JAX04

iTrader: (17)

that, and every single instruction manual ive ever read says to place the sensor after the turbo.

mike13

iTrader: (27)

The reason I'm asking so many questions is because common theory is not pre turbo, also people so they wouldn't trust someone taking reading from the tailpipe. What do you do if you have a rearmount that has a foot of piping after the turbo? Also taking into account if you take a reading post turbo you need to splice and extend the wiring harness which also affects resistance.

XtremeDime

iTrader: (16)

Im running a foot of downpipe off my front mount and it does give some inaccurate readings at idle and low RPMs but during part throttle or WOT the readings are good.

mike13

iTrader: (27)

I looked into that and talked to a Bosch rep, he said the concern is damage from the heat retained pre turbo and that most stock applications have cast iron manifolds and the turbo integrated or mounted to the cast manifold.

Again not disagreeing with anyone, just questioning on a rearmount which is the better answer for a imperfect installation.

Pre turbo- high pressure

post turbo- extending the harness, tailpipe type reading, cooler exhaust

here's some information from another site regarding mounting a WB on a rearmount.

Innovate say after the turbo, but before the cats. That would work on a front mount setup.
I called Innovate and they were on the side that said: install the bung before the cats and before the turbo.
See how confusing it is, lol.

i sure don't, but check out innovate, they have all the accessories, I saw a sensor there too.

thanks,
allen
Performance Programming and Installation
Nelson Performance

'94 Chevy Truck, ls swap w/ twins
Turbocharged Dragalanche

r572cobra

should I extend the wiring on the gauge side,or the sensor side.if i put it in the down pipe.

mike13

iTrader: (27)

I would extend it on the sensor side.

OUTLAWZ RACING

iTrader: (9)

I ran mine in the passenger side exhaust tube. And I never had a problem with it. I ran it after the turbo befor and it read slow. I had a it 2 inches away from the impeller with a turn down. I had the car tuned again after some mods, and relocated wideband bunge and the Afr was good. Even when I dynoed it in Ga the reading where .3 tnh differant with the o2 screwd into the hole in my down pipe. I guess pressure wasent a issue because of my exhaust desighn.

JAX04

iTrader: (17)

this is an interesting thought "scratches head"??????????

and as far as reading slow, i dont know, but mine is pretty darn instant, and when i even tap the throttle i see and instant result,

but hey, we all have different experiences and thats why we have a forum. so people can gather information from both sides of the spectrum and make an educated decision.

mike13

iTrader: (27)

That's why I enjoy all of the opinions.

Turbo 6.0

I extended mine on the gauge side so that if the sensor goes bad I can just swap it out for a new one without haveing to extend it.

Is there a reason extending it on the sensor side would be better?

Turbo 6.0

How is installing the wideband post turbo different than the wideband in the tailpipe at the dyno?

Zombie

iTrader: (2)

pre turbo means a/f will be skewed by high pressure. The NTK sensors are more prone to this than the more common Bosch. Since I use L1H1/L2H2 sensors in my cars I've noticed this when having the wideband pre turbo. A/f was off by as much as 1.8 AFR with really high back pressure. (verified by using pre and post turbo widebands).

My super safe 10.8:1 afr turned out to be mid 12's afr under full boost. Thankfully I never hurt anything due to being conservative on tuning.

Turbo 6.0

So...... it seems like the most common target AFR on pump gas here is about 11.5 +or- .3

I have been hearing differently recently......

I have a buddy who just finished a turbo system on his E28 325 BMW. He is on a few BMW forums and all the turbo guys there are saying to run a 12.5 AFR on pump gas. That seems more like a rich NA AFR to me?

I also talked to guy who is into older nissan's and he also said that they shoot for a 12.5 AFR. He then said "I know that kind of rich but I like to be on the safe side."

Both of these guys are running on pump gas too. Does this make sense to anybody here? Are they just running on the ragged edge? Would different cars/applications be able to run that AFR for some reason?

Zombie

iTrader: (2)

Different motors react differently to AFRs. I've noticed on LS1's that they power only changes 2-3 HP from 12.0- 13.0 and I've tried it on multiple cars.

My own car doesn't start losing power until I go richer than 11.0 on 91 oct and E85 doesn't seem to care if the AFR is 10.5-12.0. The Evo 8-9 motors love being run at 12.0 on E85 or 91 and going richer drops power pretty quick.

All testing was done on a Mustang MD500.

Everyone does their own thing with tuning and I'm no exception. I like rich AFRs because they give a bigger margin of error. I'd rather sacrifice a few HP than a whole motor.

Turbo 6.0

Lets talk about water/meth injection and AFR..........

If you are spraying pure meth, 50/50 water meth, or -20 windshield wiper fluid what effect will the different fluids have on the AFR?

Are you still aiming for 11.5 AFR and just spray the water/meth on top thus richening up the AFR (11.0 or lower) or do you lean the base AFR out to achieve 11.5 AFR while spraying?

I know IAT sensor location (before or after nozzle and IAT timing table tuning) is a big factor here so lets talk about that too. Who is adding timing with the lower IAT's achieved with the water/meth spray?

mike13

iTrader: (27)

If you extend it on the gauge side you can't undo it if doesn't work to your satisfaction, you can shorten the wires but you'll always have splices. If you extend it on the sensor side you can replace the sensor and no harm no foul.
That's all.

r572cobra

thanks,I will do the sensor side,i had it right after the header,and it stop working,aem set up.only running 7psi.only 2 years old,never ran leaded fuel.

CALL911

iTrader: (17)

FWIW Bob is correct. You want to aim for around 11.5 ideally. The higher the number actually means the leaner it is. (This may be what is trying to be stated, but it didn't seem like it).

I have heard of some guys running leaner (as in 12.0 - 12.5) and getting a little more power, but that is running pretty lean for an FI car. If you want it to last more than you want an extra 10 RWHP, leave it at 11.5

Also, running meth definatly makes it more rich. I can read my wide band and see it dip to 10.9 momentarily when the meth kicks in until my tune leans it back out to 11.5

98Z28CobraKiller

iTrader: (17)

Just target the same AFR. You'll want you IAT post meth injection and as close to the TB as possible to get the most accurate reading but don't spray the IAT with the meth directly. Meth/water will increase the octane which, along with the cooler charge temps, should allow you to run more timing. Whether that equals more power will depend on the setup.

Johnv

Interesting...
So your saying when spraying 100% meth you would pull fuel to get back to that 11.5-8 AFR
always thought we needed to have a richer target AFR (low 11s) when spraying.

My car runs 11.8 afr on pump only and dips to 11.2afr when spraying (100% meth, 12 gal/hr jet, 250psi pump)
I haven't touched fueling just added timing, works well but maybe there is more to be had with a leaner AFR as well ??