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This post is the beginning narrative of an eventual 944 Turbo engine swap with a GM LS3 EROD crate motor.

Our path began about 15 years ago. Two brothers auto-crossing and tracking their 944 Turbo and 944 S2. Auto-crossing primarily at the abandoned El Toro Marine Corps Air Station, Orange County, CA and tracking at Willow Springs Raceway, Chuckwalla Valley Raceway, and Fontana's Auto Club Speedway.





After about 5 years of these very enjoyable outings/competitions, the unexpected happened. The high G-forces resulting from a combination of wide R-compound tires and spirited driving thru the bowl at Streets of Willow starved a 944 Turbo rod bearing of oil. There were ugly engine noises and "pieces". Engine torn down for inspection and investigation of options:



Investigating the options revealed the Turbo's engine rebuild would be costly (Porsche parts and labor).
How about an engine swap?
Yeah, how about a GM LS3 engine swap with 2x the power/torque and similar weight.
How hard can it be?

This:


Plus this:


Diving right in, my brother ordered the new GM LS3 EROD crate motor with freight delivery to his garage, which I received without the "required" loading dock. The tractor-trailer driver was not pleased.



The "shoe horning" begins:





These pictures and info are about all I can contribute on the swap. My brother, traveling & returning home in about a week, can pick-up the narrative from here. If interested, be sure to ask him about:

steering linkage re-routing and proper u-joint installation,
Cadillac CTS-V accessory drive package and power steering reservoir,
Corvette bell housing and new clutch,
BMW ATE H31 Hydroboost & bomb install,
Accusump for avoiding oil starvation,
Renegade Hybrids versus Texas Performance Concepts engine swap kits,
California Air Resources Board particulars to register the engine-swapped 944LS3,
and anything else of interest, "he's tackled 'em all".

I get the whole LS swap thing in the US. It makes a lot of sense in some ways. It's just that somehow, it's wrong. There's just something about a smaller engine in a European sports car that punches above it's weight. To me, V8's are a great thing and clearly have a massive following. Which in turn leads to cheap parts and many upgrades. But, they also lead to a lazier driving style. Why change gear when you can just ride out on that fat old tq curve. Sure negates a lot of gearchanges. But that's what most of us want from these cars. A light, nimble sports car. Not an alternative to a Corvette or Camaro. It's why people find flinging a Mini Cooper, Alfa 2000, BMW 2002 etc etc through the curves so much more intoxicating and challenging than just blurting around in a lazy V8. Of course the V8 can be made to be extremely powerful but then you really avoid the charm of something stemming from the original design. It's not to say that people can't make these i4's extremely fast too. As many on this forum can attest too. Anyway, good luck to you and your brother. Hopefully you avoid those lifter issues.

I have seen a few 944/951 chassis with LS power run AX events and they are VERY competitive. The LS engine can be driven like an old man or boy racer . If it's being driven " lazy " that's the fault of the driver . In many if not most cases the LS is as light or lighter in weight than the 4 cylinder lump it's replacing.

Powerful/reliable/inexpensive is a hard combo to beat . Parts availability everywhere is a plus . Yes I am a fan . Last year I purchased a 1998 Chevy S10 pickup that was converted to LS . Went from a 2.2 four cylinder to a 5.3 . I don't know how the truck drove with the 4 banger but it's a hoot with the 5.3 . No it's not a sports car so not comparing apples to apples . Variety is the spice of life and there are plenty of options out there . I hope the OP's conversion goes well and exceeds expectations.

Excellent observation by 333pg333 - the car is a very different animal now. It can run "lazy driver" laps at Streets of Willow completely in 4th gear faster than it ever was before BUT far less engaging. Between the two of us, we had the 944 Turbo, 944S2, and 968. In some regards, the sometimes-infuriating turbo lag and lack of high-end power were the very things that made the car the most fun of the bunch. There was definitely a sense of accomplishment rowing the gears and trying to get the best out of the modestly powered platform. On the other hand, it does bring a grin to my face every time I downshift and punch it because the LS3 really shoves the driver in the back and the challenge is just different now - taming all that power without ABS or any other computer nannies.

At the end of the day, we always longed for more power and the spun bearing forced us to evaluate goals/options. Trying to squeeze more out of it with a performance built 4-cylinder would have required serious dollars and jeopardized reliability.

My brother opened up this thread for folks who may have questions but I'm not sure how active the conversion community is after all these years not to mention that the process is covered in great detail elsewhere. There were a few things that we thought were slightly trick but nothing earth-shattering:

1) discovered unused check engine light on dash
2) created a custom ring/wiper assembly to replace the horn clockspring when switching to Momo steering wheel
3) converted pop-up headlights to manual operation (we rarely drive at night, it only takes a minute, saves quite a bit of weight and space)
4) custom 3D printed air intake
5) Accusump and oil cooler combination to protect the engine in high-G loads and keep things cool (temp never gets above the first hash mark)
6) used two steering shafts (cut down) and a universal bearing supported by a heim joint to snake past the exhaust manifold
7) lots of iterations on the BMW hydroboost before settling on a solution that allows it to run without the bomb accumulator

Hey I'm interest!! I know it's been covered before but you always get that guy like me that recently (July 24) got a 951 and wasn't interested in the LS swapping a 944/951 until now.

I'm somewhat familiar with the swap, at least from a 914 perspective. I've had 6 or 7 914's since 77'. I finally ended up with a complete nuts/bolts restoration on a 75' and just don't want to cut up a decent 914 to do the swap on one.

Now, if/when engine issues happen on the 951 an LS3 will be replacing it. So, yes thanks for your time and effort to post.

