VN head flow numbers anyone?

[shane_3800]

Found this on another site:
CFM @ 25" x 1.058 = 28"

Therefore


All rounded to the nearest whole number.

Yea most software will compensate but it's not 100% Eric Weingatner on YT shows this on his Saniez bench he also has a SF 600.
It's close though. But again on a 350cfm head on the Saniez the SF 600 will flow 360cfm both @28 actual gauge vaccume.

This is why I will get the SF 600 numbers when I pull my heads.
Then on Aussie V8 there's plenty of Iron port jobs Member TK has done with flow numbers posted.

But as Eric always states you should do .200 to 1.000" lift numbers and you should look at the .400 the .600 and the 1.000 and the reason is the 1.000 numbers tell you how stable the port is. So I'll post the .200 to 1.000 numbers.
The .100 numbers are uselss because they always are inaccurate because the bench tries to suck the valve open which can add .005 to .015"

 

[shane_3800]

Also I'll get the exhaust with and without a pipe.

 

[Deuce]

This is why I will get the SF 600 numbers when I pull my heads.

I look forward to it

 

[shane_3800]

I look forward to it

My stock heads won't be off until late next year. But I have a set with bigger valves only no bowl job I got off my other engine that ended up with a window in it.
I might grab them and see if I can get them flowed.

 

[shane_3800]

So I'm about to send a head off to get flow tested, just to let you guy's know it's going to cost me $60 in freight and $120 to get it flowed.
I asked for the figures to be in .1" incriments and from .1 to 1" lift.

 

[shane_3800]

So the head is at the stair case to the fliw room right now.
I hope to have the figures by monday.
I'm going to ask if I can have the valve they used to flow the head so when ai get my flow bench I can make a proper comparison.

 

[shane_3800]

Sorry for the late post but end of year and Covid slowed things down a little. But alas I have the figures, these heads aren't completely stock as they are running a 2.020" intake valve and a 1.600" exhaust valve. There was no blending of the seats just a standard everyday valve job with bigger valves. I'll add all the port dimensions later and the throat percentage.

All numbers @28 inch of vacuum, clockwise is positive anti clockwise is negative rpm.

Intake. lift cfm. Swirl rpm.

0.100" 63.8 735
0.200" 131.4 1089
0.300" 182.6 2030
0.400" 212.6 2517
0.500" 232.0 2752
0.600" 240.7 3034
0.700" 247.3 3513
0.800" 247.3 3732

Exhaust.

sorry I will update this but the file is wrong it's the flow graph instead of the exhaust figures but it hits about 162cfm at .300 and flat lines up to about 175cfm by .800. I'll get the actual numbers tomorrow.

From the look of these figures the intake is quite strong but the exhaust is weak and probably needs lots of seat work and a better valve.

 

[Deuce]

From the look of these figures the intake is quite strong but the exhaust is weak and probably needs lots of seat work and a better valve.

Or just needs an extra 10-15° on the exhaust lobe aye.

Pretty sure stock heads are intake strong compared to the exhaust port, and then you upped the intake valve size.

Anyway, thanks heaps for adding more numbers to this thread.

 

[shane_3800]

Or just needs an extra 10-15° on the exhaust lobe aye.

Pretty sure stock heads are intake strong compared to the exhaust port, and then you upped the intake valve size.

Anyway, thanks heaps for adding more numbers to this thread.

It's more so you want the exhaust to climb higher on the graph. I can post the graph when I work out how. But it's because the exhaust is moving like it's got 100 inch of vaccum so the port will back up. More exhaust flow and less reversion using proper back cuts and seat angles will let cams be used with tighter LSA.
Also the more cubic inches added the worse the exhaust gets. This statement is true and incorrect at the same time. The more BSFC added or energy in the form of heat the worse the exhaust port will act. This head would benifit greatly from area rueling the exhaust and making a flame pad as most of the flow is at low lift.

 

[shane_3800]

This video is only from today but I watch all his videos plus all of David Vizards and a few other guys. I'm linking this video because these heads are very similar and it's interesting to see how LS heads compare.

Btw the heads I got flowed made 420hp at the wheels through a T56 magnum with a 355 crank. Camtech cam card from it is 689"/689" @1.65 264°/268° on a 108°. Opens in 45° btdc ex 82° btdc closes in 74° atdc ex 41° atdc. Advance duration in 299° ex 303°.
So in a LS1 a cam like that should rev to 8k and make 500rwhp. So it was way over cammed imo, I bought it already built.