That's probably it for the 83mm, then. I forgot you had the meth turned all the way up. I see where you get the 673rwhp number, 10*84lb/min*20% drivetrain loss, but when you approach it from another angle, you don't get those results.

You made 530rwhp at about 10:1 AFR so, (530/.8)*10*(.55 BSFC)/60=60.7lb/min. That's supposed to be well within the S475's range, right? I've never seen an Airwerks compressor map from Forced Inductions since they're apparently top secret. I've seen the Bullseye maps, but not FI's. I would imagine its more than capable of 60+lb/min though, I mean a little T4 T76 is. I really don't see how it's flowing 84lb/min and only making 530rwhp unless your BSFC was in the mid .7's. It might've been high .6's with as rich as it was, but still...

I think you could get a little more out of it by changing the exhaust side, but rating that thing at 900+fwhp and only getting 700 with boost falling off is BS. I'd send it back for a credit or something.

 

Keep in mind the converter was unlocked and skewed numbers after 5000rpm. The engine was turning that RPM, but the drivetrain wasn't. If my MAF was 20lb/min off in the calibration, everything surely would have blown up by now IIRC, Jim put down over 750hp on a T76 with that smaller housing. I doubt I am outflowing mine with significantly less power.

Either way, I am going to try my theory and turn up the boost to get it into a higher flow region on the map. I know I know, its a bullseye map, but its the same compressor lol. If it still chokes out, I will sell it and get a honda.

Doesn't BSFC increase for a decrease in AFR below stoich..? I know I'm not running enough meth for stoich to have dipped into the single digits yet...

 

arent these BWs designed for diesels? Im thinking you need to be 15+ psi for this turbo to work properly. Seems like 10psi on a 6L that is pushing MAYBE 10.5:1 CR is a little less airflow then what they are ment for lol.

someone please correct me if im wrong!!!

 

Nope, you're absolutely right. In fact thats what I just texted vanilla

Its supposed to flow another 100hp worth of air at 15psi

 

there ya go man, crank it up!!! haha.

The tire wrap definitely didnt help either.

 

On the tuning thing, dont they make larger diameter MAFs with a different cartridge that effectively extends the MAF table or allows you to scale it with higher resolution?

 

They do, but the MAFs on the Gen4 engines can handle a ton of air. The MAF table goes all the way to 145lb/min.

 

SO as long as you arent using meth you can effectively run a good MAF tune with a pretty decent amount of boost. Looks like its time for you to switch to E85 so you dont have to worry about the rich spike

 

No worries, plans for E85 are in the works as we speak

I did make a discovery yesterday... I was rummaging around underneath the truck and noticed the bottom of the turbo blanket was scorched. Found that kind of odd, so I fired it up and put my hand next to it and felt a really healthy exhaust leak right before the turbo. On further inspection I found a stover nut had worked itself off so the turbo was being held on by 3 bolts... Stovers aren't supposed to do that...I can only assume its because I reused them last time So, I made a trip to ace for parts and after tightening it all back up and putting it all back together I thought what the hell, and pulled off the actuator to the QS valve and tried turning it. Didn't budge a bit. So the dyno pulls, all the races I've had (and won a lot of) were with an engine breathing like an asthma patient through a single scroll on the T6. Going to pull the turbo and redo it tonight...

 

that would explain why the turbo seems too small...