Port VS Direct Injection
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- Опубліковано 2 лют 2023
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The OEM Engineers, as you put it, rely heavily on the PHD’S operating the Dino cells at Southwest Research in San Antonio. I am retired from GM Service Engineering, and from training at the GM Training Center outside Boston, and am a published author on things automotive. You guys are terrific, but through you we are seeing an education building that the experts at SWR already have. You should buy a plane ticket and go take a tour. Then speak with someone like Paul Ray, Roger Penske’s engineering leader for the Indy cars. They still run conventional springs and valves at 16k rpm. And so on.
While I'm sure there are smart people in San Antonio, the "holy grail" is the GM Technical Center in Warren Michigan, literally a square mile of buildings pretty much devoted to R&D and Testing. GM Powertrain has probably over 100 dyno's of all different types for pure R&D and durability studies. And speaking of PhD's, there is a good-sized library on the campus. With your advanced work with GM engines, surprised someone from Powertrain has not reached out to you.
It makes sense as you talked it through. My first thought would have been latent heat of vaporization as the biggest difference. But if you put air AND fuel into the same port size, the fuel takes up space and reduces the amount of air you can fit through the opening.
Good stuff.
I never really considered the fact that the fuel in PI takes up volume that could otherwise be air. Great info. Just helps solidify my love for the Gen V
I've listened to about every btr interview/tech talk I can find. I could look at numbers for days
Great Video, I always believed that direct injection would make more horsepower than port injection due to you could define the fuel delivery timing separate from the air delivery time entry, however what you brought up with the BMEP numbers make totally sense. Being a gearhead, it would be very interesting now to see if you did direct injection of nitrous which would be very interesting.
The only down fall is DI can only go so far and don't have alot of options for bigger fuel setup for big power. So DI is good for better power up to a certain power level prob. Then I'd like to see if you add FI to the mix.
This all makes sense now. GM has a million man hours in this camber design. What a great way to prove the technology.
BTR does more research than any other aftermarket performance shop
I attended a GDI / GTDI class in 2010 and this was one of the covered topics, no fuel in the intake air stream resulted in more cylinder airmass, this also translates to turbocharged DI systems, with statified fuel charging when needed, because the delivery timing is so precise, you can run higher compression, and lower octane and still make power.
You guys have some of the most interesting info out there. Your spintron video was also fantastic, and by far the best even though others oddly came out right after yours.
That is WILD! I wish I could get DI in my C6Z now. A max effort LS7 with DI would really hurt some boosted cars feelings!
So much wisdom. Thanks for another great video!
Great info I’m very surprised. Thanks for sharing.
It’s an improvement but I think we are ready to see pre-chamber ignition in the Gen-VI platform from GM soon.
Been waiting for this day... What a time to be a hot rod guy!!
Fantastic work, Guys 🔥
You guys need to make a video on your port injection kit for DI cars. The Gen V kit I believe
Great information!
There's a trade off between power, emissions, and longevity. DI (at 150 bar) atomizes and mixes the fuel air worse than PI, which is why it produces soot. It shoots jets of fuel at pistons and cylinder walls, which is why they turn black. I've seen modified gen 4 engines that stay perfectly clean after thousands of miles (pistons/chambers should be tan, like a good spark plug). I don't know why the EPA is sleeping on it, but USDM DI cars should have had particulate filters in 2017 like they do in Europe. Gen 6 will have 350 bar DI, and that's where DI starts to work well.
Really appreciate you guys taking the time to share this data and information. And I agree with you a significant amount. But one thing that has not been noted that neither one of the guys have brought to the table but Brian you and I have talked about this back-and-forth through some of our conversations. That Di engines necessitate different cam timing over port injection. The volume of fuel that displaces air flow in the intake port need slightly earlier intake valve opening events because of the fuel mass weighing more than airmass. If set cam events accordingly for the port injection with the DI stuff I promise you they'll probably we within 5 to 10 horsepower of each other if not more with the port injection. Compression, intake shape, design cylinder head valve angle if they're in line or if they're slightly canted like the DI head is. They rolled over and canted direct injection cylinder head is more advantageous for the same bore size and it's more in line with the cylinder bore than a 15 degree LS3 cylinder head you also have a far significant longer shortrunner as well as a raised roof for a more direct path to the back of the intake valve. Especially in comparison to the ls style cylinder head. Texture of the intake port also comes into play as well. You guys have stated that there is many similarities from between NASCAR and Pro Stock engines at 2 horsepower per cubic inch with a DI platform. With the proper cam timing events they'll be neck-and-neck.
