Not another compound turbo thread

[gmduramax]

I need help and maybe some opinions for a small turbo in a compound setup. Atmosphere turbo is a S483 billet 1.15AR on the turbine. And of course, I want 1300hp of air and instant spool.

Little back story this is for the Limo, port and polished LB7 turbo in a compound setup with an S483. This thing runs great I love the way it drives, off Idle it leaves a little to be desired compared to a VGT but driving around it shits on any VGT setup I've driven. I would say this truck is every bit of 900hp and I know I'm pushing the LB7 turbo a little too hard. So why would I change anything, well I blew an intercooler boot twice and now the LB7 turbo has in and out and side to side play. Now porting and polishing another stock LB7 turbo and welding a V band flange would be the most cost effective and easiest option but who the hell would do that.

I already made up my mind that I'm going to run a bullseye BMW ball bearing turbo, but I keep going back and forth what size I should run. For the HP I want I should run a S468 with an 87 turbine probably 1.10AR and of course I would need something bigger than the 83 for 1300hp. But I'd like to keep this truck on the same build path that James had in mind for it (very fast spool, go fast) I'm willing to sacrifice hp for spool but I want a minimum of 1000.

So finally, here is a few questions I have.
Can you over speed a shaft if your compressor wheel is too small for example S464 with an 87 turbine?
Does an 83 turbine spool better than an 87 turbine?
What's the HP limit of an 83 turbine in a compound setup?
Can the Compressor wheel be too small in a Compound setup?

I'm not opposed to a wastegate, but I'd really like to run without one.

 

[Chevy1925]

I’d think an 83 turbine would work well on a 64-67mm compressor. Iirc it’s was 72 and up you wanted the 87 turbine for more leverage on the bigger wheel.

I don’t know why but I swear I’ve never heard of a good running 464. I don’t know if it was just improper setup or maybe it’s size bs frame size that’s the issue. I’d think if you were going to go 64, I’d look at a sxe 366. I think that’s what I was looking at doing as it seemed to give the best spool up and would way out flow that modded stock turbo.

Otherwise if you wanted to stick with 400 frame, I’d go the best 467 I could find for best spool up. Then you got more air on tap than needed for 1000hp. You might be looking for a 488 or bigger once the 467 goes on though

That’s the extent that I know though. I was going to see how it worked out as it seemed opinions varied a lot here.

 

[gmduramax]

This what I was thinking but not sure if the 83 turbine would outflow an LB7 turbo including the factory gate.

64mm Ball Bearing BMW - Mid Frame | Bullseye Power Turbo Chargers and Racing Components

Bullseye Power has reinvented the compressor wheel with their exclusive leading edge technology for quicker spool times and increased flow rates, providing up to 100 horsepower more than a cast or…

bullseyepower.com

 

[Chevy1925]

I’d go with that 87, put a .90 or 1.0 housing on it and see how she does.

The only issue I could see with too much turbine is lag and then lack of drive pressure velocity not being there to spin it hard enough. I don’t really see that happening with that truck unless it’s a 96mm.

If you had a gate on the 83 turbine, that might be the way to go. Or maybe do a diverter valve since you get a deverted housing

That G converter might be getting on the right side but god damn will it put the power down when they hit.

 

[PureHybrid]

Yea I vote you go with something a touch looser and sell the G to me

 

[gmduramax]

Nah the G will be plenty for a ball bearing turbo

 

[gmduramax]

My friend ended up ordering a Bullseye BMW ball bearing S468 87 turbine .90 ar for his truck. It’ll be paired with a forced inductions S488 billet 1.32 ar so I’ll be able to test it out. Still undecided for the Limo lol

 

[MAXX IT OUT]

My friend ended up ordering a Bullseye BMW ball bearing S468 87 turbine .90 ar for his truck. It’ll be paired with a forced inductions S488 billet 1.32 ar so I’ll be able to test it out. Still undecided for the Limo lol

I would be interested in the results of this, I have been thinking about going to the 400 frame from the 300 since even with the 1.0 housing I have, it could use a wastegate, but I don't want the headache on a DD.

 

[LBZ]

LBZ not LB7 but my S464 with a .90 AR as a single ran great. Spooled fairly quick, low egt’s, no need for a wastegate as the heavy shaft in it is tough to break if you bark it. Ended up selling it with a matching twin kit to Buck Spruill but never heard back on how it ran. I never got a chance to run the twin setup.

I think a 464/480 or 483 setup is probably one of the better combo’s for durability but a lot of work to tune. Luckily I had help from some of the good folks on here to dial it in.

 

[gmduramax]

My friend ended up ordering a Bullseye BMW ball bearing S468 87 turbine .90 ar for his truck. It’ll be paired with a forced inductions S488 billet 1.32 ar so I’ll be able to test it out. Still undecided for the Limo lol

Been a while and forgot to update. I've only driven his truck for 5 minutes, but my initial impressions are all positive. With it being an 87 turbine, you do have that slight lag right off throttle like if you were slowing down for traffic and tipped back into throttle. Other than that, this thing spools fast just as fast as a factory VGT in my opinion. I'm planning on playing with timing a little to see if I can get it to spool quicker but overall, I would run this turbo instead of twins if you weren't looking for more than 700hp. I think on The Limo I'm going to see if bullseye will do this same turbo but in a 64mm to see if I can get even better spool.