how bad do twins kill your spool up?

7

72chevy

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Jun 17, 2008
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If I use my 62-65-13 turbo in a twins setup how will my spool up be effected? When I went from the hx-35 to this turbo it just seemed a little lazy to come on, if I hang another turbo under this one will is seem even lazier till it hits?
 
It's gonna be lazier because the compressor wheel, exhaust wheel, and exhaust housing are bigger than factory. More mass to move, takes more air to move that mass, means it's gonna be slower. It's called turbo lag. And your turbo should spool pretty dang quick. With twins the setup will spool slightly slower than your top turbo would as a single.
 
LOL sounds like a problem easily solved with a little bit more fuel... :evil :evil :evil
 
62/71 over a 480 compared to a single 66 is night and day difference. I think the spool up is awesome. Also, towing is exellent
 
72chevy said:
This turbo spools fine its just not instant spool up like the hx35 was.
Click to expand...

And even with twins it won't be instant spoolup. Only way to get instant spoolup is to run a water injection system at all times or go back to an hx35.
 
I don't know. My gt4094 secondary spools faster than my old HX35 secondary...

That old HX seemed on the lazy side to me. At least in comparison.
 
Tuning of the AFC can also affect how your turbo's spool, It lyes in fueling i do believe...i just know i started tinkering with mine and learnt some pretty cool stuff since ima noob doing things on my own and listening to what others have to say here on the site and in person in general. I have buddy whos got twins on his truck and they light pretty quick and their not on the small side either ;)
 
Can't tell ya the physics but basically when the water expands to steam it increases cylinder pressure and adds more volume to the exhaust thus causing more air to exit through the exhaust side of the turbo and spooling it faster. I dunno. All I know is water injection always made my turbo spool like crazy.
 
I have had some older sets of twins but what i noticed was they come on sooner and pull evenly but compared to the hit of a single, they did not hit as hard as my 2.8. They were easier to light in spur of the moment hits but was not the "awesome you gottta get twins" that i was told.

The reason they technically should spool faster is because the atmosphere turbo is doubling the pressure on the top turbo. We breath in 15 lbs or something like that so the big charger is putting 30 lbs to the high pressure turbo so it has to work less to move more air. But now you got twice the air and like most people have twice the fuel all still going through the same little exh housings and turbin wheels which to me is overloading them (too much drive pressure) which causes heat, blown hg and poor performance. I do not think internal wg's are enough to compensate for 80- 100 lbs of boost going through stock or slighty bigger turbos. To do it correctly and get fast spoolup, you need like a ED wastegate and bypass the exh past the atmosphere charger so to not overspeed it.

Long story short, my experiance is it is a pain in the butt for the maybe little bit of improvement twins provide unless you want to spend money on custom sets like MPI's or others that do this research for you. Simply hanging a s400 under the stocker is pointless in my opinion. GIVE ME A SINGLE ANYDAY.

Tim
 
I want more power but dont want to sacrafice much spoolup, it seems the only way to get that done is with twins. I also live at 4500' so my turbos are not as responsive anyway I just dont think I can get by with a single.
 
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