theedge

It has a 5 volt supply for sensors, so its impossible for it to get more than 5 volts to the input unless you wire a sensor to 12 volt... No clamping per se

RPHARRIS

damnnnnn.

I need to take some EE classes

blown 944

I am getting ready to go pick up a zener diode.

Hopefully the electronics guy knows what the heck I am saying........ b/c I hardly do

I'll update later if it works out to be voltage related ..... or not

Edman951

Sid,
I was having the same problem as you are, 2 years ago.
Havent driven my 951 much since then. Bacause i bought another car.

but i'd love to find a solution too.

Not many 951 are still runing the AFM link....

gt37vgt

just scale it back pneumatically you can pick up a plastic needle valve for a fish tank bubbler at the aquarium

blown 944

Well the diode didn't work, at least not the type they gave me. I am going to do some more research on diode types. This particular diode scaled voltage throughout the range and I didn't really feel like remapping the whole thing right then. I did test it and it would not allow more than 4.65 volts through using a 5 volt source.

I also tried to use the max clamp through the link and set it much lower (like 3.5volts) and it definately works as it would start to lean out at low boost pressure then put it back and it was fine

I had a friend over that has a 12 sec mustang and he was riding along and told me I should just leave it at 22-23 psi b/c it is already fast enough. I am starting to think that is a good idea so I can finally get my paint done and work on the other car to make the big power and stop trying to kill this one. Maybe I'll take his advice.

It is like a built in "stop or your going to spend the next month in the garage" limiter.


i went ahead and changed the supplemental nozzle jet to the appropriate one for this pressure and we went and ran them through my simulator and I will let you guess how that worked out

blown 944

Well I just realized that I can be an idiot at times.

I was not grounding the diode but rather running it inline.


I also found a nice little trick in this link as well to relieve the map pressure at higher boost

http://www.thedodgegarage.com/turbo_map.html

try again tonight.

Rogue_Ant

Sid,
Sorry I should have been a little more clear - but looks like you found it anyway


-Rogue

cpt_koolbeenz

Yup, a zener voltage regulator will not work as planned in series. Check out the wikipedia link I posted earlier. It is pretty comprehensive as far as simple zener regulators go...

It may be a good idea to just hold off on the boost for now... You should play with it at 23 psi for a while! And at least let me ride in it before you blow it up...

Bri Bro

Just a word of caution, you normally put a series resistor in front of the clamping diode to limit the clamping current.

Tom M'Guinn

I think you are looking for a version of this circuit:

http://www.teamfc3s.org/info/articles/fcd/diy_fcd.htm

blown 944

OK I got it

it turns out that is definately NOT voltage related..absolutely.......... positively.
I tried 2 zener diodes one was 4.7 and the other was 4.3. I tested them fully and then installed them the correct way. It made absolutely no difference.

So.....I tried the granger bleed valve. I started with it opening at 20psi to see what would happen (I set it using a tire pump) I took it out and it went right to 25 then had a little pop. It was higher so I was encouraged.

I then backed the valve out to relieve earlier it then went to 27but it seemed like it spooled slower and I could hear the pressure coming pretty strong form the kick panel.

I then tried a different welding tip(larger oriface) to allow more pressure to release and then turned it back in so it wouldn't open until 20 psi.

Voila perfecto . It ran right up to around 30 psi.

I am at this point very happy I figured it out .

Edman, since this is definatley it. if you want to run over 23 or so you would need to bleed some boost before the AFMLink and try to get it to run in the last cel. This cel is normally set to be at about 21-22 psi but since you are releiving boost the engine is actualy having full amount and you will need to adjust your last cels acordingly. Meaning to add fuel in the high cels. ( don't know what injectors you have but hopefully they are large enough to scale up.

Chris, I will try to hook up with you this weekend and get you some $$$. I like it

Thanks for all the help everyone

blown 944

Oh and the nicest part of the whole thing is that I am in the house before midnight

RPHARRIS

Git er' done, boss! That sounds like a success.

What does 30psi feel like? How high do you think you could go on E-85 before you start running into knock issues?

blown 944

Uh 30 feels a little .....fast .....for a 4 cylinder hoopty.

it makes me glad I have the drag radials on it . I am going to try to keep it around 25 psi as this turbo build is not the bigger one and it is a little out of it's range. I just had to get it to 25 b/c there is a definate diffrence from 22. It's like just coming up short when it really wants to get moving so I just had to keep tinkering.

AS far as knock goes, I think there is a lot more room before I have to worry about that.

When I was tuning bigger blown engines on Methanol and Ethanol (100%) we were able to run about 50 degrees lead and over 30 psi on both 500 inchers and 355 inchers. For comparison we could only use about 16-18 on blown gas at 25 psi.

I am using my same philosophy with this car. Just make sure there is enough fuel and the timing is not as critical. As a matter of fact I am thinking that on the other car I will add some timing lead to anything under 25 psi so I can add some fuel.