help

[Nikkobellic]

Hello. Trying to get some recommendations on what direction to go with my project. I have an 02 silverado 2500 with a paxton supercharger that's not plumbed in yet.
1. intercooler or no?
2. decapped injectors bad idea?
3. delete maf and tune with Sd only?
4. Upgrade fuel pump?

This will be my first time tuning or having a supercharged vehicle. It's not my daily so I can take my time while learning. I've done some reading about tuning but get overwhelmed by the amount of contradicting information Im seeing. Any help is appreciated.

[gtstorey]

1. Intercooler: yes
2. Decapped injectors: NO NO NO... Only use injectors that have known good FULL GM data. Which typically would mean actual GM injectors or one of the few aftermarket companies that provide the FULL GM data. And no decapped anything. Flow matching and a single flow rate at a psi isn't full data

Wideband yes, especially for Forced Induction.

I'll leave the SD vs MAF tuning to more experienced tuners, but I don't know that you will get a clear answer.

[Nikkobellic]

1. Intercooler: yes
2. Decapped injectors: NO NO NO... Only use injectors that have known good FULL GM data. Which typically would mean actual GM injectors or one of the few aftermarket companies that provide the FULL GM data. And no decapped anything. Flow matching and a single flow rate at a psi isn't full data

Wideband yes, especially for Forced Induction.

I'll leave the SD vs MAF tuning to more experienced tuners, but I don't know that you will get a clear answer.

Thanks for the info. Any recommendations on a brand of injectors that would work well for this setup?

[kingtal0n]

Delete the maf

I only use fuel injector clinic or injector dynamics anymore. It isn't even the data- I've tuned hundreds of setups without the data over 25 years.

The real issue is quality of the injector, as they tend to vary, and spray patterns vary, the performance as temperature changes varies, so many variables especially with cheap injectors.
You will desire the injector that can flow your HP demand near 35 to 40% duty cycle if you can afford it.
For example, don't buy '500hp injectors' to feed 500hp. Use 1000hp injectors. I prefer ID1050 injectors for 600-700rwhp gasoline applications.
By keeping duty cycle lower than 50% it will:
1. Dramatically improve low and mid-range torque with injector phase that sprays between Intake valve open and peak piston velocity
2. Reduce injector solenoid heating by giving the injectors time to rest between shots.
3. Reduce ECU injector driver heating for the same reason.



Fuel pump needs to be able to support the 110 to 125% of the HP demand at 10.8volts with more pressure than you will ever run.

Find a graph like this for your pump in question,
voltage-pump-curve.png

Notice higher pressure and lower voltage causes reduced flow. That is, fuel pumps flow the most fuel at the lowest pressure with the highest voltage.

What you want is a fuel pump that can outflow the needs of your engine at the lowest possible voltage with the highest possible pressure.

For example say you needed 50g/sec at 300KPA and you can see the pump in the chart can flow this easily at typical voltage.
However one day your alternator will fail, it isn't a matter of if, just when. And when this happens voltage could drop to 11 or 10volts and now you've blown your engine. After tuning hundreds of vehicles over 25 years I've seen this happen enough times that now I consider it as part of the pump decision process. I find a pump with more than enough flow to support the power at the lowest possible voltage.

The same goes for pressure. You can get more flow at 300KPA, but depending on the injectors you may want to turn up the pressure in the future, and its much easier to factor this into the pump decision in advance so you don't need to re-think the fuel system later. Also the regulator could fail or fuel pump could move unexpectedly- rare but I don't take chances.

Finally the pump itself will wear and age, and over time flow less and less. Therefore you would not want a pump that just barely meets your HP demand when brand new. Leave something on the table.

Tune the fuel system and engine at the lowest possible pressure. This will keep stress off fuel system components and increase pump lifespan. For example I run 800rwhp 5.3L Turbo engines on gasoline around 37psi base pressure. This means after 25psi of boost its 37 + 25 = 62psi total fuel pressure, which is ideal for many pumps as they will flow much more at 62psi than say 85psi which is where you would be if the base pressure was starting at like 60psi. You will have fewer fuel leaking, fewer pump heating and fewer pump stress, and longer pump lifespan using the reduced baseline pressure. It will also be easier to tune large injectors.

