Fuel system on thirsty lump

mgbv8 · Post by **mgbv8** » Tue Nov 24, 2009 6:33 pm

I just use the plastic and paper filters from Halfords Tom.
I use one at the inlet to my carb pump and one at the outlet. I use the same filters on the inlet to my nitrous fuel pump. I run my nitrous pump at 6psi via a regulator and it flows 255ml of petrol in 10 seconds. The nitrous pump is a holley red I think. I just cut the nipples on the filters off so it fits on the thickest bit into my 8mm fuel pipe. I havent flow tested the fuel to the carb with the two filters in line though.
The reason for the filters on the suction side of the pumps is just to protect the pumps. I can see the bottom of my race tank and I only ever use the same garage for my Vmax. There must be a teaspoon full of grit in there since the start of the year. I also found the regulator on the nitrous side does not like being dead headed. So I fitted a small return to the tank on this side to stop pressure fluctuations on launch after its been sitting in stage for a while.

JP. · Post by **JP.** » Tue Nov 24, 2009 7:42 pm

Running a Facet red top in the back with a King filter up front just before the carb.

Have fuel pressure set at 6 psi.
You should see something about 240-250 bhp at the wheels with the 6-7 psi of boost.
Thats what I saw with my stock SD1 heads.

topcatcustom · Post by **topcatcustom** » Tue Nov 24, 2009 8:41 pm

Cheers guys, Mike- thats perfectly fair enough- its still an ample amount of power in a car like that- the ace in the hand is the torque vs the puny mazda lumps output of 100ft lbs and 114bhp

Perry- its good to know the cheapies actually work! I will put a pair in before my pump, I suppose I really need to have one after the pump before the engine too?

JP- I did consider the V8 filter kings but not sure how much they support and I also didn't need the regulator built in- not that that is a problem!

And thanks for looking Paul!

JP. · Post by **JP.** » Tue Nov 24, 2009 9:22 pm

topcatproduction wrote: JP- I did consider the V8 filter kings but not sure how much they support and I also didn't need the regulator built in- not that that is a problem!

They support enough for your needs

Facet pumps do need an regulator as they are not free flow pumps but on/off pumps. While switching back to "on" mode they create an pressure pulse which the carb's floats didn't like. (had the same issues with a Weber carb).Filter kings also acts like a fuel swirl pot.

Fuel setup is still up to the job in our case, with the Merlin heads and 10 psi now ohh and I have dual feed float bowls now on our Holley 570.
AFR was still perfect on the dyno while I am still running the oem 8mm outside diameter fuel lines from the back to front.

If it wasn't up to the job it should show itself on the dyno AFR readings.
So don't worry about it to much.

Richard P6 · Post by **Richard P6** » Tue Nov 24, 2009 9:41 pm

topcatproduction wrote:Cheers guys, Mike- thats perfectly fair enough- its still an ample amount of power in a car like that- the ace in the hand is the torque vs the puny mazda lumps output of 100ft lbs and 114bhp

Perry- its good to know the cheapies actually work! I will put a pair in before my pump, I suppose I really need to have one after the pump before the engine too?

JP- I did consider the V8 filter kings but not sure how much they support and I also didn't need the regulator built in- not that that is a problem!

And thanks for looking Paul!

I had to buy another filter king recently, as mine leaked petrol around the six screw heads on the top if I dared to set it above 3 PSI.

I asked a reputable supplier what the difference was between the 85mm alloy version and the V8 version. He told me that they painted the V8 one black and that was the only difference!

Anyone know if this is correct?

Richard

topcatcustom · Post by **topcatcustom** » Wed Nov 25, 2009 8:51 am

Cheers JP, I'm not running a facet so pulsing shouldn't be a problem, and I drilled out the blank on the other side of my Edelbrock for dual fuel feed. Richard that sounds about right!!!

I think I'll get a big filter king for in the bonnet then, should I still put a pre-filter in between tank and pump or will the Holley just plough through regardless?!