DopdBrd

iTrader: (25)

So I have dual cutouts welded behind my headers on my y pipe. I was just wondering, will they affect A/F ratio when open? I spray the car and don't want to run into any problems.

evilbeef54

iTrader: (2)

as long as they are after the 02 sensors it wont effect anything

DopdBrd

iTrader: (25)

Ok, would it cause the wideband to read a little off??? I may have been running a bit lean but my A/F was around 12.3 during the whole run and didn't know if the open cutouts affected it or not.

evilbeef54

iTrader: (2)

is the bung for the wideband before or after the cutout, lol

DopdBrd

iTrader: (25)

before

LS1 SPEED

iTrader: (22)

We have seen a difference on the dyno depending on the location.

EX 1 : F-body with a single cutout in I=pipe before axle..no change

EX 2 : any car we have seen which has them near or directly off the headers did change the A/F a 1/2 point or more leaner

evilbeef54

iTrader: (2)

any idea why that is, could it be a false reading becaue it is closefr to the o2 sensor? also how was that measued? wideband or tailpipe?

LS1 SPEED

iTrader: (22)

WB

moved sniffer to cutout location

I do not have the answer as to why it makes a difference compared to the cutout being further back in the exhaust.

DopdBrd

iTrader: (25)

Hmm....I am actually thinking about ditching my Hookers for a set of LPP's this spring, if I do I might go ahead and get a single cutout in the I pipe with and electric valve. Basically because then I will be spraying a 200 shot on the stock bottom end and I'm too lazy to get under the car and uncap them LOL

LS1 SPEED

iTrader: (22)

sounds like a good plan

evilbeef54

iTrader: (2)

i planned on doing the QTP electric cutout but the only way it would mount flush aginst the manual cutout was with the electric motor pointing straight at the ground, which would only give about .5" of clearance, so needless to say that didn't work, I ended up just leaving it as a manual cutout (which i have no problems opening and closing at the track, even with a lowered car) and i saved the $200 for go fast parts, instead of convience parts

DopdBrd

iTrader: (25)

True. I had two Summit brand electric cutouts. They were actually good looking quality and worked very well, but when I mounted them on the cutouts they too were about 1/2" off the ground. I just sent them back to summit and got my money back. I think it was only 250 for two cutouts and the wiring kit.

LS1 SPEED

iTrader: (22)

The cutout has to be welded in properly to fit a E-cutout with clearance. I have a 4" exhaust, DMH cutout and a lowered car...no ground clearance issues.

evilbeef54

iTrader: (2)

yea for the electric cutout it would have either had to be welded up with the cutout facing in to the middle of the car instead of out to the door, or the tube would have to be cut and re-welded for the specific combo i had to mount it with out the motor pointing at the ground, i just said screw it and sent the part pack to summit and used the $$ elsewhere

white2001s10

iTrader: (4)

Reversion does affect WBO2 readings with a cutout. The closer to the engine the cutout is the worse the reversion.

WBO2 readings aside, a cutout will usually lean out the burn in the chamber.
How much depends on how much backpressure you have before opening the cutout. If you are running near the lean limit corked up, then yes it might cause you a problem.

In the "old days" guys had to jet up the carb & pump shot for running open exhaust.