Boy does a catted custom y suck some power
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From: Fuquay-Varina, NC
Dart 225's, Futral F14 highlift, custom 3" y/magnaflow cats, bolt ons dyno Well, I finally have before and after dyno numbers. The first set is with a cut up and rewelded Pacesetter Y. The second dyno is with a custom Y with Magnaflow 59959 3" metallic core cats. I no longer gag on fuel smell, nor do any other poor lifeforms behind me in traffic, so I guess that is worth a lot. I also no longer have the gargle/rasp between 2200-2700 on normal acceleration. I may have had the Borla wide open on the first dyno and used the next one smaller on my last one. . I guess I'll have to get a Fast setup just to get where I once was..... Oh well. I'll get a FTRA or SLP one and head to the track soon and see how it does. Sidenote on my setup, compression is right at stock since we couldn't mill the heads due to ptv clearance due to overlap/etc.
http://i25.photobucket.com/albums/c7...smooth5ORY.jpg
http://i25.photobucket.com/albums/c7...mooth5cats.jpg
http://i25.photobucket.com/albums/c7...smooth5ORY.jpg
http://i25.photobucket.com/albums/c7...mooth5cats.jpg
Last edited by Redlinez; Jul 31, 2008 at 01:25 PM.
Your power is missing because the tune is way off assuming their O2's are even remotely close.
Get the A/F ratio in the mid/high 12's around the peak TQ area and the 13.0 range around peak power (and past peak) and it will feel like a different car. You lost power because what you changed effected the scavaging of the exhaust system and now you have to properly tune for it.
Maybe it wont be the same as before but you will not be down nearly what you are now....I bet you are within a few ponies of your previous best with the right tune.
Do not continue to beat on your car till you get it retuned....its lean enough to be a reliability concern and you might lift or break a ring lind with #7 cylinder being the first to go.
Tony
PS....I agree with the other posters comment that it looks like the same graph and also the next time you tune it have them provide you with a print out set to "smoothing 5".....it does just what it sounds like smoothing the peaks and valleys of the recorded data for easier viewing. Low smoothing settings just give you an artificial spiked number for a peak....a popular way some guys can brag about a few more peak ponies and foot/lbs of torque but smoothing five makes it easier to see real trends (up or down) in the power curve.
Get the A/F ratio in the mid/high 12's around the peak TQ area and the 13.0 range around peak power (and past peak) and it will feel like a different car. You lost power because what you changed effected the scavaging of the exhaust system and now you have to properly tune for it.
Maybe it wont be the same as before but you will not be down nearly what you are now....I bet you are within a few ponies of your previous best with the right tune.
Do not continue to beat on your car till you get it retuned....its lean enough to be a reliability concern and you might lift or break a ring lind with #7 cylinder being the first to go.
Tony
PS....I agree with the other posters comment that it looks like the same graph and also the next time you tune it have them provide you with a print out set to "smoothing 5".....it does just what it sounds like smoothing the peaks and valleys of the recorded data for easier viewing. Low smoothing settings just give you an artificial spiked number for a peak....a popular way some guys can brag about a few more peak ponies and foot/lbs of torque but smoothing five makes it easier to see real trends (up or down) in the power curve.
Last edited by Tony Mamo @ AFR; Jul 28, 2008 at 07:55 AM.
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From: Fuquay-Varina, NC
Yea, that's me..... Ok, I fixed the dyno for the cats to have the same smoothing. Maybe Jay from Mayhem will chime in. I feel they have a good handle on what they're doing and they're not the internet posting dyno war types. Maybe he did do a different A/F tune for the street. I'll have to inquire, but I really appreciate the concerns and I'll ask them about it. I did take it back for a dyno retune right after having the catted Y installed, these are from last week. I set them both to smoothing 5 now.
Last edited by Redlinez; Jul 27, 2008 at 07:20 PM.
Launching!
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From: Raleigh, NC
Mike has the graphs on file so he can set the smoothing to whatever he would like. We have not and will not ever artificially inflate dyno numbers through any "dyno tricks". 14:1 out the tailpipe through cats is not lean on our setup...it equates to roughly 13.0 with a wideband right off the header. I'm more than happy to show what a richer a/f ratio did on his setup....he was in the low 400s prior to making adjustments.
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From: Fuquay-Varina, NC
Thanks Jay! I thought I would have heard some spark knock too, which you know I can hear quite well...... 401rwhp to be exact as I drove it to you.
401rwhp to be exact as I drove it to you. Last edited by Redlinez; Jul 31, 2008 at 01:25 PM.