I also get that there are folks that want a momentum car and love those tight tracks with short straights and a lot of curves. I prefer hunting GT3's at Road America. Momentum cars don't offer the opportunity to properly use breaking skills. Sure, they use the brakes, but not like slowing from 160 mph to make a 55 mph left hander.

Thanks for the measured replies in a sometimes emotional topic. Having never been in a V8 converted 944 I can't speak from experience. Although I have seen quite a few in car videos and have formed my opinions on these. Of course you can make a V8 more responsive too. I also totally get the attraction in the US as these engines are relatively cheap compared to a properly built 951 and there's a ton more material, users, aftermarket (affordable) parts compared to the very small 944 turbo world.

Having said all that, I would say that putting together a similarly priced 3lt 8v should be doable and this would comfortably compete with most n/a V8s. Modern turbos are more responsive. ECUs are cheaper and more efficient. Fuel and spark is better. A 3lt 8v can be a ton of fun and also have some serious tq. We dyno'd my old 3.1lt 8v at 550ft/lbs at the wheels and that's definitely more than most of the crate V8s that we see in 944 conversions. To be fair that was at 25psi which we didn't run on the track. I think we used mostly about 18-20psi.

I don't even think it should cost stupid money to put together a 16v 3lt+. They might have a little less early tq than the 8v, but they achieve very decent hp at significantly less boost. Our 3.2lt 16v saw 618whp @ 16psi so that's pretty darn competitive against virtually all the V8 conversions. Not saying that this motor would be cheap to reproduce, but something a little less custom using many oem parts is doable without breaking the bank.

But good luck to whoever does whatever with these old cars we love.

One thing not mentioned above, unless I missed it, is that the owners are trying to get a CARB sticker to make this car California street/smog legal. GM sells these E-Rod crate motors as 50-state legal right out of the crate, as long as you install it as specified. I've been trying to help in the background with some of the electronics requirements. There is literally no way to make a 450hp 944 motor street legal here, so a smog-hassle-free 944 with a EROD LS3 crate motor might make more sense here than it would elsewhere. All things equal, I'd rather have a built 16v 3 liter motor, but in California with smog testing to deal with, a smog-legal LS3 sounds pretty good.

Tom wrote: Thu Jan 09, 2025 7:12 pm One thing not mentioned above, unless I missed it, is that the owners are trying to get a CARB sticker to make this car California street/smog legal. GM sells these E-Rod crate motors as 50-state legal right out of the crate, as long as you install it as specified. I've been trying to help in the background with some of the electronics requirements. There is literally no way to make a 450hp 944 motor street legal here, so a smog-hassle-free 944 with a EROD LS3 crate motor might make more sense here than it would elsewhere. All things equal, I'd rather have a built 16v 3 liter motor, but in California with smog testing to deal with, a smog-legal LS3 sounds pretty good.

I got involved (via my shop) with a 2001 BMW E38 740iL that has a CARB-legal LS3 E-Rod swap. My task was on the electrical side: get the A/C and factory HVAC system working with the GM stuff. There are readily available CAN modules to make an E39 5-series or E46 3-series of the era play nice with GM stuff, but the E38 uses a BMW-specific K-bus protocol for most of the body modules. I'll spare everyone the details, but you would not believe the amount of time and effort it took to get a +12V signal from the HVAC module to the A/C compressor

Anyway, the 944 platform is excellent for either incorporating standalone engine management to the existing engine and/or a full engine swap because all such systems are external---HVAC, cruise control, radiator fans, etc can all function as is.

cda951 wrote: Sat Jan 11, 2025 2:46 pm

Tom wrote: Thu Jan 09, 2025 7:12 pm One thing not mentioned above, unless I missed it, is that the owners are trying to get a CARB sticker to make this car California street/smog legal. GM sells these E-Rod crate motors as 50-state legal right out of the crate, as long as you install it as specified. I've been trying to help in the background with some of the electronics requirements. There is literally no way to make a 450hp 944 motor street legal here, so a smog-hassle-free 944 with a EROD LS3 crate motor might make more sense here than it would elsewhere. All things equal, I'd rather have a built 16v 3 liter motor, but in California with smog testing to deal with, a smog-legal LS3 sounds pretty good.

I got involved (via my shop) with a 2001 BMW E38 740iL that has a CARB-legal LS3 E-Rod swap. My task was on the electrical side: get the A/C and factory HVAC system working with the GM stuff. There are readily available CAN modules to make an E39 5-series or E46 3-series of the era play nice with GM stuff, but the E38 uses a BMW-specific K-bus protocol for most of the body modules. I'll spare everyone the details, but you would not believe the amount of time and effort it took to get a +12V signal from the HVAC module to the A/C compressor

Anyway, the 944 platform is excellent for either incorporating standalone engine management to the existing engine and/or a full engine swap because all such systems are external---HVAC, cruise control, radiator fans, etc can all function as is.

In this case, I guess the ECU must get its VSS signal from the transaxle to get CARB approved, so my task on this one was to massage the transaxle pulse into something the GM ECU expects to see. Fortunately, I 'think' I was able to reprogram my SpeedoBooster firmware to do the trick, but time will tell....

Tom wrote: Sat Jan 11, 2025 6:52 pm

In this case, I guess the ECU must get its VSS signal from the transaxle to get CARB approved, so my task on this one was to massage the transaxle pulse into something the GM ECU expects to see. Fortunately, I 'think' I was able to reprogram my SpeedoBooster firmware to do the trick, but time will tell....

Ah, cool. One of the things I had to deal with in the BMW E38 is the GM 6-speed auto trans was stuck in first gear due to the VSS signal missing----I got HP Tuners to deal with that as well as using the ECU to activate the radiator fans based on temperature and A/C input . . . . . you are welcome to borrow the HP Tuners dongle if need be, just need to purchase a $50 token.