Have any of you guys had your car tuned open downpipe? Then later on put on a high flow cat and exhaust? I don't know if I'm going to have the tiime to get my 3" exhaust welded up back from the 3" downpipe. Will I run into problems since the exhaust will richen it up a tad probably? Like hesitation or anything? The car is being tuned with hondata. Thanks.

Nate

 

The only problem i can think of tuning wise, would be the spool up characteristics of the turbo with an open exhaust and with an exhaust. You will have a little bit more lag with a full 3" exhaust compared to just a 3" downpipe. But you will just run a little rich before you start boosting. So unless the car starts bogging out before you hit boost. You could probably lean it out for a couple more hundred rpm before the turbo hits full boost.

 

Remember the 'theory' of the honda engine managament, is RPM vs Pressure.
The ecu has no idea of the change in FLOW created by the 'new' exhaust.

The car will run richer if you tune with an open downpipe and swap in
ANY exhaust.

This is a better scenario than tuning with a small exhaust and then running
an open downpipe. (you'll go lean in this case)

My personal opinion is that you'll need a re-tune But, it'll run fine without it.

Jeffrey Atwood

 

Ok, maybe I should try and get it welded up then.. thanks guys.

 

hhmm...so if someones setup is a 3"DP w/ an e-cutout, carsound cat, 3" exhaust. (cutout used for track use) is it better to tune w/ the cut out open? and would there be a substantial difference in the a/f change?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18Flip &raquo;</TD></TR><TR><TD CLASS="quote">would there be a substantial difference in the a/f change?</TD></TR></TABLE>

This is a very difficult question to answer. It depends on the amount of backpressure with the cutout open and closed, and the rest of the setup.

I'd say .5 to 1 points in A/F ratio, but that is a very broad guess.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18Flip &raquo;</TD></TR><TR><TD CLASS="quote">hhmm...so if someones setup is a 3"DP w/ an e-cutout, carsound cat, 3" exhaust. (cutout used for track use) is it better to tune w/ the cut out open? and would there be a substantial difference in the a/f change?</TD></TR></TABLE>

Tune with it open, yes.

 

i tuned with an open 3" dp because i didn't have exhaust yet. now i have a full 3" exhaust and i'm running a little rich. it actually feels better with the exhaust on - with open downpipe there was a huge loss of power in daily driving (before boost). not a big deal either way, i don't have any lag or cutout after adding the exhaust.

 

hmmm. decisions, decisions

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18bEK &raquo;</TD></TR><TR><TD CLASS="quote">i tuned with an open 3" dp because i didn't have exhaust yet. now i have a full 3" exhaust and i'm running a little rich. it actually feels better with the exhaust on - with open downpipe there was a huge loss of power in daily driving (before boost). not a big deal either way, i don't have any lag or cutout after adding the exhaust.</TD></TR></TABLE>

me too.. it feels **** slow before the boost hits with the cutout open