1G wHAT IS A SAFE(ISH) BOOST SPIKE LEVEL?

[enriquez2000]

I guess its more creep then spike... Long story short I fixed a bunch of stuff and was targeting 18psi with some spiking to 20.. Ive turned MBC down a few times but im still getting spikes to 22-23... I worry a bit about stock internals

If you didnt read my profile car is running a small 16g, 550 injectors, link afpr and 2g maf and intake. all maintenance is on point and motor runs strong.

 

[kchaazz]

That question is very subjective. However, with your supporting mods, Im not sure youll be ok momentarily seeing 22psi when the turbo initially hits its peak spool. Just log and watch for knock. Injector duty cycle should be low enough at that rpm. Try shortening your mbc lines a bit to see if you can get the spike down some.

 

[enriquez2000]

That question is very subjective. However, with your supporting mods, Im not sure youll be ok momentarily seeing 22psi when the turbo initially hits its peak spool. Just log and watch for knock. Injector duty cycle should be low enough at that rpm. Try shortening your mbc lines a bit to see if you can get the spike down some.

Ive never logged my injector duty going over 70% or so... The line could go a little shorter so ill cut those down a bit too. Knock is only an issue at this point with multiple pulls and mainly because I still have the SMIC in place and temps are too hot after a few WOT pulls. Ill still probably pull a bit out of the mbc as id rather keep peak to 20 and settle at 18.. I know the 16g doesnt do much better over 20psi anyway.

 

[Spades]

For spiking - Is your wastegate actuator shimmed? If so, subtract 1-2 washers
For creep - Port the wastegate entry in the exh housing

 

[enriquez2000]

I have an aftermarket stainless o2 housing going on soon when I swap out my 16g for my rebuilt internals.. that should take care of the port. Ill check out the WG shims.. dont remember seeing any on there.. but i think its more creep anyway.. If I get on it itll climb up(now stops by 23) as aoon as the gauge beeps at me I let off so i dont know how long it holds that 23psi.. id rather it top out at 20 so i havent pushed my luck

 

[GPLaserRS]

That definitely sounds like creep, so the when you install that new O2 housing it should settle down. Spike would be an immediate outshot of boost target and then stabilize, and tapper off. You could also consider ported the hot side of the turbo housing and wastegate.

 

[enriquez2000]

That definitely sounds like creep, so the when you install that new O2 housing it should settle down. Spike would be an immediate outshot of boost target and then stabilize, and tapper off. You could also consider ported the hot side of the turbo housing and wastegate.

Well ill have the whole thing apart so I might as well..

 

[GPLaserRS]

I will preface that it's a huge PITA, so set aside a few hours and make sure you have all the tools and bits before you start. I went at it half cocked and had to stop to go pick up flap wheels causing a PnP that should've taken 3-4hrs took 2 wks because I lost all motivation, .

 

[Dsmkauai]

I used a holset acuator to elliminate this with my 16g. Would boost perfect 18-20psi no problem with no spikes or creep!

 

[kchaazz]

Yeah, I thought you were saying spike, which would be boost quickly ramping up to 23 psi then dropping to 18- 20. Creep is when you set boost at, in your case 18psi, and initially boost is at 18, but as RPM increases, so does boost. So, if its creep, you have to port your turbine housing a bit. There is a how to somewhere, I just dont have time at the moment to seek it out.

 

[enriquez2000]

I can search.. just want to make sure im at a safe level for now. It never goes past 23

 

[Dsmkauai]

It's never really good to have happen bro. If your not tuned for it you can easliy start messing things up, especially in a lean condition. Best is to do some port work like this. And upgrade the wg acuator so it actually holds what you want. If you have a 7-8psi wg acuator, you can really only get good control to around 14-16psi. Anymore and it can't hold that's why having one around 10-12 to start is much better for a 16g and 18-20psi!

 

[Spades]

I have an aftermarket stainless o2 housing going on soon when I swap out my 16g for my rebuilt internals.. that should take care of the port.

Aftermarket o2 housing is not the same as porting the entry point to the wastegate. The exhaust tends to flow straight down into the turbine and miss the turn to the wastegate, therefore you port the entry point to the wastegate to kinda help divert more exh gas towards the wastegate. The o2 housing sits AFTER the wastegate flapper

 

[Dsmkauai]

^^ exaclty look at the "shelf" made by my port work in the pic I posted. It helps direct to the wg and just makes controlling easier.