Scavenging/Exhaust efficiency with E Cutout

Hey, I've been considering running an e-cutout on my built gsr engine. I will be adding a chambered exhaust for quiet street driving, but need some more flow for this setup when racing/at the track. I have been reading up on the e-cutout and despite it being a turbo fave... I know it would work to some extent on n/a hondas... so here are my concerns:

I plan to install the cutout where my cat is currently located... right after the header collector on 2.5" piping.

With a properly designed header, the exhaust pulses travel thru the primaries, then as the low pressure rear end of the pulse leaves, it causes a suction effect... assisting in pulling out the following pulses... resulting in good tq #'s. The collector plays a large role in this process... and as we know.. a properly designed collector can easily impact overall header/exhaust performance. For this very reason, I find installing the cutout at the cat's location would be perfect as the collector has done it's job and the gases are on the way out.

BUT... I also know a properly designed exhaust goes from the port to the muffler....with a nice, smooth flow transition.... further heightening the extraction effect. NOW... installing a cutout WOULD allow you to run close to open header at your discretion, BUT, while the cutout is closed... it would be nice to have good low end street performance from the engine... what my concern would be is that while the cutout is closed... wouldn't the non-existent walls of the capped 'Y' off the piping cause unnecessary turbulence and lost velocity in the exhaust flow... possibly creating a slight restriction (High pressure) right after the collector ?

I mean... with the closed exhaust system... could the cutout be doing more bad than good ? I figure the turbulence would adversely affect torque production at lower rpm.

Now away from that...When it's open, one would expect the cutout to easily gain a couple (if not a few) horses and a lil torque. I know just uncapping my exhaust slightly rewards me with gains in Tq and Hp and that's with a 2.5" mandrel exhaust and an N1 w/ silencer !!

So, reading this... anyone have any insight into the effects of the CLOSED cutout ?

X2

 

Most people run e-cut because they want to run a stock/quiet exhaust when the e-cut is closed (normal driving), and all out power along with the horrendous noise when it's opened (racing). So naturally, those guys don't really care how the car performs when the e-cut is closed.

Since you would have to run some sort of a y-pipe for the e-cut, this means when the e-cut is closed, then there will definitely will be turbulance when the exhaust gas hits back, causing powerloss.

So if you want to compare performance between a closed e-cut vs 2.5" cat-back exhaust, there's no doubt that a regular 2.5" cat-back will make more power (no turbulance) than the closed e-cut.

However, if you want to compare an open e-cut vs 2.5" cat-back exhaust, then the gains are debatable. While you may gain peak and top end power with the e-cut open, you may also lose mid-range power along the way (for NA cars).

Your tuning will also change when the e-cut is opened or closed. In most cases, your car will run leaner with the e-cut open (which may enable or prohibit you to run more or less ign timing). So unless you have a standalone with multiple maps tuned for different setting, then you would have to choose which a setting you want to tune your car with.

I know a couple of people who tried e-cut and then junked the setup a short while later. The ground clearance is absolutely terrible with the e-cut installed (scraping going over speedbumps, mall entrances, potholes, etc.), it's a bitch to wait for the e-cut to open when you hit the switch, unliable (e-cut seizing up), and exhaust leak (e-cut plate).

For all-motor application, I would stay away from e-cut, IMO.

 

Well, I've been considering it... and I know about the tuning downsides (richer when closed) and I would prolly run stock timing and tune it opened... but this whole turbulence thing bothers me some.

I would only open the cutout when racing (which I do 90% of at the track)... so I am trying to figure whether I should just eat it and unbolt the muffler at the track OR spend the $$ on the cutout so I can get the extra power on demand. I KNOW if I run a chambered exhaust w/o a cutout... my setup will just NOT make the power it should.... but I need some silence on the street... this is my daily driver !

 

If you're not planning to race with the e-cut closed, then I wouldn't worry too much about turbulance. Turbulance would just decrease the efficiency of the exhaust system (poor exhaust scavenging), and contaminates the intake charge which also decrease the efficiency of the motor. It won't cause the motor to blow up or anything.

From what I have seen and witnessed, e-cut is nowhere near streetable as people advertised to be. Like I said before, if you want to mount the e-cut near where the cat converter is located, then the ground clearance is just absolutely terrible. The e-cut flange is so close to the ground that it scrapes like a bitch when going over speed bumps and road irregularities. You can't mount it higher as the e-cut flange will hit the chassis. The e-cut seizes over time, it leaks, it's slow.... I really think you're better off running a twin loop muffler like DC Sports or Hytech if you want to reduce noise with little powerloss.

The e-cut used to be a big hype, but then it died down rapidly. I guess people like myself found out that the e-cut only looks good on paper.

For turbo application, maybe there's big power to be gained from an e-cut, but for all-motor, I just don't think it's worth the hassle.

 

good points there

 

Great points made by all! I have been researching this same issue, as i love the power boost and the noise at times, but being pulled over by the damn cops out here in OC, kali like every FuC*in week, its damn annoying. But TURBULENCE, lets discuss. I am hesitant about getting it for the same reason, but look at this picture.



now i dont exaclty know how this works, as i have never handled one in person, but what if you mount this e-cutout with the way its facing where the top of the picture would be the front of the car. then welding your main exhaust pipe from your cat to the single input on the top of the picture. Then when its closed, it would be as a strait pipe, I DONT SEE ANY REASON you would have turbulence. and when its opened, air would escape out the exit port to the Right (passenger side of the car). are you guys following me. I mean this all depends where the hell the metal piece is blocking the channel is located on the inside of this design. But personally if i designed it, it would be VERY simple to rid the turbulence issue. The only reason i could see a turbulence issue, is if the "end" of the Y shaped exit pipe was capped, then you would have turbulence issues. But this one seems as though its inside at the point at which the exit pipe starts. Hence no turbulence. maybe the Electronic ones have it at the end, if thats the issue, say away from it and buy this one. **** its only 40$ instead of the 180$ they want for the electric one, and this comes with a 5 ft cable to operate inside your car

 

A header + setup designed/tuned to be run open is going to suck with any exhaust bolted up to it. You might as well just run open header and forget about power concerns when the exhaust is hooked up.

e-cutouts are junk and break, thats why the turbo guys don't run them much.

Most of the manual cutouts aren't very high quality, either, but I've been told there are one or two of decent quality out there - just buyer beware, eh?

 

when you say designed/tuned, what does that really mean. like how are you tuning the car. and basically your saying, it will run good for performance when you have it open, but when closed, basically dont think about speed and performance? But does this necessarily mean the car will run like ****, or will it just run as normal with a regular exhaust system

-josh

 

The electric cutout is capped at the end... hence my initial concerns. That manual one does not have a nice smooth block plate either, I believe the block plate is located in the side pipe, so it would promote a lil turbulence.

 

You manipulate VE when alternating between open header and exhaust. On a speed density EFI, you go rich/lean accordingly, and your ideal ignition timing changes slightly also.

 

Are there stickies or guides on this site to actually do this, like fine tune the car, like a how to guide

thanx

 

Well, I would assume you tune the car w/ the cutout open and it will just run slightly rich with it closed. Correct ?