Rb26 Cnc Head Porting

[[200]]

I am looking at an rb26 cylinder head for the rb30 twin cam head conversion.

I noticed that a place can do CNC head porting on the head, here are the flow figures,

Number 1 = modded intake

Number 2 = stock intake

Number 3 = modded exhaust

Number 4 = stock exhaust

I haven't seen any other figures to compare it with, if someone has them could they please let me know so I can compare.

[bigmikespec]

Is that ENDYN in the USA?

[GT-RZ]

lewis engines in SA do CNC head porting i think too... bit closer to home

[bigmikespec]

Yes they do, but I am not sure if it is in house or not?

The ENDYN stuff looks amazing, http://www.theoldone.com/components/cylinderheads/skyline/

[Fastrotor]

Wow, that does look amazing ! Wonder how much they charge !!.

Strange nobody as far as i've seen does cnc RB25 heads... anyone know ?

[zebra]

maybe try Bullet cylinder heads in QLD

[bubba]

Wow, that does look amazing ! Wonder how much they charge !!.

Strange nobody as far as i've seen does cnc RB25 heads... anyone know ?

http://www.lewisengines.com.au/category25_1.htm

[bigmikespec]

Wow, that does look amazing ! Wonder how much they charge !!.

I have a word doc with all their prices etc it is not that unreasonable.

Interesting they remove or "condition" both pads in the combustion chamber.

[juggernaut1]

Interesting they remove or "condition" both pads in the combustion chamber.

It is forever the perenial debate whether to remove or not to remove the quench pads.

[GTR1993]

errrr hang on, more flow on the exhaust then intake, lol.

[ylwgtr2]

errrr hang on, more flow on the exhaust then intake, lol.

thats quite normal on turbo charged engines as they really need help to get the gas out as the intake is under pressure

[ezy_09s]

^^^ I would like to see some examples of exhaust figures outflowing intakes ?!...with a smaller valve .

what heads are they ?

Edited August 21, 2009 by ezy_09s

[GTR1993]

thats quite normal on turbo charged engines as they really need help to get the gas out as the intake is under pressure

please provide some examples.

i think the numbers he had a reasonable, just reversed.

[proengines]

I think you'll find that 1 is stock intake, 2 stock exhaust, 3 modified intake 4 modified exhaust. An RB exhaust will never outflow the intake except at very low lifts. Later Mitsubishi Evo heads do for part of the range though.

They're good numbers, That looks like Audie flow software, who is the head from?

[ylwgtr2]

sorry i misread....what i meant to say is generally ive seen guys seem to concentrate more on the exhaust side to obtain more flow

[ezy_09s]

Clearly 1 & 2 are stock and 3,4 are the ported figures...i would have expected better flow figures than these .

[juggernaut1]

We don't even know what pressure the readings were taken at so a little hard to comment on flow figures.

[proengines]

They would be at 28" water

[juggernaut1]

They would be at 28" water

would be or should be?

[proengines]

I'm confident it would be @28".

You see above #1 it says CCFM, that is calculated cfm which with Audie software is either at 10" or 28" water and if the head is flowing those numbers at 10", multiply them by 1.67 to get flow @ 28" and you have a head that flows 511cfm @ 28" intake @ .5" and 392cfm on the exhaust at the same lift.

That's in the range that a 500cu/in pro stock head flows @ .8" lift and makes around 1300hp naturally aspirated @ over 9500rpm. On an RB26 it would have a sweet spot around 20,000ish rpm..

They are very good exhaust numbers, what sized valves is the head the data is from using?