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Anyone with similar mods? trying to get a HP range where I should be?

12K views 77 replies 20 participants last post by  Stillborn 
#1 ·
I have a 2009 CTS V SEDAN AUTO. Previous Dyno was with a air raid CAI and conservative tune. I was at 475 RWHP on a mustang dyno. I ran an 11.7 on stock tires at 119.8 MPH with just a tune and air raid, so it's seems to be a strong car. My current set up is the following...

New era. CAI
Green long filter
Brake duct mod-Ram air directly into the air filter
Brand new stock blower, new everything, snout.
v hat, blower, etc...courtesy of the dealer to get rid of marbles.
LPE solid isolater
Kooks coated headers
Full kooks mid pipes with high performance cats
SLP loud mouth mufflers
2.35 upper pulley-13-14lbs of boost IM GUESSING.
Weapon X track attack HX
Dual catch cans
93 octane fuel

GOING IN FOR A FULL DYNO TUNE ON A DYNO JET MONDAY. What do you guys think the RWHP will be when my tune is complete? I'm looking for a range so I have something to just give me an idea.. Also, any chance with the new set up I could break into the 10.99 at the track. I was doing 11.77 to 11.91 all day last trip to the track on stock tires.
 
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#46 ·
if he was then the dozens of top tuners would still be using stock injectors. 90% are all using id850's when making 14+psi. you cant re-write the script because you dont want to unlearn bad/false information. i think i made my point. enjoy the truth & beware the lies.
 
#48 ·
Lot's of hostility but the fact is that this entire conversation is elementary level physics. Your fuel injectors provide a mass flow rate of a liquid into the combustion chamber. Mass flow rate is a combination of velocity, density and cross sectional area (m/s X kg/m^3 X m^2). Asssuming that your fluid is incompressible, good enough for liquids at these low pressures, then density is no longer a variable. All you have left is velocity and area. Velocity in this case is generated by the pressure differential between the fuel pump and combustion chamber. So, if you want more fuel you can increase pressure OR increase flow area OR both. Injector 'size' is the cross sectional flow area in this equation and velocity is equivalent to your fuel pressure in terms of linear relationship...this is why injectors are rated at a specific pressure. If you need to get more fuel in the combustion chamber to maintain your desired AFR then you can increase the fuel pressure alone to do so as long as the rest of the fuel system components can keep up (think KB BAP). If you get the point that the fuel pressure cannot be increased then you need larger injectors. Or if you would prefer to not increase the fuel pressure to place excess strain on the pump/etc then you need larger injectors. I guess what I don't understand here is that I did not see anyone stating what FP is needed to keep the stock injectors and support 600hp and can all the other components handle that without concern?
 
#49 ·
Yes, the cars other components can handle every bit of 600 HP no problem. My car is done and if a monster. everything looks and sounds stock till you get on it and all hell breaks loose. She made 607 RWHP and 627 of Torque Un-Corrected. Corrected it made 585 RWHP and 606 Torque. 16 PSI of boost. Id runs just perfect. Love the new power. I hope I can do a 10.99 1/4. Before these mods I did 11.77 on stock tires. Yes, its an Automatic.
 
#50 ·
Maybe my post was not clear. I was asking if the other components in the fuel system were capable of supporting 600hp while maintaining stock injector size....in other words can the pump support the increase in pressure? What is the required voltage to reach this? What is the draw on the pump under high load at this voltage such that you won't be slowly burning out your pump? How accurate is the stock fpr above the intended operational range? Can all the fittings take the increased pressure? I have no doubts that the other components in the drivetrain can take 600hp. That was not my intent. I'm sure the gm engineers designed everything to a minimal 1.2 fos and probably closer to 1.5-2.0 for critical components. I'm not sure why you rattled off a bunch of timeslip information....I don't think this post is about measuring who has the longest... If that is where you want to go then I'm sure plenty of people on here can jump in and one up you...myself included with my 9.89 timeslip in my old car which was only a 2.0 liter.
 
#54 ·
I'm sorry...I guess I misunderstood the meat of the argument that was going on from post #3 to post #46 concerning fuel pressure vs. injector size where I saw a lot of 'he said' 'she said' 'my tuner said this' 'well my tuner said this' arguing where no one besides wait4me actually wanted to take the time to crunch the numbers and provide some useful information which is what the purpose of the forum is all about. Congrats on the car and I hope you can get into the 10's with it. Definitely going to want DRs though.

