I noticed that alot of guys use this when going to FI. If it has to do with ensuring that you don't run lean while under boost then why not just upgrade the stock fuel pump to a high performance unit which flows more fuel? My car is currently at The Vette Doctors to upgrade the pump. Maybe it has to do with the '98 & '99 fuel systems being different?

 

Oh man, I could go on and on for pages about this topic.

The OE fuel pump sits inside a bucket inside the tank. The bucket is there as a mini surge tank, to help prevent the fuel pump from sucking air while the tank is low and you're cornering. For a while, there were a few solutions like the LPE and Racetronix pumps that would sit inside the bucket and maintain OE functionality -- and that was it. They flowed more than stock but not enough for some of the more demanding FI cars.

You CAN now purchase a large Bosch pump that goes inside the tank -- I think a few guys on here are using those pumps with success. They are larger than the OE pump though, so I wouldn't expect much out of the bucket -- larger pump size means less fuel in the bucket, which reduces the usefulness of that safety buffer. Not to mention that the larger pump is moving more fuel than the OE pump, so it will run out of bucket fuel faster.

I personally hate fuel system jobs, gasoline stinks and the smell sticks to EVERYTHING. And it lasts for a long time, if you get gas on your clothes you might as well throw them away. If only there were a solution that didn't require you to go inside the tank...

Now with that background in mind, you can see why people would just add a BAP. It's in the $200 range and doesn't require you to do anything other than to hook it up. Off the top of my head, a BAP + a OE fuel pump will move more fuel than an LPE pump (someone correct me if I'm wrong). Some people choose to do both an LPE pump and a BAP which gets you even more fuel.

BAPs are pretty reliable and don't affect pump life if installed correctly. There isn't much you can do with pumps INSIDE the tank, so going this route is generally more elegant than many other routes you could go.

Finally, my experience has been that bigger is not always better. With FI cars and stock cubes, fuel usage is close to OE fuel usage when you're not in the throttle... so at idle and cruise, an OE fuel pump will work just fine. If you put a massive pump in the system, all you're doing at idle/cruise (which is where you spend most of your time) is sending extra fuel to the fuel rails, only for it to be heated up and returned back to the tank. If you get the fuel hot enough, your pressure will drop, and so by going bigger to solve a fuel pressure problem, you actually created a different fuel pressure problem.

This is one of the reasons I am a fan of any device/configuration that only gives you more fuel when you need it. BAPs fall in that category.

 

Very well said...thanks.

 

Anybody else?

 

I've read on LS1Tech that a 255 Walbro and 42 lb injectors won't suffice for more than about 500 rwhp, but some people are doing more with those components. For example, I just read an article in GMHTP about a guy with an '02 SS with 540 rwhp with just a 255 and 42 lbers. Of course the duty cycle of the injectors might be close to 100% with that setup.

 

I was running the stock '99 pump with 42# injectors with no problem, not sure of the duty cycle though. I am having a high performance fuel pump installed as we speak, not sure if the tuner is adding Boost-A-Pump however.