Would someone please confirm the maximum flow (cfm) of the LS6 intake...I've heard it was around 275 CFM. And if this is true, lets take a stock cubed, 11.5:1 compression big cammed motor (234/242 600 lift & LSA 114) and now compare two heads.

Head (A) is a full blown CNC ported LS6 head flowing over 300cfm at top lift .600

Head (B) is, say, perhaps, the new CNC AFR heads with flow numbers well over 300cfm, and "topping" the LS6 on flow only (explained below).

It would seem to me that there is now so much more to consider than flow, i.e. the efficiency of the combustion chamber, the velocity of flow, lets not forget valve trane geometry, and the angle of the valve. From my research, the LS6 wins these categories, but loses on the flow....

But what benefit do we calculate in here for the either heads ability to flow that in excess of the intakes capacity?????

So my thinking is on this particular combination, the LS6 head on this particular combination wins.

I'd really like some professionals to chime in on this and help me, where am I wrong and the details. For example, the LS6 has a very shallow valve angle of 15 degrees (good for flow AND valve trane geometry, i.e. less stress). Is anyone willing to share that type of detailed comparison, in supporting choosing head B over head A, in this specific engine combination

I'd like this to start a thorough and objective head comparison, as we now seem to have a true aftermarket head that more than rivals that of the LS6.

Thanks guys and gals!

Power Kraus

1987 Grand National Turbo V6 - Official Vette, Viper, Cobra Party Crasher!

: 2003 C5 6 speed for a 1/4 mile at a time!

PowerKraus@advantexmail.net

 

There 2 different part numbers, the 2001 car manifold out flows the 2002 part number by 2-3 cfm all the way across the lift range. Here are the part numbers along with some R&D examples.

Z06 2002-2003 12573572
2001 ls6 12561184

Flowed at 28" and corrected by FloCom.

open clayed.
.100 - .200 - .300 - .400 - .450 - .500 - .550.
76 - 151 - 207 - 254 - 274 - 289 - 298.

Part number 572 Z06 installed.
.100 - .200 - .300 - .400 - .450 - .500 - .550.
73 - 148 - 201 - 244 - 260 - 273 - 279.

Part number 184 installed.
.100 - .200 - .300 - .400 - .450 - .500 - .550.
75 - 150 - 203 - 245 - 262 - 276 - 281.
dont know if this will help you.............

 

I will be watching this to see what develops. As I too am wondering about this.

 

I will keep this simple..the flow data you speak of is based on a steady state flow with the valve at a given lift..The flow is measured in a continous fashion.

It reality, its open only a fraction of the time at varying open positions based on cam profile. Not to mention the changing time window based on RPM.

Phil

 

Phil,
Got it, then each runner is not seeing a continuous flow, but rather bursts. Soooo an intake that flows 275cfm, as measured on a continuous basis, does not necessarily become a bottleneck to the cylinder head that flows a much higher number (to a point). Assuming I put what you said in my own words, we truly need to compare much more than CFM in choosing between the two heads, again using this particular motor combination. I hope all that makes sense and I have understood what you said. So now we need the other particulars analyzed before we pick...Can anyone add more data as outlined in original post, and/or have some other "basic" measurements we should consider?

I don't think there is a right or wrong choice here when talking about a stock cubed motor turning less than 7,000RPM, but I'm sure I speak for many of us that would like to glean a little more information in order to put together the best combination of parts for a particular purpose...whooping **** on any car named after an animal or reptile.

Robert

 

Haha..

Exactly correct...

Also..to add something now that ya have it figured out.

Port velocity is key. The velocity of the incoming air will dictate how much air can get in over that givin amount of time. Thats why you will see people ask the intake port volume (when lookin at flow data) to help give an idea on how well the head will really perform, especially down at low rpm.

Now, interms of overall flow..Engine efficiency,RPM and displacement is something you need to look at when comparing things like Throttlebody size and overall intake flow. Its a pump, nothing more, nothing less.


Phil