KiwiRS4T

I have read quite a bit on "back pressure is bad" but found very little in the way of actual numbers for RB engines. My RB30 is making only 280 kw and it seems needs cam adjustment but also I belatedly noticed that the "3in" cannon that I bought actually narrows down to 2 3/4 in which doesn't sound a lot but will be significant. I set up a rough test rig - put a fitting in the O2 sensor bung and ran a line to my boost gauge - it probably leaks a little so pressure readings will be a little under the real number. With my stock exhaust, 3in everywhere except for the 2.75 bottleneck in the muffler, I got 0-1psi at idle, pretty much unchanged at 2000rpm and 5 psi at full boost WOT around 5500rpm. Then I stuck in my "silencer" which reduced it to about 2 1/2 in (not much you might think but 16% less flow) ) but at idle to 2000 rpm it read 1-2 psi and at WOT 8 psi so a noticeable increase in back pressure. This leads me to believe that if I change my back muffler to a full 3in straight through muffler i should see 18% more flow and a decent reduction in back pressure. Does anyone else have any back pressure numbers they can quote (together with engine type and exhaust size) preferably from a dyno but even from a jury rig like mine would be of interest!

The only self tuning the ecu does via the O2 sensor is at idle and cruise. As soon as you put your foot down the O2 sensor has no influence whatever so you really need to know what your afrs are at WOT and a check on the timing would be good as well.

Tallest Stagea one is only 4.083 - effectively the same as 4.111

If you are in Adelaide you're in luck - MV autos 1 Stirling Rd Blackwood are the experts - give Mike a ring.

$9000 (plus some unbudgetted extras) is a lot of money but not a rip off if the result is excellent. This guy has a $20k budget (albeit for a GTR) http://www.skylinesaustralia.com/forums/topic/413703-20k-for-newrebuilt-engine-options/

RB30 block

Get a GTR box and a Link (err yes like me) !!

Any aftermarket belts including Gates can be dodgy - genuine Nissan best but pull the cover off and see if its running true and check the tension.

Good chance its that coolant sensor. If you unplug it ecu uses a default map and works pretty much ok.

Another lazy question - look it up for yourself.

This guy does good work - would post it to you as a short block or put a head on (for extra) if you want: http://www.hytecheng....nz/p/sale.html Actually the Lewis Engines might be easier for you if the quality is there.

That would be R34 GTR diff - I have been trying to source one for a couple of years! There's one here but they won't post - may suit you:http://www.ebay.com.au/itm/Nissan-R34-GTR-Rear-Diff-Complete-/320980280643?pt=AU_Car_Parts_Accessories&hash=item4abbea6543

What is the total? Couldn't make it out. This looks like a gold plated build - no excuse for failure here! As above Neo have GTR rods so would be fine unless you are going for super high kw - what is your target? What turbo do you have in mind? Conventional wisdom among some of the better engine builders on this forum is you don't need to use a torque plate for RB engines. WARNING - some people including some workshops that should know better use the wrong pistons for the Neo engine and end up with sky - high compression ratio! Prices look high to me but then most things are cheaper in NZ. - You could have bought an RB30 short bllock from RIPS! As the saying goes if you can afford it and they do a good job you will forget about the price in time.

Slightly different! I have a Stagea and run slicks on the track - front castor 6 deg camber 3deg (max Cusco arms will allow) toe in zero Rear 2.5 deg camber toe in zero. Probably more camber than ideal for the street but CBF getting a wheel alignment before and after every track day. It actually drivesok on the street and tyre wear is also not bad.

You might have to machine the block to get the CR you want or get custom pistons. Ref Gerg - he knows what it takes.

Hopefully they have changed the ecu for an R34 Neo one (asuming you have a manual trans). Not sure what you mean by weird lobe but R34s have a traction control thingy there (unless your'e referring to the bov). Neos are higher compression and quite a few other differences. Nothing that should be a problem although I think you need the correct ecu (and loom) but problematical if you have an auto.

Once you start tuning with an SAFC you will find you want to adjust your timing as well. You could use an SITC if you can find one or if Nistunes work on N/A you would be better to do that.

