R33 Rb30 Conversion

[JNR24]

Hey can someone inform me of what the diffrences are between the OS 3L, and the Nissan/RB30. Please be as specific as you possably can. (No 1 liners please)

Trev

[slow_r31]

already covered in this thread back a few pages in lots of detail, pretty sure the major diff is the OS rb30 uses the rb26 block, and the nissan rb30 uses the rb30 block. but as said look back a fair few pages

[Skyrine-Dave]

already covered in this thread back a few pages in lots of detail, pretty sure the major diff is the OS rb30 uses the rb26 block, and the nissan rb30 uses the rb30 block. but as said look back a fair few pages

hahaha thats a lame response.

Trev, i cant help you out i just had to laugh at slow-r31.

pretty sure the OS 3.0 has different pistons, crank, rods, i havent looked at it in detail. as i said, just laughing

[Cubes]

OS 3ltr kit is built to rev!

But for the price of it I can live with out it.

[Sydneykid]

OS 3ltr kit is built to rev!

I totally disagree, the OS kit has the same bore and stroke as the RB30, but it uses the shorter RB26 rod length. This means a less than ideal rod/stroke ratio. So given equal component strength, the RB30 will rev more and put less side load on the rods because they are longer. This is possible because the RB30 block is taller than the RB26 block with the OS liners and spacer plate. This means the RB30 is in fact stronger.

[Cubes]

My comment was uneducated

With regards to rev's and the rb26dett bottom end.

I would assume there would be no harmonic issues.

They will be able to rev due to the aftermarket crank, rods & pistons however spend the same money on an Aussy RB30 and I'm sure it would be tougher.

Comparing the RB30E block to the RB20 & Rb25 I noticed the outside of the rb30 block what looks like a thick cast rib or something inbetween each of the bore lumps + some other ribbing that runs horizontal. The RB20 & 25 blocks are simply smooth.

Is it possible a Rb30E block would be tougher than a Rb26dett block? Maybe not an N1 block but the general run of the mill blocks?

[Cubes]

Pics of the two blocks.

Note the horizontal rib that runs towards the lower of the block and the ribs that run up inbetween the bores.

[Cubes]

Interesting day today...

I had the car on the dyno to see if an SAFC would help with the fueling.

AFM CUT.... AFM CUT... and more AFM Cuts..

But at only 8-9psi and as low as 3000rpm while feathering the throttle

Previously with the same setup on the Rb20t with its piddly ports and valves it required 17psi and around 5500rpm to get the horrid AFM cut.

We couldn't do much with it as at 6psi the car would run in the 11's then by 8psi it was starting to lean out.. By 9psi it was well over the 13's heading to the 14's.

Moral of the story....

RB20t ecu is perfectly fine for running the motor in with ZERO boost, fuel controllers etc will not help.

An Aftermarket ECU and Z32 or Q45 afm is the go.

Still has me buggered why the stock AFM is hitting 5v at such a low boost & rpm. I tried another RB AFM I have laying around, that was the same.

Feathering the throttle (otherwise it would flick to 11psi) and 8 psi at approx 3000rpm it was making 100rwkw.

[Sydneykid]

Still has me buggered why the stock AFM is hitting 5v at such a low boost though.

The AFM doesn't care about boost, it just measures the airflow.

[Cubes]

I've been saying some 'dopey' things lately..

What I really meant was why I have such issues with afm cuts at low boost when 'others' have apparently had no real issues...

Maybe that headwork I had done is doing some thing good for the airflow.

On 6psi with the wastegate jammed open it made 133rwkw at 5000rpm.

Not a bad effort considering the AFR was 11:1 and the lack of ignition timing.

I found out the car was running a shade over 5degree's ignition timing (as per the crank etc).

The other dyno place had a cheap timing light that double pulsed and made it look like it was running much more than it really was. He then hooked up his Diag tool to under the dash and said 'look' it says 15degree's... BUT the thing is that will always be 15degree's. lol.. You have to also make sure the engine it timed at 15degree's.

[Sydneykid]

Maybe try cleaning the AFM and the connections, if you haven't done it recently.

[meggala]

have you upgraded the injecotors yet joel?

[Cubes]

No sir...

I was interested to see how the stock setup would handle the rb30.

Looks like it isn't lol..

Now i'm going to do the bigger turbo, injectors, afm and powerfc at the same time.

