Jump to content
SAU Community

Recommended Posts

Just now, Birds said:

Power is directly related to torque, son. These engines aren't different enough that if producing the same power there will be a large difference in peak torque. You'd be talking ~50nm at best. The 25 will bring on the torque and power earlier and that's about it. Hardly cog-stripping material. Unless he's button clutching it with a locker and slicks he'll be right.



Tell that to a 7L V8 in an old ute that only makes 200kw but can tow a GTR on a trailer behind it without breaking a sweat. 

RB20s are junk, and their gearboxes are even bigger junk. There is a large difference in low down torque, stop looking at dyno sheets for proof and go test drive the engines back to back. How many people have you seen say that they need to ring a 20's neck above 5k to get it moving. Considering you have a high flow and brag about its response.. I don't think you could live with a 20 even though its "only ~50nm at best" 

If you're gonna convert it to 25, which you won't because you've already made up your mind, buy the box... otherwise whatever.

Completely different engine. Let's keep the comparisons sensible shall we...given we're talking about two engines that, all things equal, are 500cc different. That is why I'm happy to generalise that, with similar power levels, one won't be smashing cogs over the other.

FYI...I have driven RB20s and RB25s, back to back. I agree the former is a piece of shit that takes forever to make power, but this fact is largely irrelevant, because when it does make that power it is nearly the same peak torque being transferred through the gearbox. Load and peak torque are what smashes gears, not where in the rev range that peak is...which is ultimately the difference between a 20 and a 25.

And if we're going down the path of experience...well...I've fitted countless 20DET gearboxes to modified vehicles, from VLs and 31s to S15s and 25DE+Ts. Done a lot of 25DET gearboxes too. It is the far superior gearbox, but as long as you're not smashing synchros and dumping button clutches with slicks, you're unlikely to break the 20DET box with less than 250rwkw in a 25.

Anyway, I can't see Pat putting in a 25, as he doesn't want to overcapitalise on a 5k(?) car. Hence the garden variety detailing jobs.

  • Like 1

Quick question for the IT dudes in here. Revolution IT did the load testing on the Census website and ran it at 150% of the expected users to login at the same time. They charged the government $500,000 to run these tests. Does that seem exorbitant? I can imagine they'd have a powerhouse of a computer and server system but god damn that's a lot of money for something that still failed anyway...

well they failed so yes exorbitant.

 

to load test something that they expect 10 million hits in a couple hours...well you have to replicate millions of users, honestly to do it properly I would expect it to be more.

 

 

 

Completely different engine. Let's keep the comparisons sensible shall we...given we're talking about two engines that, all things equal, are 500cc different. That is why I'm happy to generalise that, with similar power levels, one won't be smashing cogs over the other.

FYI...I have driven RB20s and RB25s, back to back. I agree the former is a piece of shit that takes forever to make power, but this fact is largely irrelevant, because when it does make that power it is nearly the same peak torque being transferred through the gearbox. Load and peak torque are what smashes gears, not where in the rev range that peak is...which is ultimately the difference between a 20 and a 25.

And if we're going down the path of experience...well...I've fitted countless 20DET gearboxes to modified vehicles, from VLs and 31s to S15s and 25DE+Ts. Done a lot of 25DET gearboxes too. It is the far superior gearbox, but as long as you're not smashing synchros and dumping button clutches with slicks, you're unlikely to break the 20DET box with less than 250rwkw in a 25.

Anyway, I can't see Pat putting in a 25, as he doesn't want to overcapitalise on a 5k(?) car. Hence the garden variety detailing jobs.



I agree with everything in this post

I was tempted to see what would happen if deliberately inducing lag by ramping boost late (like a centrifugal charger) would be a way to get 400+kw from a R33GTST box.

Would be interesting to see what the torque curve would be like if you run say 14psi at 4k then ramp it slowly to 25psi at 7k. May be a way of keeping a box going. Should result in a big flat line for torque as opposed to a massive spike then it falling off.

12 hours ago, emts said:

well they failed so yes exorbitant.

 

to load test something that they expect 10 million hits in a couple hours...well you have to replicate millions of users, honestly to do it properly I would expect it to be more.

 

 

 

Pretty much this.. I'm not in the webhosting business so can't explain HOW they'd actually test millions of users at the same time accessing their server(s) I'd guess they'd have a bunch then just use math to multiply the load up to however many users.. 

Lets not forget the failure could be due to hackers etc attacking 'for the lulz'

And also that there's a lot more underlying than just server load.. you've got to have enough network infrastructure and bandwidth to flow all that traffic which I reckon is where it would have failed. Like the Monash. 

