tblu92

Agree with the other posts
I would again verify the ACTUAL AFR ratio again
Large stall converters read horribly on the dyno
Some Drag Radial tires or really soft tires also do not read properly
Did you check the fuel pressure at WOT ?

C5samuelt

I’ll get back to you on the fuel pressure I have an interesting question though so there’s some white smoke coming out of my oil filler neck thought it was coolant but coolant is still full the car doesn’t over heat at all it runs great is it just steam from oil u think? It really only smokes quite a bit at idle but after the dyno run I started noticing more and more smoke compression test came up good so I’m kind of leaning towards maybe motor is still breaking in or something else is up not really sure haven’t really done anything crazy other the. Doing a pull on my way home but driving like normal after

feeder82

What's with the 58lb fuel injectors? Is that stock cubes? N/A or pwer adder. Those are way bigger than needed for a head, cam stock cube motor.

RonSSNova

I’d like to see an HPTuners data log of the dyno runs.
That would be very telling.

spfautsch

Just a plain drive log with LBLMs would be telling. He's also complaining over in Tech that it's using ridiculous amounts of fuel and that the previous engine lost compression on four cylinders before this build. My guess is the lambda sensors are crossed up.

benflynn

define too big, with correct modern data injectors can be big and still run well, thank goodness or flex fuel wouldn’t work well

feeder82

Put 8cyl n/a 410rwhp in fuel clinic or any other calculator and 28lb on gas or 37lb on corn are fine at 90% duty cycle. Bigger isn't better, and much harder to tune for drivability.

spfautsch

Having self-tuned a 500-ish rwhp 383 gen2 lt-1, I would agree to a certain extent. Though that experience was with an old first-gen flash PCM running the $EE mask.

I would agree with this statement with a couple of caveats.

#1 - the P01 and newer OSs are far more capable of accommodating the "correct modern /injector/ data" and correctly accounting for grams per intake cycle
#2 - achieving closed loop idle with a 280 degree or larger cam is orders of magnitude easier with injectors sized more according to feeder82's basic recommendation, and no other unknown variables (such as an aftermarket MAF/CAI)

So you're both right, and both wrong to certain extents.

All that said, to the OP - you should take some ownership in the tuning process or you're going to be pouring money out of every orifice and may still end up "very disappointed".

First, before you take your vehicle to a dyno shop like faster proms, you would be well advised to document all your mods such as injector flow constant / low pulse data, engine displacement, MAF system data, etc. Porting heads and adding headers, a big cam and changing the intake has drastically altered the volumetric efficiency (aka VE) of your engine. Further, adding massively oversized injectors has completely changed how the PCM accounts for delivered fuel in realtime, which is crucial to achieving decent part-throttle cruise behavior and closed loop idle. Change out the air intake tract and MAF and you've just completely thrown all of the three anchor points of tuning out the window, and they will need to be re-established at the expense of considerable time gathering logged data points.

In a nutshell, you should never take a car that isn't running relatively well at part-throttle conditions to a dyno shop. The dyno shop knows you only care about an impressive peak HP number and that your credit card payment clears, while in practice there's a lot more to driving than *****-to-the-wall WOT #s to impress your friends.

I have no idea what process any of these pro tuners use, but I know from experience that it should start with basic datalogging, so as to achieve decent driveability at part-throttle cruising conditions in closed loop. Only after mastering those changes should one seek to tune for maximum power. To that end, it would be beneficial to you to gather some basic OBD-II logging of fuel trims, MAF #s, throttle position, RPM, coolant temp, etc in normal driving conditions. This information is going to tell you (or one of us) what your engine wants to be happy. Another suggestion is to buy a VCI and dump the tune from your PCM using PCMHammer, and post the bin here. This will give us the information to know what's been done and what was wrong / right.

Another area of interest you should address is answering my question regarding what cylinders were found to have lost compression with your previous engine, which you mentioned here. If those were all on one bank, that's a massively important clue that should not be overlooked.

tblu92

Typically you do not need larger injectors ONLY when the
Injector Duty Cycles exceed like 80-85%
Stock Corvette injectors can handle up to about 500 CRANK HP
If the duty cycles are in the 90's then maybe just go one or 2 sizes larger ( If you have 28 lbs then maybe 32 or 34's
58 is for a boosted Large CI engine or maybe an E85 large engine cammed

tblu92

Smoke coming out of the breathers is not a good thing Only worn out beaten engines will have that "Blow By"
Check to make sure your PCV system is plumbed correctly It should be sealed on both sides and should never vent to atmosphere --Maybe on a "race only" application
Look into a "catch Can" as well It will capture all that oil smoke and mist

C5samuelt

it’s for a power adder pro charger Coming ok as soon as I completely break in the motor too scared to put it on now as I know there’s other things wrong that I need to take care of first

C5samuelt

ended up figuring out one PCV line wasn’t hooked up I forgot the tuner took it off to plug it and I never hooked it back up it’s not smoking anymore as of what I can tell

romandian

you need to know afr and spark over the whole run. anything else is shooting in the dark. hooking up an oscilloscope would be next (youll need somebody proficient with it.)

benflynn

At what size do we run into the minimum open time? I wonder when we start operating off slope. It is far from 58. You could lower fuel pressure if u wanted to extend the opening time way low.

I understand the argument for the smallest injector needed to make your power. I have also run injectors at like 120% on a stand alone.

50lb is a oem injector, 58 is fine, not worth mentioning. If he had 1300s in there it would be different.

58 will max out your set up on e85, I’d go 1000s for adder and e85, and an adder without e85 would only be built by those with no access to e85 or no experience with its benefits. E60 even.

romandian

"off slope": that would be around 4 ms for most injectors. you probably mean minimum pulse width.

aaronc7

Just my personal experience, I was right at the limit of min pw on Deka 80s and pump gas. 2nd gear, really low load, around 2k rpm (like parking lot driving), I would hit a point where it would run really lean and injectors probably weren't firing at all. I don't remember what the exact pw was, I want to say around 1.2 or 1.3 ms. Idled just fine. Just bumped up min pw and ran it a little rich in that above scenario and it was happy.

Alvin@PCMofNC

Ask your tuner if the torque converter was locked or unlocked. If it was unlocked the results are reasonable. The graph looks like it was unlocked.

It's nice to do a locked pull on the dyno to get the whole engine speed range (instead of flashing to stall speed) but not all converters will take that. If I try one and it seems like it's slipping at all I do unlocked pulls.