I have a stock pulled Comptech kit with the 255 walby, and I still sometimes get 12.5 a/f when its cooler outside (had adjusted the RRFPR ad nauseum) . I am considering getting a bit bigger pump to make sure I don't go too lean as I lost my original motor to lean condition back in 2006. I personally wouldn't risk running the stock pump.

 

But 12.5 is a totally acceptable ratio, especially on a Stage 1 kit.

 

Yes I learned that, by speaking with ^^coolGuy094 & s2000Junky. And now my stage1 is @ 12:5 AFR. With no issue's (knocking on wood). And I hear some guys have gone even in the 13:0's.

 

I was running 13's on my stage 1, lol. Maxing at 13.5, dropping back down to high 12's.

 

It has gone higher on a couple occasions. For me personally, I'm more risk adverse, so I'd rather not have to worry about losing another motor. I'm a little rusty on the SOS setup and if it uses a box to retard timing, but on my CTSC, I just have a 12:1 FPR and a map clamp, so a couple higher gear pulls in the high 12's to low 13's is too risky for me.

 

I don't mean this disrespectfully, as S2000junky has added a lot to the S2K community, but he is not an average supercharger user, and he has gone through a couple motors over the years in pursuit of his goals. All I'm saying is that past experience doesn't guarantee future results. For a couple hundred dollars and a few hours of your time, I'd put in a higher capacity fuel pump which could possibly prevent a catastrophic failure if you hit the "perfect storm."

 

No worries. As mentioned earlier in this thread I did end up just putting the Walbro in.

 

It appears im late to the party, sorry about that. Back in my "stage one" days, it became quite apparent that the fuel pressure needed to run the proper afr wasn’t achievable with the stock fuel pump. Ive run the typical nosy walboro 255, but eventually moved on the FB340, and found that to be the best solution to deliver all the fuel needed, with a direct drop in to the stock filter/hanger assembly and be quiet. This fuel pump will work great from a base stage one system where the rrfpr is used, all the way up to 500whp+ set ups.

Obviously with larger after market injector and EMS to control injector duty cycle at the factory 43.psi base pressure, a after market larger fuel pump doesn’t have the same importance as it would with just relying on fuel pressure to deliver the amount of fuel needed.

 

Thanks for the reply. This was the theoretical conclusion I came to but I wanted to see if anyone had the experience such as yourself.

I've now had two Aeromotive 340's fail on me; the most recent while on the dyno. I've become a little skeptical moving forward about buying them again. I believe my next personal aftermarket pump purchase will be the new FB290 pump.

 

If you want a quality pump go with Weldon; however not sure if they make in-tank pumps.

Unlike anything else in the market, these are made from metal (no plastic parts) and built in the USA.