I've got 550cc primaries, 720cc secondaries and a SAFC. RB 2.5" turboback exhaust. S4 T2. I still have the stock turbo fuel pump. I assume then that the fuel pump becomes the limiting factor in my tuning, so the question is how much psi of boost should I limit myself to?

 

12?

 

well, then i guess i shouldn't even bother upgrading my pump, 'cause i was aiming for 12 psi anyways.

 

The pump is the first thing that should be upgraded. It should be done when a FCD becomes necessary. I wouldn't run 12psi on the stock pump...

 

how much would you run then? This is a temporary situation till my new pump comes. Just want to be able to drive it safely in the meantime.

 

+1

I wouldn't even consider running 8psi or more on the stock fuel pump... At the very minimum you need a stock FD pump to handle 12psi, and you would be better off with a 20B/2JZ pump or a Walbro...

 

you guys have little faith in the stock fuel pump....

yes it is recommended but sheesh give the T2 pump some credit!

 

I'd rather be safe than sorry...

 

I ran my stock pump with 720's and an SAFC for quite some time......but, I am in the market for a rebuild kit now. Hmmn....

 

maybe my pump was upgraded at one point in time but i seriously doubt it. currently i am running 10psi+ on a hybrid turbo with 4 720cc injectors and have no indications that the pump is near maxing out. the wideband is still pegged rich but i will probably upgrade the pump before doing the dyno tuning for 15PSI though.

 

If you're pegged rich at 10psi you probably have some sort of replacement pump... Unless the 720cc primaries made that much of a difference...

At 10psi though, the stock pump is really starting to run out of headroom, and is working alot harder than it should be...

 

maybe, but the car was stock when i bought it so i have doubts it has been upgraded prior. difference is i am running it on a 12v constant feed and i have a standalone.

 

LOL that's a big difference! You should still look into upgrading though, and probably getting a FPR to keep rail pressures constant...

 

Neither of those make any difference to how much power the pump can support. With the stock system it gets reduced voltage at low load and full battery voltage at high load when it needs it.