zRotary

hey, thanks for your reply.



why do you mean it would take my motor with it, past 9 psi? I think my motor should handle a bunch more, but my turbo wont make it that long i think.



hmm.. my map is 11,3AFR at 8psi, threw the whole boost area (8psi) until 7500rpm. My exhaust is a full racingbeat with a presilencer, and the ignition map is almost stock, so i dont know why i got lower boost levels from 6700rpm could it be the ported WG also? idk!



anyway, thank you very much for backup that WG thing, now i know i was right, and that i have no boostleaks at all, but its naturally that i dont get boost rise with a ported WG.



ps. i dont want my stock turbo to last forever, just 1 year or something like that. since there are guys running them with 14psi, i was sure to be safe with 12-12,5 psi. and if the turbo is down, i was going to go with a BNR St.3

One320B

I was referring to the fact if the turbo should fly apart, the compressor wheel will go first, and tiny bits of metal inbetween the housings and rotors usually dont vote well for the longevity of your engine.



As for the boost level - 9psi is optimal.. 10psi is ok, but those guys running 14psi on the stock turbo need to learn how to read a compressor map, the stock turbo has no guts really past 10psi - those extra 4psi are just hot air, lol...

zRotary

oh i see.. thank you very much for this advise! i didnt know that.

Well ok, than i will be going to run 9-10psi, and just wait for an other turbo lol

One320B

Thats the safest bet - 10psi will still make plenty of power for now.



There was a guy around here who made 298whp on the stock turbo at 10psi I believe. He did have a ****-ton of motor work though, lol...

zRotary

that was our purpose also, getting around 300whp. so i cant await the dynorun after i get a MBC

zRotary

Hey, could my boost loss in higher rpms be caused by high air temperature? (50°C) or restrictive intake?

the only restriction right now is the stock mount intercooler.



i have no MAF, the throttlebody is modded, and the UIM/LIM are ported.

One320B

Are you referring to hot atmospheric air - or how hot your intake temps are?



Restrictive intake systems can limit boost, but with a free flowing air filter (thats clean) you shouldnt really have any bottlenecks that would keep you away from 10psi. Fuel and timing play the bigger factor at the higher RPM to maintain boost... provided you've got a good breathing turbo.



Have you confirmed that your turbo is in good shape?

zRotary

Yea, the shaftplay is just normal, there are no oil-leaks and no smoke coming out of the exhaust at WOT. Also it spools up quick to 8psi at 5000rpm and holds it until 6200~

then it begins to drop.. some kind of that way:



6000rpm 8psi

6400rpm 6psi

6600rpm 4,5psi

from 6700 it holds ~3psi up to 7800rpm



I noticed weird AFR readings at high-RPM also.. as told my MODS above, i have 800cc secondaries, and my AFR are setup at 8psi running 11,4:1 and it keeps that value until high RPM are reached, lets say 6800rpm. THEN the mixture gets leaner and leaner. You will say, YEA because my map is to lean in that area..

but its not the case, my map is setup richer and richer, but it gets lean anyway.. something like that:



6000rpm 8psi AFR 11,4

6400rpm 6psi AFR 11,6

6600rpm 4,5psi AFR 11,8

6800rpm 3psi AFR 11,9

7000rpm 3psi AFR 12,1

7400rpm 3psi AFR 12,8

7800rpm 3psi AFR 13,5

8000rpm 3psi AFR 13,9



My PowerFC map is at MAX in that area, and the Injector duty is at 74% MAX.. i can only richen it up by using a trick, in telling my MAP-Sensor to inject 110% in the 7000-8000rpm area instead of 100%, then i get 11,8AFR readings at 3psi of boost.

So i wonder what causes this lean mixture at highrpm, but with rich map and, 800cc secondaries, walbro fuelpump, AND since my boost gets down to only 3psi, it should even get richer and richer and not the opposit right?



And thats where i say, it cant be a rich mixture right? because i get such sucking AFR in that rpm-range.. or is it a phenomenon that you get LEAN reading if you are TOO rich? i dont think so.. my LM-1 wideband is showing me even 7:1 readings if it must.



My ignition timing at such pressures and rpm are as follows (degree ATDC of course):



5600@ 8psi 17°

6000@ 8psi 17°

6400@ 6psi 21°

6800@ 3psi 29°

7200@ 3psi 30°

7600@ 3psi 32°

8000@ 3psi 32°



i had BASE ignition-MAP before, and was experiancing the exact same boost loss.. so i dont thing its my current ignition-timing that i am using, which causes it.. if it only would be the ignition, at least i would know what i am doing wrong.. so here is the BASE-Map:





5600@ 8psi 12°

6000@ 8psi 12°

6400@ 6psi 15°

6800@ 3psi 24°

7200@ 3psi 25°

7600@ 3psi 27°

8000@ 3psi 27°



SPLIT is 10-8° in this area

One320B

Well..



The tune looks good, but let me ask this - how different is the port timing on this engine from the previous one? Port timing can affect your peak HP and cause the stock turbo to "run out" before a normal stock port would... does this make sense?



If you blow through a 1/2" straw as hard and fast as you can, you'll feel that pressure build up in your cheeks... but now blow through a 1.5" straw as hard and fast as you can - all the air will escape very quickly and NOT build as much pressure.



Its a terrible way to describe it, but does that make sense?



Thats why bigger ports usually run larger turbos, the larger turbo will "push" more than the engine can hold thus building pressure quicker and longer....

zRotary

ahh, i see. thank you, i wasnt thinking that way, but it makes sense.



well, the porting on the front and rear iron is about 2mm to the side (towards rotorhousing) and around 5mm to the top and over the upright edge, no way down at the bottom.

some porting to the intermediate plate, ported LIM and modded throttlebody (pulled out the first plates)

the exhaust is ported to the bottom and the sides, but not to the top. this because of emissions which i have to go threw.