USMCrebel

i will be going external WG. But with the smaller hot side will you be able to fully feed the cold side? or did i get that backwards?

japan4racing

the wheel on the hot and cold side is connected..so you will still be able to spool with a smaller hot side..the hot side doesnt feed the cold..it just turns the wheel so the cold can compress the air it is sucking in..the size of the cold side is what will determine how much flow you get out of it. for instance the 60 trim t3/t4 i had came with a hot side with an a/r of .63...the last turbo i had was a t3/t67 h.o. the same exhuast housing is availible on it but just a larger cold side....so even though they have the same hot side on turbo will make 750hp while the other only 450hp pick you hot side for spool time and your cold for power levels.

obviously a larger turbo is not gonna make the power untill later than the smaller turbo..but the spool will be quicker. also with a larger cold side you will get more flow and make more power with less boost. its really common for ppl to look at boost as being hte power..20 psi off of the little 60 trim and 20 psi off the 67 h.o are 2 different animals....

USMCrebel

ok lemme try breakin this down barney style

hot side it spool time, and cold is power level, cold compresses air the hot does ?? to air.

PSI is just a number, the flow and velocity is where the power comes from.

japan4racing

the hot side is simply using your exhaust gases to spin the wheel that is attached to the cold side wheel. as air is sucked into the turbo the wheel compresses it which forces it through the piping and intercooler to the engine.

you can use the measurements of the wheel in the hot side as a guage as to how fast it may spool...a lower a/r will spool faster than a higher a/r (.48, .63, .82 ect ect)

psi is the measurement of the flow...its confusing to explain...you can think of it kinda like hydrolics or a hose with water in it...if you have a 5 gallon bucket of water with a 1 inch hose on it to drain the water out you can only move so much water through that hose...you can pump 15 psi through it but the flow is still only maybe a gallon per minute..where as if you have a larger hose with the same 15psi more water will move through it since it flows more...now you can bump that small hose up to 30psi an flow as much as the bigger hose but not as efficiently..thats why its important to lok at the maps and find a turbo thats the right size...so if you have a large compressor housing/wheel (cold side) it flows more than a smaller one...so at the same level of boost you are flowing more air to the engine. the engine is still seeing 15psi regardless of which turbo you run but a larger turbo will be forscing much more air in thus giving you alot more power

have i completely confused you yet?

USMCrebel

it takes more than a little theory to confuse me, i start getting confused when i have to decide things on my own

japan4racing

haha i hear ya....im not so worried about the theory confusing you as much as me telling the theory wrong and confusing you.

USMCrebel

so far your theories are right, always check all info given 99% of the time.
where are you at in Ga?

japan4racing

perry...its just below macon.

USMCrebel

it's only 5 hours away, if i have time i might make a trip and we can hit a track somewhere

japan4racing

silverdollar raceway is the track i frequent there is a real nice 1/8th mile east of here i think it is. macon national dragway. it used ot be pretty ghetto but they sold it and the new owners really dumped a ton of money in it and fixed it up.