Lexusloud

I wonder if the 3.5L would make more power if it could breathe better?

redspencer

iTrader: (1)

I've been collecting lots of datalogs recently based off of my straight line performance mods and from what I seen, there's plenty of air flow to be gained with headers and a catless exhaust system.

Though datalogs on this forum is fairly limited, I believe a stock IS350 has a MAF reading of 224 g/s. Using my datalogs with a FBO setup, I'm currently logging approximately 246 g/s. You can see some of my recent logs here on my build thread:
​​​​​​https://www.clublexus.com/forums/bui...l#post10251054

Lexusloud

So the idea of having a fully open exhaust from the cats back, would probably make more power. My idea of full flow exhaust cutouts, run open at the track only, might not work well if the ecu can't adjust in time to take advantage of the extra flow. If I opened them and ran to the track (about 80 miles) do you think it would that give the ecu time to adjust to the additional exhaust flow?

redspencer

iTrader: (1)

Driving 80 miles to the track while doing several WOT pulls on the drive there will suffice to having the ECU adjust to the reduced exhaust backflow.

You may want to use a phone app like OBD Fusion to determine that your KCLV is above 20 to ensure that the ECU is providing you its most optimal ignition timing advance.

Here's some more info on the subject: http://blog.rr-racing.com/news/2017/...on-lexus-ecus/ .

There's also a good KCLV thread on the ISF subforum: https://www.clublexus.com/forums/is-...and-power.html

DickH

It is possible to be slower due to too short of an exhaust, keep that in mind when installing the cutouts. Also, red and I saw gains going to 2.5" exhaust, but we also have headers and he is running catless while I have a pair of high flow cats. You might not see the gains you are hoping for. Also, our ECU doesn't adjust for flow at full throttle, the only thing that is adjusted is timing which wouldn't be based on flow.