GTX3076R GEN II VS GTX3576R GEN II on RB26

[Dose Pipe Sutututu]

Can't wait to see how a 35 hotside fairs up against a 30 hotside.

What size rear housing is that @hypergear? I've got a 1.01 twin scroll on mine.

Took it out for a squirt this morning and it was running a bit leaner, had to fix up the map. Then started to feed in boost and then it started to misfire lol...

Went home and looked at my logs, nothing out of the ordinary then it occurred to me, I've gone R35 coils lol.. running the stock OEM dwell would definitely be the issue, so pumped in more dwell.

Will be taking the car out tomorrow and seeing how it behaves, fuel is also 6 months old lol.. 

[MBS206]

5 hours ago, hypergear said:

Just a quick note, the ATR45SAT you had was a 5 years old unit, current model is different, result has been updated to dyno section. More developments are underway.

And result to share:

GTX3076R Gen 2 maxed on a built Rb25det Neo on 26psi of boost, externally gated on E85 fuel.

 

I'm curious, why the drop in rpm and hence power/torque on the graphs? 

It's like you back off after starting the run and then hit it again yet your torque/power never gets back up there.

It's a solid drop in 25kw from what I can make out when it does it.

[Ben C34]

28 minutes ago, MBS206 said:

I'm curious, why the drop in rpm and hence power/torque on the graphs? 

It's like you back off after starting the run and then hit it again yet your torque/power never gets back up there.

It's a solid drop in 25kw from what I can make out when it does it.

That's the dyno having trouble keeping the ramp under control , happens when turbos come on really abruptly.

[MBS206]

Just now, Ben C34 said:

That's the dyno having trouble keeping the ramp under control , happens when turbos come on really abruptly.

Is the rpm reading coming from a calculation on the roller speed or a sensor off the engine? 

The only time I've encountered an issue with ramp rate and having issues was actually that the dyno couldn't keep up with the tyres, at that point power just dropped as the tyres were wheel spinning on the dyno. 

When this happened neither the retarder or the engine rpm dropped like the graph is showing happened. I understand it giving the jittery issue above that, but not a drop in rpm. 

[Ben C34]

17 minutes ago, MBS206 said:

Is the rpm reading coming from a calculation on the roller speed or a sensor off the engine? 

The only time I've encountered an issue with ramp rate and having issues was actually that the dyno couldn't keep up with the tyres, at that point power just dropped as the tyres were wheel spinning on the dyno. 

When this happened neither the retarder or the engine rpm dropped like the graph is showing happened. I understand it giving the jittery issue above that, but not a drop in rpm. 

This is a hub dyno, so no wheelspin. That's probably why I have only seen it on other dynapack graphs.

[hypergear]

Thats in .82 rear housing. Power curve is in response to boost curve, unfortunately I don't have a boost reading.

I've dynoed way more powerful cars on that particular dyno there's not issues with it. The only time I had similar power outline was a boost spike. Might be a delay in ext gate response, boost spiked around 4000RPM, then dropped back to norm. Could be waste gate springs are too hard, gate is jammed, hoses connecting to the external gate is too long or parameters in the EBC not 100%. 

Edited June 8, 2019 by hypergear

[MBS206]

If it's a hub dyno, are you saying the dyno is forcefully slowing the rpm of the engine after a power spike? 

I'm legit curious on this BTW. 

[Dose Pipe Sutututu]

Add more smoothing to the graphs, job done 

[GTSBoy]

14 hours ago, MBS206 said:

If it's a hub dyno, are you saying the dyno is forcefully slowing the rpm of the engine after a power spike? 

No, it would be the boost spike causing power to rise very rapidly then the response of the controller actually pulls more boost out of it than it needed to and the output drops below where it was and takes a moment to get back - and in that moment the dyno pull has proceeded up the rpms a bit more and you get hole in the curve. It's all about the PID tuning.

[MBS206]

1 hour ago, GTSBoy said:

No, it would be the boost spike causing power to rise very rapidly then the response of the controller actually pulls more boost out of it than it needed to and the output drops below where it was and takes a moment to get back - and in that moment the dyno pull has proceeded up the rpms a bit more and you get hole in the curve. It's all about the PID tuning.

