Forced Induction on a DI 3.6L V6

[Baldturbofreak]

Originally Posted by SomeGeoffGuy

Really? So how does that work with direct injection. The benefit of DI is that you aren't compressing the fuel mixture which keeps off detonation. Now you are, so how does that work? You might not even be able to run stock compression if you are spraying fuel in the intake. Without the DI, you might aas well tear the whole system off and just run it with regular fuel injection.

-Geoff

Geoff, when you are WOT, the DI system operates like a PFI system.
IT injects fuel during the intake stroke to create a homogenous charge.
The benefit of DI when in this mode is the reduced droplet size from 2200psi, and the latent heat of vaporization occuring within the chamber.
Adding up to 30% fuel upstream will change nothing while in this mode of operation. Nor would 30% of proper AFR be ignitable.

Only in a few light light loading situations(and low rpm too) does the system actually wait until the comrpession stroke to inject fuel.

[MadMaxx]

Originally Posted by Baldturbofreak

Geoff, when you are WOT, the DI system operates like a PFI system.
IT injects fuel during the intake stroke to create a homogenous charge.
The benefit of DI when in this mode is the reduced droplet size from 2200psi, and the latent heat of vaporization occuring within the chamber.
Adding up to 30% fuel upstream will change nothing while in this mode of operation. Nor would 30% of proper AFR be ignitable.

Only in a few light light loading situations(and low rpm too) does the system actually wait until the comrpession stroke to inject fuel.

^

"Here’s how DI works. Fuel is injected directly into the combustion chamber instead of the intake port. It’s done at very high pressure; this overcomes high cylinder pressure and improves mixture homogeneity. The injection point is coincident with the spark plug, and you’ll see why in a moment. The important thing to remember is that there are three basic regimes that direct injection gasoline engines operate in: ultra-lean burn mode (for light cruise and idle), Stoichiometric for part throttle, and enrichment mode for full power.

In ultra-lean mode, the fuel is actually injected during the tail end of the compression stroke, not the intake stroke. This allows the fuel to remain in the vicinity of the spark plug, and be ignited in a toroidal pattern. (This is sometimes called a stratified charge, as the fuel is not distributed homogenously throughout the combustion chamber.) The air in the rest of the combustion chamber has little or no fuel, which reduces emissions, and greatly improves fuel economy. Air/fuel ratios can be as high as 65:1.

At part throttle, the air/fuel ratio is increased to 14.7:1 (stoichiometric); fuel is introduced during the normal intake cycle, and the engine behaves more like what we’re accustomed to seeing. At fuel throttle, the fuel mixture is enriched for max power, and to eliminate detonation, and is also a practice we’re used to seeing here in the hot rodding world. "


Cheers!

[ckaram]

Originally Posted by MadMaxx

^

"Here’s how DI works. Fuel is injected directly into the combustion chamber instead of the intake port. It’s done at very high pressure; this overcomes high cylinder pressure and improves mixture homogeneity. The injection point is coincident with the spark plug, and you’ll see why in a moment. The important thing to remember is that there are three basic regimes that direct injection gasoline engines operate in: ultra-lean burn mode (for light cruise and idle), Stoichiometric for part throttle, and enrichment mode for full power.

In ultra-lean mode, the fuel is actually injected during the tail end of the compression stroke, not the intake stroke. This allows the fuel to remain in the vicinity of the spark plug, and be ignited in a toroidal pattern. (This is sometimes called a stratified charge, as the fuel is not distributed homogenously throughout the combustion chamber.) The air in the rest of the combustion chamber has little or no fuel, which reduces emissions, and greatly improves fuel economy. Air/fuel ratios can be as high as 65:1.

At part throttle, the air/fuel ratio is increased to 14.7:1 (stoichiometric); fuel is introduced during the normal intake cycle, and the engine behaves more like what we’re accustomed to seeing. At fuel throttle, the fuel mixture is enriched for max power, and to eliminate detonation, and is also a practice we’re used to seeing here in the hot rodding world. "


Cheers!

Dudes, you're amazing! My head hurt reading this...All I know is I push on the gas and it goes! Ok, I know a little more but you get the point!

Thanks for the insight.

[Baldturbofreak]

I have a copy of the bosch DI manual, there are 7 distinct modes of DI. It's enough to make your head spin.

[SomeGeoffGuy]

Originally Posted by MadMaxx

It works no differently on DI than anything else...you aren't running anywhere near high enough static CR to predet (without knowing how aggressive timing is, kinda hard to really get into details) 93-120 octane fuel (pump/meth) Direct injection gives a higher fuel delivery granularity, and as a byproduct a higher static CR and lean condition can be achieved.... but all the rest of the monitoring and correction systems are there. If knock is detected, timing is pulled, just like anything else (actually, at a much faster sample rate since DI has awesome monitoring capabilities).

Don't overthink the system If you need current examples, check w/ the VW guys. The LS/LT 3.6L DI camaros already have wet nitrous kits available (50-100hp) from ZEX.