You don't know that the ebay one works thanks to two members - you only know that it worked for them. You don't know about the ones that didn't. Its like people who say they ran the stock turbo at 1 bar for 2 years without a problem. That doesn't mean that you can, just that they were lucky. I won't hate you if you buy an ebay turbo. I advised you to buy a stock replacement but its your car and you can do what you like with it. Just don't ask people for advice and then abuse them if you don't like the advice. Many of us are not blind to the existence of cheaper options but have in the past tried them and found them wanting.

I have solved my spewing out oil problems as above. I have not relieved/drilled out the oil returns because I don't want to pull the engine out and strip down the motor to clean the block afterwards but it seems a good move if you are at the building stage. What I have (RB30/25 with VCT and an N1 pump): 2x1.0mm restrictors 2 x 1/2in holes drilled and tapped as high as possible driver's side of sump - one hose leads to the top of a catch can the other to the bottom for a return (don't have a non-return valve in it but that seems a good idea and I may do that) . There is pretty much nothing coming out of my cam cover breathers now and I have them T'eed and going in to the catch can. This has enabled me to do two full track days without covering my engine in oil and exiting in a cloud of smoke. There is some oily mist coming from the breather on the catch can but I have a plan to deal with that. I have another catch can and will run the breather from the first into it as well as the cam cover breathers, and baffle it to try to seperate out the small amount of oil that comes through. I will vent this second can to the turbo intake. Breathers from the sump to the cam covers are not a good idea and the "head drain" at the back of the head is not really usefull for anything.

Google is your friend. Just type "what is" and add "in a car" or " for a Nissan RB" if needed.

Your best bet (and only bet really on your budget) is to get a replacement stocker from someone who is upgrading. You should have put the money for the electronic boost controller and Nismo fpr in a savings account towards an upgrade (neither is making your car faster).

Put your car on a dyno in case the afrs and timing are all wrong. Presumably its not the tunable type?

And here is an interesting view from an engine builder: >I have to wonder if the distortion form the head being bolted on >isn't less than the normal thermal distortion form the engine >being at operating temperature. Maybe they should bore engines at >operating temperature too (:-) Some people do that too - I only know of one company over here though who advertises boring a block at running temperature. Another waste of time in my opinion. Blocks don't run at an even temperature over the length of the bore and the bore walls go all over the place as soon as they have high speed piston thrust and vibration acting on them anyway. I look at it this way. Bore wear takes place mainly in a very limited area at the top of the ring travel. You can strip a newish engine down and find 1 thou of wear over just a quarter of an inch of bore length but the power and cranking pressure won't yet be much affected. That means the rings can cope with moving in and out over that 1 thou in such a short distance. Even at 3 thou wear you see little drop in power. I stripped an engine recently with 8 thou wear and that certainly was smoking a bit but power was not too bad still. Maybe 95% of original output. So does even less than 1 thou of ovality or taper over the whole length of the bore cause the rings any problems? I doubt it somehow. I don't dispute that in theory the perfect bore should be round and straight at operating temperature and with the stresses of the head and mains caps bolted on. Whether the few tenths error you end up with by not boring with these stresses in place makes the slightest difference is open to opinion. My opinion, after seeing what engines can cope with in terms of machining error and still run at peak power is as I say above. Also most engine reconditioners don't get a bore anyway near round and straight at the best of times. 1 thou taper or ovality is par for the course when I check other people's work. That 1 thou is still going to be there if they bored with a torque plate on - just in a different part of the bore I suspect. Call me a cynic. Dave Baker at Puma Race Engines (London - England) - specialist flow development and engine work. .

OK found it in the RB Manual Max taper should be 0.010mm which is what you found. Max out of round should be 0.015mm (not as stringent as CP's requirement) but still you have measured more than that. Have you called the machinist to ask them for their comments? Are the figures you came up with in line with the quality they set for themselves? And if not I guess they should fix the problem for you.

Which is why I asked OP if it had been rebored or just cleaned up and honed. Need a professional such as Gerg to comment on the expected tolerance from a full rebore and machine hone! (Too many years ago since I last had a block bored to remember) A quick Google suggests the OP's original measurements are well within the allowed tolerance. What does the manual say?