, spark plugs, water pump are only good for 60,000 miles, and the list goes on. The V8 makes it breath taking to drive and It's a great road car, but still a grocery getter if that's your choice.

 

Just remember when you're at the Porsche Dealership changing spark plugs at $140/ hr.  I'll still be trucking long beyond the life of your engine.  What I will admit while the conversion will exceed all your expectations, it's expensive when done right and is not plug and play.

[BufordTJustice]

5 hours ago, creekman said:

Thanks Judgejon...  come take a drive...

 

Buford, after your reply I needed to go to the garage and make sure the back end of the car hadn't fallen off.  You're a purist and that's ok, you've exaggerated some of the install alterations.  I installed 4130 tubing mostly just to finish off the sheet metal.  I believe Porsche has pushed the flat 6 about as far as it can go.  It's a very complicated engine to get the HP.  The clutch, spark plugs, water pump are only good for 60,000 miles, and the list goes on. The V8 makes it breath taking to drive and It's a great road car, but still a grocery getter if that's your choice.

 

Just remember when you're at the Porsche Dealership changing spark plugs at $140/ hr.  I'll still be trucking long beyond the life of your engine.  What I will admit while the conversion will exceed all your expectations, it's expensive when done right and is not plug and play.

 

With 48k on mine, it's a shame I've only got another 12k before it dies. Guess I'll enjoy it well! If I'm ever dumb enough to pay somebody else to do my own spark plugs, then I guess I'm ready to put some caveman (pushrod) tech into my Porsche.

 

But I'm not there yet. Keep your pushrods and your extra 80+ pounds and I'll keep my driving experience, 7200rpm redline, and my Porsche music. ;)

 

And, yes, I'm a purist.

 

In all seriousness, have a happy and safe Memorial Day.