Why would you have to get a re-tune to lower the boost 1-2 psi? I can set my boost controller to anything lower than what it is tuned for.

 

Add a Walbro and your 44's will be fine up to at least 12lbs. I ran 42's and a Magnacharger intank Walbro kit in a returnless system on a P-1SC kit LQ9 @ 10lbs for 25k miles with zero problems.

Rick

 

Interesting. At one point I had 43's, single GSS340 walbro, and at 8.5lb 6100rpm shiftpoint and 11.6afr my IDC was 114% on a LQ4 (this was on a A2A intercooled Kenne Bell)

What was your IDC%?

 

Im having this problem right now as well, 5.3 stock heads, t76 8psi. Walbro in tank, 42lbrs, and my injectors are at 105%. Fuel pressure drops to about 53psi at wot. Any suggestions??, Not trying to thread jack man, just in the same boat you are.

 

You need bigger injectors, if you stay returnless the fuel pressure with drop no matter what.

 

Do you think the 60s will do the job?? I would like to see mid 500rwhp as a goal. Right now the truck is around 400.

 

It would peak around 110% at 6300 shift points, AFR's in the mid 11's. I didn't run a fuel pressure gauge but I'm assuming it would drop down to 48+/- (stock returnless 58psi-10lbs boost). It could have something to do with the efficiency of a centri vs a roots. ???

 

Well it was a twin screw, and if that was the case then that would mean that my twin screw was making more power then your procharger. ( personally I doubt that there was that big of a difference.) Hard to say, lots of variables. Anyway its just interesting to compare setups.

To the original poster, yes 60's will take you where you want to go. At GM 4bar fuel pressure 60's are actually 72's. Either way you need to do something with your fuel pump. There is a member on here that sells direct fit plug and play 60's, I would go with these as they are less work and they also have a higher injector response time. (They are faster firing, easyier to tune)

 

What I was thinking that both systems make xWHP but the roots is making x + 100 (using more fuel to cover parasitic loss) to cover vs. the centri making x + 60 (using less fuel because of increased efficiency over the roots style). I know my turbo kit is making more RWHP at a similiar fuel consumption as the centri I ran before it.

2nd that. I still think you can get by on 42's but start with 60's and you won't be swapping them out down the road. I picked up a set of drop in 60lb'ers (same height as the truck stock injectors) from Muscle Motors Performance in CA. I just had to splice in new pigtails.

Rick

 

Kenne Bells are twin Screws, my TVS is a roots. This was all on my Kenne Bell.