[Nikkobellic]

Delete the maf

I only use fuel injector clinic or injector dynamics anymore. It isn't even the data- I've tuned hundreds of setups without the data over 25 years.

The real issue is quality of the injector, as they tend to vary, and spray patterns vary, the performance as temperature changes varies, so many variables especially with cheap injectors.
You will desire the injector that can flow your HP demand near 35 to 40% duty cycle if you can afford it.
For example, don't buy '500hp injectors' to feed 500hp. Use 1000hp injectors. I prefer ID1050 injectors for 600-700rwhp gasoline applications.
By keeping duty cycle lower than 50% it will:
1. Dramatically improve low and mid-range torque with injector phase that sprays between Intake valve open and peak piston velocity
2. Reduce injector solenoid heating by giving the injectors time to rest between shots.
3. Reduce ECU injector driver heating for the same reason.

Stock lq4 makes 300hp. @20 hp per lb of boost with 8 lbs it should be at 460.[all these numbers are estimated]
460x2=920 x .50 bsfc=460 divide 6.25=73.6lb per hr

To run my injectors @ 50% duty cycle I'd need 73.6 lb injectors and to run them at 40% I'd need 92 lb. Is this even close to accurate and does it make any sense?

[gtstorey]

Most people don't try to meet kingtal0n's criteria.

[Nikkobellic]

Most people don't try to meet kingtal0n's criteria.

It seems very precise and based on a lot of experience. The philosophy of buy once cry once comes to mind. I'm also brand new at this so I'll try to learn from anybody's who's willing to help. Not sure I'm willing to spend $700-900 on a set of injectors for a budget build but I don't want cheap crap that will make it impossible to tune. I'm sure there's some quality and affordable injectors in my price range.

[gtstorey]

What kind of horsepower are you shooting for? Be real about what your goals are. There is truth in what kingtal0n's said but GM is happy to run fuel pumps at higher pressures than what he is saying to use. Most people shoot for not exceeding 80-90% duty cycle at WOT.

If you think you are going to continue to build beyond what you listed, pick out parts to support that. But it you don’t need huge injectors for what you have listed. You probably will need a need fuel pump though.

[Nikkobellic]

What kind of horsepower are you shooting for? Be real about what your goals are. There is truth in what kingtal0n's said but GM is happy to run fuel pumps at higher pressures than what he is saying to use. Most people shoot for not exceeding 80-90% duty cycle at WOT.

If you think you are going to continue to build beyond what you listed, pick out parts to support that. But it you don’t need huge injectors for what you have listed. You probably will need a need fuel pump though.

I don't have a hp goal. Was mostly doing this for a learning experience so whatever it ends up with will be fine with me, I just want it to run well. I plan on getting a cam and full exhaust for it this year but that's probably it for this truck. This pump looks like it'll work. Is there a certain brand of injectors you would recommend?

https://www.highflowfuel.com/quantum...airtex-e3501m/

[gtstorey]

DeatschWerks Or Fuel Injector Clinic are probably the safest bet for aftermarket. Again depending on where you end up for HP, you might be able to use GM injectors from a different application, especially if you aren’t going to use E85.

[gtstorey]

Correction
Injector Dynamics or Fuel Injector Clinic.

[kingtal0n]

Is this even close to accurate and does it make any sense?

You can play with this and other similar online calculators. They are estimates, always leave headroom. Use different online calcs and compare by hand if you have time.
http://injectordynamics.com/injector-selector/

Performing calcs by hand is good for learning but difficult to get real world results without experience. Drivetrain, exhaust, tuning, manifold design etc... all influence final results


The way I Would go about this is understand the capability of your engine first, in its future or final configuration.
If the LS in question has gen3 internals then turbo apps is common to 650rwhp reliably, perhaps 700rwhp on alcohol, I get nervous after that.
With Gen4 internals 650rwhp gasoline turbo is a walk in the park and up to approx 1000rwhp even 1100rwhp is possible on alcohol stock engine, this goes for 4.8/5.3/6.0 on gen4 internals.
With a supercharger the limit is about 70 to 100hp less than turbo due to lack of exhaust gas cushion and a parasitic drive feature.


