A quick look at cylinder heads.

[4v6]

Man tools...lol

[nippythecoupekangaroo]

Originally Posted by Emjay

fascinating stuff as always but I have no idea what your talking about. However I do enjoy looking at photo's of shiny metal and man tools

Here,Here

[4v6]

Well as ever things dont always pan out as you think or hope.
I carried out a number of flow tests yesterday to determine if the mods to the seat were going to do what i wanted; ie, give me a gain at low lifts.
Didint work out like that tho, it seems there simply may not be anything of a restriction at low lifts to remove and hence get the gain, oh well, thats the way it goes i guess.

Still, it wasnt a wasted modification, as i got a gain somewhere else.
I carried out a series of tests on this head some years ago but i lost most all my data when my "jet" database crashed bigtime and i was unable to retrieve the tests id already logged.
Luckily i have a WR stock intake test to compare against, however, its as well to bear in mind that the WR heads are some 10cfm better on flow out the box than the kv/mb hydro heads so the gain isnt as apparently large as it is in reality, all the same, we get a useful comparison.

Heres the flow curves from the various tests.
Bottom in blue- WR standard head, Kv has ~10cfm less across the board than this.
Green- ported 1B head.
Red, result of modifying the valve seat as described.



Clearly a lot more flow from 8.5mm lift onwards, id reckon a cam with more lift and relevant characteristics would capitalize on that.

I was unable to put a 30 degree top cut into the chamber as the insert dosent have enough material to form one before impacting on the seat.
Only thing i can do there is to hand finish around each seat, retest it to see what results from it, or remove all the seat inserts, install copper alloy oversize ones and form the angles that way....lots of work tho and might not achieve much.

Other op i can perform- deshroud the valve out to the chamber walls- bore diameter willing of course as i dont want to undercut the fire ring.

[Haydn44]

Another masterly exposition from The Engine Meister on head head tuning and characteristics. These can only add to my knowledge of engine performance.

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Audi Coupe (1985) 1.8 L (poverty model)
Audi Coupe (1985) 2.0 L (injected)

[4v6]

Lol thanks Haydn, dunno what to say.

[Isimmo]

I've had quite a bit of dealings with scavenging with 4 stroke large capacity diesel engines, and reading your above post, and (maybe) reading between the lines (from Phil's posts) am I right in saying that (as stated earlier) the initial intake valve opening is less critical due to scavenging process and that any potential flow gain by your modification may come from the sharp closure of the intake valve on the compression stroke rather than the initial induction...