Different Boost Maps S14 / S15

Benne · Post by **Benne** » Mon Jul 20, 2009 5:50 am

Why are the boostmaps of S14 und S15 so different?

S14A:

S15:

engine load doesn´t matter?

Does S15 have a different boost control?

gsxryan · Post by **gsxryan** » Mon Jul 20, 2009 10:18 am

I would not use that s15 map, lol! +100 fuel at idle, Bet it would run a bit rich.

Matt · Post by **Matt** » Mon Jul 20, 2009 1:40 pm

these are boost maps, not fuel maps. not too sure on the specifics of the differences yet. thats one of the things i need to look into

PL · Post by PL » Mon Jul 20, 2009 5:12 pm

S15 boost maps have been used and adjusted on a vehicle. They work well:

http://www.plmsdevelopments.com/customers/gf_s15.shtml

S14 boost maps haven't.

I haven't even had a chance to bench test the S14 maps. If anybody else has played with them please let me know.

PL[/url]

Benne · Post by **Benne** » Mon Jul 20, 2009 8:22 pm

Thx PL, great Site!

You write:
"We found that with the 1.4mm jet (that we'd set up previously on the road) the boost would rise to 18psi but then drop off at higher RPM. So we decreased the jet size even further..."

even further to? 1.2mm?

PL · Post by PL » Mon Jul 20, 2009 8:41 pm

Thanks!

Yeah, I think it was around 1.2mm.

But it'll change depending on exactly what turbo and WG actuator you have anyway.

PL

Benne · Post by **Benne** » Mon Jul 20, 2009 9:48 pm

In my case its still the stock T28.

I already removed the restrictor between the tee the actuator solenoid, boost raises faster now, but max boost raised only by 0.1 bar.

I´ll try to swap the other restrictor/jet against a smaller one, like you did.

Another question:
boost map raw value for 4800 is only 50.
Is it that low because of driveability or cause of engine tends to knock at this rpm range?

PL · Post by PL » Mon Jul 20, 2009 10:26 pm

The boost map doesn't directly represent the boost level. It would have been because the engine wanted to make max boost at 4800, so the solenoid was closed to lower the boost. Then as revs rise boost tends to drop off so you see the values increasing to try and hold boost.

T28 will struggle to hold anything more than about 16psi above 5000 no matter what you do. Good turbo though - my favourite on an SR. Mr. Nissan chose well!

PL

Benne · Post by **Benne** » Mon Jul 20, 2009 10:45 pm

ok, so its no problem (regarding knock) to set the complete boost map to 100?

PL · Post by PL » Mon Jul 20, 2009 10:52 pm

No, you can set the boost map to whatever you want - just be careful of what the boost does.

The problem area with T28 will be 3500 - 4000. Where boost comes on. They'll make 20psi+ if you let them. But as revs rise it will drop off.

PL

Benne · Post by **Benne** » Mon Jul 20, 2009 11:24 pm

wow, I think 20 psi will mean knock...

Ok, I´ll be carefull, thanx a lot!

chris2712au · Post by **chris2712au** » Fri Sep 25, 2009 8:52 am

after the 4 k mark you can open her up.. 5000 + you should be able to use values up near 100 as the t28 flat out will only produce 14psi in these areas.. you might get more but I doubt it.. If machining a restrictor is too hard make an adjustable one.. but year the 1.2mm worked well for me when i did it..

chris2712au · Post by **chris2712au** » Fri Sep 25, 2009 9:00 am

tell me what you think of this document.. I have not had any results from people as yet.. however I did find that the most responsive place is to get the boost signal from the compressor cover on the turbo not post I/C you couls ged even more agressive with the boost control.. would love to see it with an external though.. the results were not as good as my blitz.. but you pay for that.. and full throttle no difference but on partial throttle I got more out of the blitz... tuning the nistune for partial throttle gave me spike on full throttle and vice versa.. if you could add more bleed to the high load areas it would be an awesome system.. but I dont think you can.. the MAp is not 3d.. only 2d..

Matt · Post by **Matt** » Fri Sep 25, 2009 4:07 pm

excellent document!

im starting to look into the boost maps for the ER34 but no luck yet, keep on going through the code trying to find how it works

the BNR32 GTR boost maps appear to be 3D but indexing is not purely just RPM. cant trace it either since its just not one input for each index

chris2712au · Post by **chris2712au** » Fri Sep 25, 2009 11:37 pm

hey matt is the is the nissan boost map actually 3d or is it just the way nistune represents it.. if that makes sense... I was going to do some more testing with the system.. just havent had the time.. I know my knock sensor is going off for no reason well atleast I think so.. I think it is the worn vct gear that might be doing it.. it seems to jump on light load gear changes..