Witchcraft and magic, burn the witch 
. Such patience and craftsmanship are artwork, well done!
dotted line is short radius turn, below shown as a "negative"
These all look really really nice.
How much would it cost one to have this type of work done? I have a spare BMW M10 head (actually a whole motor) sitting around that I've been thinking of doing a mild turbo build on. I'd have to ship it to you, obviously, but do you have a ballpark figure for a fairly simple 2 valve per cylinder head?
In reply to cmcgregor:
Please email me, I'll be happy to discuss this further - oldeskewltoy@yahoo.com
Wow, what's up with that shelf right before the guide?
Knurled wrote: Wow, what's up with that shelf right before the guide?
assuming you mean the unfinished exhaust bowl?? red dotted line?
That was just part of what allowed me to find an 11% gain in volume @ .350" lift.
The bowl to port work didn't hurt....
oldeskewltoy wrote: The bowl to port work didn't hurt....
a bit less drama...
removing some nasty bits from an SR20VE combustion chamber
Working the SR20VE intake short radius, bowl, and port
and the VE's exhaust side....
new client.... something called an NB....
and a bit closer view of that port.....
oldeskewltoy wrote: something called an NB....
More Miata.....
The Miata head just about finished... waiting to get 3 angle...
resurrected.....
It looke there was a substanstial amount of volume added to the ports on the last picture showed with the molds.
I say this because most of the domestic 2 valve heads people worry about keep the runners small and efficient and not unnecesarily large, which can show good flow numbers but bad power.
Do you ahve any info on runner volume before and after and how the engine it went on made power?
Opti wrote: It looke there was a substanstial amount of volume added to the ports on the last picture showed with the molds. I say this because most of the domestic 2 valve heads people worry about keep the runners small and efficient and not unnecesarily large, which can show good flow numbers but bad power. Do you ahve any info on runner volume before and after and how the engine it went on made power?
This???
oldeskewltoy wrote:oldeskewltoy wrote: The bowl to port work didn't hurt....a bit less drama...
Unported Exhaust: .050 - 32.45 .100 - 65.52 .150 - 90.95 .200 - 110.12 .250 - 122.80 .300 - 130.25 .350 - 135.48
Ported exhaust: .050 - 34.98 .100 - 65.03 .150 - 93.67 .200 - 113.32 .250 - 131.88 .300 - 142.53 .350 - 150.92
the intake @ .350" is @ 197.8cfm, while the exhaust is now @ 150.9, the exhaust to intake flow ratio is now a tick over 75% at peak lift, and over the lift range the exhaust to intake ratio is now about 71.5% (was 61% stock). This head's owner has not told me if the engine is back together.
Not a huge change at the outlet 33.6mm to 34.6mm. What I have done is to change the internal shape from a "Y", to more of a "V". This change allows for smoother blending/less turbulance as the exhaust leaves each valve.
As to the effectiveness of the exhaust re-taper. the only dyno I have with a mostly* stock engine shows substantial performance increases.
Here is port work similar to Skippy's...
I guess its the picture, but it looks like a lot of material was removed at the taper, but in the second example it doesnt seem as extreme.
Thats a heck of a gain on an otherwise stock engine.
Opti wrote: Thats a heck of a gain on an otherwise stock engine.
It also produce a flat torque "curve"...
Here is my exhaust work on a 2 valve head....
Opti wrote: It looke there was a substanstial amount of volume added to the ports on the last picture showed with the molds. I say this because most of the domestic 2 valve heads people worry about keep the runners small and efficient and not unnecesarily large, which can show good flow numbers but bad power.
Velocity is nearly as important as volume......
A few interesting things on exhaust..... 1) The 2 molds are for the same engine, but different heads. The one you commented on is a 20V 4AGE 1.6, the other casting is from the 16V version. The 20V outlet is 33.6mm (+ or -), where as the 16V outlet is 29-30mm. The 16V uses 25.5mm valves, the 20V uses 26mm valvezs So with the Toyota, the valves got a tiny bit larger, yet the port grew quite a bit more.
Now as a different POV... Nissans SR20 begin with 30mm exhaust valves and a "small" port, and by the time the VE was produced the valves shrunk 1mm, yet the port grew rather substantially.
oldeskewltoy wrote: More Miata.....
+17hp, +15#/ft - new engine now makes old engines peak torque or more for over 3000 rpm!
oldeskewltoy wrote:
from another forum said: It will be interesting to see the before and after flow-rate comparisons.
OST said: and the results.... (before) exhaust: .050" - 29.8 cfm .100" - 62.4 .150" - 95.8 .200" - 112.2 .250" - 118.3 .300" - 121.3 .350" - 121.8 Intake: .050" - 39.4 .100" - 79.8 .150" - 118.8 .200" - 150.2 .250" - 171.9 .300" - 177.8 .350" - 180.2
and now with porting, same valves, old valve job (further improvement likely with fresh 3 angle)
Exhaust: .050" - 30.4cfm .100" - 64.4 .150" - 96.5 .200" - 114.3 .250" - 125.5 .300" - 129.3 .350" - 132.0
Intake: .050" - 39.4cfm .100" - 80.0 .150" - 122.2 .200" - 156.7 .250" - 182.2 .300" - 197.3 .350" - 204.0
.300" = 7.62mm, or just a tiny bit more lift then early stock cams(7.5mm). .350" = 8.89", or nearly 9mm.
So.... flowing through the stock ports I gain 10cfm@ .350" lift on the exhaust side, and I gained nearly 24 cfm on the intake side.
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