willsctsv

Had My CTS V dynoed today on a Mustang Dyno.
The car pulled 367RWHP/323RWTQ.
torque seemed a bit low. The printout of the A/F ratios were in the 10's and the tuner said that they should be in the 13's and I could pick up easy 20-30 HP more form this LS6. I have headers, no cats, 3" B&B exhaust, CAI and a tune from a guy with the same car that tunes them with EFI live, while driving and logging info. I'm not knocking the mans tune, I felt a difference. But, more is better!
Any thoughts? I know the guys on this forum are technical, that's why I'm asking. Thanks..

Abdullah

iTrader: (2)

i would say dyno with a dynojet not a mustang dyno becuase most here are using dynojet numbers to easy compare your numbers.

obviously since you have 10.0:1 A/F ratio ( this is bad tune and very rich) you need to retune to get to the optimum 12.9-13.0 NA ratio.

Rick@Synergy

iTrader: (5)

I would disagree with using what everyone else uses. I would only judge your car by using a loaded dyno and if he goes to a dynojet, his A/F will only be off so much that he will never know whats right.

If you realy want to know what your true A/F is, then stick the wideband before the cats. You cant take a signal after cats, just is not accurate. Then get back on the mustang dyno and tune it. Loaded is better...period.

rick

willsctsv

Rick, I can go to a guy not far from me that works on Corvettes only. He said he will dyno the car before the tune, then tune it for optimum performance, lean it out on the same dyno, and dyno after the tune.
Dynojet is the dyno he uses. Is this not a worthy tune?

Rick, in response to tuning with the wideband o2's before the cats, I don't have any cats. Should that matter?

Abdullah

iTrader: (2)

Rick@Synergy, looks like you are right about tuning using wide band O2 before the cats. i thought about buying the commander wide band system for tuning my car when i do the NA 408 but my question is how about the device they have in a dyno shop it is like a kind of small black box with some buttons that has a hose that can be put at the exhaust tip to measure the gases ( if you know that device) is that an accurate way to measure the A/F ratio compared to a wide band O2?

btw, i too don't have cats in my Z28, i deleted them.

oh yeah, also what do you mean by loaded dyno?

thanks.

DynoDR

iTrader: (1)

The unit that you are talking about is still a wideband 02 it is just using a pump to "pump" the exhaust gas sample to the black box where the sensor is located. With a pump you have the delay especially if you are using a long sample hose.

A loaded dyno is a dyno that uses some type of power absorber to load the vehicle. You can hold the vehicle at any speed or rpm you choose or control the acceleration rate that you want to test with. An inertia dyno is just a heavy wheel that you are spinning and recording the time it takes to accelerate it to calculate HP. The loaded dyno uses a load cell or strain gauge to actually measure the amount of torque you are making at the rollers.

This is just a very basic explanation but I think you get the idea.