Jump to content
SAU Community

Recommended Posts

1jz head was designed by Yamaha and in my limited knowledge flows better than the RB25 head... but I am sure someone who knows abit more will give you some more specific flow rates

The 2JZ head is also desinged by Yamaha and flows better than a 1JZ by a fair margin. There was rumors going around that the 1JZ head was better but it has been proven to be bullshit.

http://www.supraforums.com/forum/showthread.php?t=339560

I remember Sydneykid stating there is not much difference between a RB25 and RB26 head flow wise it the attachments that make the difference vavles etc.

Not sure if this helps but here is a comparison between a 1jz vs rb25 with the same turbo. The RB make a fair bit more power, and the curve does not drop off as much as the 1jz this may suggest that the RB flows better but im no expert on the matter.

HKS PRO-S comparison

cheers

The 1JZ has very conservative cams which would explain the drop off in high RPM performance. Just wind the boost right up and the 1JZ will take it and out power the RB25. 1JZ747 runs mid 10's in a cressida with a stock 1JZ with stock cams but high boost. It makes an insane power level but at a shockingly low RPM. So the turbo comparison doesn't really prove much. Also your link does not seem to work?

Edited by DennisRB30
The 1JZ has very conservative cams which would explain the drop off in high RPM performance. Just wind the boost right up and the 1JZ will take it and out power the RB25. 1JZ747 runs mid 10's in a cressida with a stock 1JZ with stock cams but high boost. It makes an insane power level but at a shockingly low RPM. So the turbo comparison doesn't really prove much. Also your link does not seem to work?

... and there's a completely stock internal RB25 that did 10's in an R33 Skyline with a manual. All 4 of the engines are pretty damn good from the factory, especially given how cheap you can get the younger siblings (1JZ, RB25) for.

... and there's a completely stock internal RB25 that did 10's in an R33 Skyline with a manual. All 4 of the engines are pretty damn good from the factory, especially given how cheap you can get the younger siblings (1JZ, RB25) for.

How many passes did it do before it blew up? :P tic

The 1JZ is without question the best value for money engine you can buy. Costs half as much as a RB25. At the time of purchase my 2JZ cost less than a RB25 from the same importer which is why I picked it.

Edited by DennisRB30
Uh hang on, why did you post a question if you already know all the answers?

That '25 is still going, there's a big thread about it somewhere on SAU.

No I do not know anything about the actual twin cam RB head flows. Just that the JZ are better value for money IMO. I even posted a link to JZ headflows. But I don't know how this compares to actual tests on RBs. Saying some engine made more power does not prove much since there are too many variables. I was hoping someone tested them side by side.

Great to hear that 10sec RB25 is still going. Top work from the people involved. Got a link to the thread by any chance?

Edited by DennisRB30

RB26 heads flow more std and have higher potential than 2JZ heads. I know it's a pretty bold statement, and the difference isn't that great (~10cfm) and I'm not going to post scans of flow sheets... you'll just have to trust me on this :P Oddly enough WRX heads flow better than either. I think the stronger bottom end of the 2JZ far outweighs the slight flow advantage the RB26 head has, unless you "invest" alot of moolah into it... which is probably insignificant if you are extracting over 300cfm from the heads.

ive seen a 1jz running 14.5 af ratio's turn 406rwkw on 28 psi with stock engine. still running today.

All it had was a gt3540 82r with 38mm gate hks manifold exaust cooler 2j injectors and a safc.

He dont run it that high every day though lol

So doughboy you have actually seen comparisons of the heads done by the same flowbench operator at the same lifts? I know the JZs have slightly smaller valves, and they seem to have very small exhaust ports but the intake sides look very good.

ive seen a 1jz running 14.5 af ratio's turn 406rwkw on 28 psi with stock engine. still running today.

All it had was a gt3540 82r with 38mm gate hks manifold exaust cooler 2j injectors and a safc.

He dont run it that high every day though lol

My brother and I are fitting 2 subaru turbos on his 1JZ and are going to run over 20psi with just a SAFC, 2JZ injectors, fuel pump and pressure reg. Should be interesting :sick: Gona make sure AFR's are in the 12's though >_<

Edited by DennisRB30
So is this a general info thread?

A Nissan vs Toyota thread?

I dont see much point being this is a Nissan based forum, so who really cares what the 1j or 2j do?

Info on RB head flows is related to skylines is it not? But yeah, I agree the thread did go a bit Nissan VS toyota.

Keep in mind this is a skyline forum any view will be biased. Both are good engines they all have pros and cons, different mods are needed at equal power lvls and its hard to say that one is better then another it all depends on the project and available $$$$

The 2JZ head is also desinged by Yamaha and flows better than a 1JZ by a fair margin. There was rumors going around that the 1JZ head was better but it has been proven to be bullshit.

http://www.supraforums.com/forum/showthread.php?t=339560

I believe the 1J NA head flows more than the 2J Turbo head. They did this to make it less of a tank on the road.

