Wastegate Exhaust System?

[Campoli]

Oh well I'm sorry and for your thread then I be done a reroute for an exhaust on my pickup you get th electronic flanges and open one with one switch and close the other with the other switch pretty simple and now that I hurt ur feelings by askin a question on ur presiouse thread have a nice day

 

[2000StreetRod]

electric cut-out activation/deactivation

I've been trying to think of a simple way to automatically activate the electric cut-out in a manner similar to the DynoMax VT muffler. The key trigger parameter is not engine rpm (you don't want the cut-out open at high rpm for downhill engine braking) or throttle position (open cut-out at 1,000 rpm and WOT may not be desirable) but airflow. The MAF sensor output is the obvious choice. Ideally all engine air passes thru the MAF sensor whose output voltage increases with airflow. A voltage comparator circuit can compare the MAF sensor output to a reference voltage and activate a solenoid controlling the cut-out when the MAF sensor output exceeds the reference voltage. The reference voltage could be driver controlled via an A pillar pod mounted potentiometer. Performance testing (dynomometer) could determine the optimum airflow to activate the cut-out. The stock (55mm) MAF sensor output varied from 0.8 volts at 550 rpm to 2.1 volts at 4,000 rpm for no load on the engine. The max output for the stock or Lightning MAF sensor is less than 5.0 volts even with forced induction. With the proper choice of solenoid (relay) the cut-out could automatically open and close.

 

[CDW6212R]

What about a vacuum triggered switch, if there is one that will trigger with the normal kind of vacuum that's in the intake?

 

[R1dd1cK]

What about the electronics from a meth injection system like a Snow system? They run off MAF voltage.

 

[2000StreetRod]

prefer the voltage comparator

What about a vacuum triggered switch, if there is one that will trigger with the normal kind of vacuum that's in the intake?

Don, so far I prefer the voltage comparator idea. I can purchase a component with an operating range of 0°C to +70°C, −25°C to +85°C or Military Spec −55°C to +125°C. The reference voltage can be easily set to any airflow desired. I can incorporate hysteresis (opens when 5% above reference and closes when 5% below reference) to avoid oscillation at the reference. I already have a potentiometer mounted on my A pillar pod with a center of range detent. I can add a defeat switch next to my Accusump defeat switch. The circuit should be easy to design and build, inexpensive and take very little space. The time consuming part will be determining the optimum airflow for opening the cut-out if there is one. The dyno may show that for max performance the cut-out should be open for all airflows. Or, it may not make any difference with the cut-out after the muffler.

 

[CDW6212R]

Well done, that sounds good.

One last thought; the ideal PCM program will be different for a full exhaust versus the cutouts(none). I suggest making the full exhaust as low restriction as possible, to reduce the difference between the two PCM programs needed. You will only run one program of course, so I'm sure it will be weighted to the full exhaust side for economy(off WOT conditions).

What you can do with the WOT programming will depend on how close the full exhaust is to the cutout airflow. You could tune it for the cutouts, and accept the richer conditions at WOT when the full exhaust is used. I'd do the tuning that way, for the cutouts to be most useful, the fuel needs to be richened for that WOT use.

 

[2000StreetRod]

variable output

What about the electronics from a meth injection system like a Snow system? They run off MAF voltage.

I assume there is an optimum meth/water to air ratio just as there is an optimum fuel to air ratio. I suspect the reason meth/water injection systems monitor the MAF sensor output is to vary the meth/water injection volume as the airflow varies. On the inexpensive electric cut-outs I've considered there is no way to monitor the opening. They are assumed to be either full open or full closed. Therefore, a variable output system would not be appropriate.

 

[2000StreetRod]

open loop tuning

. . . One last thought; the ideal PCM program will be different for a full exhaust versus the cutouts(none). I suggest making the full exhaust as low restriction as possible, to reduce the difference between the two PCM programs needed. You will only run one program of course, so I'm sure it will be weighted to the full exhaust side for economy(off WOT conditions).

I think you're pointing out that for open loop there is only one A/F table and that a less restrictive exhaust will result in higher airflow requiring more fuel. As I recall my current tune provides a fairly flat 12.8:1 A/F ratio at WOT above 3,000 rpm. I haven't checked it for open loop moderate throttle.

What you can do with the WOT programming will depend on how close the full exhaust is to the cutout airflow. You could tune it for the cutouts, and accept the richer conditions at WOT when the full exhaust is used. I'd do the tuning that way, for the cutouts to be most useful, the fuel needs to be richened for that WOT use.

I agree that the tune should be set for max power (12.6:1) at WOT with the cut-out full open. For normally aspirated I doubt that there will be any advantage of the open cut-out below 3,000 rpm but I could be wrong.

 

[CDW6212R]

You have a good handle on it, and I enjoy seeing what you come up with.

 

[JCase]

I must say, I think this idea is a complete was of time and brain cells. The money, time and fabrication won't be worth the one or three HP you MIGHT gain from this endeavor.

Your time and money would be better spent taking a road trip with your girl in your Ex you've already spent too much time and money on to enjoy yourself for a minute!

 

[2000StreetRod]

delaying dementia

I must say, I think this idea is a complete was of time and brain cells. The money, time and fabrication won't be worth the one or three HP you MIGHT gain from this endeavor.

Your time and money would be better spent taking a road trip with your girl in your Ex you've already spent too much time and money on to enjoy yourself for a minute!

