................on a car with



GT35R
apexi-safc
3 inch exhaust
HKS cams and gears




can anyone give me an estimate?

 

about 10hp for ever pound of boost

 

it changes, there is no general rule for it. it depends on alot of things. Like you temperature. If the turbo is out of its efficiency range you can add boost and get no more power. And it depends on the tune.

 

Throw some race gas in and bump it up about 3psi you should see a pretty good gain. When I went to the track I was empty and put 3 galllons of 110 in, bumped the boost up a couple and it was pulling pretty hard compared to 93 and 20psi.

 

I currently run 22psi on C-16 .....
was just wondering how much difference a 3psi would make...


cause we have no dynos down here

 

yea i heard and belive the 1lb=10hp but who knows

 

5$

 

On C16 you can run 27 psi. The law of diminishing returns applies to increasing boost. You will gain a lot for a few psi and past that a lot of heat will generate and power increases will be slim to none. If you get a bigger turbo you can push more cooler air.

 

The 10hp per lb. would indicate that 10 psi over zero will procude 180 hp over a non fi 4g63 which would seem a fair estimate. The method breaks down when you consider the gains form the first lb to the gains from the last as there are diminidhing returns as previoulsy laid out.
To encasulate why this is so:
Pressure isn't what gets it done, it's O2 molecues and fuel. The more 02 you pump in the more gasoline you can burn. The percentage difference will give you a rough idea about power. The probems with estimatimations based on each individual or any individual psi are many. The first factor and one already mentioned is the rising air timeps casued by the turbo as it spins harder and faster which casues pressure to rise in a diminsihing ratio to 02 molecures . The intake ports become more restrictive as flow rates rise so it takes ever more pressure to increase the charge mass in the cylinders. The time avaliable for the cylinder to fill diminishes as rpm increases so where in the rpm range the 1psi increase occurs is a factor. The tighter you squeeze things in the cylinder the more you increase the combustion rate which necessitates timing and or f/a ratio adjustments to prevent detonation. All of these things and a few more will change the rate of change in boost to rate of change in power output.

Since you are nearing the end of the pratical boost range for your setup you can expect less than a 10 hp increase. If you can find a better answer buy it.

 

yup that makes sense. But when i turn my boost up and down i like to belive 10hp lol but its not true

 

You should test this next time you go to the dyno. I would guess 3psi= 30hp on that turbo.

 

my safc is not tuned for race gas right now. if i go to the track and throw some race gas in would i expect better times than straight up pump gas?

 

if you raise the boost, yes. but, you don't have to use c16 or even 110 just to raise the boost. you can use 100 unleaded if you are raising the boost 3psi. where you need the GOOD stuff is when you are advancing timing and pulling out fuel. you could use 110 to be safe if youd like, but c16 is waay overkill for just adding some boost.