VPC SAFC questions

[cjridert1]

hi - I cant post this anywhere but here b/c of my post # I guess?

I have a VPC thats chipped for 450's and I have 450s (550's on the way). I am running lean (among other things) and have no idea why - does anyone have much experience dealing with VPC's? Throttle response is teRriBle (because speed density sensor is mounted in TB elbow??? - I checked/set TPS). I figured I would put in 550s and tune the setup with safc - any forseen problems?? I recently checked timing, new NGK 7's, plug wires are good. Any ideas? When I am driving 16lbs feels like 9 lbs (I have a boost gauge reading right off the intake mani). Ideas, suggestions, anything would be great!


Here is a recent 3rd gear pull (boost @ only 12 lbs) (knk = knock)

rpm knk o2 timav injd injp

2200 0 .83 35 3.9 2.5
2600 0 .78 21 19.5 9.2
3000 3 .80 16 31.2 12.5
3600 22 .78 5 53.1 18
4000 20 .76 8 59 18
4600 20 .76 8 77 20
5100 19 .74 9 82 19
5600 18 .74 11 89 19
6000 15 .72 14 95 19
6600 14 .72 12 98.4 18

FT'S
low - 81
med - 84
hi - 92


Mods - VPC, HKS EVC, 16g, 8.5:1 wisecos, 2g ex mani, ported/pol head, bushur 2.5 DP and turboback, highflow cat, nippodenso pump

 

[talon187]

your going to need a 550 chip to run that but im sure you know that already. do you have a gcc with the vpc? i mean the safc2 will work but the gcc would ###### work better. are all your sensors good? i have alot of friends running vpc and gcc that are all 10 or 11 sec cars a friend of mines was running like crap and it happen to be the air temp sensor might want to check all your sensors and what not while your at it

 

[talon187]

wow wait a sec i just checked your post again 16lbs of boost on 440s? way to much boost for stock injectors max on stock injectors is 14 MAX thats pushing it as well id turn that down asap how long have you ben running that much boost? you'll blow your motor quick running it that lean ive got eagle rods wesico 9.1 pistions fpr walrbo 255 pump -6an line for the tank to the rail big 16g turbo apexi full exhuast and i dont push more then 10lbs for now your def going to need a logger but i know 16lbs of boost is way to much for stock injecors thats why your running so lean keep us updated hopefully you didnt damage your motor

 

[cjridert1]

Ill have to check the temp sensor (assuming you can test it). Do I NEED a 550 chip for the vpc if Im tuning with a safc (dont have it yet). I dont have a GCC and it seems as though the safc would be easier to tune with - maybe? Im fairly green to tuning still - why would a gcc be better? Throttle response is TerRiBle - rpms drop down a fair amount before they pick up when you push down gas. I checked/replaced/set TPS. The logger data was taken at 12lbs on 92 gas. Is 16lbs really too much for 450's? Thanks for the responses!!

 

[spyderturbo007]

Is 16lbs really too much for 450's? Thanks for the responses!!

Welcome to the board Cody.

It's possible, but I thought you were running 12lbs when we were chatting on AIM? It really depends on airflow, not boost pressure. Using 93 octane fuel and a SG of 0.76, you can push 25.84lbs/min @ 80% IDC and 32.30lbs/min @100% IDC.

Keep in mind, those are the mathematical limitations of the injectors so don't assume yours will perform to perfection.

Did you get my PM on the other board? I'm thinking that you should be able to zero everything out (12 o'clock) position and basically run the stock maps. Since the VPC is chipped for 450's and you are running 450's, I don't see why it wouldn't work. Pretty much like zeroing out a SAFC when running stock injectors.

 

[cjridert1]

Welcome to the board Cody.

It's possible, but I thought you were running 12lbs when we were chatting on AIM? It really depends on airflow, not boost pressure. Using 93 octane fuel and a SG of 0.76, you can push 25.84lbs/min @ 80% IDC and 32.30lbs/min @100% IDC.

Keep in mind, those are the mathematical limitations of the injectors so don't assume yours will perform to perfection.

Did you get my PM on the other board? I'm thinking that you should be able to zero everything out (12 o'clock) position and basically run the stock maps. Since the VPC is chipped for 450's and you are running 450's, I don't see why it wouldn't work. Pretty much like zeroing out a SAFC when running stock injectors.

I am logging this with 12lbs, but ive ran 16 before (with no difference in performance - maybe lower o2 readings since theres more air) - when I have used 16lbs in the past, I have not noticed a performance change. Ive tried all vpc knobs @ 12 and it still runs like the same garbage Ive come to know as my car. What is SG? Thanks!

 

[spyderturbo007]

SG is the Specific Gravity of gasoline I used in the calculation to determine max airflow.

I don't know that I'm going to be able to help you anymore. I'm out of ideas, other than throw the VPC in the trash and go with something more "standard" like a stock MAS / SAFC combo, or DSMLink.

Sorry buddy, but if everything is hooked up properly, I really don't know what to say.

 

[cjridert1]

I don't know that I'm going to be able to help you anymore. I'm out of ideas, other than throw the VPC in the trash and go with something more "standard" like a stock MAS / SAFC combo, or DSMLink.

I figure I will be hopefully getting my paws on a safc and keep the VPC and see if that combo works - this way i dont need to install a mas, find a diff. bov to recirc, blah blah. Let me know if you want to get rid of yours & thanks for all the help!