Why does everyone say a Zener diode is better for tricking the MAP?

[russ jerome]

Quote:

Originally posted by glhsken Ummm not all of them. I've used both, I preferred the zener..

Not disputing they will work, but comparing voltage's

http://hometown.aol.com/russjerome/images/tempgaugs.jpg

accross range for drain from Zener (it takes voltage to read).

http://hometown.aol.com/russjerome/images/scanner.jpg

they will read different.

Toggeling a solenoid to split signal between a zener and a G-valve will show a drop in voltage for the zener, the G-valve will be 100% accurate until pressure drop needed. Even though I disable my cut-out in my computers I think a daily driver would be wise to use the G-valve instead of a zener. The zeners parasitic draw under load just add's another tuning issue for me, always comes up at track Another problem I have had is trying to find a single zener that reads the same as one from same package? Take a 10 pack of 4.7v @ "...." rating diodes and bench test them under load, they will all be a little different.

[russ jerome]

sorry, wrong pics.....dont listen to a guy who cant even find his own pics

[glhsken]

Russ, I hear you 100% as far as accuracy goes, but consider who will be running them. Most people don't pay THAT much attention to the car and the cut-out's need "tuning"... for the average "Joe" fire and forget... zener. Tune the car in once and it's done.

of course.. 3 bar beats them all

[Stevien1]

I don't know about anyone else, but when I ran a G-valve cutout raiser, dirt would get in it quite often and stick open. Sucks to try and pull out in traffic and have the motor quit.

I built an adjustable zener using Dennis' page but I have yet to install it on my van.

[cybermrc]

Quote:

Originally posted by Mopar_Nutz I've always thought that a bleed style was superior to a zener because you can adjust it to get the max possible fuel before hitting cutout, where with a zener you can't. It seems that zeners will always cheat you out of a little fuel unless you get an adjustable one. bleed style; + you can adjust to get max fuel before cutout. + And if something DOES go wrong, you'll still hit cutout instead of infinite boost - they cost more zeners; + cheap + when it's in, it's in. No worries about cutout - cheat you out of a little fuel - no safety of cutout adjustable zener + no cutout ever + you can adjust to get max fuel before cutout - no safety of cutout the price is somewhere beteen the zener and bleed. Seems to me that it's all a matter of preference. Also I may have missed some points, but this is all to the best of my limited knowledge

^ I agree with him 100%!

Yes a 3 bar is by far the most superior way of doing things.

I think it's probably more a matter of preference. Some people feel more comfortable soldering and working with electronics; others would rather work at it mechanically. Each way has it's benefits and disadvantages; but I think both work equally well.

[MM Racing]

I sell the adjustable Zeners so I am a bit biased.

I feel that a Zener diode is not better then an adjustable grainger valve for exactly the reasons russ was stating about the draw on the MAP line. Also like everyone else was saying the diodes are not very accurate unless you are dropping the cash on MIL spec items and that is another story.

Argghhh that thing spoolboy makes drives me insane, its great and all in that it works, but you are dragging the entire MAP voltage down, in a way scaling the MAP voltage with that thing. It is not a clean cut at a certain voltage.

I am not trying to sell anything here but the adjustable diode that I sell and I believe that Dave St, Louis's unit is built the similiar to mine is the best way to go. Very low power loss from the circuit, in the case of my unit less then .01 W, adjustable to within a tenth of a volt , not temp dependent, and has absolutely no voltage leakage.

Those are my two cents.

[spoolboy]

Quote:

Originally posted by MM Racing I sell the adjustable Zeners so I am a bit biased. I feel that a Zener diode is not better then an adjustable grainger valve for exactly the reasons russ was stating about the draw on the MAP line. Also like everyone else was saying the diodes are not very accurate unless you are dropping the cash on MIL spec items and that is another story. Argghhh that thing spoolboy makes drives me insane, its great and all in that it works, but you are dragging the entire MAP voltage down, in a way scaling the MAP voltage with that thing. It is not a clean cut at a certain voltage. I am not trying to sell anything here but the adjustable diode that I sell and I believe that Dave St, Louis's unit is built the similiar to mine is the best way to go. Very low power loss from the circuit, in the case of my unit less then .01 W, adjustable to within a tenth of a volt , not temp dependent, and has absolutely no voltage leakage. Those are my two cents.

