Test Pipe or HFC?

OMGiGOTaZ · 08-30-2012, 11:23 PM

Ok, i think i have decided to go test pipes, seems most natural imo, a straight pipe, no bs!

KingJoseph · 08-30-2012, 11:45 PM

I have HFCs, mainly because my buddy with a 350Z had test pipes and I felt like I was getting high on fumes when I drove his car. My other reason is that, last time I took my 350Z in for emissions, they did the sniffer test (I live in Washington State). Anybody successfully passed a sniffer test with test pipes on a VQ engine? Is it even possible?

OMGiGOTaZ · 08-31-2012, 10:53 AM

I'm in Florida, no sniff tests, but I'm counting on the Smell being sweet aroma as I'm mashing the throttle!

OMGiGOTaZ · 08-31-2012, 10:54 AM

Btw, swinging through a new Tuner shop in Oldsmar to check out the turn around time on the

chrischhorn · 08-31-2012, 07:28 PM

I've got the Stillen HFC's and im throwin a CEL light. Clears itself away randomly but comes back eventually. Going to try to get o2 bung extenders to see if i can stop it from throwing the CEL so I'll chime back in later. Anyone know the thread on the o2 sensors? 18X1.5mm i assume? that way i can i get the correct size.

OMGiGOTaZ · 09-01-2012, 12:19 AM

Well, work kept me from getting to the shop so hoping I can get some mods before the Nopi run so i'm not feeling so Stock and caught with my pants

Ronin06 · 06-15-2014, 12:42 PM

I know this is an older thread, but seems like some disinformation.

1) CEL thrown due to a change in CAT will be because the ECU has found the amount of pollutants is out of param and cannot correct the A/F ratio enough to bring it back in line. The easiest solution and recommended is to tune the vehicle. Simply deleting the sensor will likely leave the ECU in the last known state of the A/F ratio.

2) Test pipes will throw a CEL on a stock ECU. Your choice is to live with it, periodically reset it or delete the sensor through a program like Uprev.

3) HFC due to their construction will be more expensive and theoretically will pass emissions testing and not throw a CEL. In practice YMMV.

4) Free flowing exhaust will produce more HP on the top and mid range. Some engines may see a decrease in low end torque. IMO I would rather have the free flowing exhaust and take the increase in HP.

5) Changes in the exhaust system will result in sound changes. Some good, some bad depending upon your taste. Personally I can live with a little more sound outside the vehicle, but would not want increase in drone. Would also want to carry on a normal conversation inside the vehicle. My goal is increased HP with moderate increase in sound.

FuTuRe is Z · 06-17-2014, 02:50 AM

I always wondered where tuners take the AFRs readings from, a sniffer on the tail pipe or from the O2 sensors on the vehicle.

I'd imagine that if you had a j-shaped O2 bung it would read slightly leaner than if the bung where right inside the test pipe. Therefore you would tune with a bit more richer AFR to offset that.

I'm pretty sure people using J-shaped O2 bungs on there test pipes are leaving power on the table because the O2 sensor is getting an in accurate AFR. Correct me if I am wrong here.

brancky3 · 06-17-2014, 09:07 AM

Quote:

Originally Posted by FuTuRe is Z

I always wondered where tuners take the AFRs readings from, a sniffer on the tail pipe or from the O2 sensors on the vehicle.

I'd imagine that if you had a j-shaped O2 bung it would read slightly leaner than if the bung where right inside the test pipe. Therefore you would tune with a bit more richer AFR to offset that.

I'm pretty sure people using J-shaped O2 bungs on there test pipes are leaving power on the table because the O2 sensor is getting an in accurate AFR. Correct me if I am wrong here.

The second O2 sensor is on the test pipe / HFC, the first one is on the header (right?). AFR readings are only taken from the first sensor, the second sensor is merely a check to see if the cat is doing its job.

njobe89 · 06-17-2014, 10:43 AM

whats the best test pipe to get? when i was getting my intake installed, a guy was on the dyno and they were saying cause that art test pipes were restricting the flow and he wasn't getting as much hp as he should.

MadChemist · 06-17-2014, 11:59 AM

Quote:

Originally Posted by njobe89

whats the best test pipe to get? when i was getting my intake installed, a guy was on the dyno and they were saying cause that art test pipes were restricting the flow and he wasn't getting as much hp as he should.

That doesn't sound right. Test pipes are the least restrictive unless he managed to get test pipes with the wrong I.D. for his application.

da mayor · 06-17-2014, 12:11 PM

I loved my MXP test pipe and didn't throw a check engine light.

njobe89 · 06-17-2014, 12:27 PM

Quote:

Originally Posted by MadChemist

That doesn't sound right. Test pipes are the least restrictive unless he managed to get test pipes with the wrong I.D. for his application.

That could be a possibility.

08-30-2012, 11:23 PM	#16 (permalink)
OMGiGOTaZ Enthusiast Member Join Date: Jul 2012 Location: Florida Posts: 316 Drives: 12 370Z Auto Sport Rep Power: 13	Ok, i think i have decided to go test pipes, seems most natural imo, a straight pipe, no bs! __________________ all you gotta do is...

