986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post - Excellence Mag December 08: Outstanding M96 engine article

Jake Raby · 10-10-2008, 02:59 AM

Allen,
The mod that you speak of that was done by Porsche in the later engines is nothing new.. It dates back to the 356 days and has proven to be effective for high speed engines. I don't quite buy the 8HP claim of the mod, because as an engine developer I know what it takes to actually make 8HP and generally it's a lot more intense than this mod.

I have seen slightly measurable differences when modifying older engines in this manner for race purposes, but in a mild state of tune with the design of the M96 engine and the fact that it's a six cylinder the gains would not be that great.

The mod has more merit on a 4 cylinder engine as the firing order of the cylinders will put one piston at TDC and the piston residing adjacent to it at BDC simultaneously. This means the pressure displaced by the pistons moving in their bores is displaced 100% by the opposing piston and the "swapping" of this pressure between both bores is optimum.. A six doesn't have that characteristic on all cylinders.

So, to directly answer your question, we would only do this mod if the application demanded it, for higher revving performance engines. The later engines that had this as factory may get the mod if requested by the purchaser. before I see that 8 HP gain in my lab back to back with no other variables present (damn near impossible) I'll have a hard time believing that is the only thing the factory did to get the 8 HP... I'd much rather keep the bores as strong as possible..

The LN Nikisil plated cylinders add more than 8 HP to an engine alone and thats due to the super low tension rings they can use and the reduction in friction that they bring to the table. Between a set of Nickies cylinders and a performance valve job wel more than 8 HP will be present over stock and EVERY engine we build here gets both the aforementioned services, as standard.

10-10-2008, 02:59 AM	#7
Jake Raby Engine Surgeon Join Date: Aug 2008 Location: Cleveland GA USA Posts: 2,425	Allen, The mod that you speak of that was done by Porsche in the later engines is nothing new.. It dates back to the 356 days and has proven to be effective for high speed engines. I don't quite buy the 8HP claim of the mod, because as an engine developer I know what it takes to actually make 8HP and generally it's a lot more intense than this mod. I have seen slightly measurable differences when modifying older engines in this manner for race purposes, but in a mild state of tune with the design of the M96 engine and the fact that it's a six cylinder the gains would not be that great. The mod has more merit on a 4 cylinder engine as the firing order of the cylinders will put one piston at TDC and the piston residing adjacent to it at BDC simultaneously. This means the pressure displaced by the pistons moving in their bores is displaced 100% by the opposing piston and the "swapping" of this pressure between both bores is optimum.. A six doesn't have that characteristic on all cylinders. So, to directly answer your question, we would only do this mod if the application demanded it, for higher revving performance engines. The later engines that had this as factory may get the mod if requested by the purchaser. before I see that 8 HP gain in my lab back to back with no other variables present (damn near impossible) I'll have a hard time believing that is the only thing the factory did to get the 8 HP... I'd much rather keep the bores as strong as possible.. The LN Nikisil plated cylinders add more than 8 HP to an engine alone and thats due to the super low tension rings they can use and the reduction in friction that they bring to the table. Between a set of Nickies cylinders and a performance valve job wel more than 8 HP will be present over stock and EVERY engine we build here gets both the aforementioned services, as standard.