...so we hear talk that a 60mm throttle opening is only suitable to say 550bhp..correct?...Most advise above this BHP go for upto 70mm...so OK....we got a 70mm throttle and an RS500 intercooler with 70mm in and out...BUT we have a turbo thats capable of 630bhp on pump fuel..aka the GT35 .82...but this only has a 50mm outlet....so why do we need 70mm everything else to get the power...surely 50mm should see the BHP?

 

Surely even more so, as its HOT at the 50mm outlet, so less danse than when it gets to the throttle.

On that same note i dunno why intercooler piping gets bigger on the cold side, when surely it should be same, or other way round...

Good thread

 

Because the whole lot is resistive, so the more small diameter sections you have the worse it gets, when you think about the mimimum size its going down though, its the ports in the head, which are only about an inch across and its only ever flowing down one of them at once too as its not like all 4 cylinder have their valves open at once.

All these hard and fast rules you keep quoting about x-mm = y-bhp etc are only rough guidelines anyway, stop taking them so seriously

 

The RS200E that Harvey did the engine for which made 670bhp on pump fuel, shared the same size throttle body as a normal 2wd, so I think you are worrying too much.

 

have to agree with chip,its the port sizes on the cylinderhead that are the restriction at these power levels.ask karl to port you a proper speced cylinderhead,

 

there are engines over 600hp that use the 60mm throttle body.

 

Lloyd i have a proper spec head mate...i am just getting to the nitty gritty about minor mods...i was gonna put the EEC4 butterfly in my 2wd body but thought hang on the turbo outlet is only 50mm!!

So basically leave it 60mm then that wont restrict power in anyway?

 

i was speeking to itg when i have some filters redesigned for the gt30
he said a for a engine to produce 600 bhp it needs to consume the same amount air of a large 3 bedroom house per minute
for a none restrictive filter ie not inducton roar you need a 5 inch inlet to the turbo
itg foam filter 8 inch round buy 14 inch long was biggest i could fit in the bay and he said that wud still be 15% restrictive biggest problem with engine bays is the heat factor ie dyno reading are always a faulse readings out to in the car due to temps etc
as for throttle body size i aint a fookin clue but karl runs a standard one
it be good to see martoons proper throttle body set up against a swedish plenum and standard thottle body as we know the mountune roller barrel was designed for 330 wrc spec not twice that so is very restrive
immy you clown its never gona be finished anyway

ps bells will be with you tues wens at latest

 

BTTT


....and i am sure Karl's TB is bored out!

 

you may be right

 

...Reyland answer the actual question...why have bigger than 50mm all the way thru..or dont you know?...

 

I just told you above phil, its resistive, so for top end flow the fewer small sections you have the better.

The other thing people forget is that changes in diameter are as important as the size itself, so if you have a 60mm inlet pipe and stupidly put a 90mm throttle body on it then back to 60mm, it would result in less flow than 60mm all the way.

 

A 3 inch 50mm section is not the same as a 3 foot long section. Haven't got time to type expanation at mo but blow through a drinking straw and cut bits off it and you will soon get the point. Mind you, i am not a PRO!