This is a comparison, back to back, of direct injection versus port injection. However if you want to compare a LS3 port injection engine, there's really no comparison. The first dyno sheet with the 630 HP power curve is our LS3 with TFS 255 heads using better 12 degree valve angles than stock 15 degree, max milling for compression, same intake, etc and there's still 45 HP difference between the port injected LS3 and port injected LT1. That power difference is like you said, the canted valve cylinder heads and the higher compression that comes with LT1 engines.
Very informative, happy I subscribed.👍
Was the methanol run through the DI system?
-- I have developed the idea that a portion of the fuel is converting to gas phase on PFI which means it's less dense, which means there's less air to react.
-- That said, on an endurance application, I prefer to keep PFI because it keeps the intake ports clean.
-- The 70hp difference computes to 10%. I wonder how much of that is evaporation from the hot intake valve, and how much of that is ledenfrost off the piston and cylinder. The way wet flow goes through the LT1 might have a defined effect in all of this, and careful consideration of tradeoffs seems appropriate.
What you guys proved about the LT1 is what I've always believed. The Gen V LT1 engines are easier to tune too!
However, what I would like to know is flow numbers on the TRINITY intake. I've called your shop twice, and emailed twice to no avail.
If you don't have flow numbers or port CC numbers, then I can't responsibly purchase something. I can give you CC numbers on the MSD intake.
Given there are no public back-to-back compairsons with the TRINITY and other Gen V intakes, I cannot rely on claims of "It makes lots of power!"
So good to see you guys bringing this info to the masses. I knew there was an airflow benefit with DI and to see the actual numbers is great. Did you use the stock GM HPFP for these tests? What HP capacity would it support on pump gasoline?
Yes we used a LT1 HPFP early on with ethanol but later switched both HPFP and Injectors to LT4. THE 785HP pulls on M1 was completely tapped out on fuel system. Those pulls were also a bit lean due to that @0.91 lambda.
The OEM engineers know what they are doing. They have data and computer modeling at their disposal no one else in the world has. When GM spends a billion dollars in R&D and machining to move to direct injection, there is reasoning behind it. I believe GM is planning to spend another billion or so on yet another generation of this engine.
Yeah, their #1 goal is emissions, their #2 goal is fuel efficiency their #3 goal is nox, their #3 goal is profitability, their #4 goal is cow farts(probably)... their #8 goal is horsepower.
I hope so. Stick with GM!
Some of the reasoning behind DI is the government’s CAFE requirements. If they wanted to continue introducing new engines into market, the brands average gas consumption had to reach a minimum rating. The best V8 a with big power numbers ( higher profit margins) get offset by the tiny 3, 4 and 6 cylinder engine efficiency.
There’s a lot of government politics involved most common people never even heard of.
this was something i never understood how di motors make so much power with minor gain in compression so its interesting to see that bsfc numbers are very similar
It's interesting how much air the fuel displaced. Plus, would guys consider that with DI you are actually effectively changing the compression ratio too, depending on how many cc's of fuel you inject?
Not only does direct injection improve air flow but it also allows you to run higher compression
BTR is welcome to use my car as a test mule for the new 225 cam.
That is so cool. Amazing tech. Stuff any gearhead wonders
Kinda cool. At 2:30 they were talking about an airflow change of about 7%. Stoichiometric efficiency is 14.7:1. Well, 1÷14.7= .068...about 7%! The fuel volume is reflected in their flow numbers!😮
Stoichiometric by MASS is 14.7:1, or ~7% gasoline. However, gasoline is 579x denser than air, so stoich by VOLUME is ~7%÷579=0.012%.
@@jaredlancaster4137 wish I paid more attention in skool :/
Would it be possible to setup the engine similar to how toyota has done their engines where the port injectors are very small and only used for idle and low engine speed and throttle. The DI is used for everything else and the port injection is switched off or just run very minimally. This keeps the intake valves clear of carbon.
What about real-world conditions not on a dyno in a room? In the heat of the day under a hood breathing extremely hot air wouldn't the latent heat evaporation make up for it or not really because it less chance of DI predetonating?
Will intake valve deposits over time negate this difference in power? (Street car)
Torque tuning is what not to love about GEN five engines!!! Brian I love all your stuff and I want so badly to love my 6.2 Cadillac L86. But I’ve never had so many issues with a vehicle in my life. So many convoluted and misleading definitions of parameters inside a stock ECU. All I put is a mild stage two cam in this thing, and it has never ran right ever since and I cannot figure out why I neither can multiple tuners. I wish there was somebody somewhere that would define each parameter inside the stock ECU, and exactly what it does and how it works with the GM algorithms to run this motor. Clearly you guys have figured it out.😢😢
On the same motor/combo/fuel-type/setup... how much more timing and/or compression ratio can you add to a Direct Injected motor over that of a Port Injected motor ?
