A modification I might regret.

[Keito]

I have the MP BOV and didn't like it blowing off all the time.
I ordered an upgraded surge valve spring from PT Performance.
It replaces the spring under the diaphram.
The claim is it doesen't blow off as much, and it's a different sound,
short, not the long woosh.
The bad is it causes more compressor surge.
Like all the mods I've done in the last 2 months, I haven't been able to try it
out. My car is still on blocks for the winter.

Keith

[Raymont]

I bought a Forge Motorsport BOV and installed it today. Works fine.

I thought I would like having an aftermarket BOV, but man is this thing annoying. It vents so often, and sometimes it will vent under vacuum changes. It has already started to get on my nerves and I have had it on the car less than 24hrs.

I imagine the Mopar BOV is probably just as annoying considering it is the same spot.

I am seriously debating taking it off soon and putting the stock recirculation valve back in. Anyone have one of these Forge valves and found a way to remedy the constant venting? I am thinking about shimming the spring or getting a higher rate spring in there. Any suggestions?

Get an RFL...... thoes are really neat. When you can make people jump cause your BOV is so loud, then you'll know what real fun is LOL....They work best on Vans and Omnis I've had a RFL on both!! You get a TON of weird looks..

[mpboost]

op amp used as a comparator.... one terminal of the op amp has a ref voltage, other terminal to the tps. hit the ref voltage with the tps and the op amp chages state. little transistor to switch the solenoid and youre all set. thats the theory as i remember it. ill have to look up a circuit.

EDIT i dreamed up a little something.... Didnt try it so I dont know if its correct. maurice, if you can have it looked at, lemme know if someone who has designed circuits recently knows if it will work. the thing im unsure of is the 47ohm resistor... the 47 ohm resistor might cause the solenoid not to function. if so I need to find another transistor that the 2n3904 will switch that will handle the 400ma that the solenoid pulls. I think the coils on those things are 30ohms. EDIT

Brian

I'll see if I can have one of the guys look that over when I get a chance. As for the 5v reference input, could a simple 2 resistor voltage divider circuit be added to provide the 5v off a 12v source?

[mpboost]

Get an RFL...... thoes are really neat. When you can make people jump cause your BOV is so loud, then you'll know what real fun is LOL....They work best on Vans and Omnis I've had a RFL on both!! You get a TON of weird looks..

Not a fan of the RFL personally.

The Forge is a direct fit and I plan to upgrade to Samco IC hoses. RFL would require hard pipes which will have more connections where there could be possible boost leaks.

[Aries_Turbo]

maurice..... the 5v source must be regulated cause alt on the car fluctuates voltage and you need to start with a regulated voltage so the voltage division for the tps trigger stays constant. the regulator is 1.59 at radio shack.

for the output i forgot that you can have the 2n3904 trigger a small relay to trigger the solenoid so that the transistor doesnt sink more than 200ma. you can also use the radio shack solid state relay. (8$ i think)

ill update the diagram.

Brian

[mpboost]

Werd up

Excellent point on the voltage dependency on alternator speed (this is why I am a mechanical engineer and not electrical).

Thanks Brian, you are the man!

[Aries_Turbo]

ok, i updated the diagram. i still might be wrong on some things. I gotta remember my op-amp and NPN/PNP transistor rules. ill double check. still have someone look at it if you can.

Brian

[Aries_Turbo]

ok i think the curcuit is right as long as the 500ohm resistor is the correct size.

when the tps voltage is lower than the ref voltage the input to the transistor is grounded and it doesnt allow the relay coil to see current. when the tps goes above the ref voltage, the output of the opamp is high (5v i think) but i dont think it has all that much current capability hence the 500ohm resistor which might have to be increased if the relay doesnt go on. you also might need some capacitors on the relay contacts and coil to absorb spikes. I need to breadboard this circuit to test it. if i get some time, i'll do it cause this would be useful in many applications.

Brian

[Tony Hanna]

Yup I noticed that too while searching

I thought maybe there was a more "grassroot" style way of doing it.....aka cheap (this is how you know I am a genuine turbo dodge guy)

Maybe I'm way off base here, but why not use a full-throttle switch like you would on a nitrous setup? They can be had for around $5.00 for the microswitch type that work off of the throttle lever. I've also seen one that's made to clamp on the pedal arm, but I couldn't find one to get a price.
If you're really wanting to go grassroot, use a rear brake light switch off of an old motorcycle. They work great as a full throttle switch.
HTH,

[Aries_Turbo]

yeah that works too. but this works for any 0-5v signal that you want control a switch with.

Brian

[mpboost]

The nice thing about doing it electronically is that it can be hidden in a black box mounted anywhere. I was even thinking it might be nice to incorporate the solenoid into the project box.

We use a few 3 way solenoids at work that are very small. It wouldn't be hard to make the whole unit as a module in a small 1.2x2.5x.5 size plastic enclosure.

[Aries_Turbo]

btw, you can get all of these parts at or through radio shack. search for a LM324 though for the op-amp. its basically 2x LM358. same op amp... just 4 of them. still small.

for the 500ohm resistor, just use a 470ohm and a 100 ohm in series. Im gonng run to RS maybe tomorrow and snag the parts and test the circuit.

you can use a radio shack 271-342 potentiometer. its a 15 turn so youll have excellent resolution.

Brian

[Tony Hanna]

yeah that works too. but this works for any 0-5v signal that you want control a switch with.

