May 26, 2019, note to a prospective client, regarding induction options:
Take a look at the VRam pages. That is THE BEST intake. A GT3 intake is larger, and if you have another $20K in mods will make more HP but not as much torque because it does not have variable intake geometry other than the resonance flap. You don’t have a 4V engine spinning to 8400 RPMs with 52mm ports, you have a 2V Hemi motor spinning to 6700 RPMs and 43mm ports (that’s 51% larger) so a GT3 intake is silly. It is the same as a 95 intake only a little nicer layout, about the same runners, and no VRam technology. It works on a GT3 because a GT3 is designed to make 400 HP and also has variable cam timing. I ought to know I own 3 GT3s and 7 spare engines.
ITBs make lots of great noises and can make more power if the engine is designed for them but low-end torque suffers, drivability is off and you need aftermarket engine management to make them work. The 993 (and every motor since through the DFI engines) uses a hot-film mass flow sensor and that cannot be used with ITBs. Aftermarket management also throws away knock sensing, which is a really bad idea, and to add it that costs about $1500 (just for knock sensing) plus you have to pay someone like me to program it all and then tune it on a dyno (which I have at my house) so yeah, if you have cubic dollars and only drive it above 5500 that’s fine. Building a motor and doing it right is a $40-50K proposition.
I have a 1982 SC I have owned since 1993. In 1993 I bought it with a 3.4 and within a week put carbs on it. Then it went to ITBs (2001 or so). Then that wasn’t enough (300+ HP, 7500 RPM limit) so I built a 3.9 with HUGE ITBs, see above (56mm, so you can drop a tennis ball in them). That was unreliable and although it made 425HP, I got tired of it after it ruined most of a track season (aftermarket P&Cs that were VERY expensive) it got pulled after driving home 6 hours from the track, in favor of a completely stock VRam, returned to the track after the motor from a crate and pulling an all-nighter, doing the conversion and returned to the track and drove. Not very well mind you, I was too tired! That was in 2007.
I then built a 3.8 using Mahle P&Cs and put a Euro RS VRam, solid lifters, hotter cams, in that and that’s what I have driven ever since. The one I make is tuned to about 350 or so. My wife has an identical engine in her 72 and I have one in my 993 as well. The charts don’t lie and are all from the same dyno with a stock SC transmission. FWIW the PC34 I built won the SCCA enduro championship so it’s not like I am a slouch. I still have the 3.4 sitting on the shelf as well as all the parts from the 3.9.
So…owning 28 Porsches (current) gives a certain perspective. I like the GT3 and the 996tt with 700 HP will scare the bejesus out of anyone but my favorite car to drive is either the Slamboni (85 Targa that I use for testing, 97 VRam in it at the moment) or the 72 Targa widebody (which is the ultimate rat-rod, completely ugly chalky red paint, bad bodywork, and 996tt brakes, stock VRam with silly exhaust, suspension matches my wife’s 72 race car, which is street legal).
See attached for my best guess. The used motors are completely tested so it’s not like a junkyard special. There is maybe a dozen hours of my time in them (I have two almost identical), Also note that the $4K gap between the used 1996 and the rebuilt 1996/7 represents about $12K in parts and labor. How that math works is mystifying but it’s more market-driven rather than cost driven. I pay a fair amount less for a core motor than a low miles example.
The dyno doesn’t lie. Again, these are real engines on the same dyno. This is crank HP, estimated, based on what other engines make on the same dyno. PC34 and T39 are outliers since they were VERY expensive engines built for a specific purpose. I’m happy to build you anything you want if the budget is adjusted accordingly!