boost and rpms
 

hey everybody . . .with a powerdyne 4.5 when does the boost kick in??at 3000 rpms right??is there a way to bump up the rpm till the boost kicks in?? because i want to get one for my daily driver . . i guess if i cant bump up the rpm ill just have to baby my car and not go over 3 grand . . superchargers are only stressful on the car if its useing boost right?? thanks for checking out my post

You should have boost at idel. With a supercharger you always have some boost. It's just not at full boost until the engine revs a little bit.

False.
False.
True.

SidewayzZ28, don't have a powerdyne so I can't answer your question, sorry.

At full throttle, the boost comes in linearly with rpm. For instance, 1 psi at 1000 rpm, 3 psi at 3000 rpm, and 6 psi at 6000 rpm.

At part throttle, the engine runs with vacuum in the intake manifold, just like it does now.

Really?? then why do I see 3psi at 3krpm 4psi at 4krpm and 10psi at 6krpm???

loadre for your information i do have a powerdyne just ordered it out of jegs should be here in within a week . . .and if i didnt have one why couldnt you answer my questions

I think there is some "boost" even at very low rpm with a centrifugal. Not really enough air to cause positive pressure in the manifold, but less vacuum than you would otherwise see.

Rich Krause

thanks everybody who gave me some information

You won't use boost that low anyway. Also, there is no boost at idle... I can't believe some of the :bs: people put on here. Put it like this, you will make usable boost above 2500 rpm. Past 3500 is when it really kicks in but normally you won't see full boost until you are close to redline.

Well this superchargers have what they call the "centrifugal lag" ?

Anyways with a lot of power is maybe a good idea that you get the boost up top, lest chance for detonation and easier to put on the road... Maybe ;)

OK, like all things, it's not exactly linear, but close. Look up the article comparing roots/centrifugal/turbo's in HOT ROD and they plot the boost vs. rpm. The centrifugal builds boost "nearly" linearly with rpm.

Also, the throttle body limits the air flowing into the intake manifold. So, unless the throttle is open, the supercharger can't pressurize the intake manifold.

The power the engine produces is "nearly" proportional to intake manifold pressure. If it built boost at idle and part throttle, then, by definition, it wouldn't be at idle or part throttle anymore.

Mike

ok thanks evrybody for the info now i understand how it works

when i install my s/c ill let ya know how im like it . . ill probally fall in loe with my car all over again lol

BS, ok, lets see. You won't make boost above 2500 RPM, but you will make it past 3500?

You will. I know I did. :)

I was in vaccuum until about 3200 rpms or so w/ my Procharger. Right around there I would be at 0 on the gauge. Even idling, you will make some pressure w/ the blower because the crank is turning. It's irrelevant until you overcome the atmospheric pressure.