I am not disagreeing that you can get it to work. I just don't think at 11.3:1 compression you should be dumping fuel into the engine with a fogger while under boost. I also don't think a Zex nitrous system is apples to apples, since it is shoving fuel and oxygen into the system together, and the Zex setup actually keeps it electronically balanced. Normally the stock PCM balances it, but they are probably running a 1-bar MAP (anyone know for sure?). I am not saying you can't get it to work, I am saying that it will work best if you can keep it in the stock PCM, which means you need a stock fuel system that can support the power.

I can't wait until somebody gets a system going. The fact is that we are in uncharted territory on these cars. I usually go conservative in these situations.

Originally Posted by Baldturbofreak

Geoff, when you are WOT, the DI system operates like a PFI system.
IT injects fuel during the intake stroke to create a homogenous charge.
The benefit of DI when in this mode is the reduced droplet size from 2200psi, and the latent heat of vaporization occuring within the chamber.
Adding up to 30% fuel upstream will change nothing while in this mode of operation. Nor would 30% of proper AFR be ignitable.

Only in a few light light loading situations(and low rpm too) does the system actually wait until the comrpession stroke to inject fuel.

It should work by theory then, so who is going to be the first gunea pig? I still think best case is when the PCM is controlling ALL the fueling. I wouldn't buy a turbo kit that required me to spray fuel into the intake, but that is just me. It is one thing to spray meth to cool the charge, but spraying fuel because your stock system is overwhelmed is not for me. It can definitely be done, but I wouldn't put a setup like that on my daily driver.

Originally Posted by Baldturbofreak

I have a copy of the bosch DI manual, there are 7 distinct modes of DI. It's enough to make your head spin.

Which is exactly why I still say (in my previous post) that the stock fuel system is going to set the baseline for how much power a bolt on turbo kit can make. Because once you add fuel outside the stock system, the PCM is marginalized in how well it can control the rest of the engine. I am not familiar with the modes of DI, but being in boost is going to change the operation of the system dramatically. The things that trigger the modes are going to be different in a boosted car. And spraying fuel outside of the PCM that controls those modes IS going to affect it's behaviour. The question is how? And the answer is that we don't know yet (at least I don't).

Yea, you can throw some hobbs switches and start dumping fuel into the intake. But for me, the only fuel I am putting in is going through the factory system, or at least a something close to it (like bigger injectors or something).

-Geoff

[Baldturbofreak]

I have been working with the bosch DI system on a daily basis since 2007. I have a car running with a secondary rail right now. So I guess the guinie pig is me. It works superb, and gives you back the 75 ft/lbs you lose when the injection event begins carrying over on the compression stroke. It's a precise microcontroller running 4 injectors in the conventinonal PFI location based upon MAP,RPM and a few other inputs.
Since it's programmed to only ramp in fuel above 260kpa and 6000rpm, it ONLY injects during homegenous rich mode. Adding up to 30% of fuel load upstream, it overcomes the hurdle of the injection window of DI.
I think changing the injectors would create more hassle than it's worth. There are more than 600 fuel tables alone.

Besides the fuel limit doesnt result an a blown motor. The cars goes "diesel" with soot when you "overrun" the fuel system. A phenomenon I like far better then running an PFI motor out to it's limit.
The main reason Im interested in the v6 over the V8 is that it has the same DI system form the solstice Ive put sooooo much time in with. hundreds & hundreds of pulls on my dyno, and and equal number of reflashes.

[Germann]

Salute to you guys with DI know-how. To tech is all new to me. Im ready to step up my v-6. My experience has only been with V-8's with boost as well as Nitrous. But with a v-6 , not to mention the new tech of DI, Im just not sure of where to go. Turbo or Nitrous. Im not looking for max HP. I prefer my pistons and rings whole and my head gaskets in place...but cant see the harm is 5 psi or a 100hp shot of juice in this package. But again, I dont know the DI strengths/weaknesses, etc. Recommendations or one of the power adders over the other?...and please dont make it into a debate over the power adders themselves, but instead based on the engine tech/architecture.....

[mike25]

Originally Posted by Germann

Salute to you guys with DI know-how. To tech is all new to me. Im ready to step up my v-6. My experience has only been with V-8's with boost as well as Nitrous. But with a v-6 , not to mention the new tech of DI, Im just not sure of where to go. Turbo or Nitrous. Im not looking for max HP. I prefer my pistons and rings whole and my head gaskets in place...but cant see the harm is 5 psi or a 100hp shot of juice in this package. But again, I dont know the DI strengths/weaknesses, etc. Recommendations or one of the power adders over the other?...and please dont make it into a debate over the power adders themselves, but instead based on the engine tech/architecture.....

ill put it this way....for what ive seen in light of this engine(very impressive thus far) and other gm di's such as the delta and kappa platforms..i think this motor is really going to impress alot of people

[Baldturbofreak]

THe only failure I have seen with a DI motor so far has been my friend's GXP. He ran 75hp/hole on a direct port. It didnt find it very funny. (haha nitrous joke) To make matters worse HPT hadnt written access for it yet so it couldnt be tuned for the jug.