Port injection cleans the intakevalve because Pcv gunks everything up.boost is we’re I believe port+di are better together
I'd still love this engine with a carb...the price for the Holley terminator x for that engine is insane compared to ls
That's really interesting thank you
Is carbon buildup no longer an issue with the latest DI so PI no longer required to wash intake valves?
LS3 engine in the C6 Corvette has
Sequential Port Injection only but way less horsepower.
Even the "Einstein of cam design" can learn something new! 😉 Very interesting test results and a new way of thinking about DI vs PI. Your analysis of why it is happening is brilliant... more air/flow vs diluted airflow due to the fuel being atomized within the incoming air prior to valve closure/combustion. Like you said, it's like a free bit of supercharging. I have one question: how will this newly gained revelation affect your DI cam designs if any?
We were surprised by how early the Intake Valve Close event needed to be compared to a Gen III-IV engine.
But when you think about the air column now having less mass compared to a port-injected engine, it makes sense. Our competitors basically used Gen III-IV cam timing events which is why they don't utilize VVT. Since we did test very early Intake Valve Close events, we found the benefit of VVT, and consequently our cams make a lot more low end torque, especially our L83 cams.
I have wondered why most dont use VVT when tuning or upgrading, seems like there is power and efficiency left on the table. @@briantooleyracing3554
It would more interesting to see a comparison to DI against fuel injection at Entry to runner as port fuel injection is already known to be sub optimal for power
There's a reason most if not all OE companies has moved to DI. This shouldn't be a surprise to anyone.
The biggest downfall of DI that I know of is the cost of the parts, its on par with diesel injectors and pumps. So that extra efficiency and power come at a cost. And then there is the intake valve deposits which will hinder possibly any benefit and beyond.
I have a question on the ZR1 LT5. Why would GM also have port injection on that engine. I think I'm missing something here that may be obvious..
Thank you.
Right on
That comparison was N/A right ?; but is the difference between Di & port as significant in forced induction applications ?
DI is great, that isn’t the question, the problem is the cost. Stock LT4 can only go so far and then your looking at 6-7K for an upgraded HPFP and Injectors.
I will say this, BTR has broke the mole on hp wisdom, I see a 2650 in the future for my ZL1 gen 6 LT4, now if you make a cam for my 6 speed ZL1 that keeps the bottom toque and keeps the toque and power flow all the way through the rpm. Sir you have a new customer coming, I have a cam for my turbo LQ4 chevelle, haven't put it in yet, but we will spread the word, I just posted about this on camaro6 ZL1 section. I might be off on the numbers a smudge, but I will correct. Thank you !
Very interesting
Sounds great now turbo it and see a different story specially with methanol im suspecting. Na there isn't anywhere near the temperature in the intake system to really warrant the need but turbo with alot of boost or non intercooler like most methanol cars out there its a different story.
How do you keep the valves and ports clean with direct injection ?
You don’t.
Problem is that it costs a bazillion dollars to tune a gen 5 vs converting a gen 5 to ported. I want to L8T swap my 72 Blazer. Cheaper to convert to ported and just use holley or a gen 4 ecm.
And where do you find DI injectors big enough to support these HP levels. Must come off of the Boosted DI engines?
We used LT4 pump and injectors.
With pork injection the cooling the air before it is compressed
Fuel is taking place of oxygen
With direct injection
You are cooling the intake charge after its compressed
And boosting the compression by adding more volume into the cylinder by adding the fuel
increase horsepower
Depends, this is partly where the magic happens in injector phasing. It's best to start injection after TDC on intake stroke but finish injection by BDC. This gives an "ideal" injection window of around 180-200 crank degrees. But this also means injection is done under no pressure from the cylinder but possibly vacuum pending where in the cycle it is on that intake stroke. This also gives that evaporation time to happen and cool off the charge prior to compression and ignition. This is why tuning these is very specific and not just for the normal average tuner!
shor tuning are you injecting during intake stroke on these tests
what HPFP and DI injectors did you run on the M1 test?
LT4 pump and injectors. The pump couldn't keep up however and ran slightly leaner than we wanted but still made the power. Fueling up top was around 0.91 lambda.
Soooooo, when will you be going back and trying stacks, and shower head injectors, up high ,,, ?
There are only 2 things I don't like about DI gasoline engines. High pressure fuel pump issues and carbon buildup. Looking forward to getting my hands on a gen5 engine when they are old enough to start showing up at the scrap yard.
Which issues have you seen with the HPFP?
Sounds like you just need a blower to get the air back in there
So basically a Gen 4 6.2 vs a Gen 5 6.2 will have about the same HP if both have intake port injection
See the horsepower difference after 10,000 miles on direct injection with carbon build up on the back of the intake valve. I will still take port over direct injection any day
It's almost as if some conventional port velocity rules are misapplied considering DI...
