Rolls

10w40 is what you want for our weather esp if you are tracking the motor and seeing higher temps. If it is predominantly a track car 50 or even 60 might be more appropriate, especially if it uses oil.

In that case find someone with a wideband gauge and at least use that yourself, better than nothing. You really shouldn't be tuning fuel without one! Knock ears would be great as well but you aren't exactly going to go spend $1k on them for a back yard tune, maybe a visit to Melb is in order? Be cheaper than a replacement motor that is for sure!

Yeah, I called it that just so he knew what I was talking about. Make sure you go to an RB specialist when getting RBs built, you want someone who has built 100s before, otherwise you have no guarantee they have any idea what they are doing. Engine building is not simple, there are 1000s of places to go wrong, and just one of them is enough to grenade an entire motor, when you are spending thousands you want everything to be perfect. I put more faith in a second hand nissan motor that is unopened for this reason, they built 100s of motors a DAY so they knew what they were doing. Says it all when you see rb30s that are 400,000kms old and still look great when stripped down.

I have a gcg turbo that basically does this, highflowed BB rb20 turbo, it is very believable. 230kw isn't a huge torque increase over the stock turbo, they will make 200rwkw if you really lean on them.

I remember someone saying the workshop actually refused to do this as they didn't want to make up a dummy head to bolt on due to time money. Certainly want to make sure they do this! if they don't normally do RBs there is a chance they didn't though.

If you have changed to known working coils then I'd say you can be fairly sure that isn't the issue, but the fact that gap makes a big difference suggests it is now primarily overfueling. Overfueling on its own can cause a misfire, I know because it happened to me. Was running sub 10:1 around 9:1 at peak torque which caused a rich misfire, was a tomei remapped rb20 ecu (car had a bunch of tomei stuff in it) but it was designed for jap fuel, had so much timing they had to retard the cas to get it to not ping. Solution was mapping a new ECU from scratch (before nistune etc) which fixed it as the tune was just simply not designed for our conditions. Sounds like you are running a stock ecu with some minor changes via the SAFC. Stock tune with extra boost, bigger exhaust and intercooler etc means you can be seeing almost 100% as much air as the stock tune was meant to cope with, the factory tune then goes massively rich and retarded to make sure the motor doesn't go pop, sub 10:1 is quite possible if it is a cold night with >12psi and lots of engine flow mods (intake/exhaust etc). As seen taking fuel out via the SAFC fixes the issue, the issue with doing this not on a dyno is you could be massively leaning the motor out making it detonate, you need a wideband and a dyno to do it properly. The other issue is you still have the retarded stock ignition maps, though if you are bending the afm signal perhaps it will fool the ecu into using lower load cells with more appropriate timing, I'm not sure. Ultimately I would recommend a nistune and a proper dyno map, if you want to do it on the cheap get a tuner with a dyno and wideband to tune the SAFC properly, you've seen it yourself, it will fix the issue. Good luck!

I wouldn't take it much over 6500-7k with standard everything, plus with stock cams and a non stupid sized turbo you don't need to take it over that to make big power. piston clearance is all based on the pistons being used, they will state what is recommended. Forged are usually quite a bit larger due to expansion.

The general consensus on here is bed rings in then go for gold. It's all the old school guys that say to drive them for 1000kms etc, it just isn't necessary today.

What is the chip? I work in micro processor development and might be able to find an alternative that uses the same protocol and mapping for the memory. edit: Or are you talking about the micro itself? not the memory?

As you found out rich mixtures compounds the problem as it makes weak spark even more likely to miss. Get it on a dyno and get it tuned properly, don't do it yourself as you will probably lean the motor out and kill it. Get new coils as well, guaranteed to fix the problem. It is 99% of the time a combination of weak spark and too rich making weak spark even worse. Small plug gap makes the spark stronger which is why it seems to help. I need a generic post for these threads, it is almost always this and this is always the fix. Check out the massive misfire from 4500 to 5000rpm thread. It'll be a combination of coils + plugs + too rich.

Incredibly unlikely but I snapped my exhaust cam shaft which had these symptoms. Good compression, turns over fine, no funny noises but won't start! Probably had bad compression at times when the cam didn't happen to be in the right place. Take you 30 seconds to take the rocker covers off. Wouldn't really make sense for this to happen, but f**k it worth checking.

Must be really hard to starve off detonation with a tiny hot side like that. Does it make full boost by 2k and then dive over at 5k? How physically big is the hotside though, is it comparable to a GT35 or is it bigger?

how much is that going to cost you? You could buy a complete short block for not much more with a warranty, I would never trust a home build.

There is obviously something seriously wrong with those compression results, get someone who knows what they are doing to strip it down and give you a report on the failure.

well you still need someone to tune it, most of the best tuners work at a workshop.

No tuner would tune it from scratch anyway, they would just tidy up the existing tune, probably 30 minutes work max to confirm everything is in check. If they say they are tuning it from scratch they are taking you for a ride as it makes no sense to wipe a tune and redo it, just a waste of time for no reason. They would most likely just touch it up and charge you more for the sake of it, I hope there are no tuners around that would do this though.

Yeah if the issue is a combination of too high comp, incorrect squish etc as an engine builder he should be checking these things and not expecting the customer to have checked everything 100% before, should at least give a discount on any work that has to be done as it is as much his fault as anyone elses. Assuming that is the issue though. I still personally think it is something completely different, eg exhaust restriction, intercooler full of oil, massive blow by or something along those lines.

Possible, but I really doubt it is the cause of his issues though.

It has probably been designed with a limited range of data, most likely the more common horsepower cars, eg 2-400hp range, your data is probably an outlier in the equation so of course it won't work for all cars. All it is is a line of best fit.

Well that's good. What has he said about squish ?

Be more like 140 max then.

This is why I tell people to buy a complete short block with warranty from someone reputable, that way theres no blame to be laid, one company did all the work and warrant it. By the time you stuff around doing it 1,2,3 times until its done properly you've spent more than the cost of a full forged short block. Still, it is the best way to learn (although expensive!)

I don't think he is responsible personally, you said he didn't run any timing and it was quite rich, really doesn't sound like tuner error tbh. Only way to know is to pay a pro to strip the motor down and document the failure, which imo you should do so you know what went wrong and don't do it a second time. If someone is to blame you need to be really sensitive about it, as if you accuse people (even if they were in the wrong) you can very quickly alienate yourself and they won't want to help you, especially if you can't easily prove it. I think getting a professional to strip it down is the best course of action from here on. Think of it all as a learning experience, thankfully you haven't spent too much money so far.

Well you would know better than me! haha What do you think would cause them go after 200kms?

Should really leave this stuff to people who have done it 100 times before, sounds like rings aren't sealing. Have you done a comp test?