Some Questions

91BLOWNBIRD

Registered User
1. So this morning I was heading to work in my newly put together 91 SC (specs on my member page) and a new challenger blew by at like 100mph. So I downshifted to 4th and caught up to him easily. I believe it was an R/T 375hp 404trq, but might have been a SRT 8. We eventually hit like 140mph :) and I was very impressed with my SC, but I noticed my Air/Fuel ratio was steady around 11.3:1

What should my Air/Fuel be?

2. My idle is very rough (I think because of the cam with 110 lobe sep) and when I come to a stop the car wants to die. Can I fix this? with my chip? or raising the idle?
 
Hi,
you should list all your relevant mods here even though they are listed on another page because people don't/won't want to go searching around for them for a question like this.
What's your vac at idle? In gear at idle?
A/F looks great if that's what you get under boost.
R/T has ~350 hp
SRT 8 has 425 hp. A simple Diablo Predator tuner puts those at about 500hp with no other changes.

I am getting a cam regrind to accompany other mods.
If I have idle problems, I would probably turn idle up a bit.
Sounds like you are not done tuning that.
Good luck with your build!

paul
 
Last edited:
ok

here are the mods:

7" K&N Conical Filter
Custom Cold Air Divider
C&L 76mm MAF w/ 3.5"-3" Reducing Hose
MP 3.5" Intake Tube
MP 85mm TB
MPX Inlet Plenum
MPX Blower W/ Coated Rotors
MP Raised SC Top
MP Overdrive Pulley Kit(25%)
Aluminum Alternator & Waterpump Pulleys(stock ratios)
MP Heavy Duty Tensioner Springs
Aluminum Accessory Tensioner
Custom Front Mounted IC
Dual 6" 1800cfm IC Fans
Grifin Super High Capacity Aluminum Radiator
Custom A/C Delete
BHJ Harmonic Balancer
1.8 Roller Rockers
Comp XE Custom Grind Cam .567/.567Lift, 212/218Dur@.050, 110 LS
Ported Heads by Gromm Racing w/ Hardened Valves 1.8 int. 1.5 exh.
Comp Elliptical Beehive Springs
All Fel-Pro Gaskets(MLS Head Gaskets)
Block Prep & Build by Gromm Racing
ARP Head/Main/Rod Studs
Wiseco .020 Over Forged Pistons From Dave Dalke
351W Cat H-Beam Rods From Dave Dalke Touched Up by Gromm Racing
Oil System Reworked by Gromm Racing
Kooks Mid-Length Headers
High Flow Cats
Magnaflow Dual 2.5" In/Out Muffler W/ Turndowns(In Place Of Resonator)
255lph Fuel Pump
60lb Fuel Injectors
MN12 Fuel Pressure Regulator
180* Thermostat
SCT Performance Custom Chip W/ Stock Setting Switch (not tuned yet)
Solid Ruber Motor Mounts

Thanks for the input...I have a manual so it idles in nuetral about 700-750, was thinking 800-900 would be better with my cam.

Also thought like 10.5:1 AFR is where it should be at WOT, Mine is like 11.3:1 at WOT
 
I typically target about 11.6-11.7 when tuning forced induction cars. Adding nitrous etc then you need richer.

fraser
 
figured out ? #2

In case anyone wants to know I answered my question #2 on my own...

On aftermarket throttle bodies there are Idle Air Screws that allow for more or less air to the IAC allowing more air raises the idle for a smoother idle with a bigger camshaft.
 
In case anyone wants to know I answered my question #2 on my own...

On aftermarket throttle bodies there are Idle Air Screws that allow for more or less air to the IAC allowing more air raises the idle for a smoother idle with a bigger camshaft.

If you where able to change the idle by using the bypass, then you have gone way out of the tolerance limits the IAC valve can handle to work properly. You've just created a boat load of new problems for yourself, such as dashpot functions, part throttle to idle transitions etc.

There is only one correct way to set idle rpm up and that is through a chip. One reason that bypass is there for is to be used to set up idle when the IAC is non functional so the car can be driven to a location to get fixed. That target RPM is typically 150 rpm's lower than what the tune has set the idle to be.

Fraser
 
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