Hey guys. I am by no means a turbo guru so I have a question on timing issues with lowered compression. I built a system for my 05' Busa from the ground up. Liquid to air intercooler , CP pistons , Carillo rods , APE studs , adjustable cam sprockets , Spacer plate , etc , etc. All the usual items are on board. Including a fully upgraded fuel rail , injectors , pump and the like. Built it around a T3/T04b 50 trim compressor initially. However I have phase 2 coming up and will be grabbing a GTX2867R from Garrett.
I rode the bike all last summer putting about 6k miles on the bike. Ran 16 pounds with autotune on the PCV ( worked my way up ) Ran 8 in the beginning. All in all the system made me crap my pants even after running an 18t front and 38t rear sprocket to help keep the nose down. Stock wheel base mind you.
Now my question is...
How far do I need to advance my timing to get this beast to go past 8k rpm without choking on itself ? And to nip it in the bud...it is NOT a fueling issue. Data logging showed an even 11.8/1 AFR regardless of boost pressures. Had to up the AFR to 12.5/1 on out of boost conditions so it would run smooth. I would hit 16 psi @ roughly 6250 rpm and it would scream like a beast until about 7500 rpm. Then by 8k start chugging out of time badly. Always the same rpm threshold regardless of what boost I was running be it 8 pounds or 10 or 16. Now having lowered my CR from 11/1 down to 8.7/1 has most likely everything to do with it. I have the beast torn apart right now for a thorough systems check. Aside from having gapped my plugs a smidge too wide everything looks great. I just need a guiding hand from a bonified turbo guru on setting my timing right. Although I know this bike rather well , this was my first turbo build ever. And jumped right into the raging river learning to swim as I go
Is there a formula I am ignorant to as far as calculating timing when lowering CR's ?
Any help would be greatly appreciated !!!!
I rode the bike all last summer putting about 6k miles on the bike. Ran 16 pounds with autotune on the PCV ( worked my way up ) Ran 8 in the beginning. All in all the system made me crap my pants even after running an 18t front and 38t rear sprocket to help keep the nose down. Stock wheel base mind you.
Now my question is...
How far do I need to advance my timing to get this beast to go past 8k rpm without choking on itself ? And to nip it in the bud...it is NOT a fueling issue. Data logging showed an even 11.8/1 AFR regardless of boost pressures. Had to up the AFR to 12.5/1 on out of boost conditions so it would run smooth. I would hit 16 psi @ roughly 6250 rpm and it would scream like a beast until about 7500 rpm. Then by 8k start chugging out of time badly. Always the same rpm threshold regardless of what boost I was running be it 8 pounds or 10 or 16. Now having lowered my CR from 11/1 down to 8.7/1 has most likely everything to do with it. I have the beast torn apart right now for a thorough systems check. Aside from having gapped my plugs a smidge too wide everything looks great. I just need a guiding hand from a bonified turbo guru on setting my timing right. Although I know this bike rather well , this was my first turbo build ever. And jumped right into the raging river learning to swim as I go
Is there a formula I am ignorant to as far as calculating timing when lowering CR's ?
Any help would be greatly appreciated !!!!