If that's the case, you'd get a drop in power as RPm increases. 

This has a drop in power AND rpm meaning it had to slow, right? RPM is measured, graph trace left to right is increasing, to get a loop, rpm had to go right to left, meaning it dropped.  That's what I don't understand. 

[Lithium]

17 hours ago, Ben C34 said:

That's the dyno having trouble keeping the ramp under control , happens when turbos come on really abruptly.

Not entirely.  There may be a SLIGHT bit of dyno control issue there but it will mainly be because there was a boost spike and drop from what I can tell looking at it - boost control isn't brilliant and I suspect the dyno would have been trying to ramp up resistance to oppose the rapid increase in torque as the torque was spooling, but then suddenly the boost dropped while the dyno was "anticipating" further torque increase so it may have dragged the rpm down for a split second before it adjusted it's resistance and that would cover the slight loop

[MBS206]

1 minute ago, Lithium said:

Not entirely.  There may be a SLIGHT bit of dyno control issue there but it will mainly be because there was a boost spike and drop from what I can tell looking at it - boost control isn't brilliant and I suspect the dyno would have been trying to ramp up resistance to oppose the rapid increase in torque as the torque was spooling, but then suddenly the boost dropped while the dyno was "anticipating" further torque increase so it may have dragged the rpm down for a split second before it adjusted it's resistance and that would cover the slight loop

That explains it more for me. 

Thanks

[Dose Pipe Sutututu]

Don't really like using the Haltech log viewer because you can only see 4 channels at time, a bit shit house - but the playback function is quiet nice.

7 month old E85, tune a little rich lol (just dumped in extra 10%, seems like the new setup wants more fuel).

Because it's double demerits, these runs were done in 2nd, ignore the road speed - it's wrong, I need to configure the ratios.

1 bar ~4000rpm

 

1.3 bar ~4300rpm

[admS15]

Nice response, thats pretty much as good if not better than my little high flow 21u in 2nd gear.

So when are you going to full tuna it on the dyno?

[Dose Pipe Sutututu]

Maybe after my trip in July, need to still tidy up a few things and see if I can get a 100mm Plazmaman cooler in there first. I suspect the 76mm eBay junk cooler isn't going to do justice.

Also it's developed a misfire when you put in more boost, I wonder if it's fuel related (7 month old E85, car was off the road since November).

Twin scroll is lyfe ?

[Lithium]

Very impressive spool, I can see why you are happy with the 1.01 hotside!   This looks better than it seems like people with open housing .82 GTX3076Rs  are getting

[Dose Pipe Sutututu]

I suspect loading up the car in 3rd would show more impressive data, however for 2nd gear pulls you can see why I'm impressed for what it is, especially on a pleb 2.5L stock displacement build with Tomei "Poocams" as some call it.

The reasoning behind the "Poocams" is the actual amount of lift for drop in cams. 260/9.15mm is more than anything out on the market that are drop in and support VCT.

Broscience sometimes works lol

[Lithium]

37 minutes ago, Dose Pipe Sutututu said:

I suspect loading up the car in 3rd would show more impressive data, however for 2nd gear pulls you can see why I'm impressed for what it is, especially on a pleb 2.5L stock displacement build with Tomei "Poocams" as some call it.

The reasoning behind the "Poocams" is the actual amount of lift for drop in cams. 260/9.15mm is more than anything out on the market that are drop in and support VCT.

Broscience sometimes works lol

Yeah.  3rd gear absolutely would show much better than that, would fully expect it to anyway.  

In regards to RB25 cams which support VCT: https://www.kelfordcams.com/nz/camshafts/nissan/rb25-nvcs/246-a-camshaft-set.html

There are a few guys around here using various spec RB25/VCT Kelford cams and they've been pretty impressive, too.

Edited June 9, 2019 by Lithium

[Dose Pipe Sutututu]

Oooo those might be new! When I looked at Kelford at the time, they didn't have VCT cams with decent lift.

After I get a new plenum and cooler, the cams might be something I revisit.

[sneakey pete]

Don't think you'd be at a power level where a 76mm plazmaman would be overwhelmed, didn't have any IAT issues with mine doing 700 to the hubs last month. Might make packaging and purchase price a bit nicer