4AF head prep and porting

[oldeskewltoy]

Bah! I'm getting impatient. I want to see numbers from that flow bench on Grunt's head.

patience


below is a unique 2 panel photo of the problem exhaust port(#1) inside the 4AFE head... AFTER it has been ported. Now you have seen the right hand side before, that is the area that has the oil drain that interferes with the port. What you haven't seen before is the #1 exhaust valve port(left side of photo) EXTENSIVE work was performed on this port, the roof, and wall were substantially changed








Below is the #4 exhaust port. You can see FAR less work here... but the reasoning is we are attempting to equalize these two ports. Take special notice of the left split in the photo below - THAT is how the buggered port above would have looked *IF* Toyota had chosen a better oil return path then the one they did choose



To compensate for the lack of oil drain on this port, just a bare minimum has been done in this port. You can see extensive roof work, but little else was done on the port walls to TRY to compensate for the crappy #1 port.......




Now for why you are all here.... the results




Port#1 (problem/extensively ported) .050"=27.4cfm, .100"=52.7cfm, .200" 92.8cfm -

Port#4(no Problem except to leave it mostly alone) .050"=27.8cfm, .100"=54.8cfm, .200"=90.3cfm


They appear VERY close... Now... a bit of averaging... add up what you have... multiply it times 2(after all the valve is @ these points twice in each cycle), now divide by 6 to get an average.........

57.633cc average for port #1
57.633cc average for port #4

EXPLETIVE YAH

[PrettyCoolWagon]

Hi OST
What was the average flow rate for port #1 & #4 prior to porting?

[oldeskewltoy]

Hi OST
What was the average flow rate for port #1 & #4 prior to porting?

I didn't have the bench prior........


The current lowest flow for any of the ports is port#3. It only has the bowl/seat blending and it flowed 23.4cfm @ .050". Port 2 is the 2nd lowest @ 25.8 cfm @ .050". The 2 center ports are MUCH easier to increase flow with just a little bit of work on the walls and ceiling and I should have no problem matching the 2 center ports to the now "equalized" outer ports

[PrettyCoolWagon]

Hmmnnn.... I wonder, does toyota or anyone else publish this kind of info?

it'd be good if you could get the same type of FE head & test flow that.. just to see the difference..

Still.. good work, nice tip on how important it is to keep flow rates of each port in the same range.

IE A lot of work on some, a little on others..

[allencr]

Come'on, go nuts on the valve head & guide boss, they've got plenty of excess lard!

[RT40Corona4AGTE]

nice work OST!

[PrettyCoolWagon]

Come'on, go nuts on the valve head & guide boss, they've got plenty of excess lard!

Not everyone agrees with overgrinding on these areas

[oldeskewltoy]

Bill.......... below is an 8 port 4AFE engine that I recently saw on ebaY.de (German ebay)

[Sam_Q]

I don't think we recieved those in Australia, bizarre port shape in those too

[Billzilla]

Bill.......... below is an 8 port 4AFE engine that I recently saw on ebaY.de (German ebay)

Yes I've got one or two of those heads here. They're not too bad and make good power with the right porting - A friend of mine in Europe has one that makes a bit over 240hp at 9,000rpm.

[Hiro]

Note the injectors in the head too (4-port heads have them in the runners).

The US got TVIS on some of their 7AFEs I think, never seen it on a 4AFE though.