Don;t call these guys Hackers, thats giving them way too much credit, it is script kiddies doing a Ddos via a zombie network. (if it was an attack)

 

It's that easy even Birds could do it.

http://www.symantec.com/connect/blogs/renting-zombie-farm-botnets-and-hacker-economy

 

the funny thing is load testing is a very similar process, get a whole bunch of boxes and start loading/posting data to the site. monitor.

 

What is interesting is that this might not actually be a DDos attack just a crappy scoping exercise.

so apparently they estimates the traffic at max 1 million users per hour, so the load testing at 150% would be 1.5 million users.
now lets say there around 10 million users submitting online.
I would guess around 1/2 would have sat down in the evening and gone ok Fk it lets do it.
so 5 million in 2ish hours or much more than they scoped.

they could have Ddosed themselves with legit traffic.

 

that also said doing it in the "cloud" is meant to mitigate this as they can just virtually throw more CPU's at it till traffic is gone. 

 

 

 

3 hours ago, Kinkstaah said:

I was tempted to see what would happen if deliberately inducing lag by ramping boost late (like a centrifugal charger) would be a way to get 400+kw from a R33GTST box.

Would be interesting to see what the torque curve would be like if you run say 14psi at 4k then ramp it slowly to 25psi at 7k. May be a way of keeping a box going. Should result in a big flat line for torque as opposed to a massive spike then it falling off.

Keeping all the bad parts of a turbo and getting rid of the good is a Mohsen spec idea.

Might as well fit a smaller turbo that will deliver the same boost and power much earlier on. The reason you'd be getting 400rwkw from the box is that the engine is seldom going anywhere near that and you've effectively dulled your turbo to perform like a small one, but with more lag. If the box can't handle 400rwkw, the day you take it to that peak is likely the day it will break. Unless the box weakness is its input shaft, 4th gear being a 1:1 is less likely to strip cogs.

Think of it this way - a chair is rated to seat 100kg. Someone 140kg sits down on it, quick or fast, that chair is eventually going to break under their weight. You can break it with 80kg if you jump on it (ala dumping clutch).

A turbo ramping up fast isn't quick enough to snap teeth; only the torque limit of the box or a sudden surge from standstill will do that.

2 hours ago, UNR33L said:

Pretty much this.. I'm not in the webhosting business so can't explain HOW they'd actually test millions of users at the same time accessing their server(s) I'd guess they'd have a bunch then just use math to multiply the load up to however many users.. 

Lets not forget the failure could be due to hackers etc attacking 'for the lulz'

And also that there's a lot more underlying than just server load.. you've got to have enough network infrastructure and bandwidth to flow all that traffic which I reckon is where it would have failed. Like the Monash. 

Oh I forgot to...carry the 1

tumblr_lkhcjft2j91qztjn5o1_500.png

  • Like 1
16 minutes ago, Birds said:

Keeping all the bad parts of a turbo and getting rid of the good is a Mohsen spec idea.

Might as well fit a smaller turbo that will deliver the same boost and power much earlier on. The reason you'd be getting 400rwkw from the box is that the engine is seldom going anywhere near that and you've effectively dulled your turbo to perform like a small one, but with more lag. If the box can't handle 400rwkw, the day you take it to that peak is likely the day it will break. Unless the box weakness is its input shaft, 4th gear being a 1:1 is less likely to strip cogs.

Think of it this way - a chair is rated to seat 100kg. Someone 140kg sits down on it, quick or fast, that chair is eventually going to break under their weight. You can break it with 80kg if you jump on it (ala dumping clutch).

A turbo ramping up fast isn't quick enough to snap teeth; only the torque limit of the box or a sudden surge from standstill will do that.

That's the thing though, most dynos have *peak* torque at ... I dunno, 4k? Usually when the car hits full boost, middle of the range.

If you backed power off in that range, your torque would not look like that. Instead of being 620nm at 4k then bleeding off to 500, you could have it peak at 500 and stay at 500 the whole way through the rev range.

Look at most people's dyno sheets, the max power figure is not where the most torque is.

At least in my car having huge power at 4k only rips tyres anyway. I'd probably result in a car which is faster through being easy to drive, and won't smash gearboxes. I am aware that losing traction means driveline stress wouldn't happen anywhere near as bad, but usually 33 boxes die from stripping gears. Under load. Usually 3rd. Usually when cars are on full boost/torque and not losing traction anymore.

 

So my idea was simply to spread that out over the rev range instead of having it all come in hardcore when the turbo spools up.
Going a smaller turbo isn't an option for me, my car has the tendency to choke the living shit out of anything smaller than a GTX3582R. I had to run a GTX3076r with a limit of 5700rpm to avoid the car melting itself.

