street_kings

I remember seeing something in a previous post, but don't remember when or the title. anywho, why exactly is it that a car doesn't build boost under load? I would assume that since the engine is still running at the entire RPM band, it would still create the same amount of exhaust? Like with a turbo, when you run it without load (i.e. charge pipes disconnected) it spools the ---- outta it. why not the engine reving all crazy like and spooling the turbo?

(yah i know my grammar sucks. :P)

J-SMITH69

not as much exhaust is created, when not under a load. fre revving your engine doesnt use as much gas as when you put a load on it.

88b16civic

Ok your at part throttle... The B-fly valve is just cracked. Its creating a HUGE pressure drop lets say 12psi drop (thats its job to restrict the ammount of air passing by making a pressure drop.). So now you have pretty much atmospheric pressure on the upstream of it and only 2psig (atm-12psi) on the manifold side. So know when that piston moves down on the intake stroke its only drawing from 2psig. Thats not alot of air molecules and not a lot of exhaust to spin the turbine....translates into no boost.

At WOT the B-fly is wide open and makes almost no drop so at worst you have atm pressure and under boost you have full boost pressure being pushed into your cylinders...a lot more air...a lot more exaust...BOOST.

Carnesd

So then you could have it in neutral and hit wot (really quick on/off the throttle), will this create boost?
(i'm not boosted yet just wondering)

MR_DR_PEP

that original post was here:

https://www.homemadeturbo.com/forum/...threadid=16880

Reddy

If your creating boost while not under a load is a sure sign that your turbine housing is too small

superpilun

why? because of the overlap between the end of the exhaust stroke and the beginning of the intake stroke? you're saying the pressure is actually coming from the turbo manifold propagating all the way to the other side of the turbo? please explain i'm curious.

street_kings

Also Curious?

ZexRex

no, it must be under load to boost

ZexRex

thats a damn good question why it dosent.. i thought about it for a while and dont know why it does.. wheres the engineering major in here to straighten this out