i am planning on dynoing my nearly stock FD on the 18th

my only mods are:
full non-sequential mod
downpipe

my question is about the wideband on the dyno... since i have the stock cat, will a tailpipe sniffer wideband be accurate?

i'm planning on doing one run off the wastegate spring and 2 runs at 9-10psi. any guesses as to what numbers it'll put down?

 

is this a guessing game? i say 250, how do you run full non-seq and no engine management...and you dont even have an intake? intakes are cheap and they do alot

 

I have dynoed with a high flow cat and a wideband before the cat. The difference between my wideband and the dyno was approx. 0.4 - 0.7

 

i removed the flappers and butterflies associated with the sequential setup, capped everything off, and left the solenoids' electrical plugs plugged in.

and i was worried about the setup being too "free flow" for the stock ECU in full non-sequential mode with an intake, but after some reading it looks like intakes arent THAT much more freeflow than the stock airbox, so i might do it anyways..

 

ok awesome, thats the useful info i was looking for...

so the .4 was before the cat (like at the stock o2 location) and the .7 was after the cat (like a tailpipe sniffer)? so after the cat it reads 3/10ths leaner?

 

not exactly, I don't have the dyno graphs and logs available presently, but the numbers were more like 10.9 AFR before the cat and 11.3 AFR after the cat

I believe the difference from the before and after the cat were in the range
of 0.4 -0.7, or another way to state this is.. the tailpipe was anywhere from a 0.4 AFR to a 0.7 AFR leaner than the pre cat reading.

Would you please post your dyno once it is complete? I am interested in what the target AFRs are, with the stock ecu, realizing of course you are not stock.

 

Look here....wideband sniffer in tailpipe after stock cat, so actual readings are RICHER!

https://www.rx7club.com/showpost.php...8&postcount=61

 

Thanks for posting the dyno graph.

Would you please explain what you mean by "actual readings are RICHER".

Richer than what?


thanks again

 

The AFRs measured in my dyno sheet were from a tailpipe sniffer. I was still running a stock cat at the time. If the AFRs were measured before the stock cat, I previously estimated that the readings would be 0.4 to 0.7 richer than after the cat (same estimate as you!). Therefore, my actual AFRs were richer than indicated on my dyno sheet (which were already at 10:1 or less for most of the higher rpm range).

 

yeah it will show leaner AFTER the cat because the cat heats up the exhaust and completes the combustion even more.

 

Rynberg,

thanks for the clarification