 

Ideally you'd just have a gearbox that can handle the torque. But rarely do we get exactly what we want in modding cars :P

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

    • OK, so regardless of whether you did Step 1 - Spill Step 2 - Trans pan removal Step 3 - TCM removal we are on to the clean and refill. First, have a good look at the oil pan. While you might see dirty oil and some carbony build up (I did), what you don't want to see is any metal particles on the magnets, or sparkles in the oil (thankfully not). Give it all a good clean, particularly the magnets, and put the new gasket on if you have one (or, just cross your fingers)
    • One other thing to mention from my car before we reassemble and refill. Per that earlier diagram,   There should be 2x B length (40mm) and 6x C length (54mm). So I had incorrectly removed one extra bolt, which I assume was 40mm, but even so I have 4x B and 5x C.  Either, the factory made an assembly error (very unlikely), or someone had been in there before me. I vote for the latter because the TCM part number doesn't match my build date, I suspect the TCM was changed under warranty. This indeed led to much unbolting, rebolting, checking, measuring and swearing under the car.... In the end I left out 1x B bolt and put in a 54mm M6 bolt I already had to make sure it was all correct
    • A couple of notes about the TCM. Firstly, it is integrated into the valve body. If you need to replace the TCM for any reason you are following the procedure above The seppos say these fail all the time. I haven't seen or heard of one on here or locally, but that doesn't mean it can't happen. Finally, Ecutek are now offering tuning for the 7 speed TCM. It is basically like ECU tuning in that you have to buy a license for the computer, and then known parameters can be reset. This is all very new and at the moment they are focussing on more aggressive gear holding in sports or sports+ mode, 2 gear launches for drag racing etc. It doesn't seem to affect shift speed like you can on some transmissions. Importantly for me, by having controllable shift points you can now raise the shift point as well as the ECU rev limit, together allowing it to rev a little higher when that is useful. In manual mode, my car shifts up automatically regardless of what I do which is good (because I don't have to worry about it) but bad (because I can't choose to rev a little higher when convenient).  TCMs can only be tuned from late 2016 onwards, and mine is apparently not one of those although the car build date was August 2016 (presumably a batch of ADM cars were done together, so this will probably be the situation for most ADM cars). No idea about JDM cars, and I'm looking into importing a later model valve body I can swap in. This is the top of my TCM A couple of numbers but no part number. Amayama can't find my specific car but it does say the following for Asia-RHD (interestingly, all out of stock....): So it looks like programable TCM are probably post September 2018 for "Asia RHD". When I read my part number out from Ecutek it was 31705-75X6D which did not match Amayama for my build date (Aug-2016)
    • OK, Step 3, if you need to remove the valve body, either to replace it, the TCM, or to do a more complete drain.  First, you need to disconnect the TCM input wires, they are about half way up the transmission on the drivers side. One plug and the wires are out of the way, but there is also a spring clip that stops the socket from sliding back into the transmission. On my car the spring clip was easy to get, but the socket was really stuck in the o-ring of the transmission housing and took some.....persuasion. You can see both the plug to remove (first) and the spring clip (second) in this pic Incidentally, right next to the plug, you can see where the casting has allowance for a dispstick/filler which Nissan decided not to provide. there is a cap held on with a 6mm head bolt that you can remove to overfill it (AMS recommend a 1.5l overfill). Final step before the big mess, remove the speed sensor that is clipped to the valve body at the rear of the box.  Then removal of the Valve Body. For this the USDM Q50 workshop manual has a critical diagram: There are a billion bolts visible. Almost all of them do not need to be removed, just the 14 shown on the diagram. Even so, I both removed one extra, and didn't check which length bolt came from which location (more on that later....). Again it is worth undoing the 4 corners first, but leaving them a couple of turns in to hold the unit up....gravity is not your friend here and trans oil will be going everywhere. Once the corners are loose but still in remove all the other 10 bolts, then hold the valve body up with 1 hand while removing the final 4. Then, everything just comes free easily, or like in my case you start swearing because that plug is stuck in the casing. Done, the valve body and TCM are out
    • OK, so if you are either going for the bigger fluid change or are changing the valve body which includes the Transmission Control Module (TCM), first you should have both a new gasket 31397-1XJ0A and a torque wrench that can work down to 8Nm (very low, probably a 1/4 drive one). You can probably get by without either, but I really didn't want to pull it all apart together due to a leak. First, you now need that big oil pan. The transmission pan is 450 long x 350 wide, and it will probably leak on all sides, so get ready for a mess. There are 24x 6mm headed bolts holding the pan on. I undid the 2 rear corners, then screwed those bolts back in a couple of turns to let the pan go low at that end, then removed all the middle bolts on each side. Then, undo the front corner bolts slowly while holding the pan up, and 80% of the fluid will head out the rear. From there, remove the remaining bolts and the pan is off. You can see it is still dripping oil absolutely everywhere...it dripped all night.... I got another couple of litres when I removed the pan, and then another few when I removed the valve body - all up another 4l on top of the 3 already dropped in step 1.
×
×
  • Create New...