View Single Post
juicersr juicersr is offline
Registered User
juicersr's Avatar
Join Date: Apr 2005
Location: Wilmington,NC
Posts: 2,425
Originally Posted by drmatera View Post
Big single pumps get very hot when supplying 900hp worth of fuel to an engine needing only 50hp to drive down the road. Heat kills motors. The voltage stepper slows the pump down to allow it to live. Why do you think most / all factory fuel pumps only manage ~500hp by themselves? Porsche used twin pumps probably because the technology was not around for high power singles, or maybe because they knew a big single in daily use will fail. The small amout of ethanol in your fuel can be combatted by using a bit of marvel mystery oil at every other fill-up to help lubricate all the moving parts.
Thanks D, but I always thought that the reason that the factory used two fuel pumps on turbos was that the CIS system needs continuous very high fuel pressures, around 100 psi or something. Correct me if am wrong.

Over a year ago, when i was replacing my pumps, everyone said that one Bosch 44 would be pefectly adequate for the relatively lower EFI fuel pressures.

Like everything else with these cars, nothing is ever simple.
'79 930/934 replica
80 RSR-look(Now in Sicily)
914/6 2.7 (Projekt 908/3)
1965 Karman Ghia-Class winner 2007 Carrera Panamericana/Ducati 900ss/GhezziBrian STW
D-Zug Produkte/
Old 03-04-2010, 08:01 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #31 (permalink)