GT3076R .63 or .82 A/R ???

[70SSElky]

Just toasted my 2871 so I am going up to a GT3076R and not sure which aspect ratio would be the better choice. The busa motor is in a sandrail that I use so load will come on a little quicker due to the weight. I boost up to 28 lbs and also shoot a little nitrous into the system (just while racing) to help with the lag and it has been great. I am pretty sure I choked out the 2871 because I hurt the turbine side at full boost +Nitrous.

So anyway, I do "dune" this car so I want as little lag as possible but am looking for good power at 28 lbs + a little nitrous without choking out this turbo. Would a .63 A/R give me the power I am looking for without choking the turbo, or do I need to step up to the .82?

 

[OZBooster]

I would think .63 or your realy going to notice the lag going from a 28 to 30 and bigger housing

 

[ogre]

although, you could offset it by using a slightly larger shot. maybe a 2 stage, actuated by a hobbs switch. big hit of nitrous until it spools say 15 psi, then step to a smaller shot from 15 psi on. or sack up and just use a bigger shot through the whole rev range. you could degree the cams differently to affect spool, or pull timing and add a little fuel down low. it'd be kinda sluggish out of boost, but would spool quicker, if that makes sense. if you're at WOT most of the time (i'm guessing in the sand you are) i'd use the larger housing, it'd be less likely to overheat with the lower restriction.

 

[ogre]

oh, and pix or you're full of it

 

[70SSElky]

Thanks guys, I went with a .63 as suggested. Just finished a new header for the T3 flange and now working on other goodies. Had to step up to the 044 fuel pump, billet clutch basket (which I should have done before), re-fabbing the exhaust (has a 3"), etc. I have the nitrous set up on a window switch and I can adjust it to shut off early or run it though all the upper rpm range, and yes, I do that once and a while! Don't know how much I will need it in the upper range now with the larger turbo.

Hope the picture works! You can see the Busa motor peeking out there. Car is gear for about 130 mph and would pull the wheels at over 100 mph with the set up that I had. It has lots of goodies, like timing retard, high energy ignition, intercooler, Meth/Water injection, timed cams, additional fuel injectors with controller, built tranny, etc.

Hoping to have it done for Presidents Day. If I can get it done and tuned.... I will come back and load some video of a run.

 

[lil charlie]