Brian

I hear ya. I'm just not that good with circuitry, so the switch was the first thing that came to mind.
After thinking about your setup, it seems like it would be really handy for those of us running alcohol injection on the older TD's with stock cals, Especially if it could be built with several outputs that are independantly adjustable. A single 3 bar map with a setup like that could be used to do the work of a number of pressure switches. For that matter, you could even use one of the outputs in conjunction with a normally closed relay on the + wire of the coil to act as a user adjustable overboost shutdown feature.
I like it. I'd just have to have somebody else build it for me or it would never work right.

[boostinhardsrt]

i know you mean, i had the mopar bov on my srt for awhile and got super annoyed quick. so, i took it off and ran the stock valve for awhile. and, eventually got hardpipe and an external bov, much better. it doesnt go off unless im in boost, but it still flutters a little when not in boost because of the tiny turbo. so if you've got the money get an external bov, cuz you'll need one when yuo go big turbo anyways

[Aries_Turbo]

ok im at Radio shack right now on the PC that they have setup there....

they dont have the opamp in stock at any of their stores but they can order it and have it shipped to your house. order a LM324... its 1.59$. they also dont have the 275-240 relay in stock either. its like 4.50$ or something and they can order that too. i now have all the parts but the op amp so ill be testing the ckt soon.

I agree that it would be useful and if you use all 4 op amps on the chip and add more relays and 2n3904's you can have a fully adjustable 4 ckt solenoid controller.... you can also control cold start injectors provided that I test the ckt and its all a-ok. gimmie a little time. ill make sure it works. I have solenoids and cold starts all over the place for testing.

if it all works out it should be cheaper than pressure switches. oh yeah, btw, you can get free sample map sensors from www.freescale.com. they are surface mount devices but they are free. search for "freescale" and the author "Joryn" over on TD.... he and I discussed those map sensors.

Brian

[mpboost]

Sorry for not keeping up Brian. I have been swamped at work and haven't had time to pass the circuit by a second set of eyes.

Surface mount map sensors? Sounds like something I saw someone using on a megasquirt.

[Aries_Turbo]

no prob. its the same map sensor that www.rs-autosport.com uses on its megasquirts. he has a little daughter board that the mps solders to.

the circuit shouldnt need a separate map sensor as the input impedance of op-amps are really high and wont change the voltage of the map or tps.

Brian

[TurboGLH]

----. I guess I'm gonna be switching to tps control after all. Everytime I get discouraged because most td'ers are just too damn cheap it produces something that wouldn't have come from 99% of the groups out there.

[Aries_Turbo]

hehe yup.

im still waiting on my op-amps..... radio shack takes 5-7 business days to have the parts at your door so itll be a bit before I get one built and in my car to test. im gonna pop it in the v6 so I can make sure that noise from the electrical system isnt going to mess it up. mouser or digikey are faster so itll be a better place to get the op-amp from but all the rest of the stuff is at RS and obtained easily. oh for the resistors... different resistors in series can be used to make different values. example: RS doesnt have a 500 ohm resistor. so I used a 470 and a 100 to make a 570 which should be close enough. we'll see.

Brian

[Aries_Turbo]

ok, i have all my parts and I breadboarded it up and it works perfectly sitting there on the couch. I used a potentiometer to simulate the tps cause the tps really is just a potentiometer. the tps signal usually will be the center wire but you should test with the key on. one wire will be +5v, the other will be 0v or gnd, the third will be variable as you move the throttle. thats the one you want to tap. I updated the circuit above and you can build it exactly as shown and it will work. all the components stay cool and all the critical currents arent exceeded. I need to hook it to the car and make sure that vehicle elec noise wont mess it up. with all the low voltage signals going through the regulator, it should be fine.

Depending on what you are driving with the 275-240 radio shack relay, (solenoid, cold start, led's, etc) you might need to drive a larger automotive relay if the current is over 1 amp.

so to figure out how much current your device will draw you use ohm's law: V=IR where V=voltage, I=Current (in amps) and R=resistance (in ohms)

so lets take a few examples of things I checked out today:

Bosch automotive relay from a cavalier: 12v coil, 72 ohms (measured by me)
so what you do is take the voltage: 14.4 (what the car makes) and divide it by the resistance of 72ohms.

14.4v = 72ohms X I ----> 14.4v / 72ohms = I = .2A which is well under the 1A that the 275-240 relay is rated at.

now a cold start injector has a 10ohm coil (all the ones I measured were around 10ohms) 12v rated so do the math and 14.4v (again the car voltage) divided by 10ohms = 1.44 amps which is a no-no for the 1A limit of the RS relay.

if you want to drive something like a cold start you can substitute a Z830-ND from www.digikey.com, in fact you can get LM324 there too. i might just change the design to use the Z830-ND and the LM324 from digikey cause you cant get them at radioshack anyway and I think digikey's shipping is faster though RS's shipping is free. depends on what what you are switching. solenoids are just fine to switch and automotive relays with 12v coils are too but cold starts need the beefier relay.

ill let you know how the circuit works when on the car. i'll hook it up to the tps and the map sensors on my v6 k car soon and drive around with the relay hooked to a led so i can see when it turns on and off. im also going to make a 4 stage one (using all parts of the LM324... you need another 2n3906, the 271-342 potentiometer, the 470 and 100 ohm resistors (youll have these cause radio shack packages have more than 4 in them) and the additional relays. you shouldnt need another 5v regulator.

if you use this for cold starts, the circuit replaces 4 hobbs switches as long as you use the relay from digikey and is much cheaper.

im going to use this to control my alky injection based off of a map sensor.

Brian