Cam change with no tune
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Pro
Joined: Jan 2017
Posts: 638
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Cam change with no tune
I had a HCI setup tuned on the dyno. AFR was 12.5 and about 25 degrees of timing. I then switch to a bigger cam. The tuner I usually use was about 3 months backed up so I decided to put it on the dyno just to check numbers. AFR is now 13.0 and timing didn't change. No signs of knock or timing retard on the data log. Not gunna lie, I've been driving it all summer like that. Should I just leave it alone or should I bring it back in to get tuned for the other cam I put it there? Thanks all!
Pro
Joined: Aug 2007
Posts: 599
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From: citrus heights ca
13.0 is getting pretty lean.some say you can go 13.5 but to me that's too much risk.for safe tune you want 12.5-12.7
you're probably leaving hp on the table by not re-tuning but depending on what your tuner charges would it be worth paying it for maybe 10hp more.if it were me would re-tune just to get the afr to a safer number.
you're probably leaving hp on the table by not re-tuning but depending on what your tuner charges would it be worth paying it for maybe 10hp more.if it were me would re-tune just to get the afr to a safer number.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
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From: CA.
St. Jude Donor '13-'14-'15
Depends on where you are getting the 25* timing figure---Are you talking about the "commanded timing" that is asked for by your tune ? OR are you talking about the "actual timing" recorded by a data logger ???
Huge difference------Larger cam swaps most always require a re-tune--for best HP and TQ and for engine safety----
Simple rule is if you ADD more airflow----you need to ADD more fuel--Hence why your AFR's went lean--- Safe lean AFR's will make more top end HP----- However richer AFR's will make more TQ---which may be a better way to go---foe engine safety and bottom end launch---
Huge difference------Larger cam swaps most always require a re-tune--for best HP and TQ and for engine safety----
Simple rule is if you ADD more airflow----you need to ADD more fuel--Hence why your AFR's went lean--- Safe lean AFR's will make more top end HP----- However richer AFR's will make more TQ---which may be a better way to go---foe engine safety and bottom end launch---
