Injector Hoses

[B@man]

I'm about to replace all of the rubber injector hosing as it's nearing it's 22nd birthday and was wondering if normal fuel injection hose can be used between the fuel rail and the injectors, the hoses on the car are the original and look like a special part, is there any reason why I can't use decent injection hose as a replacement ?

Was thinking of cutting the hose to length, adding an O clip to the injector end and a normal jubilee type clip to the rail end.

P.S. It's a Flapper.

[Wedg1e]

Yep, sounds very like what I did on my 'project' injection system. Nothing special about the hose other than size, it being fuel compatible and rated for about 10 Bar IIRC. I use those crimp fittngs at work so fitted those at the injector ends and Jubilees at the rail ends.

[B@man]

Cheers Ian,

Must be where I got the idea from !!!
May even get around to taking the injectors out and cleaning them while I'm at it.
Or should I just fit bigger ones.....

[Wedg1e]

B@man said:

Cheers Ian,

Must be where I got the idea from !!!
May even get around to taking the injectors out and cleaning them while I'm at it.
Or should I just fit bigger ones.....

I think you know the answer to that one

Mine are Jag XJ40 type, I think... about 40cc a minute more than standard but within the capability of the existing system to feed (witness my dyno report from BBWF last year). Still on small-bore fuel rail but with lowered fuel pressure.

[TVRleigh_BBWR]

You should have the smallest injectors you can use to supply enough full with out running at 100% or having to run too high a pressure, the larger the injector the slower the response time, that's why your see cars with twin injectors instead of one big one. I'm sure standard ones should be ok upto at least 270BHP. I know the standard hotwire should good for over 300BHP. this is assuming they are running ok, and are clean.

[B@man]

I'm currently running at 50psi which I believe is just about on the limit of the standard injectors, Cleaning 20 years of crud out of them may help though.

[Wedg1e]

TVRleigh_BBWR said:

You should have the smallest injectors you can use to supply enough full with out running at 100% or having to run too high a pressure, the larger the injector the slower the response time, that's why your see cars with twin injectors instead of one big one. I'm sure standard ones should be ok upto at least 270BHP. I know the standard hotwire should good for over 300BHP. this is assuming they are running ok, and are clean.

Might well apply to modern sequential injection but the old Lucas system is timed about as accurately as a rice pudding thrown from a passing train - the fuel just sits there waiting for the next cylinder to take a drag. So any high-speed firing advantage would be lost.
The 390SE ran standard injectors and was supposed to churn out 275bhp (which we all know is cobblers) but I'm sure I read somewhere that 180cc/min was insufficient to create even that much poke.
My theory was that if I fitted higher-flow injectors and dropped the rail pressure, I'd get the same fuelling as a starting point, knowing that I had enough headroom to go another 40cc - and sure enough if I turn up the fuel rail (it runs at 1.8Bar now, about 26psi?) it's like being thrown off a cliff, but at the expense of driveability.