Rolls

If you tell us what the diff ratio is and what gearbox you have we can figure it out.

Link to build thread? Sounds like a mean 31

It is possible but unlikely.

8 thou is pretty massive, why so big? If it is blowing smoke when cold it means the rings haven't properly bedded in, this isn't right. 4 thou sounds better for a street car to me.

In 5th gear up a hill?

Someone has just got in before you, if the sale falls through I'll let you know. Had them up for almost 6 months and finally two people want them at once haha.

you think 400 rwd on the street would be able to be put down without being stupid? you are crazy! haha

Yeah I think 3000rpm is unrealistic, but if you could get something around 3.5k - 7.5k I don't think that is impossible, at least I'd like to know what combination will get as close as possible, whether that is the gt3071 or 76 I'm not sure which would make a better street car.

It isn't just the compression gauge though, it is cam timing, actual compression ratio due to pistons, if they are forged, if they rings aren't yet bedded in, if you have a big cam, all of these will change the compression.

What would you say the limit where it just gets stupid is though?

studying engineering vs being an engineer ; ) lol Im pretty sure it was actually luck of the draw

I thought it only locked up under low load?

Moral of the story is tell the cop you are an electronic engineer and wear slacks and fag loafers every time you drive your skyline.

It isn't the psi that kills motors, it is the torque that kills them. If you get a tiny turbo off a starlet and run 30psi (providing you cool the intake charge enough) it won't blow the motor up because it will make absolutely stuff all torque. If you keep the power under 280kw, temperatures down and the tune far away from detonation there is no reason why you can't run whatever boost you want. Obviously there is a torque limit where the pistons just cannot take it any more, but it is well above 280kw. There are people running 400kw that haven't destroyed their pistons, so I see no reason why you would destroy them at the 270kw you were talking about. It is temperature and detonation that kills pistons, and revs that breaks rods and rod bolts/bearings, detonation also kills bearings as well. He makes a reasonable point, because at 270kw if you get the intake charge too hot, run slightly lean etc then sustained detonation at that torque level will almost certainly kill something, however if you tune properly with a coolant temp and intake temp trim table that pulls timing (boost if possible) then you should never get detonation and hence 19psi at that power level on a stock motor will be fine. I guess if you want to be 100% safe then you should limit boost, but if any of the above happens even with forged pistons it will kill the motor eventually anyway, it will just take longer. edit: Actually if you get sustained detonation even on 15psi you will kill the motor anyway, so I think it is a moot point, it should be set up and tuned so safely that det never occurs, and hence I would say 19psi is safe. Not entirely correct, 15psi on a large turbo is more airflow than 20 psi on a stock turbo with steel wheels, boost isn't the issue, mass airflow and hence torque is the issue. But the MAIN issue is poor tuning that causes detonation, if you get sustained detonation on even a stock turbo at 12psi, you will kill the motor eventually, so providing you avoid detonation and keep the peak torque under the pistons limit you will be fine. If that means running 400psi with a tiny tiny electric compressor then that is no issue. The pressure is dependant on the compression ratio and how much air is in there, the amount of air in there isn't dependant on the boost pressure, that is dependant on how much air the engine can swallow and the turbo in use. The x amount of pressure the coke bottle (piston) can handle is based on amount of mass air (eg turbo AND psi) but it is also based on HEAT which makes it far more complicated that just plain on psi.

Even if not the 5.7% difference in load could not be enough to shift the graph 500rpm, I think the differential ratio is a setting you enter in though. 500rpm is the difference in doing a short run say eg 1st/2nd gear equivalent ramp rate vs 4th gear.

Im sure but Im curious what difference changing the pipe size makes, eg a lot, or bugger all.

Yeah there is always lots of theory going around but real world results win hands down, I've always been sceptical of how much difference the size of cooler and intake piping makes.

For me yes it is great, it is the same reason people buy v8s for that low down massive torque, you are right it probably won't make it faster and might actually make it slower but that is what I want, the fattest biggest torque curve I can attain, but I also want it to hold the torque to redline. It is a street car and I love the brutal smack I get at 3k with my current highflow, however it starts to fall over by 6k, if I could get similar response with it holding to 7.5k, it would feel amazing. So lithium you never answered, how much difference do you think there would be between the GT3071 and GT3076 in terms of boost, if all things are the same, GTX or GT, twin scroll or normal, how much spool am I going to gain from the GT3071, 100rpm, 500rpm? I do realise all your points about the 76 making far more power on less boost, holding to higher revs etc, but I still would like to know, as if it is 500rpm, then even if I only make 280kw and having to lean on it very hard eg 20psi+ it is still worth it to me.

Much over 300kw and I think a GTS-4 or GTR base would be much better suited, I really doubt the extra power will make you any faster, unless of course it is a pure fun car, where lighting the wheels up and just generally having good old silly fun is the goal.

I blew the head up in my built rb25det (snapped cam shaft), now when I pulled the head off I noticed that piston to bore clearances were quite large, about ~10 thou or greater I would say, there is nothing wrong with this, the rings seal fine, the bores are perfect and it uses zero oil but it means louder than normal piston slap, and it still rattles when warm, the bottom end however is in brilliant condition.If you aren't familiar with piston slap basically all forged builds do this, just mine happens to be louder than most. Now that I have the engine out he car I figured I could upgrade the engine at the same time I am looking to build either an rb30 or 26 so I am selling the bottom end off. Now the block is about 8000kms old, had no issues when running apart from the loud piston slap, would be suitable for very high temp/boost applications due to the clearances, when it was running it was making 236rwkw on 18psi with a high flowed rb20 turbo and had zero issues. Here is the receipts for the work done, I personally did not perform this work but the previous owner did. Has arias forged pistons, arp rod bolts, stock rods and crank, new bearings. Now the motor cost $5.5k to build but I just want it gone so I am very negotiable, so lets say I'll put the price as $1k for an easy sale, I am open to offers however . Here are the receipts for the work, if you want to confirm any of the details with the work shop then feel free to give Rob at Sabbadin a call. If I get no interest in the motor I will pull the pistons out and sell them.

A tow is like $60 max

Only issue with twin scroll is the manifold needs two gates, or clever plumbing. I would certainly do it though.

I really doubt the cooler piping makes a huge difference, the vac side of the turbo as it isnt under pressure I can see making a bit of diff. Anyone changed stuff like this back to back, if so what was the difference?

What's wrong with 19psi at 3.5k?

You will almost certainly have to trailer the car there, if it runs it will be horribly rich and no doubt foul the plugs and stall multiple times, I wouldn't bother trying to drive it. If you change the AFM as well then forget about it, definitely will not run.