Jump to content
SAU Community

Recommended Posts

Hi all! I am building a few engines at the moment in Canada. I've spoke to a good friend in aus and a good friend in Canada who both build good engines and from what they both have said had got me a little mixed up on what compression to run. I am building these engines for use in Canada and the best gas that we have access to is only 91 OCT. I want to build street RB26's to be able too run 450hp on 91 oct gas on reasonable timing with about 12 psi daily driving and 15-20 psi racing. Now a friend in aus said to me for every 14.5 psi you have on a engine you go up 3 compression ratio's. Does this make sense? I was just thinking with a 8.5:1 compression on a RB26 with est 18 deg timing and over 15 psi I would get detonation. I’ve had a friend who built RB's with as little as 7.2:1 compression built for our shit gas but I have never herd these engines run so wouldn’t know if that would be any good for driving everyday. Anyhow I’ve searched on this forum already about what I want to do and have had no luck through have read and learned lots more on other things so I know you guys are pretty smart.

This is what these engines have already:

-R32 RB26's

-JUN oil sleeve

-34 N1 Pump

-std water pump

-refreshed cyl head/std cam's

-1.2 head gasket

-oil restrictor

-86.5mm over bore

-ARP head studs

-ARP rod bolts

They are pretty standard but what I want to do is advertise these to be able to slap on a bigger turbo(s) injectors and eprom and have plenty of power that will be reliable. These engines will be street used everyday and weekend drag, grip, and drift. One RB26 is in a GTS-T so it will see drift more than the other so I might add an oil pan baffle. Other than that they’re pretty much the same. If I need anything else let me know as well or if I am doing something unnecessary let me know.

p.s. I had had another thread about me looking for factory Nissan clearances or a service manual but have had no luck finding it anywhere. Some of you said you’ve seen it so if you could please point me in the right direction that would be good! I also am looking for RB26 bearings, Main and rod. We can get ACL here in Canada though no part numbers are listed in out books for any RB so a part number would be great. I am not grinding the crank as they are all in good shape so just std size I would think. Or even if a Nissan bearing set if that would do. Pretty much just a part number for what would be best for me. Thank's guy's a million!!!!!

Edited by RB30 Ceffy
Link to comment
https://www.sau.com.au/forums/topic/124937-rb26-compression-and-build/
Share on other sites

If you improve on the combustion chambers you are able to run farily decent compression and boost on pump fuel, but I have no idea on the quality of your fuel other there so I can't comment on how much you can run.

As far as the psi vs CR, i was told once that every point (0.1) of compression is worth approx 4 psi of boost.

Ya your equation is much different than mine. I’m also not sure how you guys measure the quality of your gas or I just can’t remember right now anyway. We measure our gas in octane "oct" the gas we have at the pump is normally 87oct for regular, 89oct for middle grade and 91oct for high performance but its still really crap. If we run a mixture of VP race gas and 91 it really makes out RB's run much better and smoother in Canada but that’s more toward the 98-102oct gas depending on mixture and is very expensive as we already pay over $1.07 for our 91oct. Not sure on your guy’s fuel prices.

I also plan to keep combustion chambers factory unless it is a must. Let me know if you guys think that’s a good idea for what I am doing.

Edited by RB30 Ceffy

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

    • I know why it happened and I’m embarrassed to say but I was testing the polarity of one of the led bulb to see which side was positive with a 12v battery and that’s when it decided to fry hoping I didn’t damage anything else
    • I came here to note that is a zener diode too base on the info there. Based on that, I'd also be suspicious that replacing it, and it's likely to do the same. A lot of use cases will see it used as either voltage protection, or to create a cheap but relatively stable fixed voltage supply. That would mean it has seen more voltage than it should, and has gone into voltage melt down. If there is something else in the circuit dumping out higher than it should voltages, that needs to be found too. It's quite likely they're trying to use the Zener to limit the voltage that is hitting through to the transistor beside it, so what ever goes to the zener is likely a signal, and they're using the transistor in that circuit to amplify it. Especially as it seems they've also got a capacitor across the zener. Looks like there is meant to be something "noisy" to that zener, and what ever it was, had a melt down. Looking at that picture, it also looks like there's some solder joints that really need redoing, and it might be worth having the whole board properly inspected.  Unfortunately, without being able to stick a multimeter on it, and start tracing it all out, I'm pretty much at a loss now to help. I don't even believe I have a climate control board from an R33 around here to pull apart and see if any of the circuit appears similar to give some ideas.
    • Nah - but you won't find anything on dismantling the seats in any such thing anyway.
    • Could be. Could also be that they sit around broken more. To be fair, you almost never see one driving around. I see more R chassis GTRs than the Renault ones.
    • Yeah. Nah. This is why I said My bold for my double emphasis. We're not talking about cars tuned to the edge of det here. We're talking about normal cars. Flame propagation speed and the amount of energy required to ignite the fuel are not significant factors when running at 1500-4000 rpm, and medium to light loads, like nearly every car on the road (except twin cab utes which are driven at 6k and 100% load all the time). There is no shortage of ignition energy available in any petrol engine. If there was, we'd all be in deep shit. The calorific value, on a volume basis, is significantly different, between 98 and 91, and that turns up immediately in consumption numbers. You can see the signal easily if you control for the other variables well enough, and/or collect enough stats. As to not seeing any benefit - we had a couple of EF and EL Falcons in the company fleet back in the late 90s and early 2000s. The EEC IV ECU in those things was particularly good at adding in timing as soon as knock headroom improved, which typically came from putting in some 95 or 98. The responsiveness and power improved noticeably, and the fuel consumption dropped considerably, just from going to 95. Less delta from there to 98 - almost not noticeable, compared to the big differences seen between 91 and 95. Way back in the day, when supermarkets first started selling fuel from their own stations, I did thousands of km in FNQ in a small Toyota. I can't remember if it was a Starlet or an early Yaris. Anyway - the supermarket servos were bringing in cheap fuel from Indonesia, and the other servos were still using locally refined gear. The fuel consumption was typically at least 5%, often as much as 8% worse on the Indo shit, presumably because they had a lot more oxygenated component in the brew, and were probably barely meeting the octane spec. Around the same time or maybe a bit later (like 25 years ago), I could tell the difference between Shell 98 and BP 98, and typically preferred to only use Shell then because the Skyline ran so much better on it. Years later I found the realtionship between them had swapped, as a consequence of yet more refinery closures. So I've only used BP 98 since. Although, I must say that I could not fault the odd tank of United 98 that I've run. It's probably the same stuff. It is also very important to remember that these findings are often dependent on region. With most of the refineries in Oz now dead, there's less variability in local stuff, and he majority of our fuels are not even refined here any more anyway. It probably depends more on which SE Asian refinery is currently cheapest to operate.
×
×
  • Create New...