Smaller hotside, more boost?

[Reign_Maker]

Ok, so there is no doubt I need a smaller hot side on my turbo... here's my question:

If I leave everything the way it is now, all my boost settings and stuff, and just change from 1.04 to a .68 hotside, will I get more boost?


Right now, the way she sits, my highest boost level is about 15psi, and I wont hit 15 until damn near redline... From what Majestic turbo told me, it wont matter if I change springs on my w/g, it wont matter if I change w/g all together, he said, the fact of the matter is, my A/R is so big, my engine cant spool it any faster, so I will always have a peak of 15... So he suggested I send him my turbo for a smaller hotside swap... He said that a .68 would still pull until redline: that was a concern for me, because with my old supra on a 60-1 CT26, my hp and torque numbers would peak and then start dropping off, and that sucked, I want pull all the way through... But Im wondering if I change to a smaller hot side, so my engine can spool this massive thing, what do you think it's going to do to my power band? Do you think I will be able to make more boost? Or will I still peak at 15, but just much sooner?

Jake

 

[Ckanderson]

uh yea... try .68 you'll like it

 

[shaeff]

from what i've read, i agree with Ck.

-shaeff

 

[Reign_Maker]

Thanks, Im sure I'll like it, but what will it do? What should I expect?

Right now Im doing 360rwhp @15psi... Will it increase? I just want to know what to expect when I strap this thing on...

Thanks...

 

[CPT Furious]

From what I understand, and someone correct me if I am wrong, but the smaller hotside A/R should give some faster spool time but sacrifice some high end efficiency. Some people relate it to a water hose and a pinwheel. With no spray nozzle on the hose (simulating the larger A/R), you can spray the pinwheel with water and get it to spin. However, if you use a spray nozzle (simulating the smaller A/R), you get more velocity hitting the pinwheel and get it to spin faster. Of course, there are tradeoffs to both, it just depends on what you want.

HTH and if I'm wrong here, someone please step in to correct...

 

[Ckanderson]

it will increase your torque substantialy. you will spool at like 3200 (full spool) and it will hold all the way to redline... i run a .68 on the 1j and run it to 8k with no drop in boost.

 

[IJ.]

What Turbo do you have Jake?

Cpt: Correct there's usually a point at which the tighter nozzle becomes a restriction choking off top end power as there isn't a big enough hole for the Gasses to exit.

I went tight on my GT30R with a .63 AR and it was going positive at 1400 rpm when I switched to the GT3540R I went for a 1.06 AR as the new motor will run to 8000.

I thought this was going to be a compromise with a loss of low end response but Garrett's claim of much lower spool for a given combination aren't just marketing hype as it's going positive at 2000 but will breathe easy in the upper range!

So you can have the best of both worlds !

 

[CPT Furious]

Well, poop.