So trucks have no controll over boost but the throttle hmmm thats somthing i didnt know. i was told if my wastgate was to big it would lag my turbo sown cause i would be using exhaust gas that wasnt needed is this right. if the wastegate can take 14 psi i cant see wat size difference matters if its smaller and do 14 psi then a bigger 1 that duz 14 psi i think the smaller 1 would be better? also do i have to have it connected up to all 6 exhaust ports just wondering.

but dont waste gates operate on pressure?, if so then the fact that gases flow is irrelivant, pressure and gas flow are completely different things

vltrb-o ,im sorry but i dont quite understand that post? hybrid. on full throttle a truck is at maximum boost.all gasses go through the turbine so it must be exactly the right size(not too small) or it will overboost whoever told you that second bit is leading you down the garden path. the smaller gate wont be a problem untill you reach its maximum flow capacity. if this happens you will lose control of your boost all together

this gets complicated when u think bout it, first question is does a wastegate operate on pressure? the second is what is meant by 38mm or 45mm etc waste gate is that the size of the port that connects to your manifold? once i get an answer i will explain what i mean thanks

yes it works on pressure yes its the size of the port

Quote: Originally Posted by HYBRID VL So trucks have no controll over boost but the throttle hmmm thats somthing i didnt know. i was told if my wastgate was to big it would lag my turbo sown cause i would be using exhaust gas that wasnt needed is this right. if the wastegate can take 14 psi i cant see wat size difference matters if its smaller and do 14 psi then a bigger 1 that duz 14 psi i think the smaller 1 would be better? also do i have to have it connected up to all 6 exhaust ports just wondering. i can get u one for no more then 750 for a turbosmart external 48mm wastegate

I can get u a turbosmart external gate for 724 bucks.. no **** ! www.autoshop.com.au (http://www.autoshop.com.au) when i bought mine from my mate.. i got it plus all 3 springs for 765 bucks. not bad at all.

yea cool, well if ur in sydney then i can get it cheaper like 705, 750 is including frieght for interstate people

yer im in sydney i want to look around see if i can find some cheaper wastegates i was told subzero performance as a good wastegate for $550 but i wanna look around 1st but i will keep u guys in mind if i get stuck. when i looked at wastegate pictureson the turbosmart website it looks like a spring and a valve that opens can this valve be modified in any way like hi flowed or larger valve installed etc.. just asking.

You wouldn't muck around modifying a 'gate. Just size it correctly and you won't have any trouble. It is not just a case of bigger is better. Too big, and boost will not hold stable - too small and it will overboost as the gate cannot bypass enough gas around the turbine. Go to http://www.skylinesaustralia.com and do a search for sydneykid and wastegates. He has a basic "formula" for sizing them.