Fuel management

[Dusty]

I recently posted my custom turbo instal into my 96 lk450. it runs great but I do worry if it is running out of fuel. I have put a 255lph fuel pump on her and have an egt that reads about 1300' on highway w ocasional boosting. I have a cheap a/f guage (not wideband) that is not looking lean. I have a 6lb spring on wastegate and she doesn't boost above 7psi.

I am not ready to take the plunge for ecu management and have heard from those with forced induction with my motor (1fvfe 4.5l i6) that I will get real bad milage on this motor if I try and run a rising rate regulator.

What other options do I have? Is it true that rising regulators cause bad milage?

 

[turboandrew]

Have you looked into something like MegaSquirt ECU? You are obviously very good at DIY, so it may be a good fit for you. The entry cost is quite cheap (I want to say somewhere around $300). You still might need bigger injectors (but I have no idea what size you have currently). I would also recommend a WB O2 sensor and controller. I think these things are close to $200 now. Having absolute total control over air fuel ratios with something like MegaSquirt, I bet you could get pretty reasonable milage and ensure you don't go lean while boosting.

 

[Lextreme II]

Or you can do something basic by using a FMU....

 

[stevechumo]

There're 2 types of 255 lph fuel pumps. One is standard 255 lph and the other is high-pressure 255 lph. If you use a rising rate regulator, you'll have to go with a high-pressure 255 lph. The rising rate regulator will use more fuel than with a tuned ECU, but not that much. If you drive or cruise normally, the rising rate regulator will give normal fuel. It only works under increased RPM, high vacuum, and boost. It works in linear with the boost. ***Many 50 states legal turbo kits use only the 255 hi-pressure fuel pump and a rising fuel regulator***. That means that setup isn't really providing excessive fuel. Because if it is, it won't pass smog of 50 states.

If you use a tuned ECU, you might need higher flow fuel injectors to support the fuel demand. The stock fuel injectors can only be increased to a certain amount of pulses, not much. The advantage of the tuned ECU is to trim down to the exact fuel demand, and it might cost you up to $2000 for proper setup and tuning. So the best is to consider between the costs and what you really need in the long run.

I recently posted my custom turbo instal into my 96 lk450. it runs great but I do worry if it is running out of fuel. I have put a 255lph fuel pump on her and have an egt that reads about 1300' on highway w ocasional boosting. I have a cheap a/f guage (not wideband) that is not looking lean. I have a 6lb spring on wastegate and she doesn't boost above 7psi.

I am not ready to take the plunge for ecu management and have heard from those with forced induction with my motor (1fvfe 4.5l i6) that I will get real bad milage on this motor if I try and run a rising rate regulator.

What other options do I have? Is it true that rising regulators cause bad milage?

 

[Peewee]

A RRFPR is good to use when you have an NA motor, an NA ecu, and you throw on a turbo/super charger.

Depending on what ratio RRFPR you'll need, you may need to get the better pump.

The stock fuel pressure is 42psi, and the stock FPR is 1:1.
So at 6psi boost, you are running fuel pressure of 48psi.

If you use a 1.5:1 RRFPR, at 6psi you will have 51psi pressure.
If you use a 2:1 RRPFR, at 6psi you will have 54 psi pressure.
2.5:1 RRFPR, 6psi boost, 57psi.
etc.

The low pressure Walbro 255 is good for up to 58psi, 60psi tops.
As soon as you go above 60psi, you NEED to switch to the high pressure Walbro, or you will damage the motor.

My suggestion would be to get the car on a dyno, or at the very least get a wideband o2 in there, and test the AFR's at full throttle.

From there you should be able to determine what FPR you need.

 

[Dusty]

nice help fellas. here is the old safari kit http://www.airpowersystems.com.au/safari/turbo/1fzfe_80/1fzfe_int_turbo.html
nice quote from the write up: "[font=Arial,Helvetica]Dyno figures show a marked increase in power with this set-up. Interestingly, the 1FZFE’s injectors are up to the task and no high priced, high-flow units are needed here. According to Peter Luxon of Safari, most other installations need their injectors changed. Now there’s a bonus for you!"[/font]

Ill hold off with fuel management till I get a wideband. My narrow a/f ratio is reading rich with most boosting suggesting that as long as I have my foot down (and thus the throttle position sensor is >80%) the truck is running open loop and can flow enough fuel to keep from leaning out. What scares me is when I have the cruise control set and start climbing a long mild grade when the truck isn't making boost but the turbo has elininated a vacume. in these situations I have occasionally seen the a/f guage sit lean. the egt's dont go up however

 

[stevechumo]

Dusty,

Ok, try this. Test your A/F ratio in a near normal non-turbo condition. Disconnect the air intake pipe from your intercooler to the throttle body. You may leave all vacuum lines like that. However, hook up an air filter pod before the throttle body to prevent any dust/particles entering the engine. Disconnect the battery for the ECU to reset. Reconnect the battery and drive for a few days. Now you can look up your A/F gauge to see if it's acting the same on cruising, climbing, or high RPM revving.

 

[Dusty]

nice tip. I will be doing that as soon as I get a chance