Relevant mods: Streetport, DP,MP,CB, PFS IC, Pettit intake, Power FC. The guy I bought my car from had the streetport done after the car was tuned. Im not too sure how this will affect my timing. The car definetly feels slower than it should be and im sure that getting a good tune will unleash alot of HP but I would like to have a good idea of what to look for when getting the car tuned. How would my timing have to be changed to take advantage of the larger porting?

 

^

 

seq or non-seq turbos? injector sizes?

Tim

 

Typically a street port will need some timing retard compared to stock port if the original timing on stock ports was aggressive. But the backpressure and other variables come into play resulting in unique "optimum" timing for every setup. Most tuners just use a conservative ignition setup to get started and many don't advance timing past this conservative starting point when running pump gas.

Easy thing to do if you are unsure is to look at a bunch of maps, decide how much timing you are comfortable running at first (retard the stock maps in boost some number of degrees, say 5 deg for starters), reset the split to what you are comfortable with (say 10 to 15 in boost), and start tuning AFRs at low boost while monitoring knock. Without monitoring EGT or hp/torque the only thing you can realistically do to tune timing is retard cells to bring higher knock readings down or advance cells to find the knock threshold for the motor setup, then retard a degree or two for safety, then retune as much as practical to ensure you stay away from the knock threshold as it changes (seasonal changes in air temps, gas formulation, etc.).

I can say that a ported motor with a big turbo can see knock levels at low boost and moderate timing. Even 10 psi required a bit of retard to keep knock levels in check with the ported motor and big turbo.

 

Thanks alot. That really cleared up alot of what I was looking for. Im still pretty new to the PFC and im not very comfortable tuning anything myself. Im taking the car to a shop really soon to get it tuned and just wanted to have a pretty good idea of what was going on and what direction I should point them in. I am still running the stock twins sequentially with stock injectors and a Walbro fuel pump. I would like to see around 320-330rwhp at about 12-13 psi with a conservative AFR and conversative timing.