It's such an easy upgrade that has been proven to be worth pretty big power over and over again. With everything else you have it seems silly not to. Records are made to be broken my friend... Use the improvements that time has uncovered.

 

Where is the proof of this?

Are you taking about the nnbs vs nbs intake or something else??

 

I ran a 78mm throttle body on my 385 and 84mm....it didn't appear to give a ****.

 

Turbo don't care 'bout no intake!

 

Too many statements being thrown around without significant evidence to support claims. My baseline is to be skeptical of aftermarket parts or modifications unless there is convincing evidence otherwise

 

You will only see an improvement if you are getting significant pressure loss through the throttle body, which is probably from a choked-flow condition.

So air at 120F is 0.06846lb/ft³, and lets say your turbo is moving ~110lb/min at full go.
So that's 110/.06846=~1600CFM which is 26.667ft³/s

Speed of sound is (Gamma*R*T)^.5 -> (1.4*1716*(120+459))^.5=1179ft/s

78mm TB is 78/25.4=3.07 inches, so area is pi*(3.07/2)²=7.406in²=.05143ft²

Air velocity going through the TB would then be 26.667/.05143=518ft/s or about Mach (518/1179)=0.44 ie, not even close to choke.

With a 90mm TB, the speed is Mach 0.33. There are some higher velocity losses associated with fluid through a pipe, but the TB is so short this wouldn't hardly matter.

So basically you need to be moving a lot more air than that 80mm will do to make much difference. NA or SC, sure you would benefit from a bigger TB since the engine is sucking air through it. It doesn't matter much on a turbo because air is being forced through it.

So like I said, turbo don't care!

 

Richard, couldn't that same logic be used in comparing a stock 317 head to say an AFR230 with a turbo? The 317 may not be 'choking' you but given the choice... AFR all day long.

I'm not sitting here saying that the 78mm is killing your power, but I am saying I think you're leaving power on the table. I would run the 87mm if it was me.

 

Yea, certainly. A better head flows more volume, period.

Where it gets fun is the question, how much more volume does it flow under 30psi of boost? The answer is, it flows the same as it did NA. The only difference now is the density of the air is much greater so you get more power.

In essence,
mass (power) = volume (head flow) * density (boost)

 

So again, couldnt that came logic for the heads be used with the intake? The heads are not a restriction to volume of air being moved with stock 317's, so why have that restriction anywhere else.

I know the math says that the intake is not at its limit, but who says it has to be at its limit to make less power than other options.

 

Proof look at neaufield or however you spell his name...at same psi he gained 3mph swapping intakes

3mph is typically 30rwhp