Rb20 (Redtop Head)/rb30 Block?

[madaz808]

i bought a motor and gearbox setup and just curious about it before i put it in my R31.

what i was told be the bloke i bought it off was he had it in his drift R31 car before he destroyed the rear end of the car

its aparently a VL turbo block with forged internals rb20 redtop head with rb26 internals in the head as i say wat i was told

and the gearbox is from an GT-R with the transfer case cut off and sealed up apparently they have a stronger centre shaft

hes said it was pushing 450hp-650hp depending on wat turbo/intercooler setup was used and recons it runs 500hp day in day out

now im just wondering if it could work, and or wat peoples opions are about it will attach a picture

[O2 Autosports]

it won't be a 20 head it will be a 25 head. 20's are almost impossible/pointless to fit to a 30 block.

[madaz808]

ok i was told from someone else that a rb20 redtop head was the only 20 head that bolted straight on aswell as the r32 rb25

well sound like im one step up from before anyway lol cheers

[jarrod83]

it looks like a rb20 head to me in every way, as far as im aware the rb20s dont flow as much air due to the smaller valves.. without knowing exactly whats been done its hard to speculate what sort of power its capable of, but i guess 400-450hp may be more realistic than 650hp.. i would stick on a gt30r n see how it goes

[dorifticon]

People used to bolt rb20 heads to rb30 blocks in the old days (like, early 90's) because rb25 and 26 heads were still rare and prohibitively expensive. There is a lot more modding to do to the rb20 head to fit to the rb30 block (eg bore size is different) compared with the other conversions but people did it because they didn't have much choice in those days. Nowadays nobody does it for the reasons mentioned above.

In terms of flow, it stands to reason that the head and valvetrain would be modified because stock for stock, taking off the sohc head and putting on the 2.0 twin cam doesn't net that much of a benefit, you have to mod the 20 head to make the whole thing worthwhile IMO (which is what appears to have been done in this case).

it looks like a rb20 head to me in every way, as far as im aware the rb20s dont flow as much air due to the smaller valves.. without knowing exactly whats been done its hard to speculate what sort of power its capable of, but i guess 400-450hp may be more realistic than 650hp.. i would stick on a gt30r n see how it goes

[Crans]

Don't forget the rb25de that came in the R32 looks exactly like the rb20

[R31Nismoid]

It's definately a HR31 RB20 NICS Red top head. No doubt about it.

Not R32.

As for it being a 3ltr. Look @ the block number.

Either way a LOT of dicking around to get that kinda setup to work - as frankly, it doesn't without some serious time/effort and even then the results are poor as the head simply does not flow.

[JonnoHR31]

yer even silvertop heads arent worth it because they dont flow but using a NICS head, might aswell buy an excel....

you can see from the pic that its a 30 block, the tensioner has been relocated above the water pump.

[madaz808]

i recon im gonna see how it goes all the loom has been done to suit a R31 with Aftermarket ECU he was running a wolf 3d just be something different

[Raysboostin]

i remember about 14 or so yrs ago there was a vl commo that ran a red top rb20 head. apparently theres alot of wok to get them to fit, but as said above back in the day they were the only cost effective option. have a poke around on the commodore forums u may be able to dig up some info.

[madaz808]

nw sounds good i think it would go well in my series3 R31 nothing to spectacular but still and eye soar never the less