924Board.org

!tom · Posted: Fri Sep 03, 2010 1:30 am Post subject:

Where's the return line for those flexible hose setups?

It looks like it's trying to be a CIS-style fuel line/distributor style, and we all know the hot start issues inherant in that design.
_________________
78 924 NA
5-lug

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

Return line would be off the fuel pressure regulator, which would be attached to the fuel distribution block.

I'm not sure that the hot start issues with CIS are related to the remote mounted injectors?
_________________
Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

!tom · Posted: Fri Sep 03, 2010 4:03 am Post subject:

The problem with this style of fuel distribution is how the fuel has a chance to be pre-heated. With a fuel rail, there is always fresh, relatively cool fuel flowing through the rail.

Hot start issues are caused in part by the fuel being vapourized in the fuel lines due to residual engine heat. A fuel rail helps eliminate this issue as the fuel pump can purge vapourized fule in the fuel rail prior to starting, and this can't happen with a central fuel distribution block.

Hot start issues are cured by having injectors that maintain pressure, as pressure prevents the vapourization of fuel.

Regardless, either approach can be made to work.
_________________
78 924 NA
5-lug

leadfoot · Posted: Sat Sep 04, 2010 10:13 am Post subject: Re: Injector Position