Fuel System

[Steve Lockett]

I need a little advise about fuel line and pump size.
A little history, last year the motor was putting 375
to the wheels. This year I upgraded the turbo from a
T3-TO4E 50 trim to a T66. Also new this year is a large
air/water intercooler to replace the junkyard Volvo unit
from last year. Oh yeah the head got a mild port job too.
Boost limit this year and last will be 30 psi, feeding
fuel to this little motor is a set of 83 pound injectors
controled by a Haltech.

So I'm hopeing to hit low 500's at the wheels.

Currantly the car has a Bosch pump that's good to 50 GPH
at 70 psi and -6 supply and return lines.

Do I need to upgrade? Was thinking about a 2nd Bosch pump
and -8 supply line.

Thanks for the help!!
Steve
91 Impulse RS AWD

[dyezak]

All this can be figured out with a little algebra, but unfortuneately you left some info blank. The first thing we need to figure out is airflow. Given a CFM flow rating at 1 bar for your turbo, and how much psi you are going to run at your maximum RPM you can figure out how much air you are shoving into your engine. Then based on that number using a 14:1 air/fuel ratio you can figure out how much fuel you would need to support that ammout of air.

Once you figured out how much fuel you need work your way up the line, from pump to injector to find out if each component can support. EX. If you need 300 LPH of fuel, but your pump only supports 265lph you know your pump needs to be upgraded. On the other hand if your pump is up to specs look at your fuel line. Using a crossectional flow formula you can find out how much fuel your line is going to flow at a given psi (fuel psi, not boost). You would then find out if your line is up to specs. Last and ez'st is looking at your injectors.

Supply the board with the following and we might do the math for you:
Max RPM
CFM of turbo at 1bar
Max Boost
Fuel pump flow map

[Steve Lockett]

Ok, I'll do the best I can.

Max RPM 9000
CFM at 1 bar: 400cfm Pressure ratio= 2 (14.7psi)
600cfm PR=3 (30PSI)
660cfm PR=3.3 (35psi)about the max for this turbo. Turbo specs:http://www.turbofast.com.au/FlowTS.html
It's a T66.

Max Boost: Around 30 psi,up to 35 if I need it.

Fuel Pump Flow Chart: I couldn't get a chart but here's the
specs. 20psi= 62gph, 50psi= 54gph, 70psi=50gph,100psi=43gph.
Zero vacuum pressure is set at 40psi

One more thing that may make a differnce, I'm using a
Spearco double core air/water intercooler. Intake air
temps stay pretty low from the limited testing I've done,
around 10 degrees over ambiant.

Thanks for the help!! Math was never a strong point for me!

[Le Talon]

You want the pump (or pumps) to be at least able to feed your injectors. OK, take what I'll say with a big grain of salt. This is what I "think" is logical, but I have nothing to verify what I'm saying.

Let's see. 83 pounds is about 800cc/min or 48lph (at 100% duty cycle). 4 of them is about 200lph. So your pump needs to be able to flow 200lph at your max pressure. The ratings for the fuel pumps are at 45psi, so beware.

Good site for this.

http://www.rceng.com/technical.htm

[Nick 92 TSi AWD]

For a turbo car you should be tuning for 12:1-13:1 at wot, not the na 14.1:1.
I don't have time to do any math right now, because I'm studying for, of all things, math! I'll try to do it sometime soon....

[MikeVgsx]

I just want to say your geostorm rocked, plus everyday get to hear jon vigil rave about you,saw pics of new setup looks good

[TheHondaKiller]

You should just be pushing the limits of the fuel system with the -6 and fuel pump, they should be good to ~550hp, and actually 83lbs/hr is more like 860cc, which will support 600hp or so. Right now the entire fuel system has a similar bottleneck, but a -8 feed line with an inline pump would provide extra safety around the 600hp area, and allow you to push the pressure so you could make 650hp if you had the air to match.

[Steve Lockett]

Well that's some pretty good news, I was hopeing to
hold off doing the pump and lines till later in the
season.

I'm not so sure the injectors are gonna make it to 600
hp. Right now with the boost down around 22 psi I'm
already hitting 70% duty clycle at around 8200 rpm.
I plan on spinning it another 800 rpm and 8 more pounds
of boost.

I really don't like these Semans injectors anyway, would
like to go back to Bosch and there 160 pounders. I KNOW
this motor would never max these out, at least with
gasoline.....

Can't WAIT for Englishtown this weekend!!