2wdsaff

Ok without sounding totally stupid here but can somebody explain to me simply and shortly how the boost control etc works on a 2wd cosworth....

such as whats bleed and i get that boost pressure isnt controlled just by the actuator..... please

crazyshad1

i do know that if you screw the actuator in (shorten the rod) then that increases boost. not 100% sure how bleed valves work. not sure that answers your question, sorry

benjaminsarmy

hi mate dont know much but my t3 wont boost it is only run by vacume due to boost issues id like to know too ive been told its air and fuel mix to high best advise is ask your local rolling road or keep trying on here some one will deffly help mate

2wdsaff

i know how the actuator etc works and get the adjusting etc, i just dont understand how you can get say 1.5bar when your actuator is set to 1 bar and your "bleeding" 0.5bar?????

how does the bleeding etc work?

RS1HEN

its bled out of the turbo wastegate by the actuator, into the exhaust

clarke5700

ok ill give it a go

the exaust gases exit the engine and are directed vire the exaust manifolt down to the turbine half of the turbo this in tern rotates the turbo shaft up to any think in excess of 150000 rpm

on the other end of the shaft is the compresser housing this then drags air (through a filter/ meatering head air flow meater ect ect ect) in the inlet compressing it and feeding it through an intercooler (due to the fact the turbo is bolted to the exaust manifold it has a tendancy to get hot hence the need for an inter cooler) then it makes its way to the inlet side of the engine

when the disired boost leavle has been reached the positive boost presure will act on the actuator (dependant on the type and how its set up ect) and will open the wastgate within the turbo exaust housing bypassing the exaust gases around the the turbine half of the turbo and directley into the exaust system to stop the turbo from spooling any more.

now talking about the "bleed valve" when the actuator starts to move opening the wastgate say its set to 10 psi for arguments sake the bleed valve will bleed some of the presure out of the feed pipe going to the actuatur so the turbo will have to work harded to get the actuator to move (hence now the boost presure has been increased)

and that i hape ancers it lol sooooooooooo sorry for my spelling lol

JTECH James

iTrader: (13)

The cosworth boost control is quite simple,

ok, in laymans terms going right back to basics,
the turbocharger produces boost pressure, produced by the exhaust gasses driving the turbine wheel which in turn drives the compressor wheel,

now to slow boost down we need to prevent so much exhaust gas passing over the turbine, so we open the wastegate which bypasses the turbine, so it slows down, thus producing less boost pressure.

boost control simply has to control the operation of the wastegate itself, which will control turbo speed or boost pressure...

to do this we use a wastegate actuator which is pressure operated, ie at 1 bar it will open the gate and slow the turbo,

so if we want to run 2 bar of boost, we need to stop 1 bar of the boost pressure reaching the actuator, otherwise it will open at 1 bar! so we bleed some off through the amal valve. this valve is ecu controlled and can be opened and closed at different points in the map,

theres much more to itbut thats about as simple as i can make it this late lol

edit, i see i was beaten to it lol

LHD220Turbo

iTrader: (4)

assuming you know how wastegates/actuators work?

in simple terms a bleed valve works by bleeding/diverting air away from the wastegate - therefore it "tricks" the wastegate into thinking the actual boost presure is lower.

bleed valves are OK if used in the correct manor; but people get too boost greedy and turn the bleed valve too much which then causes lean running = bang goes engine

LHD220Turbo

iTrader: (4)

beaten to it; my explanation was pants compared to Clarke & James

LHD220Turbo

iTrader: (4)

here's a good picture which shows both sides of the turbo; wastegate and actuator

clarke5700

james spelling was better tho lol

LHD220Turbo

iTrader: (4)

he was obviously paying attention in English lessons!

JTECH James

iTrader: (13)

no, i just took longer typing, hence i came in second pmsl

i`ll let you guys tackle air injectors, ,im off to bed

clarke5700

LHD220Turbo

iTrader: (4)

leave air injectors up to you James tomorrow!!

my simple understanding is they work in the opposite way; by bleeding air in. Only normally seen in big HP cars due to being more accurate! - i hope that's slighty right! lol

JTECH James

iTrader: (13)

yeah thats the idea

2wdsaff

lol at the posts! thats perfect, explained it down to a tee!!! thank you very much