08-31-2012, 10:53 AM	#18 (permalink)
OMGiGOTaZ Enthusiast Member Join Date: Jul 2012 Location: Florida Posts: 316 Drives: 12 370Z Auto Sport Rep Power: 13	I'm in Florida, no sniff tests, but I'm counting on the Smell being sweet aroma as I'm mashing the throttle! __________________ all you gotta do is...

08-31-2012, 10:54 AM	#19 (permalink)
OMGiGOTaZ Enthusiast Member Join Date: Jul 2012 Location: Florida Posts: 316 Drives: 12 370Z Auto Sport Rep Power: 13	Btw, swinging through a new Tuner shop in Oldsmar to check out the turn around time on the __________________ all you gotta do is...

09-01-2012, 12:19 AM	#21 (permalink)
OMGiGOTaZ Enthusiast Member Join Date: Jul 2012 Location: Florida Posts: 316 Drives: 12 370Z Auto Sport Rep Power: 13	Well, work kept me from getting to the shop so hoping I can get some mods before the Nopi run so i'm not feeling so Stock and caught with my pants __________________ all you gotta do is...

06-17-2014, 10:43 AM	#25 (permalink)
njobe89 A True Z Fanatic Join Date: May 2014 Location: Atlanta, GA Posts: 5,227 Drives: 2013 370z BS 6MT Rep Power: 174284	whats the best test pipe to get? when i was getting my intake installed, a guy was on the dyno and they were saying cause that art test pipes were restricting the flow and he wasn't getting as much hp as he should. __________________ 2 plus 2 times 2 = ? ... hint, it's not 8 Stillen CBE, Stillen Gen 3, TP's, Uprev tuned - 324whp/264tq

08-30-2012, 11:45 PM	#17 (permalink)
KingJoseph Base Member Join Date: Jun 2012 Location: Redmond, WA Posts: 180 Drives: 2012 Nismo 370Z Rep Power: 13	I have HFCs, mainly because my buddy with a 350Z had test pipes and I felt like I was getting high on fumes when I drove his car. My other reason is that, last time I took my 350Z in for emissions, they did the sniffer test (I live in Washington State). Anybody successfully passed a sniffer test with test pipes on a VQ engine? Is it even possible?

08-31-2012, 07:28 PM	#20 (permalink)
chrischhorn A True Z Fanatic Join Date: Jan 2012 Location: Mililani, HI Posts: 1,566 Drives: 2014 Juke Nismo RS Rep Power: 16	I've got the Stillen HFC's and im throwin a CEL light. Clears itself away randomly but comes back eventually. Going to try to get o2 bung extenders to see if i can stop it from throwing the CEL so I'll chime back in later. Anyone know the thread on the o2 sensors? 18X1.5mm i assume? that way i can i get the correct size.

06-15-2014, 12:42 PM	#22 (permalink)
Ronin06 Base Member Join Date: Mar 2014 Location: Urbandale, Iowa Posts: 87 Drives: 14 silver sport 370Z Rep Power: 11	I know this is an older thread, but seems like some disinformation. 1) CEL thrown due to a change in CAT will be because the ECU has found the amount of pollutants is out of param and cannot correct the A/F ratio enough to bring it back in line. The easiest solution and recommended is to tune the vehicle. Simply deleting the sensor will likely leave the ECU in the last known state of the A/F ratio. 2) Test pipes will throw a CEL on a stock ECU. Your choice is to live with it, periodically reset it or delete the sensor through a program like Uprev. 3) HFC due to their construction will be more expensive and theoretically will pass emissions testing and not throw a CEL. In practice YMMV. 4) Free flowing exhaust will produce more HP on the top and mid range. Some engines may see a decrease in low end torque. IMO I would rather have the free flowing exhaust and take the increase in HP. 5) Changes in the exhaust system will result in sound changes. Some good, some bad depending upon your taste. Personally I can live with a little more sound outside the vehicle, but would not want increase in drone. Would also want to carry on a normal conversation inside the vehicle. My goal is increased HP with moderate increase in sound.

06-17-2014, 02:50 AM	#23 (permalink)
FuTuRe is Z Enthusiast Member Join Date: Nov 2013 Location: CT Posts: 263 Drives: 2014 370z Rep Power: 12	I always wondered where tuners take the AFRs readings from, a sniffer on the tail pipe or from the O2 sensors on the vehicle. I'd imagine that if you had a j-shaped O2 bung it would read slightly leaner than if the bung where right inside the test pipe. Therefore you would tune with a bit more richer AFR to offset that. I'm pretty sure people using J-shaped O2 bungs on there test pipes are leaving power on the table because the O2 sensor is getting an in accurate AFR. Correct me if I am wrong here.

06-17-2014, 12:11 PM	#27 (permalink)
da mayor Enthusiast Member Join Date: Dec 2009 Location: Long Island, NY Posts: 313 Drives: #TheGoldenZ Rep Power: 15	I loved my MXP test pipe and didn't throw a check engine light. __________________ #TheGoldenZ [GTSPEC][RAVSPEC][AutoVisionNY][631Coatings vinylwrapped][Evo-R][SoFreshLifestyle][Intrack Tires][Project Mu][MXP][HempsteadAutoCollision][SNTRL]

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