4k full boost on s15 t28

[bentvalves]

Hi fellas,

Got my car back together and finally time to map it after all these years! I have tomei 256 cams, vg30afm, exhaust, big intercooler, port/polish, 20 over forged pistons, power fc commander.

Today we started mapping the car on the street, and seem to be having an issue with AFM being maxxed, at a mere 15 psi. Tuner reckons that at 22 psi on an sr20 is when you would start to get to the outer cells during map trace (bit over my head bear with me)

So tommorow we try a borrowed AFM, and go from there.

My main question though, is the fact that my car seems to be coming into boost a bit late. I see full boost prolly between 3500-4000rpm and I have an AVCR to fine tune controlability.

Please folks steer me in the right direction, Im almost positive my timing belt was installed properly, double/triple checked. But what else would cause boost to come in late? Im almost forced to believe that perhaps timing is out a tooth?

people on sxoc say 3500-4k rpm for this turbo sounds about right........that to me sounds crazy though.

what do you guys thinks?

Greg

[c-rad]

That sounds about right to me... especially with the cams. My S15 T28 hits full boost around 3500-3700.

[Masterdebater]

it hits full boost sooner than that but the ca doesnt actually make good power until up at 3800-4000 rpms. i have full boost at about 3000 with a 3 inch catback and a cleared cat

[r34 gtr]

i was seeing full boost (~18-20psi) at around 3800rpm with my gt28r, which is pretty much exactly the same thing. sounds right to me!

[Liquid_Neon]

so wait a second... if my SR T25 full boosts at 3500-3800... thats bad?

[r34 gtr]

not really. how much boost are you running through it? 7psi i would be a little concerned, but at 15psi doesnt sound bad. is it the big turbine? .86 rear end or whatever they run? the gt28r really isnt that big a turbo, so you need to remember that here. this isnt some t04z or precision sc61, its a t-28, and its only a bit bigger than the big sr t-25.

[Liquid_Neon]

not really. how much boost are you running through it? 7psi i would be a little concerned, but at 15psi doesnt sound bad. is it the big turbine? .86 rear end or whatever they run? the gt28r really isnt that big a turbo, so you need to remember that here. this isnt some t04z or precision sc61, its a t-28, and its only a bit bigger than the big sr t-25.

Sorry to thread jack, but all the talk of hi rpm boost got me thinking. I'm just running a stock SR T25 with my CA waste gate actually, seems to only run 5 or 6 psi. and i don't get to 5 or 6 till 3500 or so. Plus im pretty sure my gauge might be a wee bit off, since it doesn't quite hit 0psi when i turn the car off. Ive been think i might have a small exhaust leak at the turbo.. but haven't really made sure.