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rb30neo Ultimate street response


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Thats an awesome result ^^^^^

I think my VCT gear is shagged, was making tapping noises which has now turnt into a grind type noise.. so game over for now lol..

 

 

 

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On 6/2/2018 at 9:06 AM, GTSBoy said:

25HP of N2O injected from 2000rpm onwards.

this is probably the only real solution, your car is not laggy to begin with and i cant think of another turbo which will offer enough real world differences.

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7 hours ago, STATUS said:

this is probably the only real solution, your car is not laggy to begin with and i cant think of another turbo which will offer enough real world differences.

Yeah im not really complaining that its laggy, there is lots of compression  off boost and is far better than a RB25 with a 3076..

But i think maybe as a street car it would be more fun if the torque curve shifted to the left atleast 500rpm.  My experience of the VL turbo was a strong pull from 2000rpm to 4000rpm which at the time was hilarious especially after being used to a mitsubishi magna.  A car that has strong torque from lower in the revs is far more entertaining than one that gets crazy from 3500rpm as by then my licence is going to be lost and ive become anti social lol.  So i have a 0.63 rear in possession and i reckon what the hell lets bolt it on and see how the dyno compares, maybe cause E85, cams, sinco mani and any other means i can pull off an extra fat curve which in lower gears will feel more rewarding with a 3.7 diff etc to get traction..

 

Edited by AngryRB
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I would get a modern turbo and not run a 0.63 choker rear housing, if you have a bit of cash spare go twin scroll.

I dare say a GTX3071 in TS fashion with a 1.0x sized rear housing would make about the same power as your GT3076 but come on heaps earlier

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I reckon most will say that all else being equal the 0.63 will bring the turbo on a little sooner . But they're are not real big for a GT30 and some consider them (0.63 turbine housing) marginal on an RB25 .

My gut feeling is that those type B 260 Tomei Poncams are costing you part throttle and low to mid range torque . The only person I've spoken to about these was Wolverine , he had or has them in a Neo era Stag and found they cost valuable poke in the normal drive type engine speed ranges . Personally I don't like any RB25 Poncam , I dug up a timing numbers a while back and it seems Tomei gave them a little more duration timing but shit loads more overlap timing compared to the factory cams . Something like double the overlap timing . My finding in a 33 spec RB25 is that they gave a slightly more throaty idle and made surprisingly more low note exhaust boom noise . I reckon I lost the low to medium nice part throttle torque and when it did get going typically on an RB25 at around 3500 revs it came on quickly . Its not impossible that Tomei set them up to lose down low so that when they came on it was with a noticeable rush . Hectic stuff for the kool dudes .

Factories rarely if ever set cams up to work like this because it not what 80% of people like or will tolerate . As I mentioned if you want to bring everything in 500 revs earlier then refitting the factory cams should help  because they designed them to work more in the rev range you want it to .

Some people like to think putting bigger cams in a bigger engine is a must but I doubt very much Nissan would have used cams set up anything like RB25 Poncams . 

Now to VL Turbos - manual ones anyway . Gearing wise they were nothing like R33 or R34 turbo Skylines including the GTRs . VLTs had a wider ratio gearbox with something like a 3.58 first . The diff ratio was I think 3.45 . They had a pretty soft cam and small - like RB20 bore inlet manifold runners . Static compression ratio was about 7.8 to 1 .

Actually gearing wise a VLT was more like the four cylinder S chassis cars except the gearbox ratios were still wider and the diff ratio taller . If it was easy to do a 3.9 or 3.7 from an S14 or 15 could be handy but you need to think about the Skyline boxes taller 1st 2nd 3rd ratios as in hill starts and getting it off the line .

Anyway an RB30 with a Neo turbo head and inlet manifold should not be lacking poke provided the static compression ratio is at least 9 to 1 . Cams with a lot of overlap timing will cost you in the every day drive rev ranges because you lose trapping efficiency in the cylinders , meaning there is less air to compress and compression pressure will be down compared to what factory cams will give . Please don't quote me but "if" I remember correctly standard RB25T cams have something like almost zero degrees of overlap timing with the actuator switched off . On I think is around 20 degrees .

