My guess would be that due to the error in the dyno it wouldn't look like much of a difference either way. Of course I could be wrong, this is just a guess. Anyone ever test them side by side on a dyno car, everything else equal, and see a significant (>3hp) average difference?

 

Only one way to find out, get ya a CNC TB from Rev Extreme and see.

 

We did our testing in our Tampa facility with the enclosed climate controled dyno which we could dial in to duplicate the air every run & not only compared the CNC designs, but ran them against our hand ported TB's, (do a Google search on Pete Incaudo Porting, he is the engineer behind this) and we were surprised with the gains...so I have to disagree.

The mirror finish will actually have a NEGATIVE effect on the volumetric efficiency. When I attended Reher Morrison rcing engine building school years back they showed us on the flow nech just how the super slick surface actually causes the air molecues to drag on the surface creating turbulence and althought the flow may not show lower CFM, the efficiency of the flow is negatively affected. Then they showed how leaving the small CNC machining marks it broke up the molecues on the outer edges and they acually worked like minature "ball bearings" and INCREASED the volumetric efficiancy. In the old days we used to spend hours & hours polishing the ports on heads after working them....and then I find out later it was not only a waste, but it cost HP.

Bo's are a super nice piece, no downside on them....

 

stock is 78mm intake and TB

 

very nice!!

you guys doing 5th axis surfacing? or just doing this on a standard 3 axis?

also maybe I missed it, but are you doing the bump stop mod aswell?

I have never seen a set of cnc'd heads before in person. I have always wondered if they are surfaced like this.

 

Ha ha, I don't have the money to waste on a part when I already have one, plus dyno time and tuning for efficiency...I'll just live with the thought that they are within error of each other, until someone else has the cash to throw around and do the actual test to prove one significantly better than the other.

 

You sure? Not that I don't believe you or want to start an argument, just looking for the cold-hard facts on this. Got any references from official sites (not other threads in LS1tech where someone states it's 78mm). Seems a lot of people say 75mm, since the stock TB is 75mm, yet some still say 78mm. Got a reference?

 

i am interested to know about the bump stop mod as well?

 

 

i think i will stick with yuors Bo

 

This is done on a 3 axis machine.

We can add the bump stop mod.

Yes, CNC heads are left with the mill marks.

Working on them as well....but it is a ways away yet before release.

 

stock TB on what is 78?

 

Not on a LS1 or LS6:
2.950" = 74.93mm
LS1 blade


LS6 blade

 

Just the kind of research I was looking for!

 

Just wondering with all that extensive R&D yall did, how did you possibly look over the fact that the TB is actually 75mm instead of 78?

 

ahhh ahah ha ha bitch slap!

thanks Bo White for clearing that up.

 

They are referred to as 78 by most but as you can see by the pictures the blade is only 75. We don't change the bore size on the stock ones. We do make Billet 90,92,95,100mm in both cable & DBW and 105,110,115mm cable for use with the Beck sheetmetal intake.

I see you have a Vengance tune & ported TB....give Ron a call to ask him about our abilities in developing killer products.

Any doubt to the amount of R&D we do just takes a visit to the shop to show you what we do day in & day out.

 

where does this 78 misconception come from, is there a stock 78mm? All the porters I have seen dont touch the blade so there isnt an oversize, all the TB's seem to be 75's, but I am also fairly new to the LS1 community so maybe I missed something, wondering where the "myth" came from if it is a myth..

edit: also my bitch slap comment was not directed at you, it was directed at the douche that came in the thread and posted wrong info and left.

edit 2: if you know they are 75's, they should be referred to as 75's not what they are commonly referred to as, not trying to bash you but mis-information spreads like wildfire it seems compared to real info. And also that could come back to bite you since you said they are 78 and the customer recieves a 75.

 

probably because FAST came out with the 78mm intake and matching 78mm throttle body, so people assume the stock one is also 78?

 

yep mine measured 75mm however the ridge in front of the blade chokes it down to around a 73mm rthus the reason for porting...im with bo i dont think theres enough material to go 78mm,,,,