i have a built b16 turbo with 550 injector msd and a holley fuel pump the only thing i have stock is the fuel regulator i was wondering if i need to bump up the fuel pressure? the car runs like i have a big turbo when i only have a t3 t4 with 50 trim at 12 psi everytime i shift fast it boggs the air fuel ratio is on the money so i know im not running rich if anybody know whats up and can help me out with my problem that would be great and it only happens shifting fast at full throttle thank

 

How about your timing? is the care actually TUNED??

 

I assume the car is tuned considering 550cc inj., and boosting 12 psi, well at least let's hope. First thing that comes to mind is the tune, wastegate not holding or you may possibly be shifting way too soon. Give us more info on your set-up and at how many rpm's are you shifting. How much HP are you making and what type of management?

 

the car is some what tuned for fulll throttle daily driving runs a little rich some times i dynoed the car and it made 310 and 195 shifting at 8400 i did not do the tunning so i dont know about the timing i know its at a safe setting, im at full throttle shifting at 8200 8400 everytime. i was mainly wondering when running a car that has that size of injectors or bigger do you need more fuel pressure? i have no boost controller im getting my boost from a 1 bar spring. i dont if the regulators are different from the LS to the GSR ect. cause the only thing i have stock on that motor is the fuel rail and fuel regulator. thanks guys!

 

oh ya its tuned with crome program

 

who tuned the car?

 

ok so first you said it doesnt run rich and it runs perfect. then you say it does run rich. sounds like a conservative tune on a basemap. and the b16 is meant to Rev. 8200 seems like a low shiftpoint. alot of b16's i see going 9-9500 RPMs i only say that because you said the car is BUILT. so assuming you took at the precautions of someone with a built motor

 

Def talk to your tuner. It does sound like a basemap and almost seems as it wasn't tuned on a dyno. 550's are perfect for your set-up specially for you'
re H.P. Post up your dyno sheets and A/F ratios as well as timing sheets so tuners can take a look!

 

ya im going to deffently go to talk to him. but thanks anyways guys for your opinions i really appreciate it! and if i can get those print outs i'll post them up and see what you all think.

 

Think about your wastegate when you shift. If you let up, you close the TB and usually drop into vacuum (pipes still have boost). This vacuum slams shut your WG, meaning all exhaust gasses are forced through the turbine wheel. When you shift full-throttle, the WG stays open and all the gasses flow through the WG. With no load on the motor, you'll push far less exhaust volume through the turbo (most of which bypasses the wheel). To sum it up, your turbo's shaft speed slows more during full-throttle shifting than when you let up. I'd bet if you put a MAF sensor on the turbo to datalog air flow, you'd notice more air is pulled during shifts when you let up than when you shift full-throttle.

I know that sounds odd, but its close to how you usually can't build boost by reving it in neutral. No load = low exhaust gasses = slow turbine.