It doesn't, although you can argue with me again about it as I am not an electronics expert, although the guy who designed the circuit is an electronics engineer in aviation. All I know is that previous to install, 12psi was X voltage, after install, 12psi is still X voltage. So it does NOT drag the voltage down.

Dennis

[4sfed4]

Quote:

Originally posted by spoolboy It doesn't, although you can argue with me again about it as I am not an electronics expert, although the guy who designed the circuit is an electronics engineer in aviation. All I know is that previous to install, 12psi was X voltage, after install, 12psi is still X voltage. So it does NOT drag the voltage down. Dennis

I will also second what Dennis is saying. I made an adjustable zener using the instructions on his page and I didnt see any type of voltage drop due to the addition of the diode to the MAP circuit and I have datalogged the car both ways. If there is a voltage drop, it must be very very small as my scanner doesnt see it. Maybe its only a few hundredths of a volt?

In my mind, the adjustable zener is an excellent solution. If you have access to an air compressor, you can dial the zener in nearly perfectly before you even drive the car.

Of course, a perfectly done 3 bar cal is the ultimate way to go, but thats not an option for everyone.

[89daytonaTII]

why do I run a zener..... hmm probably because it cost me 30cents. Yeah it's not perfect and I can tell it's cheating me out of a bit of fuel. But I see it as an extremly cheap and very simple way to elimnate cut out temporalily until I can afford a proper 3bar setup.

[stampederunner]

I dont want to hijack this thread but i see eveybody saying that 3 bar setups are the way to go. So I tryed to reasearch it at thedodgegarage.com but didnt have much luck. So my question is what cars will it work on and how much would it cost? Hopefully somebody culd explain this a little for me and everybody else that might be confused.

[turbovanman]

Quote:

Originally posted by stampederunner I dont want to hijack this thread but i see eveybody saying that 3 bar setups are the way to go. So I tryed to reasearch it at thedodgegarage.com but didnt have much luck. So my question is what cars will it work on and how much would it cost? Hopefully somebody culd explain this a little for me and everybody else that might be confused.

I was going to say the same thing, thanks! I have lots of 3 bar maps.

[beefalobilly]

Quote:

I dont want to hijack this thread but i see eveybody saying that 3 bar setups are the way to go. So I tryed to reasearch it at thedodgegarage.com but didnt have much luck. So my question is what cars will it work on and how much would it cost? Hopefully somebody culd explain this a little for me and everybody else that might be confused.

I'm pretty sure they're talking about 3-bar calibrations. In other words you buy a computer with a 3-bar map and don't have to deal with tricking the map anymore (since it's 3 bar) You can buy these from fwdperformance.
I guess you could do your own 3-bar cal with moparchem but if you want to go that route give yourself a few years to figure it out

[stampederunner]

so can ANY computer be programed for a 3-bar? I have been told u need a 87 and up computer is this true?

[shelbyplaya]

Quote:

Originally posted by turbovanman Hey guys, I am running a Dawes cut-out raiser and have no problems with how it works. I see posts all the time on using a Zener diode. You all say it works better? Why? They both trick the MAP so why is the diode better? Thanks!

4.8 volts (?) is cut out i believe on TD's, i have a 4.7 volt zener diode on one of tonas. i found it was MUCH easyer to tune then when i tryed with a cut-out raiser. and it's also more of a 'garentie' thing for me knowing that i donthave to mess around with a cut-out raiser when it gets cold or hot (brass expanding/contracting?) and it's also not bleeding boost/vac away from other sensors. also it's just another thing i donthave to check on all the time to make sure it hasent rattled loose or the spring weairing out or the ball not seating proper

[shelbyplaya]

Quote:

Originally posted by 89daytonaTII why do I run a zener..... hmm probably because it cost me 30cents. Yeah it's not perfect and I can tell it's cheating me out of a bit of fuel. But I see it as an extremly cheap and very simple way to elimnate cut out temporalily until I can afford a proper 3bar setup.

WHAT...


you got riped off, i got mine for 17cents