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Re: [Fot] Tr6 PI and racing

To: "Terry and Cindy" <Roadandtrack2@hypermax.net.au>, "fot"
Subject: Re: [Fot] Tr6 PI and racing
From: "Charly Mitchel" <charly@mitchelplumbing.com>
Date: Mon, 4 Aug 2008 12:40:21 -0700
This is an olde subject that I'm rekindling now.  What is the working 
pressure of the PI metering unit?  I seem to recall that the injectors close 
at about 80psi.  What is the minimum needed to run them at 6000rpm's?
I've got a gauge connected to my pressure line at the pump relief valve and 
get a drop to about 90psi @ 5000 rpm's and can't hardly see 6000 rpm's.  I 
think this is a fuel pressure problem as I've checked timing, ignition and 
metering unit and that seems to be okay.  I've got plenty of vacuum @ idle 
and can richen it up easily via the choke cable.  Could this also be the 
maximum fuel adjustment?
I'm still running a Lucas pump and I show 120 psi when idling and cold, the 
pressure drops a little as the fuel warms up.  When I accelerate the 
pressure starts to drop to about 100 psi and as I get to 5000 rpm's the 
pressure drops to about 90 psi.  Any thoughts or ideas?  I'm looking at 
going to the Bosch pump, but I also want to make sure this is the right area 
to focus.
Thanks, Charly Mitchel
TR6 #44

----- Original Message ----- 
From: "Terry and Cindy" <Roadandtrack2@hypermax.net.au>
To: "fot" <fot@autox.team.net>
Sent: Thursday, June 09, 2005 4:13 PM
Subject: RE: Tr6 PI and racing


> We have used Lucas PI on race cars since it was new. I have experience
> with them on outright formula race cars and triumphs
>
> The system off a TR6 or 2.5PI is fine up to a point. The biggest problem
> you will have is the pump. Lucas PI pumps were great when new, but are
> now mostly stuffed. We use a bosch pump but they produce such pressure
> when loaded , that they destroys the TR relief valve. We run 2 modified
> Lucas valves in parallel. The other hassle is that in other than flat
> out use, there is a lot of hot fuel being returned to the tank. If you
> live in a hot are, you will need a fuel cooler in the line. Also, don't
> be tempted to run a small tank, as the fuel  gets too hot.
>
> The vacuum control unit is biased to "nice" road car use. For race use
> find a "snail cam" arrangement and ditch the vacuum controller. These
> were fitted to all the proper Lucas race systems and can still be found.
>
> The Lucas bung seals in the metering unit will not handle many types of
> modern unleaded fuel without stuff up. Test one in a sealed jar of the
> petrol you use for a few weeks
>
> We have not found much improvement with lengthening the intakes , but
> have proven they like a very long snorkel with cold air intake feeding
> the plenum box. Basically, the longer the better
>
> A couple of local racers have converted their system to full electronic
> with a single throttle body, but none of them have ever found meaningful
> power increases as far as I'm aware
>
> Terry
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