16v head differences - port designs revisited

Way back in '03, for some reason I printed off the entire Vortex 16v FAQ, a fairly well known thread. This week I came across the printout, skimmed through it for nuggets of info, came across this post still online:

Now this was 2003 and it's not an effort to pick holes in what someone's written (the 2.0 exhaust port bit I don't know anything about). The later 27mm valves wouldn't have been an issue in the USA, since they never got the ABF...

More an interesting opportunity just to revisit the topic, as I don't recall big discussions on inlet and exhaust tracts...

This pic has gone off the net AFAIK, so this is scanned in from printed paper



Obviously this is as it came. AFAIK, it's an 027 head (left) versus an 051 right, which could be 9A/6A or the later ABF (more info on 027/051/D-suffix etc head number types on the 16v head info thread).

AFAIK, there's a water cooling channel in the port divider on the one to the right.

Edit, yes, from Brian.G's epic head cutaway thread here:

 

They still say this in vortex. I came across some threads the other day and the OP was asking about what head to use and someone gave the same answer as the one you quoted above. I believe BrianG is the man to give the details since he examined the matter in depth

 

Here you go. Pics I took a couple of weeks back.

Late 9a/ABF 'D' Head ports.

 

Trap!

Beware the dogma claiming a physically larger port, be it in or ex, permits greater gas flow and therefore superior performance - -

Illogical, else we'd have 2" diameter ports on 500cc per cylinder engines

 

Indeed, but I'm always at a total loss when it comes to forced induction because that just comes down to cramming as much air into the cylinders as possible.

 

Heads up!

The laws of physics don't change one iota

A well executed NA head achieving around 400ft/sec in, 300 ft/sec exhaust at max. torque, ex flow 70 - 80% of intake, generating combustion chamber swirl rather than tumble, appropriate squish, and "dead space" concentrated over the exhaust valves and spark plug, works best with street vehicles equipped with complementary components running pump fuel

The same principles apply to forced induction

www.theoldone.com

This character's work of >25yrs ago was highly controversial at the time, yet one way or another appears to have been adopted by most credible manufacturers and tuners

 

http://www.theoldone.com/articles/badtothebone/

 

Very well summarised!!!

 

Further to Chris kick starting this thread, I thought it about time I put a KR head on the flowbench to see what it does against the ABF & 9A's that have been on.

A quick measure up before to see how much bigger the inlet ports actually revealed something interesting...the port entries at the split point / divider are smaller!

Going further into the port it does get a little bigger by the time you get to the width of the guide area, but only around 1mm. I hav'nt measured it properly yet but will in due course, but the acid test is in how it was going to flow.

Well, if I was a betting man I'd have done ok...



As you can see it the pic...against a std 9A there is'nt much in it...a bit better toward the upper lift areas, with a peak of 106cfm...well 105.8 but thats being picky!

The really interesting thing is what it looks like when a std ABF flow curve is put over it...



The ABF is stronger off the seat up to the mid lift where they level out, then it outflows the KR up to peak lift...106 v's 110.

I made an interesting discovery which I had'nt seen from memory until I stripped the KR...I'll investigate a little more before mentioning it...anyone wanna have a guess?

I'll do some basic porting in the not too distant future to see how it responds, and try a test to see if my hunch could be part of the flow difference.

In the mean time...dont run out and buy up all the KR heads on the planet because they look like they may flow better...ABF's may go up in value now tho...anyone wanna buy one!

 

Can we work with head part numbers rather than engine codes? Especially concerning the 9A as there are 2 different versions. Was the flow tests done on an early 9A head?

 

Interesting information Jason. Could you write down all of the values in a table?

 

This is what I like about this forum. Proper info backed by flow bench results. Top work gents.

 

Balanced flows?

Exhausts too please Mr H!

 

Standard KR 027 as tested by me, 54.7LPS = 115.9cfm. Forgot to add, my test ends TB, the previous was another KR head but i don't know what casting. The results seem quite low to me. You can see where i became coil bound near the end.

 

Interesting indeed! I know once Jason gets the grinder out, they will all probably flow the same anyway.

Gurds

 

tomtubs, I am interested to understand how would measurements to correlate to what was shown in this test using similar software if you were to applied a similar pressure drop of 25.4cm H20.


As all data was witnessed, would there be concerns in the data acquisition process that would account for the deltas between what you have tested, what mr hillclimber is demonstrating and what is advertised elsewhere?

Given the conditions in the engine are dynamic, what specific condition (s) are we attempting to simulate with a constant depression at 10"(25.5mm) of water, applied to measure port flow/velocity.

What is the correlation between the flow coefficient of a port and tumble in the 16v engine.
The latter approach is what I would expect VW would take in any decesion update to the combustion chamber and gas exchange path.

Lets discuss...

 

I have seen and read the results from the link above and one thing I feel I must highlight is the dia of the adapter used in their test.....both Jason & Tom have used the same (or as near as dammit) bore adapter which is line with the bore of the engine the head is intended for whereas the external link uses a bore adapter of far greater dia and therefore the results obtained inaccurate and can not be compared IMHO

 

For the benefit of this discussion, lets just keep to the results on Jasons flowbench. Flowbenches are like rolling roads, they are all different to greater or lesser degrees.

By the look of the ABF vs KR flow profiles, I suspect the low lift flow of the ABF is aided significantly by the revised valve shape of the ABF. The valves that I have looked at are a completely different shape on these two models of head. The ABF profile is much less "penny on a stick".

 

ABF is the top one.

 

Give that man a coconut!

Well done Neal... I was surprised to see the flat back valve in the KR, having only ever seen the tulip shape in the ABF, and from memory the 9A is the same as the ABF valve shape.

When time permits, I'll swap the valves over and re-test both head types...could be interesting.

Oh and next time can you get the pics in focus Neil!...