flycutting depth vs mass (041 heads)

[RFbuilt]

hello guys

I figured id post this question here,  as there are more road/circuit based people here (udo and others)  plus overall, more vw guys driving long distances

I have a set of (pair of) 041s  hand ported heads with 40x35.5 valves
it has 38.2cc on the chambers , with a little bit of unshrouding done to it
bored for 94s

the cc is okay, as I know I can get a few more cc's from it if needed (when setting compression)

my question is, based on some online chart/figures ive seen
040 heads with 0.100" flycut = 37cc
                with 0.160" flycut = 31cc

given that the 040 might be a lil different than the 041 , I suppose the 041 was close to a 044 combustion thickness

if the heads  seem to be flycut atleast 0.100 maybe 0.120"  given that it is a 041 not a 040
would the removal of such mass  cause less ability to dissipate heat?

looking to try a 94x74 , as a semi daily semi roadracing/circuit motor
nothing wild , but  would probably see 7laps of racing once a month

or are they left to be used on 1/4 mile short stints only?

short history on the heads :
aprox 80-100miles use, then my friend's fan grenade LOL , disassembled the engine and went with 044s after
his was a road race car too..
thinking of using this, since  the guides ,springs and the rest are almost new

(im being cheap lol)

anythoughts?
Udo?
Torben?

[Torben Alstrup]

Are these heads the older ½" plug thread or the newer 3/4" plug thread ?

T

[RFbuilt]

wait 2 seconds.. il go downstairs to check    its 11:04pm here haha

-------
just checked,  newer I think.. as they have 3/4 reach plugs

041 / go3  casting

[Torben Alstrup]

OK. Those are the best version of the 041 heads. Strength wise they are somewhere between a 040 and a CB 044 head. Cooling wise they are only slightly down compared to an 043. Dependant on the porting they are capable of 160ish hp without welding.
When they are flycut that deep I would not take any material away anywhere. If the volume needs to be increased, dish the pistons instead.
I would pay a lot of attention to the cylinder tops and sealing area along with using the right heads studs. Then I see no problems in using them for street or race.

T

[RFbuilt]

sweet! 

yes I checked between the fins and the chamber thickness  is pretty similar to 044s

I would plan on thermal barrier coating the chambers, if that is a decent idea in your mind?

[Torben Alstrup]

I have only worked with thermal coating twice. One turbo engine and one 2180 type 1 with Elliminator heads. There is no doubt that the thermal coating works. But if you want to do that you need to coat both the heads and the pistons to take advantage of the benefits. Reason is that if you do not coat the pistons they will have to take significantly more heat, resulting in much higher risk of cylinder scuffing or worst case scenario a seized piston.

T

[RFbuilt]

yes T

you are right..

the piston tops and skirts will be coated for sure

IMO ...the piston coatings is what ive used extensively  even in inline4 engines

so i am confident with that,   i just didn't know if the chambers  would significantly help 
and i take from your experience they do.. so i will def do that
including valve face to be coated

thanks again Torben