Base image S14A vs S15

[FreakensNL]

He all,

I just compared the base image of a S14A and a S15 (FP) and there is a crazy difference in timing, i thought they were the same engine type?!
Could anyone explain this?

[Matt]

Yes the S15 models dropped a lot of timing.... Nissan were much more conservative in that model

This was noticed with ADM S14A/S15 models too

[FreakensNL]

Later(??) models of the S15 had the more aggressive timing, why would they drop that much timing??
12deg up top !
Would love to hear peoples theory on this

Strange that they do report the same kW and Torque figures, and that the s14 is supposed to have less power than the S15 when clearly that should be the other way around if you ask me..
S14A:
Nissan 200SX Power: The 200SX's 1998 cc (121.9 ci) engine reaches its peak power of 197 bhp (146 kW) @ 6400 rpm.
Nissan 200SX Torque: The Nissan 200SX produces torque measuring 195 lb-ft (267.0 Nm) @ 4800 rpm.
S15:
Nissan Silvia Power: The Silvia's 1998 cc (121.9 ci) engine reaches its peak power of 247 bhp (184 kW) @ 6400 rpm.
Nissan Silvia Torque: The Nissan Silvia produces torque measuring 203 lb-ft (275 Nm) @ 4800 rpm.

So there is nothing different about the engine itself?!

I did notice a difference in the K-value, so that explains the TP-load index and perhaps a different walk path
S14A: 31.000
S15 27.000

[Matt]

K value is different because S15 uses 480CC injectors, S14A uses 370CC

This shows that Nissan adjusted K value (and every single TP related table and value) when adjusting injector size

[FreakensNL]

I understand, i meant that the last load-column on the S15 is "104" and on the S14 it's "134"

but wouldn't you expect the S14 to have more kW when looking at the timing figures?

[Matt]

K is lower on the S15 due to larger injectors, so resulting TP will be lower (TP=K * MAF/RPM) which is why S15 TP scales are lower

[FreakensNL]

But why does it have 10 deg more timing up top?
I also see this in other S15 ecu base maps, all the same engine right?? so should be able to safely run those stock maps

This looks like some s15 's have 20% more hp than others..

[Matt]

Not sure with the extra timing. Have to ask Nissan

[FreakensNL]

Hahaha damn... was hoping to get a better answer from the Nistune community
(just trying to understand before changing)

Perhaps someone has any idea of why they did this?!

[unex]

I would say s15 timing table looks like crap. So maybe they hired cheaper tuner?

[FreakensNL]

Hahaha exactly! so how can it have 250bhp?
There has to be a reason behind it, will ask F-Steve when he's in the Netherlands as hes a bit of a "Pete" around here

[PL]

Yeah good question. Short answer is that nobody but Nissan knows. Often what happens is that the car is released with Rev A of the tune. Then as they get customers actually using the local fuel and reporting back with stories of knock and broken engines they start tweaking the tune. So Rev B often has less timing to cater for dodgy fuel. Or in case of Australia - dodgy fuel, hot climate and brainless drivers.

Check the S13 SR20DET maps 50F00 and 50F01. You'll see the maps are very similar except the later one is richer and they removed some timing in the last column. Smacks of anti-detonation tweaking to me!

What I have noticed is that S15's tend to be knock monsters. Has anyone else seen this? I've got lots of local cars that just won't take timing. I've discussed this with other tuners locally and they all agree but nobody knows why. They look the same as S14a but the S15 seems to detonate earlier. Maybe change to combustion chamber design? Anyone know?

PL

[FreakensNL]

Wow, those S13 maps are indeed anti-detonation tuned, interesting


Seems to look like it, can't come near the numbers of the s14a..
Instant detonation


Maybe interesting; Comparison of the s15 sr20det; AT vs MT


I'm guessing less timing down low because the AT is still on full boost when gear shifts
so the EGT's are getting higher because you don't release throttle, but the more timing up top???

[UNISA JECS]

Yeah good question. Short answer is that nobody but Nissan knows. Often what happens is that the car is released with Rev A of the tune. Then as they get customers actually using the local fuel and reporting back with stories of knock and broken engines they start tweaking the tune. So Rev B often has less timing to cater for dodgy fuel. Or in case of Australia - dodgy fuel, hot climate and brainless drivers.

Check the S13 SR20DET maps 50F00 and 50F01. You'll see the maps are very similar except the later one is richer and they removed some timing in the last column. Smacks of anti-detonation tweaking to me!

What I have noticed is that S15's tend to be knock monsters. Has anyone else seen this? I've got lots of local cars that just won't take timing. I've discussed this with other tuners locally and they all agree but nobody knows why. They look the same as S14a but the S15 seems to detonate earlier. Maybe change to combustion chamber design? Anyone know?

PL

The crazy thing is im tuning a friends S13 with the 50F00 ECU and the walk path at 9-10psi with stock turbo, maf, injectors stock base image is LOAD TP 56 which is no where near column 16 (104), now is something wrong with the ECU lol so how can we be sure those S14 and S15 walk paths are at column 16? Is this something we know for fact, cause that would change a whole lot of my thinking lol I actually made another thread on this hoping someone could answer now im real curious, seems like that ECU has premeditated built in room for growth.

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[Matt]

With factory PSI it wont reach those columns. Assuming that Nissan kept in mind people like to increase the boost in their cars, and it would then take that path (or if the hose disconnected from the actuator and it was running full boost)