legacycentral bbs

What would be the highest safest boost with a vf12 in a '91SS, no IC, 3"CES TBE, K&N panel filter? Don't want to break anything. Also, what would your guess be for crank HP?

I think I ran 9 or 10 psi intercooled on a stock exhaust without the muffler. That's about what I'd run with my exhaust and no intercooler, at the very most. A VF12 flows a lot more air than the stock VF11, so I'd suggest running it at wastegate boost (around 8 or 9psi probably) and you should be OK. I run my 16G at wastegate boost around town, and it's kinda quick.

BHP at 9 psi on a VF12 would probably net you close to 190 or so BHP.

Matt Monson, any others have any opinions?

I agree with Phil...the VF12 flows a considerable amount more air volume than a VF11, and running it non-intercooled with anything more than wastegate boost is kinda playing with fire, so to speak.

You should pick up an AWIC and a walbro pump, then you can start having fun

I ran about 13psi on the vf11 with an intercooler before it ran out of its efficiency range according to the dyno

Why aren't you using an intercooler with the vf12? I'm not sure if you could have a high enough pressure to overcome the size of the turbo and still be unintercooled.

The opportunity to purchase a vf12 came up, and I will be picking it up this weekend. The rear cam seal weeps and will have the turbo out to make it easier to get at the cam seal to replace it. Thought that would be a good time get the vf12 in. Getting an intercooler is a step in the evolution of enjoying this car. That is why my intent is to get the vf12 in there at this point. IC first? Bigger turbo first? It just happens that I will have the turbo in hand first. Is it a fatally flawed plan? Also, currently do not have a boost controller installed, and will have a boost gage in before I replace the vf11 or at the same time.

I think it would be better to put an intercooler in at the same time as the vf12.

a boost gauge is VERY important, it is basically telling you what the engine is doing, well a vacume/boost gauge can tell you the boost, bad valves, clogged exhaust, etc.

I am going to get a boost gage and the vf12 in first, and then work on getting a plan and parts together to install a IC. If it is not running well after the vf12 is in I'll just have to accelerate the IC install plan.

BAC5.2 wrote:I think I ran 9 or 10 psi intercooled on a stock exhaust without the muffler. That's about what I'd run with my exhaust and no intercooler, at the very most. A VF12 flows a lot more air than the stock VF11, so I'd suggest running it at wastegate boost (around 8 or 9psi probably) and you should be OK. I run my 16G at wastegate boost around town, and it's kinda quick.

BHP at 9 psi on a VF12 would probably net you close to 190 or so BHP.

what CHP ballpark would 190 BHP put you in? 250 CHP?

I think he is refering to baud HP as in crank HP.


Get a WRX IC. Cheap and easy.

93forestpearl wrote:I think he is refering to baud HP as in crank HP.


Get a WRX IC. Cheap and easy.

baud hp? there is a term i have never heard.

i assumed he meant Brake Horse Power as in at the wheels.

Doesn't crank HP refer to the power before it goes through the transmission? What mfgs. reference, ie 160hp for a stock SS. That is the number I need to compare with. EDIT: Aren't crank horsepower and brake horsepower interchangeable terms?

BHP = CHP.

WHP < BHP.

Compare 190BHP to the claimed 160BHP. You'd be lucky to see that jump.

Well, what I'm saying is, you're going to have to redo the pcv hoses, and the turbo to intercooler tube anyway, so why not throw an intercooler into the mix also? I'm sure you could find a WRX one for less than 100 bucks.

i would feel better if you put an intercooler on :-p

heh im gonna agree too. if you are changing the turbo, you might as well get an intercooler on it too since your alrdy there. plus isnt the vf12 sort of in between a td04 and td05? i wouldnt run that any higher than stock boost either. right now im boosting close to 11-12 psi un-intercooled on my vf11. i wouldnt go any higher than that on my setup.

As far as intercoolers go, which is the best way to go. The Saab or WRX? Maybe this response can stay with this topic, and further IC discussion for my application I should probably post on the Intercooler section.

Lots of discussion on this already. I think almost everyone would agree you may as well do the WRX intercooler if going topmount. Frontmount's better.

OK. Thanks to all of you for your input. A WRX intercooler is what I'll do, sooner or later. Now i'll start reviewing WRX IC installs and make plans to get r done.

i do have a spare one... was barely used on a wrx. they said it had about 5k miles on it. comes with the y pipe too. ill let it go for 70 dollars shipped. let me know what you think.

Thank you. I better get this. PM'd you.

Project_Legacy wrote:heh im gonna agree too. if you are changing the turbo, you might as well get an intercooler on it too since your alrdy there. plus isnt the vf12 sort of in between a td04 and td05? i wouldnt run that any higher than stock boost either. right now im boosting close to 11-12 psi un-intercooled on my vf11. i wouldnt go any higher than that on my setup.

Pretty much all 90degree VF's are between a TD04 and a TD05. The VF12 is the biggest of the 90 degrees, but it's still not that big of a turbo.

ah ic. i thought the vf12 and vf8 were able to push at most like 14-15 PSI effeciently tho. thats what i thought any way.