It spit the block and bent the rods into horse shoes.
The pistons were in the oil pan. But you know what? The ringlands were still intact, rods bent but didnt break. And aside form the destroyed reluctor ring the crank was still straight.
point being that massive detonation will kill any motor, but the destructive failure shows just how strong some parts are.
That was the 2.0L DI motor. From the parts list I believe GM put the same time and care into the design and the materials of the LLT as well.

I beleive the sleeves are the point we should watch on this motor. 3.6L is a big bore for this block, Im not sure how much wall is there.
In the LNF camp you can buy a long block from certain vendors for about $3500 new. The whole damn motor. Not chump change, but in the world of high performance engines it's bording on so. It left me irreverant of how hard I would push our LNF in the name of research. It never had a failure, even after sparkplug killing pings at high boost.
Hopefully the LLT is equally affordable to replace.

[SomeGeoffGuy]

Originally Posted by Baldturbofreak

I have been working with the bosch DI system on a daily basis since 2007. I have a car running with a secondary rail right now. So I guess the guinie pig is me. It works superb, and gives you back the 75 ft/lbs you lose when the injection event begins carrying over on the compression stroke. It's a precise microcontroller running 4 injectors in the conventinonal PFI location based upon MAP,RPM and a few other inputs.
Since it's programmed to only ramp in fuel above 260kpa and 6000rpm, it ONLY injects during homegenous rich mode. Adding up to 30% of fuel load upstream, it overcomes the hurdle of the injection window of DI.
I think changing the injectors would create more hassle than it's worth. There are more than 600 fuel tables alone.

Besides the fuel limit doesnt result an a blown motor. The cars goes "diesel" with soot when you "overrun" the fuel system. A phenomenon I like far better then running an PFI motor out to it's limit.
The main reason Im interested in the v6 over the V8 is that it has the same DI system form the solstice Ive put sooooo much time in with. hundreds & hundreds of pulls on my dyno, and and equal number of reflashes.

Secondary rail sounds great - that is a lot different than the hobbs switch triggered fogger that most people refer to in this situation. A piggy-back setup like that sounds perfect.

How much power you getting out of the Solstice with this setup?

-Geoff

[Baldturbofreak]

We were @ 411whp stdcorrection, pre secondary system on the gt35R car.
The secondary was installed a month ago and it has been road tested and tuned for it's shakedown. The car is in NC right now (and it drove there) with its owner, and will be back in a few weeks for some dynotime.

Our own GXP met an untimely demise at the hands of my Frakkin mother in law on father's day. (gee thanks)
It will be months before I have a straight rolling chassis again..

Im not sure about the site rules, but I can shows some dynographs that illustrate the 5800rpm phenomenon and how it chops torque, but maintains AFR in the form of a black sooty mess. Remember these cars are Wideband feedback equipped and do a fast job reacting to changes. It will just keep widening the PW until AFR is maintained, unfortunalty well into the comrpession stroke.

After we installed the new intake manifold and injection system on The Gt35R car, we took it out on the highway and did some work on the tune. (Its nice to fuel realtime with the Microsquirt) The car pulled very noticably harder back to back fuel/no fuel.
Adding anything in below 5K resulted in a loss, this was strictly about 5500-8000rpm.
The car pulled clean and strong (and sootless from what I could tell) right up to 8K.

I cant wait to see the comparisons from his last pre-secondary runs to the ones we take in August.

What IM really stoked about is adding a secondary tank and pump with some good ol' E85 to feed the second rail (right now she drinks from the low pressure schrader pre-DI pump). Should allow us to press into the high 20's, low 30's on "pump gas".

[Baldturbofreak]

Known facts about the LNF pcm for comparison:
-The MAF reads out to 912 Grams/sec. About 120lbs/min If I remember correctly. Thats 1200hp folks.
-The Pcm is also hardcoded to understand 512Kpa.
-The Pcm does backup airflow calculations by measuring the pressure drop across the TB.THis is the only way to accomplish backup in case of MAF fail due to the widely fluctuating VE's effected by VVT.
-System is Wideband feedback equipped
-Fuel injectors flow 122lbs/hr @ 2200psi (it's rumored that the LLT's are ~96lbs/hr)
-On demand pump has never lost pressure on me, even at 200hp more than stock.
-Pump control could potentially unleash 3000psi and a bit more breathing room on the stock injector.
-System is "torque demand" based. Meaning that your right foot is commanding 0-100% torque. The pcm then calculates the optimum throttle angle, cam angle, and in the LNF's case boost pressure to achieve the torque being requested.
- Is very protective of the engine and will go into halfpower mode when it doesnt like what it sees.
-Individual cyl knock detection.

[SomeGeoffGuy]

Awesome news on the MAF range. That is the first wall we always hit on the f-bodies. Then we had to just tweak the power enrichment to keep it in fuel. What is that about a 5 bar MAP too? Man, this thing has SO much potential.

I am glad there are people like you figuring this stuff out, so when cheap skates like me can afford one of these, they will will be making 500 to the ground with a turbo and a tune.

-Geoff

[Baldturbofreak]

For sure brother. She's (the camaro) a bit of a fatgirl compared to the 3000lb solstice.
We're gonna need 500 to the tires to gimme that same special feelin'.