906 flow

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MOPAROFFICIAL

MOPAROFFICIAL

Oogliboogli
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I started a series on porting the 906 big block head and I've done some work on a port trying to emulate what I did back in 2008. While doing this I was on the hunt for that big number but in the process found some very interesting things and I want to talk about that.
.100-.400 lift
What got me thinking about this was last night I watched Eric weingartner go over and give his opinion of a CNC ported set of 906 heads. Eric spoke of them gave his opinion showed the flow numbers and then compared them against some of his own which he had I believe three flow sheets for back when he was taking iron work. The thing he doesn't mention 'but if you use your eyeballs'..you can see he uses a way bigger valve @ 2.25, while the cnc 906 is at 2.14. His numbers are pretty average and don't do much better than the CNC had with the smaller valve so that tells us a lot but he admits he is not a Mopar guy and he just went through the motions, which I admire. He did have a good 10cfm over the other in the .200-.400
Without going back and looking in my flow sheets I'll just say that at one point when messing with the valve job in Bowl after doing the kind of short side work I do I was seeing very high numbers .1 through .400 but only around 240 something/barely 250 at .500 and then hanging...
For example with the stock 2.08..
@.200 147 cfm
@.300 220 cfm

Once I work that head up to the peak flow I desired which was around 282 or so that same 220 turned into 190s just like Eric's and just like the CnC had he showcases and gives his opinion on.
I would like to hear from others including Jim ,Dwayne, Jesse on this.

Which head would you rather have on the street one doing like the CNC version in the video or one flowing huge like that 220cfm .300 number?
 
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Did you see the dyno head test on the 440? If your low budget, any porting you do will help, but if you have some bucks too spend, go aftermarket.
 
The old Mopar Muscle magazine did some porting of the common BB heads, around the year 2000 I believe. Will have look for it.
My understanding is that the 915/906 heads had the 'ski jump' added to the port floor to improve the airflow around the short turn.
 
Bewy said:
The old Mopar Muscle magazine did some porting of the common BB heads, around the year 2000 I believe. Will have look for it.
My understanding is that the 915/906 heads had the 'ski jump' added to the port floor to improve the airflow around the short turn.
Click to expand...

These?
Part one
Part two
Part three
 
I never saw any of Eric's videos until this morning. Interesting results on the 906 CNC 2.14//1.81, the 902 hand ported 2.25/1.81, the hand ported 452 (with 2.055/1.60 valves?), must have left Chevy valves on the parts list 'cause the 452 valves should be 2.08/1.74 stock.

On a 8.9:1 440 with 346 heads (2.08/1.74) and an XE285HL camshaft, every time we ported and lost flow at .100-.300 lift and gained flow at .500-.600 lift, we gained horsepower across the entire rpm range. Gotta say we never saw a 30 cfm drop. The most I recall was 7 cfm @ .300".

When all we did was install 1.81 exhaust valves in place of the 1.74 we gained peaks of 11 LB-FT and 16 HP.

Very seldom have we ever tested the MOPAR big block iron heads with stock sized valves. We usually go to right to 2.14, 2.19, 2.20 or 2.25/1.81.

We have tested a 902 head with 2.25/1.81 valves. If Eric did actually test the 902 head with 2.25/1.81 valves, that head with those valves has the potential to considerably exceed his listed flows. I think the 902 test like the 452 test may have listed the incorrect valve sizes.
 
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I wish I had numbers for you from a set of 906 heads I have on a shelf In my house. I bought them used from a friend in the 1980’s and they have a little what looks like splash zone in the roof. Pretty sure they came from out west but like I said my buddy bought them. I went 9.82 with them in my 1974 duster back in 1991 on super stock springs. They had 3/8 valves in them with I think 2.14 valves in them. Now that I have a seat machine I may take them off my shelf for some upgrades one of these days.
 
pittsburghracer said:
I wish I had numbers for you from a set of 906 heads I have on a shelf In my house. I bought them used from a friend in the 1980’s and they have a little what looks like splash zone in the roof. Pretty sure they came from out west but like I said my buddy bought them. I went 9.82 with them in my 1974 duster back in 1991 on super stock springs. They had 3/8 valves in them with I think 2.14 valves in them. Now that I have a seat machine I may take them off my shelf for some upgrades one of these days.
Click to expand...
You're good at pics, you could always post some if you wanted.
If we ask nicely, could you when you get some time.
I'm asking nicely.
 
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