I'm going to be making a downpipe with an e-cutout and I was wondering where to put the cutout. I'd like to put it directly after the turbo exhaust, much like this design.


I'm debating between that design and possibly locating the cutout closer to the cat.

What I'm wondering is if having the cutout so close to the turbo exhaust will create a negative effect. What I've heard is that turbo's like to have back pressure. This would greatly reduce back pressue....is this a bad idea?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by asianspeed &raquo;</TD></TR><TR><TD CLASS="quote">What I'm wondering is if having the cutout so close to the turbo exhaust will create a negative effect. What I've heard is that turbo's like to have back pressure. </TD></TR></TABLE>

You've heard drastically wrong. Turbos love low pressure, it's one of the best things you can do for your turbo to increase efficiency provided it doesn't create boost creep. Why do you think everyone gets the biggest damn downpipe they can fit?

The ONLY downside to that setup is that a shop will worry about you melting the dyno straps. That's "pretty" close to how mine is in terms of where the exit is.

With this setup spool drops a good 500 rpm and it makes a buttload more power at the same boost for me Just make SURE you tune for the dump OPEN not closed!! High backpressure creates false 'rich' readings on widebands.

Oh yeah, I should also mention that if you want to be a stickler for track rules, the rules at MY track state that all dumps must exit behind the driver's seat. So technically I have an illegal setup, but they've never called me on it. Your call if you want to risk it.

 

also one other thing to take into consideration...is intake charge contamination...you dont want any exhuast gases gettin sucked back into the turbo...i have a 3" ubend that pretty much does a 180 off the turbine and heads right towards the drivers side...just below my oil drain heading towards the front drivers side tire....works well and i have spliced into the mandrel bend w/ my stock exh...so when i put my plate on the end of the 3" bend...it routes thur the stock exh...

from the tiny gsr exh &gt; open dp on my ls/vtec w/ hx35 turbo i see about a 6-700rpm decrease in full boost...and it spikes a hair

 

my cutout is right under the steering rack, or where my feet are on the drivers side. i put it that far back so i could get an o2 sensor before the cutout for tuning/monitoring purposes. it does make a very noticeable difference in power over a full exhaust.


downside- good chance you will creep. cutout open i run a solid 3 psi above the wastegate spring, and it would occasionaly creep up a few more psi about 7k rpms and up

 

like drumking said routing it like in the pic is a terrible idea. There will be huge contamination of the intake charge.

 

search the ecut threads. there's one where tony1 posted an ecut that he did. it looks really good. he had it designed to come out after the oil pan before the cat i think.

 

Im thinking of doing an ecut setup with a recirculating dump

Can you pass emissions with setups like these?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by undercoverdc2 &raquo;</TD></TR><TR><TD CLASS="quote">search the ecut threads. there's one where tony1 posted an ecut that he did. it looks really good. he had it designed to come out after the oil pan before the cat i think.</TD></TR></TABLE>

that was my thread, here's the link. tony's pic isnt up tho, but there are a few others.

https://honda-tech.com/zerothread?id=1470648

 

tony1's pic dont work

I made a thread myself

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Oceanic &raquo;</TD></TR><TR><TD CLASS="quote">Im thinking of doing an ecut setup with a recirculating dump

Can you pass emissions with setups like these?</TD></TR></TABLE>mine reciculates about 18" away from the turbo...in the 2.5" splice going to the stock exh...

and yes it will pass as long as the cutout isnt leaking! if you have a hard time get the tuning right...make a pipe that literally goes from the wg port to the exh...and make a plate to block off the turbo...run it w/ stock maps & injectors and call it a day

 

cable driven seems to be the only way, who makes them

 

i think that pic is a good idea,
just add an extension to the cut out, so it dumps the exhaust away from the engine compartment..

 

If there is a mechanical unit I would

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by raene &raquo;</TD></TR><TR><TD CLASS="quote">

High backpressure creates false 'rich' readings on widebands.
</TD></TR></TABLE>

Really? How is that?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by adseguy &raquo;</TD></TR><TR><TD CLASS="quote">

Really? How is that?</TD></TR></TABLE>

i only speak from experience and ive notice the slight a/f changes...

but id say its not because of the exh...its because of the reduced pressure differential not apparent w/ a restrictive stock exh & cat

 

So would I be just as well off putting the cutout after the oil pan? That way the exhaust gases don't recirculate in the engine bay...and I'll be legal on the track.... I won't be a pain in the *** while on the dyno...and I won't get boost spikes. I think that's more than enough reason to put the cutout further down the pipe, but definately before the cat for sure!

 

I think the closer to the turbo the better pwoer your gonna make, need room for all your sensors though i suppose

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Oceanic &raquo;</TD></TR><TR><TD CLASS="quote">I think the closer to the turbo the better pwoer your gonna make, need room for all your sensors though i suppose</TD></TR></TABLE>

Can anyone confirm that having the cutout too close to the turbo can cause boost spikes?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by raene &raquo;</TD></TR><TR><TD CLASS="quote">High backpressure creates false 'rich' readings on widebands. </TD></TR></TABLE>
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by adseguy &raquo;</TD></TR><TR><TD CLASS="quote">Really? How is that?</TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Another effect is that higher pressures contain more oxygen and fuel molecules and thus require a larger pump current to come to equilibrium. This gives the indication the mixture is richer than it would be if measured at normal atmospheric pressure. This effect is particularly important for turbo engines where poor sensor placement can fool you into thinking you have a richer mixture than you really have. </TD></TR></TABLE>

From TechEdge... read up...

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">All pump cell wideband sensors are pressure sensitive. They should not be placed where the working gas pressure is much above or below atmospheric pressure, otherwise different calibration curves must be used for best accuracy. </TD></TR></TABLE>

 

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by raene &raquo;</TD></TR><TR><TD CLASS="quote">

From TechEdge... read up...

</TD></TR></TABLE>

I knew how they worked, but that was a good read. Thanks!