Not sure fuel pressure is rising with boost sufficiently

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Timbuick

Member
Joined
Oct 5, 2009
Messages
431
Took my GN out with a buddy on board to check fuel pressure is rising 1:1 with boost, I have an in car f/p gauge and boost gauge but no logging device.
I stomped on her in third at about 40 mph and the car shifted down and went into boost. My boost gauge raced from 5-18 pounds in what seemed like about a second, then I backed off. My Buddy said f/ p went from 38-56.
My concern is this: I have a RJC boost controller for my TE34 to bring in the boost very quickly, my question is, how do know that f/p is rising at the same speed as boost as I have the impression it is lagging behind?
 
Anyone?
I'm aware that the golden rule is f/p to rise 1:1 with boost,,just not sure how that is verified.
 
its hard to verify the rate of rise visually. But the fuel pressure needs to be 1:1 as you have said.

the base pressure is what the fuel pressure is, engine idling, vacuum line off the regulator. The engine vacuum pulls the pressure down, and boost pressure pushes the fuel pressure up.

The stock regulator in these cars is 39 psi (base pressure). so at idle you would see 39 psi (vacuum line off) or about 32 psi with the vacuum line on.

at 18 psi, you should have 39 + 18 = 57 psi.

so either watch the pressure gauge at WOT or have the co-pilot do it. Or you can install a pressure transducer and datalog it.

Bob
 
thanks Bob, just a quick question. Is there a pressure transducer for these cars? I googled without luck.
 
Thanks Bob, just subscribed to the thread. Quick run out in the car tonight showed f/p rising with boost under progressive acceleration, I'm stil a bit leery about full throttle, although I have no knock showing when I stomp,on it.
 
It's just the very fast rate that the boost comes on. When I kick her down the boost just jumps round the dial with this new turbo, I then glance down at the f/ p gauge and it seems to be lower than boost.
it's probably just me focusing on the scanmaster and boost gauge and by the time I glance
down to the console mounted f/ p gauge I'm probably de- accelerating and the boost is coming down.
Gues I'll just have to trust the KR figures on the scanmaster
stil pretty new to the learning curve with these cars, just three years in!
 
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