Fuel system on thirsty lump

topcatcustom · Post by **topcatcustom** » Thu Sep 25, 2008 1:48 pm

Hi, I want to make sure my engine gets all the fuel it needs when it wants it, so I was thinking about running a silver top facet pump with a nice inline filter (somewhere around the bulkhead area) with another pump alongside which I can turn on with a dash switch (partly for looks & breakdown backup!!) for when I really want to put my foot down! I will need a regulator somewhere by the filter (5/6psi?) and will probably use 8 or 10mm stainless braided hose (might help keep temperature low through engine bay). Was wondering about 1 or 2 of these? Also do I need a lift pump near the tank and another near the filter/carb? http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... :IT&ih=004
(Btw its a 4l blown RV8 with edelbrock 4bbl, occasional track use & fun!)
I want it to look good & perform well so any layout ideas and advice please!!!

Ian Anderson · Post by **Ian Anderson** » Thu Sep 25, 2008 3:08 pm

Facit Red top should move enough fuel - mount it down low and near the tank - they are called pumps and not suckers for a reason!

Now I read somewhere that bet on 12 - 15 cc of fuel per HP per minute.
so 15 * 300 * 60 /1000 /4.5 = 60 gallons per hour (for a 300hp engine) - slightly more than a red top but then how long are you realistically making 300 hp?

If you are still worried put on a low pressure Carter pump - they will move 130 gallons per hour! (it then boils down to how big is your fuel tank?)

Ian

chodjinn · Post by **chodjinn** » Thu Sep 25, 2008 3:10 pm

The Sytec filters are good, but you could use any filter really. For a road/track care, personally I would use either a Facet Red Top, or for a bit more money a Holley Blue pump, along with a Filter King.

My old TT 3.5 on carbs use a red top and filterking and was good for about 250bhp but not much else.

Don't really need two pumps though, bit of a waste of money. Fitting a regulator will keep the pressure the same if you have one or ten pumps, and having a switch to turn on when racing is also pointless.

If you must run two pumps, run them in parallel, that was if one pump fails while nailing it you engine won't be starved of fuel.

As for mounting the pump, I would put it as close to the tank as possible, keep it away from the engine bay!!

As for lift pumps etc they are generally only required when using a swirl pot etc for EFI installations.

topcatcustom · Post by **topcatcustom** » Thu Sep 25, 2008 3:55 pm

Thanks for the quick replies, when I said 2 pumps I did mean in parallel so that I could get the volume of fuel through without the pressure- I assume 10mm hose would be best, and I think an inline filter would be easier for me as won't be much space for a filter king, (why I was wondering about 1 Sytec filter after each pump before the hoses join again (2x 8mm into 1x 10mm))
As far as pumps go if 1 would do, we had some problems with a Ford RS200 and having Holley (steel internal) pumps they had managed to rust a little and seized- which has put me off a little...

Ian Anderson · Post by **Ian Anderson** » Fri Sep 26, 2008 5:24 am

I've heard a lot of people with failed Holleys - but presumably hey are the ones who shout. - how many were fitted with no problems?

If using 2 pumps don't forget to put a non return vlave in each fuel line or if one pump fails the second will pump the fuel back through the bust pump to the tank and nt to the carb

Ian

topcatcustom · Post by **topcatcustom** » Sat Nov 22, 2008 11:24 am

Sorry I posted this in wrong area!
Would it work? Forgot to put non return valves after each pump btw, as will only use 1 most of the time...

Ian Anderson · Post by **Ian Anderson** » Sat Nov 22, 2008 11:41 am

You are making it an expensive and complicated system. (IMO)

Why not have 1 pump mounted in tank so it is pushing and not sucking - they prefer to push!

Make sure the pump is sized for your max use it will not be working hard most of the time so should even last longer.

So tank to pump to filter to regulator to carb
I'd probably even suggest a filter king filter regulator and gauge in one unit (less to go wrong) and less connections!

