monkian

Hi its my first post here.. I'm building up an RST 1.6 engine to race spec but unsure what size and downpipe i need to use... the aim is 300hp

I have steel rods , big valve head .. lighened bottom end etc and plan to run the GT28RS turbocharger.


I know i need to run a 3 inch downpipe.. i just wondered what bore system u guys are running .. as I was thinking a 3 inch system might be too big ?

Any ideas.. no silly answers.. pls
regards

xr3iturbo

usually 2.5-3inch is ok dont want alot of back pressure so 1 nice cossie box at rear should do good

JamboRS

what benefits has a cossie back box got over the rst one?

xr3iturbo

just thought better flow as cossie comes with more than that standard

s2_rsturbo

i always thought smaller the better because of back pressure but couple years ago was told by a well known car modding garage (dont want to mention in case i get in trouble) that on turbo cars the bigger the better. Dont know how much truth in that but i personally noticed the difference in a positive way

JamboRS

too big is just as bad as too small,havin too big a bore causes less back pressure and more chance of fuckin the turbo up
an escort turbo is quite capable of makin 250bhp with a 2.5 inch bore exhaust
then after that it becomes restrictive so a 3" is then needed
pm christian and beccy,he went from a 3" to a 2.5" bore coz the 3" was too big for jis spec but had too go back upto a 3" bore when he took his engine further as it was holdin the power back