Its not worth spending any more $$ on 'to see if' and 'how much power' it will do. Tuning is expensive..

If I could see the stock injectors and afm would handle the job with a powerfc then I would get it tuned with the stock turbo just 'to see' what sort of power it would make.

It appears the rb25 head has around the same airflow as the rb20t at ~6psi less boost. You can really notice it also as the rb20t doesn't really respond much to 1-2psi however the rb30det you can really feel the extra grunt from just that 1-2psi.

[meggala]

we have found with stock ecu tuning 160-170 rwkw on stock afm and injectors and 195 rwkw when you add the z32 afm when are you finding boost coming onand are you useing the .63 or .86ex housing?

I hadny had much personal experiance with an rb 25 till I gotmy rb 25 cefiro but it is a very differnt motor to the rb25 Ican see why your having issues.

I hope you get the result you were after when your done.

cheers

meggala

[meggala]

re your question on block strenght I think the rb 26 block will be better although I am sure the rb30 is very strong.Its been interesting followingf this thread and even this far down the path I am still a fan of the rb26 as opposed to the rb 30. one of my friends with a stockish rb 26 will be in adelaide for a few months in the new year. I'll see if I can get you guys together to compare as his rb 26 is in an r32 it makes 250 rwkw.

cheers

[Fitzpatrick Speed Works]

the rb26 block and rb20 block that is uses in the gts4 are the same block and although the rb30 block is taller on the scales the rb26 block weighs more. it has a much thicker side wall and has alot of horizontal girdling that the rb30 doesnt have and plus the way the sump bolt up to a rb26 with suds and bolt and nuts that run through the block rather than being taped into the block like the rb30 it would be a lot stronger. will try and get pics soon to show what i mean.

[Cubes]

I've done a little more researching in to my fuel cut on the stock setup at low boost.

Apparently my AFM isn't hitting 5v. It cuts some times as low as 3.6v.

Its got to do with the calculations the ECU performs according to duty cycle & AFM.

Basically my injectors on the stock fuel pressure are maxing out (hence why it begins to run lean just before it cuts).

The ECU knows this and cuts fuel.

I would have thought the injectors would not have trouble in the lower RPM's due to the injectors having more time to pump fuel in per duty cycle, as the motor is running slower that 80% of the time would be a longer duration.

What I think is happening here is the fuel pressure regulator is not raising fuel pressure enough once on boost. Which is obvious as now it is flowing so much more air at a lower boost.

So the injectors are left there struggling with bugger all fuel pressure increase. How it increases the duty cycle of the injectors to the point of no return buggers me as I don't think the ECU knows what sort of boost the car is running. UNLESS the map sensor on the firewall does comunicate with the ecu in a round about way?!?! Doesn't really add up but its happening..

[Alf]

the rb26 block and rb20 block that is uses in the gts4 are the same block

Being a 4wd engine the thicker block would be nessecary as they have a sump/diff hanging off the block.

The bathurst GTR's had a thicker block than ur normal rb26dett, they kept cracking the normal RB26 blocks and it was only making approx 600hp.

An rb26 converted to rwd is of course stronger but then the RB30 also has a strong reputation too especially on the 1/4 mile.

On the street I'd choose an rb30 for driveability an rb26 is overkill unless your wanting insane power.

But at the end of the day it comes down to $$$ Rb30's are cheap and plentiful, I got my rb30 block for nothing. :cooldance

The R32, tubbed, 3/4 chassis, 1400hp RB30DET build i'm witnessing should throw the cat among the pigeons

[Cubes]

I've just been down the local U-Pull it parts to pocket myself a VL AFM plug to suit the Z32.

I had a quick look around at the R31 Skyline blocks.

They appear to have all the coolant/oil gallery's tapped + they have the machined surface for the lower tensioner.

The one I've taken pics of was an 86 model.

Also an interesting thing to note is the powersteer bracket looks the same as the R32 bracket with a slight difference to the upper left mounting hole. The R32 bracket you have to cut a bit off so it sits flush on the block.

The R31 bracket already has this done obviously.

[Sydneykid]

How it increases the duty cycle of the injectors to the point of no return buggers me as I don't think the ECU knows what sort of boost the car is running. UNLESS the map sensor on the firewall does comunicate with the ecu in a round about way?

I Don't know about the standard ECU, but the Power FC Commander shows boost levels and the PFC has a tunable boost correction table. So it certainly knows how much boost there is.