Help me get more fuel out of the tank!

[TurboJ]

Hello again!

Many of you will be familiar with my long-term project:

http://www.vwdiesel.net/forum/index.php?topic=17081.0

I have once again continued my work on this beast and it's coming along pretty nicely.
I still have some little problems to solve though.

The big one currently is how to feed my monster injection pump.

I have 10 mm fuel lines that will go under the car - these are only just about enough, but will have to do.

Now, the fuel pickup unit in the fuel tank is the problem. The feed and return pipes are way too thin. I need matching 10mm pipes there.
Can you suggest any solution?

I have 4 fuel tanks that I could use, and their respective pickup units, which are from...
-mk2 1.8 carb engine
-mk2 1.8 GTI with pickup pump
-mk2 diesel
-mk3 diesel

Using the lift pump of the GTI would be one option, but then I would need a zero-pressure catch tank for the fuel feed lines... You know, an IDI pump will not keep its timing solid if you put pressure in the feed line - take my word for it!

Maybe some Golf2 or Golf3 model would have bigger pipes there as standard? Or maybe there is a way I could modify one of the aforementioned tank / pickup unit to fulfill my needs.

Your help is much appreciated!

[R.O.R-2.0]

why are you running fuel lines that HUGE? the pumps still only flow like 15L an hour or something small like that..

most guys run stock sized fuel lines without issue, even on the hottest of hotrod diesels (giles pump, big injectors, big turbo, yadda yadda)

if you need more fuel volume, why dont you just pressure feed the pump with the stock fuel lines?

cause im not aware of any fuel line connections for a VW that are already 10mm (3/8") fittings.. pretty sure nothing came with that large of fuel lines from the factory..


why, oh why, are you running such huge fuel lines?

[TurboJ]

There are hot engines and there a HOT engines. My 200 hp+ 1.6 TD is very mild compared to the wild ones, but I don't want to cut corners here.

One 1.6 TD that ran 200 hp without an intercooler did snap its timing belt right when the injection was turned up just a little bit...

We're not using VW pumps even. We're using BIG pumps.

Believe me, I need the big lines. And when I put in an Evo 2 engine, then even more so.

OH, and VW knows this need for big lines too. An Audi inline 5-cyl 2.5 TDI will have 12 mm feed lines as stock.
My engine is built to produce 1.5 times as much power and torque as such an engine.

So, if we could get back to the issue at hand..

[R.O.R-2.0]

There are hot engines and there a HOT engines. My 200 hp+ 1.6 TD is very mild compared to the wild ones, but I don't want to cut corners here.

One 1.6 TD that ran 200 hp without an intercooler did snap its timing belt right when the injection was turned up just a little bit...

We're not using VW pumps even. We're using BIG pumps.

Believe me, I need the big lines. And when I put in an Evo 2 engine, then even more so.

OH, and VW knows this need for big lines too. An Audi inline 5-cyl 2.5 TDI will have 12 mm feed lines as stock.
My engine is built to produce 1.5 times as much power and torque as such an engine.

So, if we could get back to the issue at hand..

whats an evo2 engine?

and i agree, you DO need bigger lines.

[RabbitJockey]

I thought using a feed pump was fine Giles had said before it does not effect timing because the pressure goes to both sides of the advance piston and he had tested this on his test bench

[theman53]

I have often wanted to do the same thing. If nothing else for a cooler fuel charge possibly.

Giles did test that and that is what he came up with. IIRC it was him and Burn Your Money that did it and they ran up to 40psi without affecting timing. Maybe Burn will chime in.

[RabbitJockey]

There are hot engines and there a HOT engines. My 200 hp+ 1.6 TD is very mild compared to the wild ones, but I don't want to cut corners here.

One 1.6 TD that ran 200 hp without an intercooler did snap its timing belt right when the injection was turned up just a little bit...

We're not using VW pumps even. We're using BIG pumps.

Believe me, I need the big lines. And when I put in an Evo 2 engine, then even more so.

OH, and VW knows this need for big lines too. An Audi inline 5-cyl 2.5 TDI will have 12 mm feed lines as stock.
My engine is built to produce 1.5 times as much power and torque as such an engine.

So, if we could get back to the issue at hand..

whats an evo2 engine?

and i agree, you DO need bigger lines.

I think he means the next engine he will build for this car

[burn_your_money]

Giles did test that and that is what he came up with. IIRC it was him and Burn Your Money that did it and they ran up to 40psi without affecting timing. Maybe Burn will chime in.

That is correct. It does increase internal pump pressure by whatever psi you are feeding the pump with. Keep that in mind so you don't blow seals.

[carrizog60]

what pump are you using?iveco?

[TurboJ]

We have seen strange things happen to timing when a feed pump is used...  

I'm not challenging Giles' results but I would still rather not run a feed pump - it may be OK on some cars but not all it seems.

I think I have found a way to do the fuel lines /feed also. I'll use Audi TDI fasteners for the fuel lines to the floor bottom and I'll drill out the stock pipe inlet and outlet from the fuel sender unit and replace them with some hydraulics connectors after I overbore the holes. I'll try to look into the bottom part of the senders tomorrow as I have four different ones at my disposal.

As for the Evo 2 engine, yes I'm referring to the next engine - time will tell when that will be reality, but for now the Evo 1 engine is a 1.6/1.9 hybrid with very many custom parts, and the evo 2 will be a 1.9 mTDI most likely. Running for a reliable 200 hp on the Evo 1, and 250 hp with broad torque curve on the Evo 2. We will see... At least the Jetta is coming on now that I finally have some spare time!

The pump - yes it's an Iveco 10mm pump, with some special "Aki" modifications  

*edit*  the stock Audi 12 mm lines I mentioned, are in fact on a 2.5 V6 TDI, sorry to misinform.. That does give hope, though that 10 mm would be enough for my solution!

[Toby]

I think you are off base here. An 8mm line should be enough to support 300 hp. It is done on a regular basis on gas cars. You might need a low pressure feed pump, but no need for huge lines, if flow is the issue.

[TurboJ]

Well, flow is only part of the problem.

Excessive vacuum is the bigger problem - the pump will have a hard time sucking the needed fuel through a thin straw. That strains the pump and also puts more load on the cam belt. Those can snap anyway with these big pumps so I'm not going to risk it!

[R.O.R-2.0]

Well, flow is only part of the problem.

Excessive vacuum is the bigger problem - the pump will have a hard time sucking the needed fuel through a thin straw. That strains the pump and also puts more load on the cam belt. Those can snap anyway with these big pumps so I'm not going to risk it!

well, if you PRESSURE FEED the pump, i see no issues with VACUUM..

[AudiVWguy]

Your solution to the lines should work well. Yes it would be like using a 10 foot straw to drink a can of soda. I understand you need a solution that you are comfortable with. It sounds like the mods that you made to your pump could be affected by how the fuel is supplied. Are you going to be on the road this spring?
Cheers,
-JB

[Toby]

The thing is, you aren't burning that much fuel even at 300 hp. You are just kidding yourself. Magical thinking.