So is this a general info thread?

A Nissan vs Toyota thread?

I dont see much point being this is a Nissan based forum, so who really cares what the 1j or 2j do?

What if you had a 1J or 2J in your Skyline....I think I read correctly at the top where it says 'Skylines Australia' or is it just Skylines that have RB's fitted Australia?

Open your mind a bit.

I do have a 2JZ in my skyline :(

If its true about NA's flowing more its mainly in the exhaust ports because they are kept small on the turbo engines to give awesome turbo response.

The turbo on the other side was not a problem for me, even though it was my first engine conversion and my first attempt at making an exhaust. If anyone is worried about this and its the reason they don't want to fit a JZ itno their skyline PM me about it.

JZ Skylines FTW :D

I would love a R33 or 34 4 door with a 2JZ. I might do it one day. IMO, Nissan make better cars Toyota make better engines. Give credit where its due I say :yes: I am allowed to think skylines are an awesome car and JZs are an awesome engine. Combine the two for the ultimate I say :)

Edited by DennisRB30

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Even more fun, leave all the ADAS stuff plugged in, but in different locations, hopefully avoid any codes!   And honestly, all these new cars with their weird electronics. Pull all the electronics out Duncan, and just shove an aftermarket ECU and if needed a trans controller in, along with a PDM. Make it run basic but race car styled!
    • To follow up a question from earlier too since I had the front bar off again (fking!) This is what is between the bumper and the drivers side wheel And this is the navigator side, only one thing but its a biggy! So basically....no putting coolers in the wheel arches without a lot of moving other stuff. Assuming I move to properly race prepping this car I'll take that job on and see how the computers respond to removing a whole bunch of ADAS modules
    • So I prepped the car for another track day on Wednesday (will be interesting to see coolant temps post flushing out and the larger reservoir, with a forecast of 3-14 being 20o cooler than last time I took it out). Couple of things to mention; since I am just driving the car and not taking a support vehicle, I took the rear seats out and just loaded the back up Team Trackday style. Look at all that space! To cover off removing the rear seat....it is weird (note the hybrid is probably different because it wouldn't have folding rear seats) Basically, you remove the lower seat base, very similar to a r series but it is a clip that pulls forward to release the base rather than it being bolted down. Easy Then, you need to remove the side section of the rear seat on each side. There is a 14mm head nut at the bottom of the side piece, the it slides upwards off a hook at the top to release; you also need to unhook the seatbelt from the loop at the top. Then the centre piece is weird. You need to release/fold the seats forward with the tab in the boot on each side From there, there are 2,x12mm headed bolts holding the rear of each seat to the folding bracket, under the trim between the rear seat and the boot (4x christmas tree clips there, they suck). The seat is out but you can see where the bolts attach to the bracket
    • As discussed in the previous post, the bushes in the 110 needed replacing. I took this opportunity to replace the castor bushes, the front lower control arm, lower the car and get the alignment dialled in with new tyres. I took it down to Alignment Motorsports on the GC to get this work done and also get more out of the Shockworks as I felt like I wasn't getting the full use out of them.  To cut a very long story short, it ended up being the case the passenger side castor arm wouldn't accept the brand new bush as the sleeve had worn badly enough to the point you could push the new bush in by hand and completely through. Trying a pair of TRD bushes didn't fix the issue either (I had originally gone with Hardrace bushes). We needed to urgently source another castor arm, and thankfully this was sourced and the guys at the shop worked on my car until 7pm on a Saturday to get everything done. The car rides a lot nicer now with the suspension dialled in properly. Lowered the car a little as well to suit the lower profile front tyres, and just bring the car down generally. Eternally thankful for the guys down at the shop to get the car sorted, we both pulled big favours from our contacts to get it done on the Saturday.  Also plugged in the new Stedi foglights into the S15, and even from a quick test in the garage I'm keen to see how they look out on the road. I had some concerns about the length of the LED body and whether it'd fit in the foglight housing but it's fine.  I've got a small window coming up next month where I'll likely get a little paint work done on the 110 to remove the rear wing, add a boot wing and roof wing, get the side skirt fixed up and colour match the little panel on the tail lights so that I can install some badges that I've kept in storage. I'm also tempted to put in a new pair of headlights on the 110.  Until then, here's some more pictures from Easter this year. 
    • I would put a fuel pressure gauge between the filter and the fuel rail, see if it's maintaining good fuel pressure at idle going up to the point when it stalls. Do you see any strange behavior in commanded fuel leading up to the point when it stalls? You might have to start going through the service manual and doing a long list of sensor tests if it's not the fuel system for whatever reason.
×
×
  • Create New...