Exhaust Change - Re-tune Required?

[Christov]

Howdy,

 

I'm looking to change my exhaust, currently my car is tuned to 380rwkw. Current exhaust system is - factory dump pipe, venom high flow cat and cat pipe. Factory catback with middle muffler removed.

 

I am only looking at changing my exhaust from the cat back, to either a venom cat back or something similar.

 

Question is, will I need a re-tune?

 

I've heard mixed reports.

[k31th]

cat-back is fine to change, most of the time, as that doesn't change flow characteristics anywhere near as much as a the catalytic convertor or the dump pipe. Change it, but don't hammer the crap out of it straight away and get it run up on a dyno to check that the AFR's are stable and then you can go on with it as-is. If it doesn't run up with stable AFR's compared to your current tune, then you should get a re-tune to suit your setup

 

good luck

[Christov]

That’s a very sensible idea, thank you!

 

Do you think it would be possible to check if it’s running lean based on the OBD2 reader for oxygen sensors on each bank?

 

My tuner is a long way away from me so I’m trying to avoid having to go there.

[k31th]

that's basically how a dyno run would check it, but it's better to be able to log it completely to check all of the load points. A dyno is the best for that sort of thing.

[Puffwagon]

1 hour ago, Christov said:

will I need a re-tune?

Tl;dr probably not but check it to be safe.

 

23 minutes ago, Christov said:

Do you think it would be possible to check if it’s running lean based on the OBD2 reader for oxygen sensors on each bank?

Short answer is no as narrow bands will only tell you if you are richer or leaner than 14.7:1. It's only good for cruise tuning.

 

Keith summed it up. It's safer to check.

 

Rather than go to your tuner you could order a wideband online, weld in a bung and check it yourself if you know how.

 

It should be fine though cos no one should let a car go from the shop on the ragged edge of not enough fuel...but ya never know...so get it checked one way or the other.

 

2 minutes ago, k31th said:

check all of the load points.

A shop will just check WOT and maybe half throttle then go for a drive around the block to make sure it drives ok. That's all you need to do. Ain't no one got time for checking all the load points.

[Christov]

Cheers Puffwagon

[Puffwagon]

No probs.

[stretch4660]

So can I fit my venom 3 inch turbo back with hi-flow cat and baby the car around for a few weeks before I go get it tuned, I’ll be buggered if I’m paying someone else $200 to fit it when I can do it myself no worries for free.? ?

 

Basically can I drive with hi-flow cat without a retune, but take it easy or not.?

[k31th]

yes, you can drive it around without using boost, no worries.

[stretch4660]

Fantastic, thank you sir