Studies indicate that seniors (I'll be 67 next month) can delay the onset of dementia by exercising their mind (brain cells) by solving problems. I don't enjoy crossword puzzles, games of solitaire or video games. I enjoy automotive "tinkering" to determine first hand how things work and to disprove automotive "myths" (i.e. throttle body spacer improves the performance of a fuel injected engine). Being a retired electrical engineer I have a tendency to overly complicate the solution of a simple problem. I enjoy modifying my Sport much more than driving it (about 3,000 miles per year). It rides rough, is noisy, has a high center of gravity and corners poorly compared to other vehicles I've owned (Jaguars, Alfa Romeo, BMW). I'm looking for a 1997 BMW 840 for short road trips thru the mountains with my "girl" - wife for 40 years.

I agree with you that there will be minor (if any) performance improvements with my planned replacement exhaust system. It may be comparable to improving the intake system which I have spent considerable time and money on. However, the stock exhaust system is now 13 years old and will need to be replaced soon so I'm going to have "fun" doing it.

 

[JCase]

Fair enough Sir.

This might be of some interest to you:

http://www.quicktimeperformance.com/QTEC/

::QUOTE::

Quiet For The Street, Riot For The Strip!!
Go from stealth quiet to wide open power and experience the gains even if you are already enjoying an aftermarket exhaust system. You control the volume, you control the power. Open your exhaust with the flip of a switch. Run it closed, run it all the way open or any position in between. Adjust your back pressure to save gas.

Does not matter whether you call it a electric exhaust cutout, exhaust dump or e-cutout you know your getting the ultimate exhaust upgrade for your car or truck.

Good Luck!

 

[2000StreetRod]

PowerFlash bandwidth?

I've tried three times to datalog my front and rear O2 sensor voltages to compute the front to rear switching ratio and each time I got a no data from device error after a short time period. I suspect the problem is there is too much data for the bandwidth of the PowerFlash. Next time I'll try just one bank instead of both and eliminate as many other PIDs as possible.

I observed a few interesting things in the last datalog which lasted about two minutes after a cold engine start. The Bank 1 front sensor ranges from .05 to .85 volts while the Bank 2 front sensor ranges from .05 to .94 volts. The Bank 1 front sensor has deteriorated some with age and probably should be replaced. The Bank 1 rear sensor output is always 0.00 which means either the PCM is not reading it or there is a problem with the sensor. However, I have no O2 sensor related diagnostic codes. The Bank 2 rear sensor reads 0.108 at engine start and gradually increases to 0.118 volts. The Bank 2 front sensor cycled 37 times during the first two minutes while the rear never completed one switch.

I'll try another datalog of only bank 2 front and rear sensors with the engine warmed up.

 

[CDW6212R]

It's good that you have patience to do that, it is helpful for tuning and to identify bad or questionable O2 sensors.

 

[JCase]

How about installing a pressure sensor somewhere on your exhaust and base your signal off that? Back pressure (or lack of) is ultimately what your looking to control isn't it?

 

[2000StreetRod]

exhaust sensor pressure

How about installing a pressure sensor somewhere on your exhaust and base your signal off that? Back pressure (or lack of) is ultimately what your looking to control isn't it?

That is a good idea and should work fine. There are mechanical ones for $100 or so but I'm not aware of one with an electrical output. Also, because the sensor is connected to a high temperature source I suspect the reliability would be less than a MAF sensor. I would still want to build a voltage comparator to activate opening the cutout when the pressure is above a user set amount.

If I end up installing a supercharger, another idea would be to have an electrical vacuum/boost gauge and use the sensor output compared to a user set voltage to control the cutout. That might be better than using the MAF sensor output.

 

[FIND]

Or, you could also consider adding a switch on your dash to control whether or not the cutouts will open, THEN add an RPM switch to actually open the cutouts beyond a certain RPM. That way you could still maintain exhaust flow through your system at low RPMs to keep up velocities, but open up once you are pumping out so much exhaust your exhaust system will be an obstruction.

Not that your way is bad, I was just thinking this might be a little less complicated a system.

Though really, cutouts open so slow, I don't know if you would even want any system that opens them as you are going based on RPMs, boost or even momentary flow rates. Best just to run them on a switch IMHO. Plus, the switch can double to send a signal to the switch for your chip to change tunes for your ECU.

 

[JCase]

:: Deleted ::

Nevermind.

Wasn't telling you anything more than you already knew!

 

[2000StreetRod]

rpm switch & slow response

FIND, I've already considered an rpm switch and even purchased one (see post #27 thru #36). As I've previously posted the VIS is strictly rpm dependent (above or below 3,000 rpm) which I think is appropriate.

Your comment about the slow response time of an electrical cutout is pertinent and something I have not adequately considered. I was planning on adding hysteresis to avoid oscillation but slow response is probably a more significant concern. I was assuming full closed to full open would only take a few seconds. I need to get some specs on electrical cutouts. My initial implementation will be just using an electrical switch mounted on the lower front of the center console next to my Accusump defeat switch.

I'm close to deciding to add a Banshee/M90 kit which is part justification for improving my exhaust system. I will upgrade the exhaust first to gain the most from the supercharger and to avoid retuning due exhaust changes. James will probably want the cutout kept open for all engine conditions for performance testing and kept closed for drivability testing to reduce the number of variables. Performance datalogging will have to be done on the dyno.

 

[hunterdan]

Instead of using an electric cutout where response time is important, how about using a pneumatic cylinder or valve rated for height temps? Rigging something up with a solenoid using an rpm switch shouldn't be hard at all. Plus response times will be almost immediate. You would just need an air compressor with a reserve tank and draw from the alternator could be minimal. Hardest part would be finding some sort of cylinder to stand the temps.