View Single Post
kenikh kenikh is offline
3 restos WIP = psycho
kenikh's Avatar
Join Date: Feb 2005
Location: North of Exit 17
Posts: 7,729
I just found this thread - glad to see the P cars are coming around. After falling in love with the idea of meth injection from info gleaned from the Evo/Sube guys, I have been designing my engine around this constraint. The major reasons I have decided to go with a staged 100% meth injection system are the cooling and octane advantages of this setup.

My plan is to run relatively high static compression. The evaporative cooling and knock resistance should allow a turbo 911 to run static CRs close to watercooled motors. The advantage of running static CR in the high 8s for offline performance is pretty evident, especially in a small turbo like mine (2.3L). I firmly believe that 9:1 @ 1 BAR is reliably possible with 100% meth and a big water/air IC.

In terms of failsafes, If you go with engine management/EFI, it is pretty darned safe to run meth injection, since most newer meth systems have fault detection. Additionally, many of the newer engine management systems like Don's Link allow not only mutliple maps, but map switching based on sensor input.

Built correctly, you can design a meth injected engine in such a way that the moment a fault is detected, your "hot" map switches over to your "limp mode" map. Since EMS can adjust ignition and boost, you basically create a map that backs everything off, and saves you before things go south. For me, with the higher static CR, it would be perfectly reasonable to remap the motor to open the wastegates 100% in fail mode and drive the car NA in an emergency.

So, has anyone actually made headway in adding meth/water injection to their cars yet?

- 1965 911
- 1969 911S
- 1980 911SC Targa
- 1979 930
Old 10-14-2009, 09:47 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #23 (permalink)