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Has Anyone Done A 26/20?

No.96

By No.96,
in Engines & Forced Induction

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The Dan Grand Master

The Dan

Posted
Posted
the coin needed to get the RB20 head to slow that of a RB25 (is you stroke to 2.4) doesn't justify the cost IMO.

But ye, 26/20... lol

Do any of the mods we do justify the cost?

Not really.

If you wanna build a tough 20, then you're going to build one. And you wouldn't bother putting a 26 head on top...way too much work reducing the combustion chambers. The only downside to a 20 in the cylinder head department is the valve sizes. Fix that and put decent cams in and away you go. 20's are stronger, rev higher more safely etc, etc.

It's like the CA18, everyone says they are a piece of shit 'go for the SR', but they are wrong. A fresh CA will outdo a fresh SR with similar dollars spent

Lithium Grand Master

Lithium

Posted
Posted

Here was me initially thinking this was a topical pisstake thread relating to the RB26 vs 30 one hahaha.

Seeing as there was a question asked about trying to make an RB20 breathe I may as well try an answer - doesn't one of the R34 offerings have a Neo RB20 head? Are they any better than the R32 one? Maybe that could be something worth looking at?

T04GTR Grand Master

T04GTR

Posted
Posted
Heres a picture of the intake port job we did on my rb20head to flow for the rb24 build

post-23119-1236223233_thumb.jpg

I can't get one of the exhaust because the manifold is urrently attached too it.

so why did you open up the port entry to slow down the air? did you touch anywhere near the valve seat?

murrayis Mentor

murrayis

Posted
Posted
so why did you open up the port entry to slow down the air? did you touch anywhere near the valve seat?

Of course... rite down to the valve seat. intake is port matched also.. no problems with air speed at 30psi :banana:

psi Experienced

psi

Posted
Posted

Toque x Revs = horsepower.

So, RB20 doesn't have mcuh torque, so rev the poor little thing as hard as you dare!

In order to rev really stinking hard, it will really want to breathe..

This thread doesn't seem that silly when you boil it down. Sure, there may be a better way of getting the airflow your after, but I cant see the issue with starting with a head that already is known for lots of air and has a massive amount of parts you can buy off the shelf to help you.

Issues doing any kind of build will always bugg you,

but i bet everybodies jaw would hit the floor if they got past by an RB20 revvvvving @11 000rpm.. or higher! The sound would be like an R1 on roids.

Say good bye to any spare time and all your cash! but you sure have proved one thing, nobody is going to beat you to it!

I say Go for it..

Lithium Grand Master

Lithium

Posted
Posted

How are you going to address the fact that the bore sizes are seriously huge mismatches? 78mm bore into a chamber designed for something with a 86mm bore? Its not going to be nice in there at all.

The Dan Grand Master

The Dan

Posted
Posted
How are you going to address the fact that the bore sizes are seriously huge mismatches? 78mm bore into a chamber designed for something with a 86mm bore? Its not going to be nice in there at all.

+20

It's not a stupid idea but it's stupid if you try it. People are always trying to re-invent the wheel. You don't need a 26 head on a 20 block to make power. Just because it's a 26 head doesn't mean you are automatically going to be able to rev it to 11k and make 1000hp. Thats a crock of shit. And as far as revving an engine to 11k, It's not just the cylinder head that limits rpm. Crankshaft, rod length, stroke etc all play a role. With a cast crank you are not going to safely rev a 20 past 9500rpm.

It's like putting a 20 head onto a 30 block. Stupid. Increasing compression ratio in a forced inducted engine is as simple as increasing boost. Plus chamber sizes are far too different to make it work. Going that way is more practical than 26 head on 20 block though. The valves will hit the edges of the block on the way down and you won't get the head gasket to seal.

But if you have unlimited funds and want to make something that no one else has, then go for it. You will have an engine that people will say 'wow, that's impressive' but then will wonder why their mum's corolla can nearly keep up with it.

dano4127 Veteran

dano4127

Posted
Posted (edited)

TUF120

http://www.boostcruising.com/forums/index....=317565&hl=

AFAIK was running a 26 head on his 20...

He is on this site but cant remember his user id?

edit here he is! http://www.skylinesaustralia.com/forums/RB120WHY-m24062.html

Edited by dano4127
Roy Grand Master

Roy

Posted
Posted

I have a 26 bottom end and head. What would b easiest is that i throw the RB20 crank in the 26 block with 26 head. Running the 86mm bore will give me a bit more diplacement but also increased weight of the pistons. But the shorter throw crank would make the thing a crazy rev happy engine. Dont understand why you would do it though, other then for shits and giggles or a class of motorsport that dictates your cc

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