Rb26 Cnc Head Porting

[[200]]

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?

+1mm oversize on intake and exhaust.

I am curious to see if anyone would like to compare any other flow figures they might have for an rb26 with the price they paid.

Core head assembly is $850 USD

CNC porting is $1760 USD

It is from theoldone.com

[bigmikespec]

I thought so, would be good to hear from some of their customers who have had "the works" in terms of head mods.

[[200]]

1 - stock intake

2 - stock exhaust

3 - modded intake

4 - modded exhaust.

all testing at 28" on laminar-flow bench

[proengines]

That's not a bad price for what you get, including a brand new head. You'd need to run their roller wave pistons as well looking at the lowered intake quench pad. Endyne came up with their "soft head" design and looking at their Honda engines, it works.

I just want their workshop, it's very impressive.

[bigmikespec]

That's not a bad price for what you get, including a brand new head. You'd need to run their roller wave pistons as well looking at the lowered intake quench pad. Endyne came up with their "soft head" design and looking at their Honda engines, it works.

I just want their workshop, it's very impressive.

Soft head? For those who don't know and are willing to learn it means...

[proengines]

Mike, have a read at http://www.theoldone.com/components/pistons/index.html there is a basic description of the roller wave design near the bottom of the page. If you can access the old forum on the website there is a lot more about it there.

These guys are running very high comp 11/12:1 with forced induction and the right cams and making some unreal power from Hondas using this design.

[bigmikespec]

Excellent, will have a read.

Thanks

[Beer Baron]

pricing seems pretty fair. and the work looks very nice. I wouldn't hesitate to try one. you would be wise to use a set of their roller wave pistons as awell to get the most out of their chamber design. head looks fairly similar to the guy I use in japan as far as what he does with the quench pads and for the same reasons too. using their special pistons I imagine means you can reap the benefits of the revised/removed squish zones without the disadvantage of loss of response (piston design gets it back).

[STATUS]

http://www.bulletcylinderheads.com.au/nissan_rb26.php

good flow figures as well and local (SA), i still haven't sent my SR20 and RB heads of to them yet but ive seen good results... from a customers engine.

Edited August 24, 2009 by URAS

[Beer Baron]

The bullet figures look great too. very close. giving away a little bit of flow at higher lift but are on top at lower lift which is good. and overall not as much exhaust side gains. but they don't specify what valve size just that you can ask for std or oversize.

[benz_200t]

What do you guys think about making your intake port smaller??

And this figure came from an stock yamaha R6 only with the intake part has done the "smaller" porting size.

I know its for a motorcycle and a Natural Aspirated engine, could we have similar result if its been done to our the RB's?

Yamaha R6

- Stock Ports 103.1 HP

- 20% Smaller Ports 104.1 HP

- 30% Smaller Ports 108.3 HP !!

CBR 600F3

Before & After

The Blue Line represents a cylinder head that was "flow bench ported" by a well known U.S. motorcycle performance tuning company.

The Blue Line shows that enlarging the stock intake ports a small amount, caused this engine to lose power throughout the entire power curve.

The good news is, The Red Line shows that after fixing the "flowbench ported" head by making the ports 35% smaller... this CBR 600F3 gained more than 10 HP !!

Since The Blue Line's head ports were already "flowed out" even bigger than stock, there was about an extra 3 horsepower recovered.

In this case, a stock head would have worked better than the flowbench ported head.

Feel free 2 comment....and for the full URL:MotoTune USA

[STATUS]

What do you guys think about making your intake port smaller??

And this figure came from an stock yamaha R6 only with the intake part has done the "smaller" porting size.

I know its for a motorcycle and a Natural Aspirated engine, could we have similar result if its been done to our the RB's?

Yamaha R6

- Stock Ports 103.1 HP

- 20% Smaller Ports 104.1 HP

- 30% Smaller Ports 108.3 HP !!

CBR 600F3

Before & After

The Blue Line represents a cylinder head that was "flow bench ported" by a well known U.S. motorcycle performance tuning company.

The Blue Line shows that enlarging the stock intake ports a small amount, caused this engine to lose power throughout the entire power curve.

