rb26/rb20 (2.4l) Head hybrid questions.

[Nismo_Boy]

A mate and myself have been discussing the idea of using an rb26 head onto an rb20 block that would be built using a 2.4lt style stroker kit.

The reason I ask is, the cost of building a decent Rb20 head out weights the cost of an Rb26 head in which in stock form would be similar in spec.

I’ve down numerous searches and can’t find much info on what work, and how much work is needed in making it fit. I know the Rb20 head fits the rb30 block with work, so in turn I can’t see why the Rb26 head wouldn’t fit onto the Rb20 block.

Any help would be great.

- Josh.

[Roy]

Things like different head stud diam are probably the easiest thing to fox. The biggest problem is the difference in bore, which could be up to 6mm depending on the bore you decide to run.

So that means welding up the head Then there is possible dramas over the coolant/water galleries, id think it woudl be easier to do some headwork to the RB20 head for acceptabel results, rather then play and perhaps ruin an RB26 head trying to get it right

[GTR-Ben]

You do know they have different bore sizes right?

[Nismo_Boy]

You do know they have different bore sizes right?

Yes, but my question was what work was needed in making it fit

Cheers Roy, sounds like its in the "to hard pile" now heh.

- Josh.

[Penfold]

Grab the latest HPI magazines, I think thats exactly what they've been doing as their current project.

[TTT]

easier and cheaper ways of making alot more power.

I'll give you directions.

go back from here to the "Forced induction performance forum"

look up top at all the stickies.

find one tht is 91 pages long.

read him.

[Nismo_Boy]

Gtst, That was an option, But my mate wants a 2.4lt, as the conversion is less common, and "different".

Penfold, thanks, I'll check out the lastest one.

[predator]

yeah.. 2.4 is something different.. why stay with the pack. If I blow the Passage motor I might do something like that.

Personally I wouldn't dick too much with putting a different head on there - too much dicking around. The stock head should see you towards 300rwkw with maybe some porting, and cams.

You might want to speak to col-gtsx josh.. he had a Tomei 2.2L kit in his old GTS-X .. i think he said it had up around 300rwkw.

[Nismo_Boy]

Cheers Gordo, I'll have a word to Col-gtsx when his on msn next.

The stock head should see you towards 300rwkw with maybe some porting, and cams.

The power goal is more then 300rwkw. Thus our theory on using the rb26 head, which now seems too hard, and can't really be done.

[Angry]

why not go to town on the rb20 head.. and get rb26 size inlet valves fitted .. thats the only point of weakness that i can understand the rb20 head has ....restrictive inlet....something like 28mm ..compared to 36 or something like ..i forget.

i'm also in the process of source parts for my rb20 - rb24 build up for my r31coupe ..only thing i'm looking to do different is the pistons, probably toyota 4agze ones...as i dunno about spending over 2grand on tomei ones and leaving the bore paper thin and having to resleeve it.

Matt

[Roy]

Looking at a std RB20 head, i think your in for a bit of fun trying to squeeze oversize valves in there:) Even with the combustion chamber opened up a few mm to accomodate the bore increase, there still wont be too much space for bigger valves:(

Im still waiting to win the lotto so that i can buy the $10k 2.8L GTR stroker kit from HKS:) Use the stroker crank with GTR HKS rods, 82mm pistons, solid lifters, some 270deg cams with 10.25mm lift...plenty of head works and extrude honed inltt with bigger thtottle body...lol a HKS T04Z:)

Pu55 box will idle at about 1400rpm and rev to 10,000rpm and make funny power at 1.6bar...a close ratio 5 spd box would be cool... then perhaps those Endless 6 caliper brakes i dream of...all im my little R32 GTST, then go to the track and make ppl easrs bleed:)

...oh well lunch is over, time to stop dreaming:)

[Roy]

Looking at a std RB20 head, i think your in for a bit of fun trying to squeeze oversize valves in there:) Even with the combustion chamber opened up a few mm to accomodate the bore increase, there still wont be too much space for bigger valves:(

Im still waiting to win the lotto so that i can buy the $10k 2.8L GTR stroker kit from HKS:) Use the stroker crank with GTR HKS rods, 82mm pistons, solid lifters, some 270deg cams with 10.25mm lift...plenty of head works and extrude honed inltt with bigger thtottle body...lol a HKS T04Z:)

Pu55 box will idle at about 1400rpm and rev to 10,000rpm and make funny power at 1.6bar...a close ratio 5 spd box would be cool... then perhaps those Endless 6 caliper brakes i dream of...all im my little R32 GTST, then go to the track and make ppl ears bleed:)

...oh well lunch is over, time to stop dreaming:)

[Nismo_Boy]

Angry, We had thought about that, but as roy said not much space, that and I couldn't see the money in getting the work done, last time I did it on a Rb25 head.

Roy, On a serious non dream momment, would the 2.8lt kit even fit in the rb20?

What the heck would be the over all CC size then.

[Roy]

I cant remember exactly, I think it worke dout to be just under 2500cc:) Not money well spent, but meh, imagine ht esweet music at 10,000rpm:)

[Sydneykid]

I cant remember exactly, I think it worke dout to be just under 2500cc:)  Not money well spent, but meh, imagine ht esweet music at 10,000rpm:)

From memory 2,465 cc's:cheers:

[Roy]

I cant remember the stroke of the HKS crank. if anyone knows then its easy enough to work out

[Angry]

what about the older style engine of the NICs/ECCS redtop engines ..ive seen that the silvertop head is a 6 port and the older redtop head 12port - but it has the throttle butterflies , but with them removed ..it raises the eyebrows to me .. if there is possibly a greater potential for more flow? ..

coz now i'm thinking to sell my silvertop long motor and go with a old redtop block and build that bottom end up ... so i can use my original gear in the car ..

Roy u want more silvertop bits?

Matt

[Wazz]

if your power goal is more than 300rwkw go a different engine.. rb20 isnt exactly the best option.. mind you im almost ready to do the 2.4 rb20 job aswell along with a little rb26/30 aim power of the 2.4 rb20 is only 400rwhp so yer more than enough for a lil rb20 26/30 on the other hand.. well yer who knows wat sorta power figure i'll end up with

[«Cyph3r»]

what about the older style engine of the NICs/ECCS redtop engines ..ive seen that the  silvertop  head is a 6 port and the older redtop head 12port - but it has the throttle butterflies , but with them removed ..it raises the eyebrows to me .. if there is possibly a greater potential for more flow? ..  

coz now i'm thinking to sell my silvertop long motor and go with a old redtop block and build that bottom end up ... so i can use my original gear in the car ..

Roy u want more silvertop bits?

Matt

Can anyone confirm if the redtop older motors head flows better then the silver top and if so what work would be involved in the swapover? Any electrics gonna cause issues?

[Roy]

From what i have heard the heads/inlets dont flow near as well, but i have heard the bottom ends/blocks are stronger...how true that is i have no idea:(