Hey just wondering if trifecta will be enough of a tune to hold a turbo at 5 to 7lbs of boost? And what kind of injectors should I buy or can I use some off a ss/sc or a ss/tc?

 

A trifecta turbo tune, sure...5, 7, 9, 45629psi whatever you want.

As for injectors, please do more reading about the SS/TC

 

yes they will they can tune any psi.. i have trifecta tuning on my 2.4

injectors. get some from zzp. they sell 2.4 specific injectors. if u have a 2.4 not sure on 2.2s

 

INJECTOR SIZING DEPENDS DIRECTLY ON TURBO SIZING, BOOST PRESSURE ALSO RELIES ON TURBO SIZING....

I can run a small turbo at 25psi @ 250cfm but a bigger turbo running 10psi can push 250cfm also...

so before you "decide" on what boost pressure you want to "tune" to and what are good "injectors" do some research first...

you will need to have a turbo that is going to be able to run in it's efficiency range yet have enough room both ways to both decrease output and increase input, depending on the turbo and it's flow rates will determine what sizing your injectors have to be....More air, More fuel, if your stock injectors aren't at max duty cycle then a small turbo @ 10psi may be okay with them....however...choose an injector with a duty cycle that has room to expand and decrease as well....keep it in the middle, this gives you options down the road


so here is a formula for you to use....

Pounds of fuel per hour per injector = expected brake horsepower x 0.55 / number of injectors

so, you want 200 horsepower, then 200x0.55=110
110/4 (if you have a 4cyl) = 27.5pounds per hour

but with 27.5 being said.....you SHOULD go the next size up to give you room for improvement later down the line if you should choose,

lets say your car is 140hp stock and you want 200hp, injector size has already been computed so lets work on turbo size

performance gain = (desired bhp/original hp) - 1

so 200/140=1.43
1.43-1 = .43, so 43% power increase over stock

so lets say you have a 2.2 4 cyl, L61 engine Bore is 86mm (3.386in) Stroke is 94.6mm (3.724in)
so Cubic Inch Displacement = #of Cyl x .7854 x Bore^2 x Stroke
CID = 4 x .7854 x 3.386^2 x 3.724
CID = about 134 cubic inches
for the sake explanation lets say the engine has 85% Volumetric efficiency.....so choosing the turbo would be done like this for choosing your airflow rate

airflow rate = CID x RPM x .5 x VE / 1728

so lets say AR=134x6500x.5x.85 / 1728
AR = 214 CFM natually aspirated
now multiply that by the expected performance gain 1.43
306 CFM

Now you have your CFM Rate and your Pressure Ratio....time to start looking at compressor maps X axis is the CFM, Y axis is the Pressure Ratio

find a turbo that is at a target of 70ish in the efficiency range on the map using your newly found numbers....



The RED lines indicate approx where the two meet for this GT28rs Turbo...

The approx PSI of the turbo would be about the same as the performance gain percentage of 43%, so
14.7 (atmospheric pressure) x .43 = approx boost pressure
Approx boost pressure would therefore equal 6-7psi
6-7psi with a GT28rs Turbo on a an L61 engine in theory would give a 60hp increase

but all these numbers are for explanation sake...do your own research and see what you find out there

sorry for the complex explanation, hopefully this will help somebody..

here is a link that explains more

http://www.turbobygarrett.com/turbob...o_tech101.html

there are 2 more pages that explain more, Good Luck



Advice....buy a kit with an all inclusive package then have it tuned Right

 

fixed 110/4 = 27.5.. If you needed a 55 # injector for 200 HP something is wrong.

Its a tune, I hope they can do any amount of boost you want. And the SS/TC injectiors are DI, wont work.

 

Oops, i was tired when i wrote all of that, so i divided by two, thanks for the correction, but here is some more information:

That was taken straight from Designing and Tuning High-Performance Fuel Injection Systems by Greg Banish.

The numbers I used where merely for example but within the correct realm of the BSFC, and for forced induction cars, it's between .55 and .65 depending on who you talk to, some even take it from .55 to .70

by the way Mff stands for Minimum Fuel Flow

As for the tune holding a certain boost pressure that part is wrong. The ONLY way that would work is you had an additional electrically operated valve, similar to the N75 Valve found in VW and Audi vehicles, the computer uses this valve to open and close the wastegate. So basically the boost feed line is plumbed into the N75 valve and the vacuum output is plumbed out of the N75 into the wastegate actuator. The N75 reacts based on what the ECU is reading from the MAP Sensor, so if the MAP is saying the boost is too high, it opens the N75 valve and the wastegate opens and the pressure goes to what is tuned. Other than that, you will HAVE to have a mechanical or electrical boost controller. So before that is misinterpreted, the wastegate CAN be set for a certain boost pressure via springs and shims. Depending on boost depends on the spring. Now if you are wanting to be able to adjust the boost that you get, you will have to have boost controller that is plumbed into the wastegate vacuum port. Since springs are NOT precise and a boost controller is, this setup is ideal. I do not know if Vince can "add a valve" like the N75 but it could be logically possible if he is in fact tuning via the binaries in the ECU and not just tricking the ECU into false readings. (He is notorious for doing this)