Again from memory Poncams were more like 20 degrees switched off and 40 switched on . There is a thread here that I quoted the standard R33 and R34T timing numbers and the three RB25 Poncam ones ie R33 and R34 A and B . 

A . 

Edited by discopotato03
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Thanks disco, makes alot of sense and the engine also has a high revving feel to it and the booming noise at 2k and under, it actually feels like its labouring at low revs.

Compression is there still as it feels a bit jumpy and jerky on low revs also, a comp test would be interesting actually.

This clip shows flooring 3rd, i can live with this but i want more rapid spool as i said, so stock cams maybe give that back.

 

 

 

 

 

 

 

Edited by AngryRB
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Some people buy Poncams just for the lumpy idle (not saying this is you  but maybe that's the market they are aimed at).. So put the stockers back in. Also road test all your mods - do not rely on Dyno charts alone - they are useful but do not always tell you what you will feel on the road.

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11 minutes ago, AngryRB said:

Can the poncams be modified/reground to keep the lift but reduce duration?

Absolutely.  That's trivial.  But you'd probably be better off going to the same people that you would ask for that do be done (ie, Kelfords) and get them to make you a set of actually decent cams with MORE lift and the right balance between total duration and overlap.

But, looking at your video, you're at 1 bar at 3200 rpm.  Don't know if I'd be upset with that, myself.

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Like i said im not really complaining, i just want to pull the curve to the left more and fatten it up.

So i have been quoted ~$400 to regrind the tomei down to whatever duration i want and retain the 9.15lift..

Would a 240duration and 9.15lift be a good thing for area under curve?

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Probably a little more than 240 would be good, so long as the overlap was right.  The problem is that if you are keeping the same max lift you really can't change the location of the lobe centre..... so you can't move the open and close events around to correct any overlap problem without making the lobes asymmetric.

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Either just leave it alone or put the stock cams back in. Looking at my boost curve 1 bar is achieved at 3500 and that's with a .63 front so you are doing pretty well.

2013.11.21 Boost curve 001.jpg

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4 hours ago, RRob said:

Have you tried advancing the inlet cam? will cost you up top if you go too far. 

I did but i think requires tuning at same time as it became quite lumpy and shaking at idle. 

After reading many threads looks like these cams are suited for up to 8000rpm.   Far too much for my needs, plus a GT30 is too small for this much duration even though its not laggy.

So i think a lower duration and overlap but keep 9.15 lift is worth persuing at this stage.  See how much area under curve is possible.

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https://www.sau.com.au/forums/topic/404955-highly-modified-r33-gtst/

this car was around a few years ago with a well sorted RB30 and GT3076. check out the dyno sheet and compare it to yours but i dont think you are far off.

i had an RB30 and GT3582 0.82. i could make 1 bar at 3500 if i made the boost controller really ramp boost on aggressively, but there was zero traction in 1st-3rd below 100km/h. your clip shows it keeping traction as you accelerate from 2000rpm and in the real world, thats way more useful than turning your tires into smoke.

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Thanks titan, ive actually been trying to beat or equal al's dyno curves cause they look so good.

Is interesting, assuming he used an r33 head and 256 cams with 98ulp hes got 150kw at 3000rpm compared to my 100kw, so im well behind but catch up by 4k.. 

50kw at 3k is significant in a streeter, i guess if i ran 20psi and ramped up the boost controller plus advancing the intake cam id be close..

Food for thought...

 

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I've had a few false starts trying to add 2c to this topic but keep ending up tied up with other things, but I thought I'd at least throw this out there: 

It's one of the best performing RB setups I've seen, I love it.

 

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On 6/11/2018 at 12:28 AM, AngryRB said:

Thanks titan, ive actually been trying to beat or equal al's dyno curves cause they look so good.

Is interesting, assuming he used an r33 head and 256 cams with 98ulp hes got 150kw at 3000rpm compared to my 100kw, so im well behind but catch up by 4k.. 

50kw at 3k is significant in a streeter, i guess if i ran 20psi and ramped up the boost controller plus advancing the intake cam id be close..

Food for thought...

 

Didn't you mention your VCT is cooked? I would be focusing my energy on fixing that.

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