Looking forward to cams and tunes targeted at the 6.6 L8T.
Since the L8T currently uses the tiny and quiet awful L83 cam timing events, any of our cams from our L83 Stage 2 cam with 210 intake duration all of the way up to our monster 230 cam will all work. You might have to use 1 degree more of VVT retard.
@@briantooleyracing3554 any suggestions on those of us with 2020 up software? All I’m hearing is that it hasn’t been cracked yet. I’ve got a 2022. I also bought a “spare” L8T. Probably to put in my 84 Blazer, or 77 Trans Am (6.6 TA!). Do those cams you suggested require spring/pushrod adjustment?
Ok so why is my cammed btr 225 lt1 6.2 making the same hp as a btr stage 2 cam ls3 ?
Well, it's certainly not the LT1 engine or the proven cam, so I'll let you deduce the issue from there.
@Brian Tooley Racing to be honest, i thought a btr 225 cam would produce more with how aggressive it drives and surges on stock stall. 488whp on 93 through a 6l80. I feel a customer grind mild lunati would do just as good.
@@MrDulvalius69 I think you should entertain the thought of your problem isn't the cam. Our cams are ground in bulk, they're all the same, and yet you're making poor power, so it's not the cam.
@Brian Tooley Racing honestly i dont think there is a problem. If i was running e85, I would have been around 505 ish hp. Most stage 2 cam lt1's are making 500-515 with my mods. I chaulk it up to dynos and being a A6 (not a manual 7). Im just surprise the cam put down "ok" power for how aggressive it is.
Its great that DI makes more power....but the trade off is carbon fouling on intakes and valves across multiple automotive brands plus the added complexity of low pressure pump and added high pressure pump and i swear the new vette sounds like my cummins diesel with that ticking pump noise. Its the same problem with fly by wire throttle new tech doesnt necessarily mean better if fly by wire throttle is so great why do things like pedal commanders exist? When direct injection becomes another generation of refinement then change over. Reinventing the wheel?
I love horsepower... 💪😂
@@briantooleyracing3554 i do too, and you guys are amazing not criticizing you at all...some of this new tech just needs the kinks worked out
Very interesting video, and I appreciate your sharing this. But as I was watching, I immediately thought the numbers didn't check out.
You reported a 7.3% loss of airflow due to fuel displacing air in the port in the port injected engine. But fuel does not take up 7.3% of the air going into the engine; by my math, the fuel volume going into the engine is just 0.0144% of the air volume assuming a 12:1 AFR. Am I missing something, or did I do my math wrong? If my math is right, then fuel in the port displaces a negligible volume of air, and your conclusion is totally wrong, the airflow and power gains coming from a totally different mechanism.
I don't think you're wrong, it's much more likely that I am wrong. But the math just doesn't check out. I want to understand this better. Help!
My math says that it is only possible for the gasoline to displace 7.3% of air if you were running an AFR of 0.023:1, or 42x more fuel than air(by mass).
I'll still take a carb over efi.
Power is power at the end of the day, doesnt matter how you get there
Has anyone found carbon buildup on an EFI or a carburetor setup? Doesn't seem as though it occurs?
Does running port injection reduce airflow and therefore power because of the space it takes up?
Edit: it's the fuel itself?
Ok so why is my cammed btr 225 lt1 6.2 making the same hp as a btr stage 2 cam ls3 ?
Maybe the LT1 is not tuned properly or as aggressively as the LS3.
@@j88l98irocz 488 wheel hp on 93, @ 25 degrees of qot timing and 12.7 on the wideband
Not all engines are created equal and those numbers sound crazy low considering I have 500whp numbers on multiple bolt-on e85 LT1's. My personal car with the 230 cam and cnc stock heads with MSD and ethanol made 638whp.
@ShorTuning EFI Calibration Specialist most lt1s with my mods make around 500-515 with e85. You can find videos from all sort of reputable companys showing off their stage 2 cam creating 500-515 wheel. To say you made that without a cam, well id be skeptical. I wouldnt say "crazy" low. But a little lower then normal. Not sure what to say....its quality parts, btr ect. So...i chaulk it up to the dyno. 638 na? Sounds max effort, and sounds like the engine has been torn apart woth all kinds of mods. Maybe upped the compression, miled heads ect. Mine is literally cam installed with off the shelf heads (prc from texas speed) and bolt ons.
It isn't what I'd call max effort. Heads have to come off anyway due to lifter replacement during the cam swap so milled them 0.030” and they have GPI CNC porting program run on them. BTR230 cam, MSD intake, 103mm TB, flex fuel sensor, rotofab CAI, LT's and a lot of tuning. I can't re-iterate enough that your average LS tuner isn't going to pull out power that someone well versed in GenV tuning will.