Price it up and then price yours up with all the end fittings etc

I believe in the KISS pricnipal (keep it simple)

Ian

topcatcustom · Post by **topcatcustom** » Sat Nov 22, 2008 12:00 pm

I am more worried about the nitrous fuel solenoid getting whatever it needs! I think the only reason it looks complicated is because there are 2 pumps instead of 1, will the facets not be ok pulling fuel up about 1ft (max)?

CastleMGBV8 · Post by **CastleMGBV8** » Sat Nov 22, 2008 3:00 pm

TC

Just a thought and slightly off topic`, but was wondering how you were going to mate the blower to the relatively small carb plate on the manifold.

I was wondering if you got hold of an EFI manifold and either extended the trumpet base and mated the blower to that then you would probably have much better distribution alternatively remove the trumpet base and bolt an adaptor plenum direct to the EFI manifold.

The trumpet base dimensions internally are 315mm. long x 118mm wide.

If you use the EFI manifold it would give you the opportunity to go EFI with just a throttle body on the blower.

Kevin.

topcatcustom · Post by **topcatcustom** » Sat Nov 22, 2008 5:23 pm

Hi Kevin, I have an offy 360 which I am milling out, then putting a spacer on top and a thick ally mounting plate on top to bolt the blower to. Adds up to a nice big plenum full of petrol and nitrous mix- add one backfire...

Back to the plumbing... may be a little OTT but will certainly be ready if I decide to up the power in the future... still not sure about the nos- does it really need its own pump- and if so how much flow & pressure?

Ian Anderson · Post by **Ian Anderson** » Sat Nov 22, 2008 8:29 pm

Actually your system is fairly basic.

Try fuel injected with returns into a twin tank set up and swirl pot system
Return has to go back to tank tht fuel is drawn from or the other tank will overflow etc. etc. etc.

I still think a single suitably sized pump is more than adequate

And yes the pumps will suck about 1 foot so long as it is not straight up - they will even do that but not as effectively as pump mounted low and near the tank.

Ian

topcatcustom · Post by **topcatcustom** » Sat Nov 22, 2008 8:56 pm

Thanks Ian, does anyone know about the nitrous side?
Maybe I will look at using a big single pump and hooking up a seperate pump and line for the nos... Holley pumps recommended?

p.s. are in tank pumps not normally high pressure for injection?

topcatcustom · Post by **topcatcustom** » Mon Nov 24, 2008 9:37 am

Modified!

mgbv8 · Post by **mgbv8** » Mon Nov 24, 2008 7:17 pm

If you dont want any expensive problems, the important thing is to make sure you have the correct fuel to Nitrous ratio. Even if this starves the carb.

I havent read back, but what sort of plate / injection are you using for nitrous?

To be honest, my Carter Marine pump runs the fuel and nitrous systems up to a 100 shot. But you should make sure the pump is mounted low down so its flooded all the time. This way it pushes better.
You also need to wire the whole nitrous system through a good quality fuel pressure cut off switch. (best I've found is from WON) Both the Real Steel ones failed and nearly lost me an engine as they both stuck in the safe position.

I fitted the Holley red top to do the gas system only as a bit of insurance. And that I run my carb at 4 psi and my nitrous fuel at 6 psi.

topcatcustom · Post by **topcatcustom** » Mon Nov 24, 2008 8:10 pm

I have a regulator for the carb, and will put a cut off for the nos fuel supply. I have a plate but may use injectors or something- not decided yet!

There is a bit of an issue with getting the pumps below the tank so I may end up making a surge tank in the boot and use another pump to keep it topped up

But not over keen on that the more I think about it! The lowest I can really mount the pumps is about 10" above the bottom of the tank- is this still not really ideal? I want to keep them in the boot as the only space available below it (under car) will have a big spinning propshaft and 2 bloody hot exhausts running right underneath! Only real downside about the mx5- very limited space!

....actually... I may be able to mount the under the boot as by then the exhausts will be running either side of the car and I could put them behind the diff.... (above the diffuser

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