In all cases the HP Limit is given by the pump- not the engine. A 2L engine and 6L engine both limited to 500hp with a 500hp pump attached. When I say PUMP I mean compressor.
First, determine the max HP (in terms of BRAKE horsepower not RWHP) decide right now if you intend or ever see yourself upgrading to a larger pump, then use that for the calculation in CFM Or Lb/min common units.

Learn to read the compressor map. And keep in mind the compressor map includes both kinetic energy and static pressure enveloped into a single term using Bernoulli equation even though it should be using the energy equation which has a term for friction losses. In other words if pressure drop and velocity increases the compressor will maintain it's speed line at some given pressure ratio even though intake manifold pressure has dropped. Pressure ratio does not mean boost pressure and compressor maps do not account for friction.

Play with matchbot on borg warner website.
Pay attention to the difference between Volume flow and MASS flow.
Compressors flow VOLUME they do not flow MASS directly. We convert the volumetric flow rate into MASS by including the density of air based on temperature.
This has implications when you look at compressor maps, as many will say CFM and some will say lb/min and there is a relationship from CFM to lb/min or other units.

If you need help with this post picture of your compressor map and we can go through it.
Most compressor maps lean to the right so the highest possible point is often unachievable in V8 applications due to the very high boost requirement to get there.

The reason all of this is so important is, lets say we calculate the flow rate of the engine at some boost like you attempted, well it doesn't matter what the engine can flow if the supercharger can't flow a bit more than that.
And the flow of the pump must not only support the engine rate but also the friction of plumbing. Every turn, pipe, intercooler inline, is friction and will reduce the flow and power potential of the supercharger.
For example lets say you have a 50lb/min compressor at the pressure ratio decided upon, we can estimate roughly a generic intercooler and plumbing will eat 2 or 3lb/min, the air filter pressure drop will eat a half or 1lb/min, and age will eat another 1 or 2lb/min over the course lifespan. This is leaving you with a 44lb/min compressor for endgame. That would be say 440bhp capable so maybe 370rwhp and approaching 400rwhp if more ideal? Funny how a 500hp supercharger can turn into 370rwhp. Everything takes a chunk, Include headroom and a plan for the flow rate before you buy parts.


Injector wise, consider gasoline and alcohol fuels, I assume you want gasoline. I assume you want 500rwhp or something like that. It will take almost 600bhp to get 500 to the tires so 60lb/min at some pressure ratio given air temp.
For superchargers we don't care about boost or focus on boost, well. I don't. The drive ratio will give you power output. Calculate blower RPM vs blower flow rate at some engine RPM and that is your power output. The engine has no choice but to make it. Boost will be whatever it lands on depending how the engine is config. IF it has tight exhaust manifolds and a stock cam for example the boost will be very high. If it has a good flowing combo the boost will be much lower.
Either way, power is roughly the same. Some compressor maps do a lot better at higher pressure ratios so engine mods can work against you in some situations. I am generalizing because I don't know your combo or supercharger drive or flow rate or anything.

Anyways. 600bhp is more like 670bhp minus the blower parasite of 60 to 80hp perhaps (it might only be 50bhp). Engine will need fuel for around 670bhp to make 600bhp which nets say 510rwhp or so through a 4l80e and some friction loss of large tires or something. That should give you something to start working on. I would go for the ID1050 from injector dynamics because plenty of headroom for the future and highest quality you can get, plus you can always re-sell them for hefty sum, its not like throwing money away. Quite alcohol compatible as well.
Fuel system wise I would prefer for gasoline a dead-head style fuel rail to minimize leaking and reduce fittings for a mere 500rwhp it is ideal.
Return style regulator in the engine bay, set to 38-42psi baseline no matter what injectors you got. No down sides to low pressure if you have the injector to make up for it, everything gets better.
Fuel pump wise you always want an in-tank pump. Do whatever necessary to make it easily to access and inspect as needed.
I like the Aeromotive Stealth 380, it will support an easy 700bhp on a 5/16" fuel line dead headed gasoline, which is right up your alley and absolutely cheap as they get for that kind of support.