Guessing there was some miscommunication here since based on your last post you were only posting numbers and timeslip info as an update to your dyno tune rather than as a response to what I was asking in the previous post...which is what I took it as at first. In other words, sounded like you were trying to say 'shut up, my car is fast.' Apologies if that wasn't the case.

I am still curious to hear information about our fuel pumps though. Can someone chime in on what they can reliably support or is it just best to go off the manufacturer's data sheet? I am seeing guys run 700-750 bhp on the stock pump but curious how much that is overdriving the design.
 
#59 ·
Sounds like Phil doesn't know how to alter fuel pressure in his tune, so he goes the larger injector route.

If the customer is happy, then it was a sucessful tune, regardless of the methods used to get the end result.

All this bickering makes me question if I need to get a more expensive car to avoid the childish behavior in this forum.
 
#61 ·
yah, that should be a reasonable solution. i say, do it! do it! or spell sucessful the right way and you'll be far better off. you c?
i would suggest not belittling yourself to post in such a "childish thread" would be a more mature way to handle it, instead of
pointing out whats wrong instead of whats right. people like you (always whining about others) can never be satisfied by
buying /acquiring new things, its the same thing as taping sandwiches all over your body in an attempt to stop hunger.
 
#63 ·
just wasted 30 minutes reading through this bickering and thought id point out o few basic rules of tuning efi...
Injectors can only flow so much fuel before they become unstable/unpredictable (90%+ idc)
You can raise fuel pressure to compensate for too small of injectors, but that only safely works until you hit 90% idc
The fuel pump will loose efficiency the higher the volt draw on the pump and you will run out of fuel up top at some point no matter what you do
You need to datalog in order to know what is happening or your just guessing

Point is, if you want to play, you gotta pay. Dont skip on the basics when trying to modify efi...you need fuel.
Congrats to the op, sounds like you made good power with basic mods.
 
#64 ·
i got tired of being right from the first post. some people need added attention to understand logic.
i'm glad my truth ended up being co-signed,... albeit the truth needs no co-signer.
give me one choice of love, fame, fortune, or truth... and i'll take the truth every time.
 
#65 · (Edited)
For Stillborn, you really need to get over your self. W4M has way more knowledge on CTS-V's than you do and is correct in saying that 600 RWHP is possible on stock injectors. Here's the proof. I make 603 RWHP and 587 FT POUNDS torque [14 pounds boost] with my 2012 CTS-V on a DynoJet with a W4M tune with STOCK injectors. A/F ratio 11.3 during pulls on a cold day. BTW, your statement that increased fuel pressure doesn't make for more flow is so wrong. Flow through any injector is increased by added pressure to that injector. It appears that your tuner hasn't the knowledge to make stock injectors work at 600 RWHP and you take that as proof that larger injectors are always required at 600 RWHP.
 
#66 ·
replacing your fuel pumps prematurely is now your worst nightmare. i sure hope they dont fail at wot. lol you got it all figured out w4m fan club member. btw, if my tuner told me he was going to raise my voltage on my pumps to band-aid my need for added fueling, i would tell him to gtfo of my car and leave his shop.
 
#67 ·
You do understand that the Corvette uses the same pumps to fuel 636 HP, same injectors too. GM just raises the voltage. Guess there are a lot of Corvettes out there with failing fuel pumps??? I'd sure like to line our cars up on the strip and show you what stock injectors can do. 125 mph @ 11.09 so far. At 513 RWHP you surely didn't need to spend the money on bigger injectors. But I will say, it can be tuned that way if you want to spend the money.
 
#68 ·
gm also has the proper software and know how. i would not want an outside source (while voiding the warranty) doing any voltage changes to compensate for
a lack of fuel issue. the majority of shops "getting it done" at the track change out the injectors once 90+% dc has been reached....it's been this way across the board (for those that tune) for a long time now. is there another way to skin a cat? i guess so, but i'll be more comfortable with the voltage being unchanged as i've seen (on other forums) some of the best shops frown on such activities. can you get away with it? sure, but you can also get away with murder,...until karma has it's way with you. my car makes the same hp as the zr1 with my mods and has stock injectors with 90% dc at 11.4 afr. any more hp mods and i need injectors as the indicators indicate. =]
 
#70 ·
Im going to chime in: Ive been modifing cars from Vipers to Mustangs for the last 20 years. YOUR BOTH Right!!! Its a matter of preference. Gt500's owners have been increasing fuel pressure for years via boost a pumps to allow higher limits of stock injectors. The downside is some say it stresses the fuel pumps over time which could lead to engine failure. Tuners have their preferences. Id only increase the voltage to a point.. I dont like to take chances with my luck.
 
