View Full Version : Fuel system upgrade: full replacement vs. upgraded stock

09-14-2005, 01:21 PM
I've been thinking about exactly what to do when upgrading my fuel system.

From what I've read it seems the popular thing to do is a stock-style pump that is mounted inside the tank (again, like stock) but with improved capacity, combined with upgraded wiring. (For example, Walbro 340 + "Hot Wire" kit) I understand that this is a setup that a lot of guys are running--apparently with great success--but I can't seem to shake the feeling that it's "polishing a turd".

I am inclined to scrap the stock "setup" altogether and start anew. Drop the gas tank, clean it out, and weld in a sump. Run AN plumbing to an external filter and pump (Weldon, Barry Grant, Aeromotive...etc...) and then run a nice, fat, AN line up to the engine. Of course, the wiring would all be new. This way there is no possible restriction or pressure drop possible due to clogged or kinked lines, etc, and you'd KNOW that the pump was more than adequate for one's fuel flow needs.

Any thoughts?

09-14-2005, 01:36 PM
Pros - Really, that is the best possible way to do it. More volume done right. No worries!

Cons - However, it is also the most expensive. Many do not have sufficient welding skills and would have send the work out. Plus, the stock tank has a plasic inner baffle that will be hard to work around for a sump. This type of system is overkill for the average 'recipe' car. AN lines/fittings are VERY expensive, and take some talent to assemble correctly. Plus, such a system gives away the 'stealth' nature of any car. Hard to be sneaky when your pump is louder than your engine. :winkgrin:

It comes down the need for capacity vs. stealth, I think. Most cars on the street are sub 600 HP (even sub 500 or 450 HP) and simply don't need a mongo fuel system. Just one that is stouter than stock.

I agree with your approach. I just don't think its for everyone.

09-14-2005, 02:21 PM
And to add to Scott's comments ...

If you want to make more HP, then you can also go to a "Double pumper" system with 2 intank pumps (with second pump staged with boost).

High volume pumps will need some extensive plumbing and regulation, since the stock lines and regulator can be "flooded" (basically not enough return volume at idle with stock style regulator and return lines).

If this is a really fast car (i.e. 9s/low 10s), then it starts making sense to looking at this type of effort and expense. For a street car in the high 10s/11s, there are several good stock based solutions that are quieter (external pumps are habitually noisey), work well and are less expensive.

09-15-2005, 01:03 PM
Yeah, the cost is definatley a concern. Though, it may not be so bad as I already have quite a few AN fittings lying around from other projects.

A couple of quick questions though...

About that plastic baffle: I think I know what you're talking about, my S-10 had something similar. Do you think it is possible to yank it out through the hole at the top of the gas tank where the OEM pump and sending unit are inserted?

What kind of HP can the Walbro in-tank pump support? I'm not trying to run 9's here!

I am decidedly not interested in the "double pumper" option. If I have one fuel pump and it fails, then my car won't run. But if there's two and one fails, then I'm running dangerously lean...not a good idea. I'd rather put the money towards one better/bigger pump.


09-15-2005, 01:49 PM
Single Walbros have been in the 10s with a full weight car (my friend Chuck has gone 10.90s) but it's pushing it (figure mid 500s HP).

Double pumpers have been well into the 9s and I've run my double pumper to 680 HP on an engine dyno with plenty of fuel to spare.

The plastic baffle/bucket is a must for these cars with an intank pump. Without it you can easily get cavitation on a hard launch (they will pull over 1g in an 11 second car).

The stock fuel system isn't bad ... like anything, the faster you go, the more you need to upgrade. If you are looking at a solid 11 second car though, I think the money would be better spent on a Walbro, an adjustable regulator, and a hot wire kit. Quiet, dependable, enough fuel for your goals and "stock".

09-15-2005, 02:05 PM
The baffle is tank-sized. It can not be pulled out through the pump opening on top.