HossinatorSS

iTrader: (1)

alright here's the deal. I have an STS kit @6.5psi and an AEM wideband. Before header wrap, as soon as push the gas to the floor it my AFR goes below 11, been like that since I picked it up which is fine (rather be too rich than lean). I wrapped from the cats to the "y" (ran out of wrap) and now my AFR is 11-11.5 with one reading of 11.9 that I saw. I understand that the wrap should spool the turbo lower in the rpm range, but would it affect it this much that the computer can't keep the desired AFR where it was before? If this is fine than I won't worry about it but it just seemed weird that it would change that much and I haven't even finished wrapping it yet.

Is it possible that the exhaust temp is increasing such that it's affecting my AFR reading (WB O2 is mounted post turbo).

Thanks for any input guys. I tried to do a search but i kept getting an error page.

Juiced

iTrader: (2)

the sensor could be going bad if condensation is allowed to build up on it.... why is it mounted post turbo? idealy it;s suppose to be before the cats if you are using them or 12-16" from the head

cablebandit

iTrader: (37)

if the sensor is before the turbo, the extra heat in the ypipe may have changed the pressure in the pipe which will affect the wideband readings

mcx

...are you happy with how the car responds to the wrapping otherwise???noticable investment??

engineermike

It is possible that the hotter exhaust requires less pressure to spin the turbine. Less exhaust pressure means more airflow, more power, and thus more fuel required.

Mike

Kevin Doe

iTrader: (1)

only wrapping them won't affect the afr.

HossinatorSS

iTrader: (1)

It's mounted post turbo to make sure it is the O2 sensor heater that is in charge of heating the air for readings (they would be off pre-turbo or at least that's the theory).

I knew that wrapping the pipes would decrease spool-up time. I guess I expect my AFR to be leaner in the rpms when the turbo first spools because when it was tuned no boost would build there so now there is more airflow coming from the turbo. I've had a chance to drive it some more and it appears that the AFR stays in the ~11.5-11.8 range all the way to redline. Before, it would be below 11.0 (My AEM only goes done to 11) pretty much as soon as boost started building.

I guess my concern is that at 11.8 I might be too lean and I haven't even wrapped the intermediate pipe yet. I referenced Corky Bell's "max boost" and the other popular book with the tuning crowd "How to Tune and Modify Engine Management Systems" by Hartman. Bell says 12.5-13.0 and Hartman says ~12-12.5 IF fuel is not used to cool intake charge air. I'm just worried that that's why my car was tuned to be that rich because I have no IC @6.5 psi. Also, I thought most on here were running lower AFRs with forced inductions. Lastly I checked Heywood's "Internal Combustion Engine Fundamentals" and it said I was okay.

Maybe I'm just being paranoid but I don't want to 1) run too lean 2) Be okay AFR wise but the extra fuel was used to cool the IAT especially with the warmer weather coming.

cablebandit

iTrader: (37)

ahh...shoot for 11.0-11.5 to start with to be safe...some folks report less than 20hp going up to 12.0-4

black98ws6ta

iTrader: (77)

That A/F is fine. Worry about it when it gets into the 12's.

HossinatorSS

iTrader: (1)

Okay, thanks for the help! I know there's a difference between guidelines/theory and actual practical applications. Thanks.

ZL1Killa

iTrader: (17)

you wouldn't believe the difference.. .just finished doing my car to simply the y-pipe.. going to do rest later (didn't have time to finish)

mcx

..ha ha ...i believe because i've done it as well[last summer]..mine is wrapped from the manifolds and all the way to the rear turbo.

HossinatorSS

iTrader: (1)

I definately noticed a difference too, and I only did from the cats to the "y". the boost definately comes on quicker and stronger than before. Just don't wanna blow anything up!