#71 ·
Ok...so everyone that is arguing on here does realize that the IDC% is seperate from fuel pressure right? As in an IDC of 80% at one fuel pressure equates to a different amount of fuel at a different fuel pressure. This is an over-simiplification but you could run 50% IDC at 40PSI fp and get the same amount of fuel as 100% at 20PSI fp. Stillborn and gotboost either don't understand this or have made the decision that they aren't comfortable increasing the voltage going to their fuel pumps.

----------

ctsv4now, w4m, dwbowen and blaine 321 have all tried to explain this over and over again...I guess it is liking talking to a wall guys. You tried.
 
#72 ·
why are you comparing different size injectors flowing at different rates via pressure? as in doing so you just upended your own debate. thanks.
so you would be happy if a tuner down sized your stock injectors in favor of a higher voltage output? thats the kind of logic we have going on here
folks. you shouldn't look one way down a two way street buddy... you'll get crushed sooner or later. :thehand:

maybe you should try going snorkeling with a swizzle stick and maybe you'll understand the physics of it all. you can breath
at normal capacity with a larger diameter tube (snorkel) vs straining to get air with an instrument not designed for ideal conditions
to get the life saving air you so desperately need. could you survive with that swizzle stick? sure, but for how long?
 
#73 ·
Stillborn, thank you for explaining elementary school physics to someone with a PhD in fluid dynamics who works on supersonic projectile aeroballistic design for a living. I am sorry that the majority of discussion and 'facts' stated by people on the forums comes from those who are not educated in the subject they believe they are 'experts' in...but I am not one of those people and that is the only reason I state my profession. I will not provide advice or information on topics that I neither have first hand knowledge of or an understanding of the physics or mechanics behind. I have absolutely no problem carrying on a debate with someone, having a technical conversation, or even simply agreeing to disagree when the other person can actually sit down and crunch the numbers instead of blabbing about over-generalizatons and comparisons to situations which offer no benefit to the conversation.

Based upon your response above, I have no choice but to think that you simply are unable to grasp the concept that half a dozen people in this thread have tried to explain to you time and time again. Statements like 'get crushed sooner or later" or trying to draw a one to one comparison to a human being pulling vacuum through a pipe does not provide any benefit to anyone on the forum in terms of technical knowledge. If you go back to my original posts on this thread you will see that I was asking questions about the voltage ranges for our fuel pumps, the safe ranges to operate in, questions about a kbbap, if our injectors were the same as the Zr1, and questions about the safe ranges for the rest of fuel system equipment (FPR, etc).

All that aside, we all understand that you went the route of getting larger fuel injectors and not raising your fuel pressure. That was your choice. And that is one way to get the job done. No one is arguing that...at all. That method will give you the greatest potential when you do more mods down the line. You do not need to defend your actions by making negative statements about the alternative method. All everyone is trying to say is that the injectors can be made to flow more fuel by increasing the fuel pressure, maintaining a safe IDC% and maintaining the same AFR. And you are only increasing fuel pressure above the intended range of the pump during WOT. I also have no doubts that the pump can handle another 10-20% in voltage and therefore provide another 50-100hp of potential just in fuel pressure increases...I doubt the pump was engineered with a FOS of less than 1.2.
 
#74 ·
just for the record i have stock injectors at 90% dc. at 11.4 afr and 17* of timing. any more hp mods and injectors will be needed. but this was never about me, it was in fact about the op saying he would 'NOT' need injectors via the advice of w4m. i was only informing the op he would in fact need injectors and a voltage increase was the jerry rig way...his tuner opted for injectors as the majority of tuners who understand "fueling" and all that implies will attest to going that route. i dont want to take another bow, but since you called me back for yet another encore i will. gratzie, gratzie.

and you're right about another 50-100hp available on the stock injectors, all us guys with just an upper pulley and cai are living proof of said increase...
but once you add headers or more psi to said equation, you WILL NEED INJECTORS.
 
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