Not making boost with Magnuson any input???

[PIGSMOKR]

Ok just built my motor with forged bottom end with 639 lift blower cam, 265cc prc heads with long tubes. My Magnuson already has 3.2 pulley and I also added 1.1 cog drive. Car runs great at normal driving put trying to roll into the gas the car makes no power. The s/c makes no noise at idea or wot. Boost gauge reads 22 vacuum psi but driving at wot only goes up to 0 I'm wondering if the heads are just to big for the Magnuson or what. Cause I was expecting it to whining loudly with the cog drive. Any input would be helpful. Thx. Also we've checked to make sure the accurater works and there are no vacuum leaks.

[SUKXOST]

I've seen multiple threads/posts similar to this and most of them seem to be boost leaks or lines that came off entirely....just took em a while to find it. Best of luck

[yotaman96]

Sounds like the bypass valve is stuck open.

[PIGSMOKR]

We pluged it up so it should a made boost at all times and drove it down the road and still didn't change anything. We've sprayed carb cleaner all around to check for leaks and nothing has changed. I'm kinda lost at the moment.

[1LESSPROBLEM]

Are you in the 6 rib belt drive still? Could be slipping badly.

[PIGSMOKR]

This is how we have it at the moment

[PIGSMOKR]

It is but I have aftermarket belt tensioner for that reason

[H-E]

Have you been to the dyno? What is your CR?

[ayousef]

Originally Posted by PIGSMOKR

We pluged it up so it should a made boost at all times and drove it down the road and still didn't change anything. We've sprayed carb cleaner all around to check for leaks and nothing has changed. I'm kinda lost at the moment.

it might be a damaged bypass valve thats still stick open regardless whether its plugged or not, I think you can move the actuator with your hand (not sure) try doing that at idle and look at your boost gauge for any changes, also try to hear if the blower noise changes.

PS, with the cog rear it should whine even at idle and part throttle cruise.

[old motorhead]

22" of vacuum when? Idle, cruise, decel?

[10aSSee D]

It sounds like the bypass. My whipple got stuck open once and I didn't know it until I romped on it and there was no whiplash power. Popped the hood and flipped the actuator problem fixed. You may want to make sure yours isn't stuck.

[PIGSMOKR]

At idle. What we are coming to find it seems with big cam and big heads I need to run more boost. I ordered 2.8 pulley so we can see what that dose.

We put the car on dyno to add more fuel and up the Rev limiter to 5800 rpms cause I'm still breaking motor in.

[Bo White]

How much boost are you seeing now?

[old motorhead]

Originally Posted by PIGSMOKR

At idle. What we are coming to find it seems with big cam and big heads I need to run more boost. I ordered 2.8 pulley so we can see what that dose.

We put the car on dyno to add more fuel and up the Rev limiter to 5800 rpms cause I'm still breaking motor in.

You don't have a huge cam if you're seeing 22" at idle. Even with a big cam, you should see 9ish psi unless you have a really big cube stroker motor. Even then, you should see very measurable boost. Going to a smaller pulley won't cure your problem if you have no boost now.