General Cylinder Head Flow Numbers discussion

[Stan Weiss]

Originally Posted by HawkBrosMav

Hi All,

I'd like to keep this discussion as general as possible to encourage dialogue on the topic. If you're open to disclosing specifics that is totally up to you, but I feel like there are probably a few opinions on this topic and it could be a bit of an interesting discussion.

Basic question here is when you have your heads done or you do them yourself in legal stock eliminator form (whatever that means in this day and age to you individually) what is the most important improvement in flow characteristics you are looking for? 80-90% of us have less than .500 lift, so are you looking to see the numbers from .400-500 to jump? Are you looking at port velocity? are you looking at average from specific lift values? something else?

This isn't really a discussion on "HOW TO GET THERE" but more with your end results compared to where the heads started stock what makes you decide the heads are going to make you .800 .900 1.00 under capable verse the stock castings?

Brad

I have not done an stock eliminator heads but looking at the rules, I do find it interesting what is being talking about. It looks to me the only area one can get creative is the valve job.



Stan

[Ralph A Powell]

You need to read the gray area part of rules. Most of the heads are ported( acid and others ways the camouflaged) to pass tear downs!

Originally Posted by Stan Weiss

I have not done an stock eliminator heads but looking at the rules, I do find it interesting what is being talking about. It looks to me the only area one can get creative is the valve job.



Stan

[Stan Weiss]

Originally Posted by Ralph A Powell

You need to read the gray area part of rules. Most of the heads are ported( acid and others ways the camouflaged) to pass tear downs!

Ralph,

Thanks. Didn't I hear a couple of years ago NHRA got something like a FARO, touch probe / laser scanner for checking stock ports?

Stan

[Dissident]

Folks,

One should realize a few points in a cylinder head discussion of NHRA stock eliminator head and manifold components. "trust but verify" is a good methodology to follow.

1) The rule book might state one thing but in practice the "passed tech" cylinder heads are quite another and many examples of ported/reshaped and covered up have passed with abandon. That includes manifolds. It is sometimes a discretionary call as it states in the rulebook. Methinks that there was (is) at least one lawsuit that reflects same.

2) Cylinder head rules indicate that the valve job is "legal" all the way down to the valve guide. This area can be very creatively used by something like a single point cutter that can re-contour the area described. Other methods can also be used.

3) Starting off with primo castings is the best beginning, but not totally necessary if one goes the route mentioned in 1) above.

Regards to All that like this kind of stuff,
HB2
Dissident

[SSDiv6]

Originally Posted by Stan Weiss

Ralph,

Thanks. Didn't I hear a couple of years ago NHRA got something like a FARO, touch probe / laser scanner for checking stock ports?

Stan

With core shift and with the high number of different cylinder head part numbers for the same engine combination, it would make it very difficult.

This is a true story...
Many years ago I got a call from NHRA asking me about technology to shrink metals, especially cast iron. The reason was that there was a particular engine combination that every time the engine went through tear down, the cylinder heads were compliant and at the next race, the car would go faster.

So, NHRA purchased a pair of the suspect cylinder heads from a junkyard, sends the cylinder heads to a trusted shop to have them built to the rule book guidance and when they poured the cylinder heads, the port volumes were bigger than the suspect cylinder heads!

I explained to NHRA that during the casting process, a temperature differential or the abundance of Ferrosilicon will cause shrinkage of cast iron. The reason why many racers check and flow lots cylinder head castings. ...or the cylinder heads were spray welded to add more material.

[Ralph A Powell]

Yes they have one they got it image the fuel heads and we’re going to use it on the the Factory Showdown cars but the further they got into the deal they just through up the hands up and gave up on them but still use it on the Fuel cars.


QUOTE=Stan Weiss;629202]Ralph,

Thanks. Didn't I hear a couple of years ago NHRA got something like a FARO, touch probe / laser scanner for checking stock ports?

Stan[/QUOTE]