The good news is, The Red Line shows that after fixing the "flowbench ported" head by making the ports 35% smaller... this CBR 600F3 gained more than 10 HP !!

Since The Blue Line's head ports were already "flowed out" even bigger than stock, there was about an extra 3 horsepower recovered.

In this case, a stock head would have worked better than the flowbench ported head.

Feel free 2 comment....and for the full URL:MotoTune USA

id say that bike was probably under cammed for the " fully " ported head work. Its the same principal with most engines and here in aus the 4V cleveland is the most well known. We fit tongues into these engines (4v heads) all the time to increase airspeed when running mild to hot cams and 4v heads, but whack in a BIG cam and the ports come into thier own..

[Fastrotor]

Just to add to this, i've only ever seen cnc heads guys advertise Rb26 heads, but even though its not on there website (that i could see) , Bullet say in there magazine adds they have programes for the rb25 and rb20 also.

[juggernaut1]

id say that bike was probably under cammed for the " fully " ported head work. Its the same principal with most engines and here in aus the 4V cleveland is the most well known. We fit tongues into these engines (4v heads) all the time to increase airspeed when running mild to hot cams and 4v heads, but whack in a BIG cam and the ports come into thier own..

Seems like a few engines have there intakes ports made smaller.....another is the old school 2 litre pinto found in Cortina's and Escorts. Fill intake port floor with Devcon on race motors with big cams and torque and hp climbs.

I also made twice the stock rwhp with mine using stock carby and cam with same duration as stock (268 degrees) but more lift and head porting by me with larger rimflow valves - good enough to pull faster lap times than my neighbours XAGT coupe around Barbagello and within a second of my brothers C.O.M.E built 355 stroker Torrie.

Edited August 26, 2009 by juggernaut1

[bubba]

Just to add to this, i've only ever seen cnc heads guys advertise Rb26 heads, but even though its not on there website (that i could see) , Bullet say in there magazine adds they have programes for the rb25 and rb20 also.

Dude, I gave you a link to Lewis Engines on the last page where it has their RB20 and Rb25 and Neo heads.

[shanef]

+1mm oversize on intake and exhaust.

I am curious to see if anyone would like to compare any other flow figures they might have for an rb26 with the price they paid.

Core head assembly is $850 USD

CNC porting is $1760 USD

It is from theoldone.com

these are of a 26 head i had done for a monster rb26/30 33gtr i'm building for a friend. all the headwork was done by will @ jhh in brisbane. basics are 1mm os valves both sides & what he classify's as a 'race master spec port, polish & chamber work'. all port/chamber/valve seat work came to $1500.

I must say though, you shouldnt base the real world performance of a head on what it flows on a static bench, you should only use a flow bench as an indicator only.

[shanef]

^^ those figures dont seem too impressive....but flow bench figures aren't the bee all as you say.

In fact my mate with the 6 second capri who does all the cylinder head work does not even use his flow bench anymore..he has chased figures on the flow bench only to see nothing gained or even less on the engine dyno.

So these days i just trust his knowledge when he says its going to make good power it will..dont worry about flow figures

engine hasnt been run yet so i cant say how it performs.

pics of the head are in here - http://www.skylinesaustralia.com/forums/Rb...es-t245266.html

[ezy_09s]

^^ those figures dont seem too impressive....but flow bench figures aren't the bee all as you say.

In fact my mate with the 6 second capri who does all the cylinder head work does not even use his flow bench anymore..he has chased figures on the flow bench only to see nothing gained or even less on the engine dyno.

So these days i just trust his knowledge when he says its going to make good power it will..dont worry about flow figures

[Beer Baron]

yeah like shane said the numbers don't tell everything. there is a whole lot of complicated shit going on inside a 4 valve combustion chamber that cannot be completely explained just by the figures the head flows. it gets even more complicated when you add boost as we do... the proof of the pudding is in the eating... shane will know if the head is any good when the thing is running..

[Fastrotor]

Bubba, i meant "cnc" programs for rb25 heads, not just porting in general