I need input for a Boost issue.

[hchays]

I have a Powerdyne belt drive supercharger on my 95 Lightning. I had it rebuilt by Powerdyne about a month ago. I am having trouble getting an boost out of it, when I bought the truck it was the same way. When I had it rebuilt I asked the guy at Powerdyne what size pulley it has and he said it is a 9 pound pulley. I can only get about 2 - 3 pounds out of it. I have the FMU, external pump, 75mm throttle body, 42 pound injectors. I took it out to Edgewater last weekend and I had a detonation issue. I backed off the timing and it got better but was still there. My main issue is that I am only getting 2 - 3 pounds of boost from a fresh 9 pound supercharger. By the way I have JBA shorty headers and 2 1/2" with flowmasters out the back. Any input would be helpful.

[PaulFiveOh]

Have you negated any vacuum line issues to make sure your gauge isn't giving you a bad read?

[YouGotJunk]

Need to check all your vaccum lines period..vaccum leaks and so on are going to be a big reason on any boosted car not wanting to make much boost.

[ibstrokin]

What does your gauge read with the eng off, sometimes they will read +/-. I wouldn't suggest spinnig that powerdyne any faster though, they are notorious for breaking. I used to have one, it broke about 5-6 times before powerdyne refunded my money.

[hchays]

I have been working on that. It had a couple of major leaks that I fixed. That did not change anything. There is some vac lines running behind the engine/heads. The issue that I have is I am a Carb guy, this EFI sh$t is not my thing. I am not sure what needs a vac line and what does not. I have done away with the smog pump and the A/C so that helps free up some space but like I said now it is to the point of what needs to have a vac line and what can I get rid of? I know the map needs a line, there are like three little relay looking boxes that have a plug and vac line????? Should there be anything behind the heads? It's a b@#ch to see back there?

[hchays]

What does your gauge read with the eng off, sometimes they will read +/-. I wouldn't suggest spinnig that powerdyne any faster though, they are notorious for breaking. I used to have one, it broke about 5-6 times before powerdyne refunded my money.

With the engine off it reads 0.

[PaulFiveOh]

I have been working on that. It had a couple of major leaks that I fixed. That did not change anything. There is some vac lines running behind the engine/heads. The issue that I have is I am a Carb guy, this EFI sh$t is not my thing. I am not sure what needs a vac line and what does not. I have done away with the smog pump and the A/C so that helps free up some space but like I said now it is to the point of what needs to have a vac line and what can I get rid of? I know the map needs a line, there are like three little relay looking boxes that have a plug and vac line????? Should there be anything behind the heads? It's a b@#ch to see back there?

Those lines back there NEED to be connected unless you have block off plates.

IE: If you took your air pump off and removed those hard lines, you also need to block off the holes in the back of the heads! I'm not sure if its possible to screw in block off plates with the head on the motor, in the engine. I'm sure someone knowledgeable can shed some light on that.

Make sure the vac lines under the upper mani are connected as well.

Also, if you were detonating at only 2 or 3 lbs, thats another issue in of it self, but might be clue as well as to whats going on.

[hchays]

Those lines back there NEED to be connected unless you have block off plates.

IE: If you took your air pump off and removed those hard lines, you also need to block off the holes in the back of the heads! I'm not sure if its possible to screw in block off plates with the head on the motor, in the engine. I'm sure someone knowledgeable can shed some light on that.

Make sure the vac lines under the upper mani are connected as well.

Also, if you were detonating at only 2 or 3 lbs, thats another issue in of it self, but might be clue as well as to whats going on.

I forgot I also was running Shell 93 octane. As for the holes in the back of the head, does anyone have an easy fix for that? I have always had a bad time dealing with those.

[white01]

Also you might want to register for a forum called NLOC. Its the National Lightning Owners Club, there is a wealth of info and guys that are willing to help there. There is a Gen 1 forum and and Gen 2 forum. If you run this by them they will help you out. Link....http://www.nloc.net/

Hope this helps,

Rich

[347sc]

Old spark plug and ultra copper will plug the air holes in the heads. They will not cause any boost issues.

[PaulFiveOh]

They will not cause any boost issues.

I really don't know so I'm asking: Are those holes completely isolated from the vacuum system in the motor?

[hchays]

I really don't know so I'm asking: Are those holes completely isolated from the vacuum system in the motor?

Yes, I think they are isolated from the vacuum system. That is why I did not make them my number one priority. They do need to be plugged though.

[PaulFiveOh]

Well good deal then, like everyone stated I would double check the vacuum lines everywhere.

[hchays]

I have checked the vacuum lines. I did not seem anything that seemed like a leak. I even sprayed carb cleaner and got nothing. Any other ideas?

[347sc]

It would be a large vac leak to cause what you are discribing. Like the discharge tube not on all the way. Look at your pcv line as another cause, they blow out

[Rick93coupe]

Are you guys sure they cant introduce a vacuum leak? If you look at this diagram for a mustang, you can see that they are tied into the system. If it were me, I'd plug everything that didn't need to be plugged in to a vacuum source. If your not worried about smog, pay really close attention to whats coming from the vacuum tree and see where its going.
http://i121.photobucket.com/albums/o238/Rick88coupe/mustangFoxFordVacuumDiagram.jpg

[347sc]

They are connected to the exhaust and smog pump. They do enter the motor thru the egr system but not the vacuume side of it. exhaust gasses would torch vac lines

[Rick93coupe]

makes sense.

[bangingears]

If it has a mass air flow sensor then the MAP sensor becomes a Bap sensor and shouldn't have a vaccum line running to it. That can cause screwy things with your timing because the ECU is adding and pulling timing thinking you are driving up and down mountains and compenstating for the different atomosphic pressures. Just a thought....

P.S. If it has a tiny or dirty air filter pull it and take it for a drive to see if that helps, make sure belt is a banjo string.

[NXcoupe]

Your PCV system should be disconnected from the intake manifold vacuum, as when the intake is full of boost, it will put the boost into your crankcase. You vent them to atmosphere on both sides and plug the line that goes to the intake tube side of the equation.

[dedpedal]

That powerdyne might be 9 pounds on a 302, but when you add 49 cubes, it might not flow enough air to feed 9 psi to the 351.

[hchays]

That powerdyne might be 9 pounds on a 302, but when you add 49 cubes, it might not flow enough air to feed 9 psi to the 351.

When I asked mike @ Powerdyne he knew what it was on and said that supercharger would make 9 pounds. I guess he knows what he is talking about?? Even if he was wrong it should still make more than 2 - 3 pounds.

[hchays]

Does anyone know what the three little black relay looking boxes that have a plug and a vacuum line are? Do they need to be there? They are by the throttle body.

[Rick93coupe]

Are you talking about the ones on the backside of the passenger strut tower? If so they are for polution controls.

[Rick93coupe]

That powerdyne might be 9 pounds on a 302, but when you add 49 cubes, it might not flow enough air to feed 9 psi to the 351.

I think Kevin is on to something here. Since boost is a measure of restiction, and it made the same amount of boost before and after the rebuild, it just may not be able to support enough cfm on the 351 to make any more boost.