Hi, just a quick question, my car was tuned at a 11:5:1 A/F at 8 pounds or so.....on a greddy cat-back with a 2.25" test pipe and 2.5" DP.

Now I'm planning on putting a 2.5" cutout on my DP, I know it will become leaner but will it become lean to the point where I would have to get a re-tune ? Let me know thanks !

 

my a/f ratio or boost didnt change at all when i installed my e-cutout. nothing that noticable anyways. i guess because it was a cutout and not open downpipe.. because half the exhaust still goes out the back. every setup is different though.

 

What kind of gains can you see with one of these things at the same psi ?

 

I've seen between .3-.5 leaner with my setup(e-cutout). Try it and see is the best I can tell you. As long as you stay below 12:1, you'll be fine.

 

my car runs about .5 leaner... this on an all-motor set-up though

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18cHatch06 &raquo;</TD></TR><TR><TD CLASS="quote">my car runs about .5 leaner... this on an all-motor set-up though</TD></TR></TABLE>
mine probably runs .5-.7 leaner on a boosted motor. Versus 2.25" full exhaust with 2.5" downpipe and cutout.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Offer &raquo;</TD></TR><TR><TD CLASS="quote">Hi, just a quick question, my car was tuned at a 11:5:1 A/F at 8 pounds or so.....on a greddy cat-back with a 2.25" test pipe and 2.5" DP.

Now I'm planning on putting a 2.5" cutout on my DP, I know it will become leaner but will it become lean to the point where I would have to get a re-tune ? Let me know thanks !</TD></TR></TABLE>

tune it with the E-cut OPEN. you won't have any problem. I'm using one too and once you get it, I don't think you'd want to close it unless you're going out to see you GF at night. lol

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Offer &raquo;</TD></TR><TR><TD CLASS="quote">What kind of gains can you see with one of these things at the same psi ?</TD></TR></TABLE>

it depends but in my car it pulls GOOD.

 

or next to a cop in cali

 

tune with the cutout open, then when its closed you might be half a point richer or so. you will more than likely see less boost or at least slower spool wiht it closed though, so be ready for that to happen

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by blackeg &raquo;</TD></TR><TR><TD CLASS="quote">tune with the cutout open, then when its closed you might be half a point richer or so. you will more than likely see less boost or at least slower spool wiht it closed though, so be ready for that to happen</TD></TR></TABLE>

I've actually seen quicker spool with mine closed. It doesnt begin to spool as fast, but it hits full boost quicker and moves the powerband down a little

 

going from a 3" downpipe with a tapered 2.5" exhaust and stock muffler TO a 3' open downpipe i went from about 11.8:1 (muffler) to about 13.0:1 (3" open downpipe) and my boost went from 10psi to 13psi. just a heads up...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by the.hamburglar &raquo;</TD></TR><TR><TD CLASS="quote">going from a 3" downpipe with a tapered 2.5" exhaust and stock muffler TO a 3' open downpipe i went from about 11.8:1 (muffler) to about 13.0:1 (3" open downpipe) and my boost went from 10psi to 13psi. just a heads up...</TD></TR></TABLE>

was that on a internal wastegate ?

 

you need to tune your car with the E-cut open... that's way too off. My boost level never changed. weird.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hoya_10fintec &raquo;</TD></TR><TR><TD CLASS="quote">you need to tune your car with the E-cut open... that's way too off. My boost level never changed. weird. </TD></TR></TABLE>
its common to reach higher boost levels when you free up your exhaust.

 

So if I have a 8.7 psi spring in my tial 38mm...and I add the cutout....will it intend to boost higher then 8.7-9 ??

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SOHC_MShue &raquo;</TD></TR><TR><TD CLASS="quote">
its common to reach higher boost levels when you free up your exhaust. </TD></TR></TABLE>

well i guess my exhaust was already pretty free flowing then...

 

The AFR is not the only thing to consider. A significant change in backpressure will also change the ignition timing requirements. If you are already tuned with it closed, I would re-tune with it open.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Offer &raquo;</TD></TR><TR><TD CLASS="quote">So if I have a 8.7 psi spring in my tial 38mm...and I add the cutout....will it intend to boost higher then 8.7-9 ??</TD></TR></TABLE>

my car has an 8.7 psi spring and it makes no less than 12 psi without even a boost controller installed. thats with a full 3" downpipe and exhaust