turbo psi question.

[kennyb01]

Anyone running around 13 psi? I was wondering what duration/lift you run exhaust side and when you hit boost. I was hoping to run 12 or 13 lbs but was concerned with whether the stock cam's are beefy enough to spool before higher rpm's.

[yoshimitsuspeed]

I believe you misunderstand the relationships of boost and cams.
Just as with an NA bigger cams will sacrifice low end for more top end. Cams are generally one of the last things you will change on a turbo setup and only once you are chasing big numbers. The stock cams will give you quicker turbo spool and better off boost low RPM power than bigger cams will.

[Rogue-AE95]

Cams are generally one of the last things you will change on a turbo setup and only once you are chasing big numbers. The stock cams will give you quicker turbo spool and better off boost low RPM power than bigger cams will.

How about stock early bigport cams on a smallport head, aiming for 250-300 HP? I think I had asked this in the old forum before it died. I thought it was recommended to me at the time to stick with early bigport cams instead of looking at aftermarket cams for my power goals.

[yoshimitsuspeed]

Cams are generally one of the last things you will change on a turbo setup and only once you are chasing big numbers. The stock cams will give you quicker turbo spool and better off boost low RPM power than bigger cams will.

How about stock early bigport cams on a smallport head, aiming for 250-300 HP? I think I had asked this in the old forum before it died. I thought it was recommended to me at the time to stick with early bigport cams instead of looking at aftermarket cams for my power goals.

I have never seen a dyno that convinced me the early cams showed enough gains to warrant swapping them.
If you are taking them out anyway and happen to have an early set laying around you might as well throw them in. Otherwise I would hold off on cam mods for now and once you hit walls or want to change the characteristics of the motor you can think about what you want to do.

[Rogue-AE95]

I have a smallport head that's been disassembled down to almost bare aluminum. And a second one that's untouched except for removing the cams to pull the head from the Geo Prizm I pulled it out of. One of those will end up getting the OST porting treatment someday. Probably the latter since the former suffered a small nick between combustion chambers

I had figured on using a set of early bigport cams in the someday-OST-ported head since it would be modified.

[yoshimitsuspeed]

I have a smallport head that's been disassembled down to almost bare aluminum. And a second one that's untouched except for removing the cams to pull the head from the Geo Prizm I pulled it out of. One of those will end up getting the OST porting treatment someday. Probably the latter since the former suffered a small nick between combustion chambers

I had figured on using a set of early bigport cams in the someday-OST-ported head since it would be modified.

Sounds like a decent plan. If you end up shooting for higher numbers you might decide to go with a moderate cam but no sense worrying about it before you are ready.

[Rogue-AE95]

Thanks. I think I asked this same question on the old C4AG before it crashed, and got the same reply (possibly from you, lol).