Porting Rb26 Head On 500Whp Setup?

[R31Nismoid]

- Remove the exhaust bumps and polish exhaust ports.

I thought removing the exhaust bumps wasn't a good idea...

Something to do with water galleries if memory serves me correct? Could've been something else but i remember it being mentioned, just wish i could remember who it was that this discussion was with so i could find out more

[Ryan1200]

Bumps removed here been running ok since 2005...

[black bnr32]

there was a great video documenting an rb26 build and it showed/explained porting. it was on another forum from a while ago and unfortunately i can't find it. does anybody else remember it?

[levinboy]

Yeah I'm not saying you can't make more than 400hp at the wheels with that turbo but if you're going to tell me your RB26 is standard bore and stroke, runs on 98 and under 22psi of boost, then I would say you are wrong. You can, however, make 450rwhp UNCOMFORTABLY if you want to pump in 30psi of boost and water meth injection or 30% meth or E85 etc.

-9's are smaller than -7's and you can only ever expect 400rwhp out of -7's. Sure a little more can be had but usually that will be related to the fuel being used.

Running std bore and stroke, 98 and 22psi trailing to 19ish

[sven]

Our 32 gtr runs 34 n1`s @ 20 psi and is making 330awkw,

If anyone can find a good video on 26 head porting i would be keen to have a look at it also.

[Beer Baron]

yeah nismoid, the bumps are there for a reason. if you look at where the exhaust studs are there needs to be a corresponding amount of metal around them for strength, that bump is carried into the bottom of the water gallery, to keep the side width the bump is carried over again to the top of the water gallery and then into the exhaust port outlet. you can remove it but you end up with very thin wall between the exhaust port and the water gallery. it's not usually a problem as many people have done it but you end up with very very thin wall thickness there.

[marksuxass]

Our 32 gtr runs 34 n1`s @ 20 psi and is making 330awkw,

If anyone can find a good video on 26 head porting i would be keen to have a look at it also.

Some vids.

finsihed result

Pocket clean up.

http://www.youtube.com/watch?v=DBGKP4nqcGE

yeah nismoid, the bumps are there for a reason. if you look at where the exhaust studs are there needs to be a corresponding amount of metal around them for strength, that bump is carried into the bottom of the water gallery, to keep the side width the bump is carried over again to the top of the water gallery and then into the exhaust port outlet. you can remove it but you end up with very thin wall between the exhaust port and the water gallery. it's not usually a problem as many people have done it but you end up with very very thin wall thickness there.

+1. I have never seen anyone run into problems from removing the exhaust bumps though. This mod is useless unless your running after market exhaust manifolds or if you have you standard ones matched.

[tm_r33]

not entirely an expert on the 26 head but assuming its ports are similar to that of the 25 heads then there are great figures to be had from standard head design.

i actually read something not to long ago that shed light on just how well the 25/26 heads flowed!

and as mentioned before, velocity has a huge role in engine behavior. sure on a 1000hp dyno queen or drag engine it may not come into the equation, BUT i have friends in who have put longer runners and similar things on race bike ect. to create more velocity and it completely alters torque curve and delivery characteristics.....

maybe useless info but someting to consider guys.

[marksuxass]

These heads do flow well from factory, but one look into the ports and you can see theres room for improvments. Alot of the transitions are poor (bowl area inparticular), smoothing these out will aid in velocity and reduce turbulance, overall giving you a more "smoother" flow.

A God at building rb engines once said "From the headgasket down its just a pump, from the head gasket up is where all your powers made".

Some good read:

http://www.skylife4ever.com/2011/04/rb26-engine-assembly-how-to-build.html

[R31Nismoid]

^ That plagiarist website really gives me the shits!

Nothing on there they guy has done himself. It's just ripping someone else's hard work for his own benefits.

Still a good read though, saw it a few years back. Should probably read again haha.

[GTR_001]

does anyone have any before and after pictures from a modified 26 head?

[R31Nismoid]

What line did i cross exactly? The one where people call it how it is and you get upset?

All you've done for the last 6 months here is predominately start threads that do nothing but plug your own website.

Most of the "news" or "interest articles" are just a copy/paste from other websites, sources etc. Which really most don't care about as we've generally already seen it. However in some instances you don't even credit the original authors yet other users here have been able to do so in 5mins, thats just poor.

At least other people doing the same, at least link back to the main page as a bit of fairness. You however link back here by taking people to your own build thread

Oh and benefits, come come, you think people are silly?

Ads on your site - more traffic you get (via us), the more the ad's earn you

Of course you'll respond with the "it just covers the hosting costs", like everyone else. Overtime though you know more traffic, more income.

[NYTSKY]

not entirely an expert on the 26 head but assuming its ports are similar to that of the 25 heads then there are great figures to be had from standard head design.

i actually read something not to long ago that shed light on just how well the 25/26 heads flowed!

and as mentioned before, velocity has a huge role in engine behavior. sure on a 1000hp dyno queen or drag engine it may not come into the equation, BUT i have friends in who have put longer runners and similar things on race bike ect. to create more velocity and it completely alters torque curve and delivery characteristics.....

maybe useless info but someting to consider guys.

My friends 25 head flows up to 750rwhp no dramas. Stock head with Poncams and springs.

25 ports are bigger than on a 26.

[WHITER33GTS-T]

does anyone have any before and after pictures from a modified 26 head?

I do have some pics somewhere. Before and after. Mine only had a little tickle, .5mm valves, and modified for 280 degree cams

[MJTru]

So off topic I didnt learn nothing about the damn hump in the exhaust ports.

[NismoSTune]

I'd leave the head stock for 500whp. Many examples out there with 500+whp gtr with -5s. Why "fix" it if you don't need to, unless it's cheap like a few $100.

2 cents.

[33GTRV]

Basically for peace of mind all you do is clean up the casting traces and blend the short side and cutter marks. The beauty of forced 4 valve heads.

[MJTru]

Ok. This is way better. So ill leave the bump in the exhaust ports. As we speak I have already clean up those areas. I was just wondering about those bumps in the exhaust ports. I came across an artical that mentions removing them if you are going to run aftermarket exhaust manifolds.

Can anyone tell why these bumps are there in the fist place.????

[Shoota_77]

They're part of the casting for the exhaust manifold bolts to my understanding.
You'd think they'd be able to find a way around that but apparently not...

[MJTru]

But ive seen so much photos with people taking them off. Now all thats needed is somone to blow it wide open and post some dyno results with it in and the other with it removed from the head.

But I guess it wouldnt be a well worth while venture.

Or even flow chart showing the difference with it in and having it out. (The difference in the way the head flows air)