RB25DET Neo R34 updating to slot maf and misc.

[tsuokun]

Good day everyone.

I have a couple of questions and thought to post.

I have been running Z32 MAF and various levels of tune now for 8 years and thought it is time to move away from the good old Z32 maf, on to a slot style. So I have placed an order for a HPX N1 and looking forward to its arrival.

First a couple of things about my car (relevant or not):

-Stock in-mani (for now at least)
-HX35/40 Hybrid turbo on stock mani (for now) - HX40 turbine and HX35 compressor (yes, plenty of room for the engine to breath, were it not for the cast iron log) WG authentic 44mm Tial welded on the turbine housing
-I am after a boost level of close but under 2bar and hope to get a bit over 500hp out of the thing.
-Tomei Procam 260° 9.15 lift on the exhaust side, Intake stock with VTC retained
-Engine is fully rebuilt with forged internals etc.


Before the ex-cam it managed 420hp @ 1.3bar in dyno.
What else.

Anyway, the last full tune was done about 2 years ago with a friend. Since we had't read the Neo Tuning notes properly, my load scales are now slightly nuts: 25 - 255 . There were some other things going on as well, such as kicking the VE maps to 255 and leaving out the factory boost sensor and things of that sort. (you live and learn..)
Anyway, I have restored the VE map from factory rom and the boost sensor has also found its way back to the engine room, so I hope to be in the correct path now.
(I was having a multitude of strange behavior, all of which are mostly sorted out now)

So first question: Is there any easy way to go back to stock scales without complete retune?

Then moving on to the MAF; am I in for trouble if I try to just swap the Z32 to HPX with the scales I have now?

And a slightly silly one: when calculating the VQ maps in Nistune, the tube diameter is to be selected. I gather this is the inner diameter of the tube, but would like to confirm this.
I am currently pondering which size of housing to pick and would prefer to keep 3" OD as that is the size of the pipe to turbo inlet. So I suppose if I choose 3" OD housing that has 2.75" ID, it would still be enough for my HP target?

I would not otherwise be so reluctant to retune the whole thing, but I have moved to Japan now and especially here in the Tokyo area it is next to impossible (also illegal, as anywhere else ) to tune on the road and I haven't had much luck finding a place that would either rent some dyno time, or even do the tuning for me. I can do some basic stuff but for example ignition is one of the things that are not exactly doable alone on the road.

Attached is my current tune, apart from VTC activation RPM that was raised to 6400RPM from stock 5100.
I wish I had a log to go with it, but it appears something ate the file while I wasn't looking..

Thoughts?

Thanks in advance.

[Matt]

So first question: Is there any easy way to go back to stock scales without complete retune?

Are you running feature pack? Since its 8 years ago I think that maybe not... in that case there was no choice but to scale to 255 depending on MAF/injector size since you only had K constant

If you were to rescale from say 255 to 160 load then you would do it like this (with feature pack)
Lower K by 38%
Increase TIM by 38%
Scale both maps (fuel and timing) to 160 load
Check the above has near stoich mixtures at cruise

Then moving on to the MAF; am I in for trouble if I try to just swap the Z32 to HPX with the scales I have now?

Fortunately after doing the VQ tables, I made a Z32 version for HPX and then a 'max load' version. If you use the Z32 version it should be close to an actual Z32 MAF. Since we switched out the Z32 MAF and calibrated the HPX to use the same maps

And a slightly silly one: when calculating the VQ maps in Nistune, the tube diameter is to be selected. I gather this is the inner diameter of the tube, but would like to confirm this.

Yes it normally works from ID, but we have a dropdown for 3", 3.5" and 4". Don't recommend 4" since too much air flow turbulence

I am currently pondering which size of housing to pick and would prefer to keep 3" OD as that is the size of the pipe to turbo inlet. So I suppose if I choose 3" OD housing that has 2.75" ID, it would still be enough for my HP target?

I think that should be fine. Look here:
viewtopic.php?f=10&t=2428

[tsuokun]

Thank you for the reply, Matt.

I seem to have left out some important bits;

-It is a feature pack yes. Actually I used to run E85 in Finland so it has the flex sensor and the works.

-Injectors are 1000cc EV14 Bosch

-Since the AEM 360lph decided to melt itself ( )for no apparent reason, I bought a Nismo fuelpump as there is only gas available here anyway.

But allright, I suppose my plan of attack is to try to get the scales back first and once that is sorted out, I will proceed with the MAF swap. And will settle for a 3" OD housing with some air straighteners.

Speaking of the EV14s, I read another topic where you mentioned a latency number that usually goes with them, but I noticed mine was quite different from that. Would that have some impact on idle? (Mine is quite rough) I am sorry I cannot produce the numbers to compare right now as I am not near a computer with Nistune..

Cheers!

[tsuokun]

viewtopic.php?f=11&t=3748&p=27421&hilit=ev14#p27421

Here was the mention of the latency. Currently mine sit at 1200uS so a whole lot more (?) than 850uS mentioned as a starting point.

I did some tweaking on the scales, K and TIM and will later go and give this rom a try.

What I noticed though, was that the original load scale for timing was above that of the fuel map. Is this normal?

[tsuokun]

Well, I played around a bit with it but everything went surprisingly smoothly. Matt is a wizard apparently! (as we all know)

I did as told, restored the factory scales and lowered K 38% and did the same to TIM. Under boost it was running mid 13s and there was audible knock so today I thought I'd do some proper logging and some TIM adjustments.

But alas, my USB to 4 port serial thingamabob failed miserably, so I was unable to get the fueling on logs. Anyway, I added about 20% more TIM from the already added 38% and got the mixtures to stay at mid 11's on boost. As the scale curve was slightly different, there were a few knocks when coming to boost but top end until the limiter was all good.

I did try to fiddle around with the latency and I think it ended up at 1050uS. The trims were not zero though, but +4% long and -5% short mostly. I was hoping the log would catch them but apparently not so this is from memory.

Thanks again for the great advice.
Oh and the most important part is that the behavior when driving in traffic with zero to minimal throttle does not result in kangaroo-effect anymore, so the car feels much better now.

Maf, housing and some honeycomb are on their way, so hopefully I can install them soon and see how that goes.

[Matt]

Sorry for the delay, but seems like you got it. I've noted despite that latency table, that with ID 1000CC injectors we use about 1150uS with my car to get the idle right, so that is what I use as a starting point. They tend to like to be open more at idle

With the trim, they (STFT/LTFT) from what you wrote almost cancel each other out so that is fine where they are. You can use the clear trims button to reset them