what is fuel surge
02 March 2001, 11:54 AM
#3
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Marc,
Imagine a full tank of fuel and then imagine throwing the car about on track, i.e. high G-turns. The fuel pickup is never going to be uncovered as the fuel sloshes about, so the engine will always be getting fuel.
Now imagine the same situation with say 1/4 tank. The fuel can freely slosh about and in some high G turns the fuel pickup may become uncovered for a second or two. This is a bad thing especially if you are at full throttle and on max boost. Your cylinder isn't going to get the fuel it needs for the perfect air/fuel ratio. In fact it is going to be very lean. If it is lean you are going to get det, which is bad. Or you are just not going to get any fuel at all and you will get a big power loss.
Either way it is a 'bad thing'.
Someone will correct me if I'm wrong here, but I think fuel surge affects the STi's more than it does the UK cars. I guess this is down to the shape of the tank.
The easy solution is to not let the fuel level run to below the level at which you start getting fuel surge. I've heard 1/4 tank bandied about.
Of course, on a track day, that will mean you filling up more often.
Another option is a fuel surge tank/swirl pot and a booster pump. This basically keeps a small amount of fuel up front near the injectors and is surge proof. This is fed by the main tank pump. So although the main tank pump keeps 'missing' the fuel in high G corners (only happens for a second or two), the surge tank is always full and has more than enough fuel to keep the injectors supplied during these moments.
Sales Pitch Warning !!!
Powerstation do a kit for the Scooby that I witnessed during testing at Donington on their STi. Still had no running problems even when the fuel needle was below the E mark. Nice. They have some info. on the kit at:
Imagine a full tank of fuel and then imagine throwing the car about on track, i.e. high G-turns. The fuel pickup is never going to be uncovered as the fuel sloshes about, so the engine will always be getting fuel.
Now imagine the same situation with say 1/4 tank. The fuel can freely slosh about and in some high G turns the fuel pickup may become uncovered for a second or two. This is a bad thing especially if you are at full throttle and on max boost. Your cylinder isn't going to get the fuel it needs for the perfect air/fuel ratio. In fact it is going to be very lean. If it is lean you are going to get det, which is bad. Or you are just not going to get any fuel at all and you will get a big power loss.
Either way it is a 'bad thing'.
Someone will correct me if I'm wrong here, but I think fuel surge affects the STi's more than it does the UK cars. I guess this is down to the shape of the tank.
The easy solution is to not let the fuel level run to below the level at which you start getting fuel surge. I've heard 1/4 tank bandied about.
Of course, on a track day, that will mean you filling up more often.
Another option is a fuel surge tank/swirl pot and a booster pump. This basically keeps a small amount of fuel up front near the injectors and is surge proof. This is fed by the main tank pump. So although the main tank pump keeps 'missing' the fuel in high G corners (only happens for a second or two), the surge tank is always full and has more than enough fuel to keep the injectors supplied during these moments.
Sales Pitch Warning !!!
Powerstation do a kit for the Scooby that I witnessed during testing at Donington on their STi. Still had no running problems even when the fuel needle was below the E mark. Nice. They have some info. on the kit at:
02 March 2001, 07:39 PM
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<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by marc:
<B>can anyone out there tell me what fuel surge is and how it affects detonation and what you can do to avoid it as I will be doing a few track days want to know the warnings[/quote]
<B>can anyone out there tell me what fuel surge is and how it affects detonation and what you can do to avoid it as I will be doing a few track days want to know the warnings[/quote]
04 March 2001, 09:05 AM
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Don't be so confident Marc - I have a P1 and same thing happens - total loss of power for a split second. I always run with 1/2 tank plus now on track days. May look at that swirl pot idea though.
Bob
Bob
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