Recipe for 250+ hp with 3400/3500?

[Guest]

6400 is fine for me. But can the 3x00 oiling system, rod bearings, and rods handle much over 6400 anyways ?

I shift my LX9 at 6500 in 2nd gear and above (I have 1st gear set lower, for short shifting), and have done so for about 6 years now that the engine has been in the car, yes, I've had a few issues and had to replace the engine once, but none of those problems have been oil delivery related, mostly head gaskets, and one pair of pistons destroyed, but I'm quite sure that was due to an electrical component failure months earlier that caused the engine to abruptly stop. Anyway, I've I had the engine over 7000 RPM, and it kept pulling, again with no signs of oil problems, no uncontrolled pressure drop or increase. About the only reason I'm limiting my shifting RPM to 6500 is because of the stock rods. I feel at 6500 RPM, and making about 400 HP on an engine that in stock trim makes about half that, I'm probably stressing the rods enough as it is, though I know people take same design rods (powered rods) to much higher RPM and higher power levels in other GM engines with little to no problems, I'm just not willing to push it any higher, repeatedly. The oiling systems in the gen3+ 60 degree V6 are quite good with the crank priority oiling.

The LZ9 I'm building is being done so to sustain much higher RPM (8500 RPM+), even though I may not need to spin it that high to achieve my goals. The limiting factor for RPM in these engines is in the valve train, specifically the RPM range the cam works in and the valve springs. In my experience the stock valve springs have limited RPM to about 5600 to 5800 RPM before valve float was noticeable and the engine just didn't want to rev, though the effect would be seen lower in RPM, that 5600 to 5800 RPM was like a brick wall. The stock cam generally runs out of steam at a lower RPM. The studs I was waiting for are now in, and I will hopefully have the block home soon to start assembly, once the machine shop gets done with the block prep.

[BillS]

This thread makes interesting reading for me as I swapped a 3.4 iron head engine into an old MG that weighs a lot less than the Porsche (down closer to 2,000 lbs.) but of course the older engine makes less power (when I did this about 14 years ago, the later engines weren't as easy to find as they are now.

[v2rocket]

With a full tank and me in it the 944 is a little under 3000lbs.
The LZ9+swap parts should come in within 50lbs or so of the stock setup.

The later evolution of the 944, the 968, had 240hp so this should be a similar driving experience, just with more torque

[v2rocket]

Figured I owed an update.

i ended up swapping a 3.9 into my 944. Used a cut up F23 transmission to make a bell housing, made an adapter plate to the 944 torque tube.

Made custom engine mounts and weld-el basic log manifolds. Equal length 2” y pipe into a 2.5” exhaust out the back.

i left the Vvt phaser locked advanced, then dialed the can hear back 1 tooth retarded; net result is cam is 1.8 degrees advanced from straight up. Car runs great, a lot of power, very fast, very loud. Torque is unbelievable.