Again, do any of you guys know with any certainty if there is there any point in replacing the fuel supply nipple in the tip of the basket with the larger AN-6 fitting if you are not going to be replacing any of the fuel lines downstream of the fuel pump? Just trying to see if that extra step is only necessary if opening up the rest of the system.

I just read the Radium fuel pump test article from the provided link above and one thing that stood out was the fact that the Walbro 400 E85, while pumping substantially more volume than the stock Bosch 040 pump, did so at the expense of drawing about 20Amps versus 6Amps for the Bosch. That is a huge difference!!! Can our wiring safely handle this kind of a draw? I'm assuming this kind of high draw will also create substantially more heat. Granted, the test was that of the Walbro 400 model and not the 450 but I would assume that the 450 being larger will draw even more than the 400. Comments?

 

I just PM'd Tim. Hopefully he will chime in.

 

You are correct on the fitting. Tim may have an answer regarding voltage and load.

 

No - there is no point in changing the nipple if your not going to change the fuel line. Now, with that said, the nipple is the smallest point, but it is only marginally smaller than the fuel line. I can measure then for you tonight as I have both I front of me.

With respect to ampage. The walbro is a lot more. It's quite a lot more. Wity respect to heat, my testing has show d no difference between the walbro and stock pump. There is so much fuel around the pump, and most of the heat is generated from the fuel returning from the engine. But, when I did my wiring I ran 20amp wire from the pump to the connector, and then on the outside I ran a relay with a 20amp wire from the battery straight to the fuel pump. The reason I did this was to ensure the wiring would not be an issue, along with ensuring the fuel pump was always getting the highest and most consistent voltage.

 

Ok, thank you. Post up the measurement when you get a chance.

 

just want to clarify that i didnt use the walbro 400 but rather the walbro 465

 

I too am in the same boat as the OP. I'm running billet 18's with 72# inj and Tony's tune. Although my pump is working fine I also am looking to upgrade slightly. Was thinking to go with the GT2 pump but was also looking at options. I've been running this set up for a few years with no problem on the stock pump and I've been at 1.4+ before. Put down 550/640 on Tony's dyno at 1.3. He said at that time I was ok with stocker.

 

I emailed Tony for his opinion as well, but haven't heard back from him yet.

 

The gt2 and turbo has the same fuel pump. The gt2 flows more because it doesn't have the jet pumps that are needed to lift the fuel up to the fuel pump basket.

changing to the gt2 pump alone will do nothing. You would need to change the tank and everything inside to get the additional flow that the gt2 has.

 

LQQK has really put some time into this.
+1 on his points and great idea to run an independent 20A power wire.

 

GT2 does have one lift pump for the fuel. I have a gt2 tank and basekt that came with it. same pump as turbo but still has one jet pump as opposed to 2 on the 996tt. Car needs jet pump, gotta get the fuel into the basket

997TT basket and pumps can easily work too. Just wire one pump to be the main pump with stock wiring and plumb it to feed the jets. wire the second pump to come on at 6psi on a hobb switch. it would be an awesome upgrade on a 996. second pump wouldnt waste 30% of its flow feeding the jets and jsut feed the rail.

 

I agree, gt2 must have a jet pump also. Regarding the 997tt twin pump set up, have you done it or can you point to a car that has had the conversion done? I would love to see the logistics of it. Many people talk about it, but it's like the lochness monster, no one has actually seen it for real....

I like simple. Give me a better pump like the walbro that can easily be retrofitted with the stock basket and I think that may be the way to go. With two pump, Hobbs switched, custom wiring, it's just more that can fail. My $0.02, and I stayed at a holiday inn last night....

 

I have been playing more and more with the system. I have been machining a restricter pill that I am installing in the line that feeds the jet pumps. As noted in previous posts in this thread the jet pump kills flow. So I was thinking along the lines of as the pump size is increased (flow) the feed to the jet pumps can be reduced (regulator regulates pressure not Liters/hour), 997 use a 6mm line to feed one pump and low psi tap off the bottom of the two pumps for the other jet pump which is far less flow then the 996 system uses.

 

That is the stock 997t fuel pump setup.

Blue: low psi jet pump. it is feed off the first stage of both pumps. there is a ball check that is forced by flow of running pump to stop fuel being pumped into the non running pump.

Red: High psi jet pump. this is feed off the final stage of the pump that is ran when tank is under 13 gallons. It is a 6mm line and the port out of the pump is far smaller.

Green: feed to engine. Notice no check valves as the pumps have them built in.

 

Anyone thought about trying the Kenne Bell Boost a pump

http://www.kennebell.net/KBWebsite/A...boostapump.htm