Walbro 307 vs. 340

[GotGrunt]

I know they are basically the same thing but I have the 307 right now. When would I need to upgrade to the 340? Ive done an adjustable FP reg. and injectors since I've added the 307 and I was gonna do a hot wire and volt booster upgrade soon. I was wondering if there is any hp gain from change?

 

[Intercooler]

With what you have the 307 will do just fine. The 340 just has a curve that flows at a higher pressure so if you had 50's and was running over 70 PSI at WOT all the time the 340 would benefit you. The only time you would see a power increase in the 340 over the 307 is if you needed the fuel but for now you should be fine. If you have the bucks to spend and want one go for it!

 

[GotGrunt]

Just what I wanted to hear, Thanks... I'll worry about something else for now and save that for later

 

[lalonde441]

sorry a little off topic but not much....what kind of HP gains would you get anyway over a stock GN pump going to say
30lb injectors
thrahser chip 92 octane
and a hotwired 307 fuel pump with adj fuel pressure reg.
thxs.

 

[Razor]

You can also shim the 307 and hot rod it.Increase its pressure output and flow.

Theres a little window on the top of the pump that shows a little spring.Insert a solid wire in this slot to compress the spring and whalla.

I learned this from Hank from the board.

Cheaper than replacing the pump.

 

[Racetronix]

Modifying the Walbro GSS307 is not a good idea!
About a year and a half ago Walbro changed the armature in the GSS307 to one that is slightly less efficient that the one in the GSS340 to keep the price of the pump down. That is why at an equivalent flow the GSS307 draws about 16% more current than the GSS340 at 13.5 volts. IMO the GSS307 is fine for a NA motor running 40-50PSI but not the best choice for the turbo Buick. Modifying the GSS307 to perform as well as a GSS340 at higher pressures will shorten its life considerably and void your warranty. Given the small price difference between the two pumps it is hardly worth considering the GSS307 for high pressure applications. This is why I pulled the GSS307 package from the Racetronix ads.

Jack
Racetronix

 

[UNGN]

Originally posted by lalonde441
sorry a little off topic but not much....what kind of HP gains would you get anyway over a stock GN pump going to say
30lb injectors
thrahser chip 92 octane
and a hotwired 307 fuel pump with adj fuel pressure reg.
thxs.

well... with a stock GN pump, the best I could do was 14.3's@95 mph on the fews runs it would let me make a full pass. If I had added any mods, it could not have gone any faster with the stock pump.

After a 307 install and a few mods (dump pipe, cone K&N, tires) it went 12.20's @ 110+ un-hotwired.

So that's what? 150 HP?

A pump won't add HP. It will just allow the mods you have to add hp.

 

[The Radius Kid]

Originally posted by Racetronix
Modifying the Walbro GSS307 is not a good idea!
About a year and a half ago Walbro changed the armature in the GSS307 to one that is slightly less efficient that the one in the GSS340 to keep the price of the pump down. That is why at an equivalent flow the GSS307 draws about 16% more current than the GSS340 at 13.5 volts. IMO the GSS307 is fine for a NA motor running 40-50PSI but not the best choice for the turbo Buick. Modifying the GSS307 to perform as well as a GSS340 at higher pressures will shorten its life considerably and void your warranty. Given the small price difference between the two pumps it is hardly worth considering the GSS307 for high pressure applications. This is why I pulled the GSS307 package from the Racetronix ads.

Jack
Racetronix

Good point.We had this discussion on the southern board not too long ago,and Walbro basically confirmed what you said to one of our board members.